Optimized "(X - N * M) / N + M" to "X / N" if valid
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Commit Message
Hi,
This patch tries to optimize "(X - N * M) / N + M" to "X / N".
As per the discussions in PR108757, we know this transformation is valid
only under some conditions.
For C code, "/" towards zero (trunc_div), and "X - N * M"
maybe wrap/overflow/underflow. So, it is valid that "X - N * M" does
not cross zero and does not wrap/overflow/underflow.
This patch also handles the case when "N" is the power of 2, where
"(X - N * M) / N" is "(X - N * M) >> log2(N)".
Bootstrap & regtest pass on ppc64{,le} and x86_64.
Is this ok for trunk?
BR,
Jeff (Jiufu)
PR tree-optimization/108757
gcc/ChangeLog:
* gimple-match-head.cc (optimize_x_minus_NM_div_N_plus_M): New function.
* match.pd ((X - N * M) / N + M): New pattern.
gcc/testsuite/ChangeLog:
* gcc.dg/pr108757-1.c: New test.
* gcc.dg/pr108757-2.c: New test.
* gcc.dg/pr108757.h: New test.
---
gcc/gimple-match-head.cc | 54 ++++++++++
gcc/match.pd | 22 ++++
gcc/testsuite/gcc.dg/pr108757-1.c | 17 ++++
gcc/testsuite/gcc.dg/pr108757-2.c | 18 ++++
gcc/testsuite/gcc.dg/pr108757.h | 160 ++++++++++++++++++++++++++++++
5 files changed, 271 insertions(+)
create mode 100644 gcc/testsuite/gcc.dg/pr108757-1.c
create mode 100644 gcc/testsuite/gcc.dg/pr108757-2.c
create mode 100644 gcc/testsuite/gcc.dg/pr108757.h
Comments
On Wed, 17 May 2023, Jiufu Guo wrote:
> Hi,
>
> This patch tries to optimize "(X - N * M) / N + M" to "X / N".
But if that's valid why not make the transform simpler and transform
(X - N * M) / N to X / N - M instead?
You use the same optimize_x_minus_NM_div_N_plus_M validator for
the division and shift variants but the overflow rules are different,
so I'm not sure that's warranted. I'd also prefer to not split out
the validator to a different file - iff then the appropriate file
is fold-const.cc, not gimple-match-head.cc (I see we're a bit
inconsistent here, for pure gimple matches gimple-fold.cc would
be another place).
Since you use range information why is the transform restricted
to constant M?
Richard.
> As per the discussions in PR108757, we know this transformation is valid
> only under some conditions.
> For C code, "/" towards zero (trunc_div), and "X - N * M"
> maybe wrap/overflow/underflow. So, it is valid that "X - N * M" does
> not cross zero and does not wrap/overflow/underflow.
>
> This patch also handles the case when "N" is the power of 2, where
> "(X - N * M) / N" is "(X - N * M) >> log2(N)".
>
> Bootstrap & regtest pass on ppc64{,le} and x86_64.
> Is this ok for trunk?
>
> BR,
> Jeff (Jiufu)
>
> PR tree-optimization/108757
>
> gcc/ChangeLog:
>
> * gimple-match-head.cc (optimize_x_minus_NM_div_N_plus_M): New function.
> * match.pd ((X - N * M) / N + M): New pattern.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.dg/pr108757-1.c: New test.
> * gcc.dg/pr108757-2.c: New test.
> * gcc.dg/pr108757.h: New test.
>
> ---
> gcc/gimple-match-head.cc | 54 ++++++++++
> gcc/match.pd | 22 ++++
> gcc/testsuite/gcc.dg/pr108757-1.c | 17 ++++
> gcc/testsuite/gcc.dg/pr108757-2.c | 18 ++++
> gcc/testsuite/gcc.dg/pr108757.h | 160 ++++++++++++++++++++++++++++++
> 5 files changed, 271 insertions(+)
> create mode 100644 gcc/testsuite/gcc.dg/pr108757-1.c
> create mode 100644 gcc/testsuite/gcc.dg/pr108757-2.c
> create mode 100644 gcc/testsuite/gcc.dg/pr108757.h
>
> diff --git a/gcc/gimple-match-head.cc b/gcc/gimple-match-head.cc
> index b08cd891a13..680a4cb2fc6 100644
> --- a/gcc/gimple-match-head.cc
> +++ b/gcc/gimple-match-head.cc
> @@ -224,3 +224,57 @@ optimize_successive_divisions_p (tree divisor, tree inner_div)
> }
> return true;
> }
> +
> +/* Return true if "(X - N * M) / N + M" can be optimized into "X / N".
> + Otherwise return false.
> +
> + For unsigned,
> + If sign bit of M is 0 (clz is 0), valid range is [N*M, MAX].
> + If sign bit of M is 1, valid range is [0, MAX - N*(-M)].
> +
> + For signed,
> + If N*M > 0, valid range: [MIN+N*M, 0] + [N*M, MAX]
> + If N*M < 0, valid range: [MIN, -(-N*M)] + [0, MAX - (-N*M)]. */
> +
> +static bool
> +optimize_x_minus_NM_div_N_plus_M (tree x, wide_int n, wide_int m, tree type)
> +{
> + wide_int max = wi::max_value (type);
> + signop sgn = TYPE_SIGN (type);
> + wide_int nm;
> + wi::overflow_type ovf;
> + if (TYPE_UNSIGNED (type) && wi::clz (m) == 0)
> + nm = wi::mul (n, -m, sgn, &ovf);
> + else
> + nm = wi::mul (n, m, sgn, &ovf);
> +
> + if (ovf != wi::OVF_NONE)
> + return false;
> +
> + value_range vr0;
> + if (!get_range_query (cfun)->range_of_expr (vr0, x) || vr0.varying_p ()
> + || vr0.undefined_p ())
> + return false;
> +
> + wide_int wmin0 = vr0.lower_bound ();
> + wide_int wmax0 = vr0.upper_bound ();
> + wide_int min = wi::min_value (type);
> +
> + /* unsigned */
> + if ((TYPE_UNSIGNED (type)))
> + /* M > 0 (clz != 0): [N*M, MAX], M < 0 : [0, MAX-N*(-M)] */
> + return wi::clz (m) != 0 ? wi::ge_p (wmin0, nm, sgn)
> + : wi::le_p (wmax0, max - nm, sgn);
> +
> + /* signed, N*M > 0 */
> + else if (wi::gt_p (nm, 0, sgn))
> + /* [N*M, MAX] or [MIN+N*M, 0] */
> + return wi::ge_p (wmin0, nm, sgn)
> + || (wi::ge_p (wmin0, min + nm, sgn) && wi::le_p (wmax0, 0, sgn));
> +
> + /* signed, N*M < 0 */
> + /* [MIN, N*M] or [0, MAX + N*M]*/
> + else
> + return wi::le_p (wmax0, nm, sgn)
> + || (wi::ge_p (wmin0, 0, sgn) && wi::le_p (wmax0, max - (-nm), sgn));
> +}
> diff --git a/gcc/match.pd b/gcc/match.pd
> index ceae1c34abc..1aaa5530577 100644
> --- a/gcc/match.pd
> +++ b/gcc/match.pd
> @@ -881,6 +881,28 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
> #endif
> ))))
>
> +#if GIMPLE
> +/* Simplify ((t + -N*M) / N + M) -> t / N. */
> +(for div (trunc_div exact_div)
> + (simplify
> + (plus (div (plus @0 INTEGER_CST@1) INTEGER_CST@2) INTEGER_CST@3)
> + (with {wide_int n = wi::to_wide (@2); wide_int m = wi::to_wide (@3);}
> + (if (INTEGRAL_TYPE_P (type)
> + && n * m == -wi::to_wide (@1)
> + && optimize_x_minus_NM_div_N_plus_M (@0, n, m, type))
> + (div @0 @2)))))
> +
> +/* Simplify ((t + -(M<<N)) >> N + M) -> t >> N. */
> +(simplify
> + (plus (rshift (plus @0 INTEGER_CST@1) INTEGER_CST@2) INTEGER_CST@3)
> + (with {wide_int n = wi::to_wide (@2); wide_int m = wi::to_wide (@3);}
> + (if (INTEGRAL_TYPE_P (type)
> + && (m << n) == -wi::to_wide (@1)
> + && optimize_x_minus_NM_div_N_plus_M (@0,
> + wi::one (TYPE_PRECISION (type)) << n, m, type))
> + (rshift @0 @2))))
> +#endif
> +
> (for op (negate abs)
> /* Simplify cos(-x) and cos(|x|) -> cos(x). Similarly for cosh. */
> (for coss (COS COSH)
> diff --git a/gcc/testsuite/gcc.dg/pr108757-1.c b/gcc/testsuite/gcc.dg/pr108757-1.c
> new file mode 100644
> index 00000000000..349318a7c82
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/pr108757-1.c
> @@ -0,0 +1,17 @@
> +/* PR tree-optimization/108757 */
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fdump-tree-optimized" } */
> +
> +#include <limits.h>
> +#define N 4
> +#define M 3
> +#define GAP 0
> +typedef unsigned int UINT;
> +typedef int INT;
> +#define UMAX UINT_MAX
> +#define IMAX INT_MAX
> +#define IMIN INT_MIN
> +#include "pr108757.h"
> +
> +/* { dg-final { scan-tree-dump-not " = x_\[0-9\]\\(D\\) \\+ " "optimized" } } */
> +/* { dg-final { scan-tree-dump-not " = b_\[0-9\] \\+ " "optimized" } } */
> diff --git a/gcc/testsuite/gcc.dg/pr108757-2.c b/gcc/testsuite/gcc.dg/pr108757-2.c
> new file mode 100644
> index 00000000000..7302e9c606c
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/pr108757-2.c
> @@ -0,0 +1,18 @@
> +/* PR tree-optimization/108757 */
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fdump-tree-optimized" } */
> +
> +#include <limits.h>
> +#define N 4
> +#define M 3
> +#define GAP 2
> +typedef unsigned int UINT;
> +typedef int INT;
> +#define UMAX UINT_MAX
> +#define IMAX INT_MAX
> +#define IMIN INT_MIN
> +#include "pr108757.h"
> +
> +/* { dg-final { scan-tree-dump-times " = x_\[0-9\]\\(D\\) \\+ " 16 "optimized" } } */
> +/* { dg-final { scan-tree-dump-times " = b_\[0-9\] \\+ " 16 "optimized" } } */
> +
> diff --git a/gcc/testsuite/gcc.dg/pr108757.h b/gcc/testsuite/gcc.dg/pr108757.h
> new file mode 100644
> index 00000000000..9e12d106aad
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/pr108757.h
> @@ -0,0 +1,160 @@
> +#define NOINLINE __attribute__ ((noinline))
> +UINT NOINLINE
> +opt_u1 (UINT x)
> +{
> + if (x < (M * N) - GAP)
> + return 0;
> + UINT a = x - (M * N);
> + UINT b = a / N;
> + return b + M;
> +}
> +
> +UINT NOINLINE
> +opt_u2 (UINT x)
> +{
> + if (x > (UMAX - (M * N) + GAP))
> + return 0;
> + UINT a = x + (M * N);
> + UINT b = a / N;
> + return b - M;
> +}
> +
> +INT NOINLINE
> +opt_s1 (INT x)
> +{
> + if (x < (M * N) - GAP)
> + return 0;
> + INT a = x - (M * N);
> + INT b = a / N;
> + return b + M;
> +}
> +
> +INT NOINLINE
> +opt_s2 (INT x)
> +{
> + if (x < IMIN + (M * N) - GAP || x > 0)
> + return 0;
> + INT a = x - (M * N);
> + INT b = a / N;
> + return b + M;
> +}
> +
> +INT NOINLINE
> +opt_s3 (INT x)
> +{
> + if (x < (M * N) - GAP)
> + return 0;
> + INT a = x - (M * N);
> + INT b = a / -N;
> + return b + -M;
> +}
> +
> +INT NOINLINE
> +opt_s4 (INT x)
> +{
> + if (x < IMIN + (M * N) - GAP || x > 0)
> + return 0;
> + INT a = x - (M * N);
> + INT b = a / -N;
> + return b + -M;
> +}
> +
> +INT NOINLINE
> +opt_s5 (INT x)
> +{
> + if (x > (-M * N) + GAP)
> + return 0;
> + INT a = x - (-M * N);
> + INT b = a / N;
> + return b + -M;
> +}
> +
> +INT NOINLINE
> +opt_s6 (INT x)
> +{
> + if (x > IMAX - (M * N) + GAP || x < 0)
> + return 0;
> + INT a = x - (-M * N);
> + INT b = a / N;
> + return b + -M;
> +}
> +
> +INT NOINLINE
> +opt_s7 (INT x)
> +{
> + if (x > (M * -N) + GAP)
> + return 0;
> + INT a = x - (M * -N);
> + INT b = a / -N;
> + return b + M;
> +}
> +
> +INT NOINLINE
> +opt_s8 (INT x)
> +{
> + if (x > IMAX - (M * N) + GAP || x < 0)
> + return 0;
> + INT a = x - (M * -N);
> + INT b = a / -N;
> + return b + M;
> +}
> +
> +UINT NOINLINE
> +opt_u3 (UINT x)
> +{
> + if (x < (M << N) - GAP)
> + return 0;
> + UINT a = x - (M << N);
> + UINT b = a >> N;
> + return b + M;
> +}
> +
> +UINT NOINLINE
> +opt_u4 (UINT x)
> +{
> + if (x > (UMAX - (M << N)) + GAP)
> + return 0;
> + UINT a = x + (M << N);
> + UINT b = a >> N;
> + return b - M;
> +}
> +
> +INT NOINLINE
> +opt_s9 (INT x)
> +{
> + if (x < (M << N) - GAP)
> + return 0;
> + INT a = x - (M << N);
> + INT b = a >> N;
> + return b + M;
> +}
> +
> +INT NOINLINE
> +opt_s10 (INT x)
> +{
> + if (x < IMIN + (M << N) - GAP || x > 0)
> + return 0;
> + INT a = x - (M << N);
> + INT b = a >> N;
> + return b + M;
> +}
> +
> +INT NOINLINE
> +opt_s11 (INT x)
> +{
> + if (x > (-M << N) + GAP)
> + return 0;
> + INT a = x - (-M << N);
> + INT b = a >> N;
> + return b + -M;
> +}
> +
> +INT NOINLINE
> +opt_s12 (INT x)
> +{
> + if (x > IMAX - (M << N) + GAP || x < 0)
> + return 0;
> + INT a = x - (-M << N);
> + INT b = a >> N;
> + return b + -M;
> +}
>
Hi,
Richard Biener <rguenther@suse.de> writes:
> On Wed, 17 May 2023, Jiufu Guo wrote:
>
>> Hi,
>>
>> This patch tries to optimize "(X - N * M) / N + M" to "X / N".
>
> But if that's valid why not make the transform simpler and transform
> (X - N * M) / N to X / N - M instead?
Great catch!
If "N * M" is not constant, "X / N - M" would be better than
"(X - N * M) / N". If "N, M" are constants, "(X - N * M) / N" and
"X / N - M" may be similar; while for this case, "X / N - M" should
also be fine! I would try to update accordingly.
>
> You use the same optimize_x_minus_NM_div_N_plus_M validator for
> the division and shift variants but the overflow rules are different,
> so I'm not sure that's warranted. I'd also prefer to not split out
> the validator to a different file - iff then the appropriate file
> is fold-const.cc, not gimple-match-head.cc (I see we're a bit
> inconsistent here, for pure gimple matches gimple-fold.cc would
> be another place).
Thanks for pointing out this!
For shift, I guess you may concern that: 1. if the right operand is
negative or is greater than or equal to the type width. 2. if it is
a signed negative value. They may UB or 'sign bit shift'? This patch
assumes it is ok to do the transform. I may have more check to see
if this is really ok, and hope some one can point out if this is
invalid. "(X - N * M) >> log2(N)" ==> " X >> log2(N) - M".
I split out the validator just because: it is shared for division and
shift :). And it seems gimple-match-head.cc and generic-match-head.cc,
may be introduced for match.pd. So, I put it into gimple-match-head.cc.
>
> Since you use range information why is the transform restricted
> to constant M?
If M is a variable, the range for "X" is varying_p. I did not find
the method to get the bounds for "X" (or for "X - N * M") to check no
wraps. Any suggestions?
Again, thanks for your great help!
BR,
Jeff (Jiufu Guo)
>
> Richard.
>
>> As per the discussions in PR108757, we know this transformation is valid
>> only under some conditions.
>> For C code, "/" towards zero (trunc_div), and "X - N * M"
>> maybe wrap/overflow/underflow. So, it is valid that "X - N * M" does
>> not cross zero and does not wrap/overflow/underflow.
>>
>> This patch also handles the case when "N" is the power of 2, where
>> "(X - N * M) / N" is "(X - N * M) >> log2(N)".
>>
>> Bootstrap & regtest pass on ppc64{,le} and x86_64.
>> Is this ok for trunk?
>>
>> BR,
>> Jeff (Jiufu)
>>
>> PR tree-optimization/108757
>>
>> gcc/ChangeLog:
>>
>> * gimple-match-head.cc (optimize_x_minus_NM_div_N_plus_M): New function.
>> * match.pd ((X - N * M) / N + M): New pattern.
>>
>> gcc/testsuite/ChangeLog:
>>
>> * gcc.dg/pr108757-1.c: New test.
>> * gcc.dg/pr108757-2.c: New test.
>> * gcc.dg/pr108757.h: New test.
>>
>> ---
>> gcc/gimple-match-head.cc | 54 ++++++++++
>> gcc/match.pd | 22 ++++
>> gcc/testsuite/gcc.dg/pr108757-1.c | 17 ++++
>> gcc/testsuite/gcc.dg/pr108757-2.c | 18 ++++
>> gcc/testsuite/gcc.dg/pr108757.h | 160 ++++++++++++++++++++++++++++++
>> 5 files changed, 271 insertions(+)
>> create mode 100644 gcc/testsuite/gcc.dg/pr108757-1.c
>> create mode 100644 gcc/testsuite/gcc.dg/pr108757-2.c
>> create mode 100644 gcc/testsuite/gcc.dg/pr108757.h
>>
>> diff --git a/gcc/gimple-match-head.cc b/gcc/gimple-match-head.cc
>> index b08cd891a13..680a4cb2fc6 100644
>> --- a/gcc/gimple-match-head.cc
>> +++ b/gcc/gimple-match-head.cc
>> @@ -224,3 +224,57 @@ optimize_successive_divisions_p (tree divisor, tree inner_div)
>> }
>> return true;
>> }
>> +
>> +/* Return true if "(X - N * M) / N + M" can be optimized into "X / N".
>> + Otherwise return false.
>> +
>> + For unsigned,
>> + If sign bit of M is 0 (clz is 0), valid range is [N*M, MAX].
>> + If sign bit of M is 1, valid range is [0, MAX - N*(-M)].
>> +
>> + For signed,
>> + If N*M > 0, valid range: [MIN+N*M, 0] + [N*M, MAX]
>> + If N*M < 0, valid range: [MIN, -(-N*M)] + [0, MAX - (-N*M)]. */
>> +
>> +static bool
>> +optimize_x_minus_NM_div_N_plus_M (tree x, wide_int n, wide_int m, tree type)
>> +{
>> + wide_int max = wi::max_value (type);
>> + signop sgn = TYPE_SIGN (type);
>> + wide_int nm;
>> + wi::overflow_type ovf;
>> + if (TYPE_UNSIGNED (type) && wi::clz (m) == 0)
>> + nm = wi::mul (n, -m, sgn, &ovf);
>> + else
>> + nm = wi::mul (n, m, sgn, &ovf);
>> +
>> + if (ovf != wi::OVF_NONE)
>> + return false;
>> +
>> + value_range vr0;
>> + if (!get_range_query (cfun)->range_of_expr (vr0, x) || vr0.varying_p ()
>> + || vr0.undefined_p ())
>> + return false;
>> +
>> + wide_int wmin0 = vr0.lower_bound ();
>> + wide_int wmax0 = vr0.upper_bound ();
>> + wide_int min = wi::min_value (type);
>> +
>> + /* unsigned */
>> + if ((TYPE_UNSIGNED (type)))
>> + /* M > 0 (clz != 0): [N*M, MAX], M < 0 : [0, MAX-N*(-M)] */
>> + return wi::clz (m) != 0 ? wi::ge_p (wmin0, nm, sgn)
>> + : wi::le_p (wmax0, max - nm, sgn);
>> +
>> + /* signed, N*M > 0 */
>> + else if (wi::gt_p (nm, 0, sgn))
>> + /* [N*M, MAX] or [MIN+N*M, 0] */
>> + return wi::ge_p (wmin0, nm, sgn)
>> + || (wi::ge_p (wmin0, min + nm, sgn) && wi::le_p (wmax0, 0, sgn));
>> +
>> + /* signed, N*M < 0 */
>> + /* [MIN, N*M] or [0, MAX + N*M]*/
>> + else
>> + return wi::le_p (wmax0, nm, sgn)
>> + || (wi::ge_p (wmin0, 0, sgn) && wi::le_p (wmax0, max - (-nm), sgn));
>> +}
>> diff --git a/gcc/match.pd b/gcc/match.pd
>> index ceae1c34abc..1aaa5530577 100644
>> --- a/gcc/match.pd
>> +++ b/gcc/match.pd
>> @@ -881,6 +881,28 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
>> #endif
>> ))))
>>
>> +#if GIMPLE
>> +/* Simplify ((t + -N*M) / N + M) -> t / N. */
>> +(for div (trunc_div exact_div)
>> + (simplify
>> + (plus (div (plus @0 INTEGER_CST@1) INTEGER_CST@2) INTEGER_CST@3)
>> + (with {wide_int n = wi::to_wide (@2); wide_int m = wi::to_wide (@3);}
>> + (if (INTEGRAL_TYPE_P (type)
>> + && n * m == -wi::to_wide (@1)
>> + && optimize_x_minus_NM_div_N_plus_M (@0, n, m, type))
>> + (div @0 @2)))))
>> +
>> +/* Simplify ((t + -(M<<N)) >> N + M) -> t >> N. */
>> +(simplify
>> + (plus (rshift (plus @0 INTEGER_CST@1) INTEGER_CST@2) INTEGER_CST@3)
>> + (with {wide_int n = wi::to_wide (@2); wide_int m = wi::to_wide (@3);}
>> + (if (INTEGRAL_TYPE_P (type)
>> + && (m << n) == -wi::to_wide (@1)
>> + && optimize_x_minus_NM_div_N_plus_M (@0,
>> + wi::one (TYPE_PRECISION (type)) << n, m, type))
>> + (rshift @0 @2))))
>> +#endif
>> +
>> (for op (negate abs)
>> /* Simplify cos(-x) and cos(|x|) -> cos(x). Similarly for cosh. */
>> (for coss (COS COSH)
>> diff --git a/gcc/testsuite/gcc.dg/pr108757-1.c b/gcc/testsuite/gcc.dg/pr108757-1.c
>> new file mode 100644
>> index 00000000000..349318a7c82
>> --- /dev/null
>> +++ b/gcc/testsuite/gcc.dg/pr108757-1.c
>> @@ -0,0 +1,17 @@
>> +/* PR tree-optimization/108757 */
>> +/* { dg-do compile } */
>> +/* { dg-options "-O2 -fdump-tree-optimized" } */
>> +
>> +#include <limits.h>
>> +#define N 4
>> +#define M 3
>> +#define GAP 0
>> +typedef unsigned int UINT;
>> +typedef int INT;
>> +#define UMAX UINT_MAX
>> +#define IMAX INT_MAX
>> +#define IMIN INT_MIN
>> +#include "pr108757.h"
>> +
>> +/* { dg-final { scan-tree-dump-not " = x_\[0-9\]\\(D\\) \\+ " "optimized" } } */
>> +/* { dg-final { scan-tree-dump-not " = b_\[0-9\] \\+ " "optimized" } } */
>> diff --git a/gcc/testsuite/gcc.dg/pr108757-2.c b/gcc/testsuite/gcc.dg/pr108757-2.c
>> new file mode 100644
>> index 00000000000..7302e9c606c
>> --- /dev/null
>> +++ b/gcc/testsuite/gcc.dg/pr108757-2.c
>> @@ -0,0 +1,18 @@
>> +/* PR tree-optimization/108757 */
>> +/* { dg-do compile } */
>> +/* { dg-options "-O2 -fdump-tree-optimized" } */
>> +
>> +#include <limits.h>
>> +#define N 4
>> +#define M 3
>> +#define GAP 2
>> +typedef unsigned int UINT;
>> +typedef int INT;
>> +#define UMAX UINT_MAX
>> +#define IMAX INT_MAX
>> +#define IMIN INT_MIN
>> +#include "pr108757.h"
>> +
>> +/* { dg-final { scan-tree-dump-times " = x_\[0-9\]\\(D\\) \\+ " 16 "optimized" } } */
>> +/* { dg-final { scan-tree-dump-times " = b_\[0-9\] \\+ " 16 "optimized" } } */
>> +
>> diff --git a/gcc/testsuite/gcc.dg/pr108757.h b/gcc/testsuite/gcc.dg/pr108757.h
>> new file mode 100644
>> index 00000000000..9e12d106aad
>> --- /dev/null
>> +++ b/gcc/testsuite/gcc.dg/pr108757.h
>> @@ -0,0 +1,160 @@
>> +#define NOINLINE __attribute__ ((noinline))
>> +UINT NOINLINE
>> +opt_u1 (UINT x)
>> +{
>> + if (x < (M * N) - GAP)
>> + return 0;
>> + UINT a = x - (M * N);
>> + UINT b = a / N;
>> + return b + M;
>> +}
>> +
>> +UINT NOINLINE
>> +opt_u2 (UINT x)
>> +{
>> + if (x > (UMAX - (M * N) + GAP))
>> + return 0;
>> + UINT a = x + (M * N);
>> + UINT b = a / N;
>> + return b - M;
>> +}
>> +
>> +INT NOINLINE
>> +opt_s1 (INT x)
>> +{
>> + if (x < (M * N) - GAP)
>> + return 0;
>> + INT a = x - (M * N);
>> + INT b = a / N;
>> + return b + M;
>> +}
>> +
>> +INT NOINLINE
>> +opt_s2 (INT x)
>> +{
>> + if (x < IMIN + (M * N) - GAP || x > 0)
>> + return 0;
>> + INT a = x - (M * N);
>> + INT b = a / N;
>> + return b + M;
>> +}
>> +
>> +INT NOINLINE
>> +opt_s3 (INT x)
>> +{
>> + if (x < (M * N) - GAP)
>> + return 0;
>> + INT a = x - (M * N);
>> + INT b = a / -N;
>> + return b + -M;
>> +}
>> +
>> +INT NOINLINE
>> +opt_s4 (INT x)
>> +{
>> + if (x < IMIN + (M * N) - GAP || x > 0)
>> + return 0;
>> + INT a = x - (M * N);
>> + INT b = a / -N;
>> + return b + -M;
>> +}
>> +
>> +INT NOINLINE
>> +opt_s5 (INT x)
>> +{
>> + if (x > (-M * N) + GAP)
>> + return 0;
>> + INT a = x - (-M * N);
>> + INT b = a / N;
>> + return b + -M;
>> +}
>> +
>> +INT NOINLINE
>> +opt_s6 (INT x)
>> +{
>> + if (x > IMAX - (M * N) + GAP || x < 0)
>> + return 0;
>> + INT a = x - (-M * N);
>> + INT b = a / N;
>> + return b + -M;
>> +}
>> +
>> +INT NOINLINE
>> +opt_s7 (INT x)
>> +{
>> + if (x > (M * -N) + GAP)
>> + return 0;
>> + INT a = x - (M * -N);
>> + INT b = a / -N;
>> + return b + M;
>> +}
>> +
>> +INT NOINLINE
>> +opt_s8 (INT x)
>> +{
>> + if (x > IMAX - (M * N) + GAP || x < 0)
>> + return 0;
>> + INT a = x - (M * -N);
>> + INT b = a / -N;
>> + return b + M;
>> +}
>> +
>> +UINT NOINLINE
>> +opt_u3 (UINT x)
>> +{
>> + if (x < (M << N) - GAP)
>> + return 0;
>> + UINT a = x - (M << N);
>> + UINT b = a >> N;
>> + return b + M;
>> +}
>> +
>> +UINT NOINLINE
>> +opt_u4 (UINT x)
>> +{
>> + if (x > (UMAX - (M << N)) + GAP)
>> + return 0;
>> + UINT a = x + (M << N);
>> + UINT b = a >> N;
>> + return b - M;
>> +}
>> +
>> +INT NOINLINE
>> +opt_s9 (INT x)
>> +{
>> + if (x < (M << N) - GAP)
>> + return 0;
>> + INT a = x - (M << N);
>> + INT b = a >> N;
>> + return b + M;
>> +}
>> +
>> +INT NOINLINE
>> +opt_s10 (INT x)
>> +{
>> + if (x < IMIN + (M << N) - GAP || x > 0)
>> + return 0;
>> + INT a = x - (M << N);
>> + INT b = a >> N;
>> + return b + M;
>> +}
>> +
>> +INT NOINLINE
>> +opt_s11 (INT x)
>> +{
>> + if (x > (-M << N) + GAP)
>> + return 0;
>> + INT a = x - (-M << N);
>> + INT b = a >> N;
>> + return b + -M;
>> +}
>> +
>> +INT NOINLINE
>> +opt_s12 (INT x)
>> +{
>> + if (x > IMAX - (M << N) + GAP || x < 0)
>> + return 0;
>> + INT a = x - (-M << N);
>> + INT b = a >> N;
>> + return b + -M;
>> +}
>>
Hi,
Jiufu Guo via Gcc-patches <gcc-patches@gcc.gnu.org> writes:
> Hi,
>
> Richard Biener <rguenther@suse.de> writes:
>
>> On Wed, 17 May 2023, Jiufu Guo wrote:
>>
>>> Hi,
>>>
>>> This patch tries to optimize "(X - N * M) / N + M" to "X / N".
>>
>> But if that's valid why not make the transform simpler and transform
>> (X - N * M) / N to X / N - M instead?
>
> Great catch!
> If "N * M" is not constant, "X / N - M" would be better than
> "(X - N * M) / N". If "N, M" are constants, "(X - N * M) / N" and
> "X / N - M" may be similar; while for this case, "X / N - M" should
> also be fine! I would try to update accordingly.
>
>>
>> You use the same optimize_x_minus_NM_div_N_plus_M validator for
>> the division and shift variants but the overflow rules are different,
>> so I'm not sure that's warranted. I'd also prefer to not split out
>> the validator to a different file - iff then the appropriate file
>> is fold-const.cc, not gimple-match-head.cc (I see we're a bit
>> inconsistent here, for pure gimple matches gimple-fold.cc would
>> be another place).
>
> Thanks for pointing out this!
> For shift, I guess you may concern that: 1. if the right operand is
> negative or is greater than or equal to the type width. 2. if it is
> a signed negative value. They may UB or 'sign bit shift'? This patch
> assumes it is ok to do the transform. I may have more check to see
> if this is really ok, and hope some one can point out if this is
> invalid. "(X - N * M) >> log2(N)" ==> " X >> log2(N) - M".
>
> I split out the validator just because: it is shared for division and
> shift :). And it seems gimple-match-head.cc and generic-match-head.cc,
> may be introduced for match.pd. So, I put it into gimple-match-head.cc.
>
>>
>> Since you use range information why is the transform restricted
>> to constant M?
>
> If M is a variable, the range for "X" is varying_p. I did not find
> the method to get the bounds for "X" (or for "X - N * M") to check no
> wraps. Any suggestions?
Oh, I may misunderstand here.
You may say: M could be with a range too, then we can check if
"X - N * M" has a valid range or possible wrap/overflow.
BR,
Jeff (Jiufu Guo)
>
>
> Again, thanks for your great help!
>
> BR,
> Jeff (Jiufu Guo)
>
>>
>> Richard.
>>
>>> As per the discussions in PR108757, we know this transformation is valid
>>> only under some conditions.
>>> For C code, "/" towards zero (trunc_div), and "X - N * M"
>>> maybe wrap/overflow/underflow. So, it is valid that "X - N * M" does
>>> not cross zero and does not wrap/overflow/underflow.
>>>
>>> This patch also handles the case when "N" is the power of 2, where
>>> "(X - N * M) / N" is "(X - N * M) >> log2(N)".
>>>
>>> Bootstrap & regtest pass on ppc64{,le} and x86_64.
>>> Is this ok for trunk?
>>>
>>> BR,
>>> Jeff (Jiufu)
>>>
>>> PR tree-optimization/108757
>>>
>>> gcc/ChangeLog:
>>>
>>> * gimple-match-head.cc (optimize_x_minus_NM_div_N_plus_M): New function.
>>> * match.pd ((X - N * M) / N + M): New pattern.
>>>
>>> gcc/testsuite/ChangeLog:
>>>
>>> * gcc.dg/pr108757-1.c: New test.
>>> * gcc.dg/pr108757-2.c: New test.
>>> * gcc.dg/pr108757.h: New test.
>>>
>>> ---
>>> gcc/gimple-match-head.cc | 54 ++++++++++
>>> gcc/match.pd | 22 ++++
>>> gcc/testsuite/gcc.dg/pr108757-1.c | 17 ++++
>>> gcc/testsuite/gcc.dg/pr108757-2.c | 18 ++++
>>> gcc/testsuite/gcc.dg/pr108757.h | 160 ++++++++++++++++++++++++++++++
>>> 5 files changed, 271 insertions(+)
>>> create mode 100644 gcc/testsuite/gcc.dg/pr108757-1.c
>>> create mode 100644 gcc/testsuite/gcc.dg/pr108757-2.c
>>> create mode 100644 gcc/testsuite/gcc.dg/pr108757.h
>>>
>>> diff --git a/gcc/gimple-match-head.cc b/gcc/gimple-match-head.cc
>>> index b08cd891a13..680a4cb2fc6 100644
>>> --- a/gcc/gimple-match-head.cc
>>> +++ b/gcc/gimple-match-head.cc
>>> @@ -224,3 +224,57 @@ optimize_successive_divisions_p (tree divisor, tree inner_div)
>>> }
>>> return true;
>>> }
>>> +
>>> +/* Return true if "(X - N * M) / N + M" can be optimized into "X / N".
>>> + Otherwise return false.
>>> +
>>> + For unsigned,
>>> + If sign bit of M is 0 (clz is 0), valid range is [N*M, MAX].
>>> + If sign bit of M is 1, valid range is [0, MAX - N*(-M)].
>>> +
>>> + For signed,
>>> + If N*M > 0, valid range: [MIN+N*M, 0] + [N*M, MAX]
>>> + If N*M < 0, valid range: [MIN, -(-N*M)] + [0, MAX - (-N*M)]. */
>>> +
>>> +static bool
>>> +optimize_x_minus_NM_div_N_plus_M (tree x, wide_int n, wide_int m, tree type)
>>> +{
>>> + wide_int max = wi::max_value (type);
>>> + signop sgn = TYPE_SIGN (type);
>>> + wide_int nm;
>>> + wi::overflow_type ovf;
>>> + if (TYPE_UNSIGNED (type) && wi::clz (m) == 0)
>>> + nm = wi::mul (n, -m, sgn, &ovf);
>>> + else
>>> + nm = wi::mul (n, m, sgn, &ovf);
>>> +
>>> + if (ovf != wi::OVF_NONE)
>>> + return false;
>>> +
>>> + value_range vr0;
>>> + if (!get_range_query (cfun)->range_of_expr (vr0, x) || vr0.varying_p ()
>>> + || vr0.undefined_p ())
>>> + return false;
>>> +
>>> + wide_int wmin0 = vr0.lower_bound ();
>>> + wide_int wmax0 = vr0.upper_bound ();
>>> + wide_int min = wi::min_value (type);
>>> +
>>> + /* unsigned */
>>> + if ((TYPE_UNSIGNED (type)))
>>> + /* M > 0 (clz != 0): [N*M, MAX], M < 0 : [0, MAX-N*(-M)] */
>>> + return wi::clz (m) != 0 ? wi::ge_p (wmin0, nm, sgn)
>>> + : wi::le_p (wmax0, max - nm, sgn);
>>> +
>>> + /* signed, N*M > 0 */
>>> + else if (wi::gt_p (nm, 0, sgn))
>>> + /* [N*M, MAX] or [MIN+N*M, 0] */
>>> + return wi::ge_p (wmin0, nm, sgn)
>>> + || (wi::ge_p (wmin0, min + nm, sgn) && wi::le_p (wmax0, 0, sgn));
>>> +
>>> + /* signed, N*M < 0 */
>>> + /* [MIN, N*M] or [0, MAX + N*M]*/
>>> + else
>>> + return wi::le_p (wmax0, nm, sgn)
>>> + || (wi::ge_p (wmin0, 0, sgn) && wi::le_p (wmax0, max - (-nm), sgn));
>>> +}
>>> diff --git a/gcc/match.pd b/gcc/match.pd
>>> index ceae1c34abc..1aaa5530577 100644
>>> --- a/gcc/match.pd
>>> +++ b/gcc/match.pd
>>> @@ -881,6 +881,28 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
>>> #endif
>>> ))))
>>>
>>> +#if GIMPLE
>>> +/* Simplify ((t + -N*M) / N + M) -> t / N. */
>>> +(for div (trunc_div exact_div)
>>> + (simplify
>>> + (plus (div (plus @0 INTEGER_CST@1) INTEGER_CST@2) INTEGER_CST@3)
>>> + (with {wide_int n = wi::to_wide (@2); wide_int m = wi::to_wide (@3);}
>>> + (if (INTEGRAL_TYPE_P (type)
>>> + && n * m == -wi::to_wide (@1)
>>> + && optimize_x_minus_NM_div_N_plus_M (@0, n, m, type))
>>> + (div @0 @2)))))
>>> +
>>> +/* Simplify ((t + -(M<<N)) >> N + M) -> t >> N. */
>>> +(simplify
>>> + (plus (rshift (plus @0 INTEGER_CST@1) INTEGER_CST@2) INTEGER_CST@3)
>>> + (with {wide_int n = wi::to_wide (@2); wide_int m = wi::to_wide (@3);}
>>> + (if (INTEGRAL_TYPE_P (type)
>>> + && (m << n) == -wi::to_wide (@1)
>>> + && optimize_x_minus_NM_div_N_plus_M (@0,
>>> + wi::one (TYPE_PRECISION (type)) << n, m, type))
>>> + (rshift @0 @2))))
>>> +#endif
>>> +
>>> (for op (negate abs)
>>> /* Simplify cos(-x) and cos(|x|) -> cos(x). Similarly for cosh. */
>>> (for coss (COS COSH)
>>> diff --git a/gcc/testsuite/gcc.dg/pr108757-1.c b/gcc/testsuite/gcc.dg/pr108757-1.c
>>> new file mode 100644
>>> index 00000000000..349318a7c82
>>> --- /dev/null
>>> +++ b/gcc/testsuite/gcc.dg/pr108757-1.c
>>> @@ -0,0 +1,17 @@
>>> +/* PR tree-optimization/108757 */
>>> +/* { dg-do compile } */
>>> +/* { dg-options "-O2 -fdump-tree-optimized" } */
>>> +
>>> +#include <limits.h>
>>> +#define N 4
>>> +#define M 3
>>> +#define GAP 0
>>> +typedef unsigned int UINT;
>>> +typedef int INT;
>>> +#define UMAX UINT_MAX
>>> +#define IMAX INT_MAX
>>> +#define IMIN INT_MIN
>>> +#include "pr108757.h"
>>> +
>>> +/* { dg-final { scan-tree-dump-not " = x_\[0-9\]\\(D\\) \\+ " "optimized" } } */
>>> +/* { dg-final { scan-tree-dump-not " = b_\[0-9\] \\+ " "optimized" } } */
>>> diff --git a/gcc/testsuite/gcc.dg/pr108757-2.c b/gcc/testsuite/gcc.dg/pr108757-2.c
>>> new file mode 100644
>>> index 00000000000..7302e9c606c
>>> --- /dev/null
>>> +++ b/gcc/testsuite/gcc.dg/pr108757-2.c
>>> @@ -0,0 +1,18 @@
>>> +/* PR tree-optimization/108757 */
>>> +/* { dg-do compile } */
>>> +/* { dg-options "-O2 -fdump-tree-optimized" } */
>>> +
>>> +#include <limits.h>
>>> +#define N 4
>>> +#define M 3
>>> +#define GAP 2
>>> +typedef unsigned int UINT;
>>> +typedef int INT;
>>> +#define UMAX UINT_MAX
>>> +#define IMAX INT_MAX
>>> +#define IMIN INT_MIN
>>> +#include "pr108757.h"
>>> +
>>> +/* { dg-final { scan-tree-dump-times " = x_\[0-9\]\\(D\\) \\+ " 16 "optimized" } } */
>>> +/* { dg-final { scan-tree-dump-times " = b_\[0-9\] \\+ " 16 "optimized" } } */
>>> +
>>> diff --git a/gcc/testsuite/gcc.dg/pr108757.h b/gcc/testsuite/gcc.dg/pr108757.h
>>> new file mode 100644
>>> index 00000000000..9e12d106aad
>>> --- /dev/null
>>> +++ b/gcc/testsuite/gcc.dg/pr108757.h
>>> @@ -0,0 +1,160 @@
>>> +#define NOINLINE __attribute__ ((noinline))
>>> +UINT NOINLINE
>>> +opt_u1 (UINT x)
>>> +{
>>> + if (x < (M * N) - GAP)
>>> + return 0;
>>> + UINT a = x - (M * N);
>>> + UINT b = a / N;
>>> + return b + M;
>>> +}
>>> +
>>> +UINT NOINLINE
>>> +opt_u2 (UINT x)
>>> +{
>>> + if (x > (UMAX - (M * N) + GAP))
>>> + return 0;
>>> + UINT a = x + (M * N);
>>> + UINT b = a / N;
>>> + return b - M;
>>> +}
>>> +
>>> +INT NOINLINE
>>> +opt_s1 (INT x)
>>> +{
>>> + if (x < (M * N) - GAP)
>>> + return 0;
>>> + INT a = x - (M * N);
>>> + INT b = a / N;
>>> + return b + M;
>>> +}
>>> +
>>> +INT NOINLINE
>>> +opt_s2 (INT x)
>>> +{
>>> + if (x < IMIN + (M * N) - GAP || x > 0)
>>> + return 0;
>>> + INT a = x - (M * N);
>>> + INT b = a / N;
>>> + return b + M;
>>> +}
>>> +
>>> +INT NOINLINE
>>> +opt_s3 (INT x)
>>> +{
>>> + if (x < (M * N) - GAP)
>>> + return 0;
>>> + INT a = x - (M * N);
>>> + INT b = a / -N;
>>> + return b + -M;
>>> +}
>>> +
>>> +INT NOINLINE
>>> +opt_s4 (INT x)
>>> +{
>>> + if (x < IMIN + (M * N) - GAP || x > 0)
>>> + return 0;
>>> + INT a = x - (M * N);
>>> + INT b = a / -N;
>>> + return b + -M;
>>> +}
>>> +
>>> +INT NOINLINE
>>> +opt_s5 (INT x)
>>> +{
>>> + if (x > (-M * N) + GAP)
>>> + return 0;
>>> + INT a = x - (-M * N);
>>> + INT b = a / N;
>>> + return b + -M;
>>> +}
>>> +
>>> +INT NOINLINE
>>> +opt_s6 (INT x)
>>> +{
>>> + if (x > IMAX - (M * N) + GAP || x < 0)
>>> + return 0;
>>> + INT a = x - (-M * N);
>>> + INT b = a / N;
>>> + return b + -M;
>>> +}
>>> +
>>> +INT NOINLINE
>>> +opt_s7 (INT x)
>>> +{
>>> + if (x > (M * -N) + GAP)
>>> + return 0;
>>> + INT a = x - (M * -N);
>>> + INT b = a / -N;
>>> + return b + M;
>>> +}
>>> +
>>> +INT NOINLINE
>>> +opt_s8 (INT x)
>>> +{
>>> + if (x > IMAX - (M * N) + GAP || x < 0)
>>> + return 0;
>>> + INT a = x - (M * -N);
>>> + INT b = a / -N;
>>> + return b + M;
>>> +}
>>> +
>>> +UINT NOINLINE
>>> +opt_u3 (UINT x)
>>> +{
>>> + if (x < (M << N) - GAP)
>>> + return 0;
>>> + UINT a = x - (M << N);
>>> + UINT b = a >> N;
>>> + return b + M;
>>> +}
>>> +
>>> +UINT NOINLINE
>>> +opt_u4 (UINT x)
>>> +{
>>> + if (x > (UMAX - (M << N)) + GAP)
>>> + return 0;
>>> + UINT a = x + (M << N);
>>> + UINT b = a >> N;
>>> + return b - M;
>>> +}
>>> +
>>> +INT NOINLINE
>>> +opt_s9 (INT x)
>>> +{
>>> + if (x < (M << N) - GAP)
>>> + return 0;
>>> + INT a = x - (M << N);
>>> + INT b = a >> N;
>>> + return b + M;
>>> +}
>>> +
>>> +INT NOINLINE
>>> +opt_s10 (INT x)
>>> +{
>>> + if (x < IMIN + (M << N) - GAP || x > 0)
>>> + return 0;
>>> + INT a = x - (M << N);
>>> + INT b = a >> N;
>>> + return b + M;
>>> +}
>>> +
>>> +INT NOINLINE
>>> +opt_s11 (INT x)
>>> +{
>>> + if (x > (-M << N) + GAP)
>>> + return 0;
>>> + INT a = x - (-M << N);
>>> + INT b = a >> N;
>>> + return b + -M;
>>> +}
>>> +
>>> +INT NOINLINE
>>> +opt_s12 (INT x)
>>> +{
>>> + if (x > IMAX - (M << N) + GAP || x < 0)
>>> + return 0;
>>> + INT a = x - (-M << N);
>>> + INT b = a >> N;
>>> + return b + -M;
>>> +}
>>>
On Thu, 1 Jun 2023, Jiufu Guo wrote:
> Hi,
>
> Jiufu Guo via Gcc-patches <gcc-patches@gcc.gnu.org> writes:
>
> > Hi,
> >
> > Richard Biener <rguenther@suse.de> writes:
> >
> >> On Wed, 17 May 2023, Jiufu Guo wrote:
> >>
> >>> Hi,
> >>>
> >>> This patch tries to optimize "(X - N * M) / N + M" to "X / N".
> >>
> >> But if that's valid why not make the transform simpler and transform
> >> (X - N * M) / N to X / N - M instead?
> >
> > Great catch!
> > If "N * M" is not constant, "X / N - M" would be better than
> > "(X - N * M) / N". If "N, M" are constants, "(X - N * M) / N" and
> > "X / N - M" may be similar; while for this case, "X / N - M" should
> > also be fine! I would try to update accordingly.
> >
> >>
> >> You use the same optimize_x_minus_NM_div_N_plus_M validator for
> >> the division and shift variants but the overflow rules are different,
> >> so I'm not sure that's warranted. I'd also prefer to not split out
> >> the validator to a different file - iff then the appropriate file
> >> is fold-const.cc, not gimple-match-head.cc (I see we're a bit
> >> inconsistent here, for pure gimple matches gimple-fold.cc would
> >> be another place).
> >
> > Thanks for pointing out this!
> > For shift, I guess you may concern that: 1. if the right operand is
> > negative or is greater than or equal to the type width. 2. if it is
> > a signed negative value. They may UB or 'sign bit shift'? This patch
> > assumes it is ok to do the transform. I may have more check to see
> > if this is really ok, and hope some one can point out if this is
> > invalid. "(X - N * M) >> log2(N)" ==> " X >> log2(N) - M".
> >
> > I split out the validator just because: it is shared for division and
> > shift :). And it seems gimple-match-head.cc and generic-match-head.cc,
> > may be introduced for match.pd. So, I put it into gimple-match-head.cc.
> >
> >>
> >> Since you use range information why is the transform restricted
> >> to constant M?
> >
> > If M is a variable, the range for "X" is varying_p. I did not find
> > the method to get the bounds for "X" (or for "X - N * M") to check no
> > wraps. Any suggestions?
>
> Oh, I may misunderstand here.
> You may say: M could be with a range too, then we can check if
> "X - N * M" has a valid range or possible wrap/overflow.
Yes.
Richard.
> BR,
> Jeff (Jiufu Guo)
>
> >
> >
> > Again, thanks for your great help!
> >
> > BR,
> > Jeff (Jiufu Guo)
> >
> >>
> >> Richard.
> >>
> >>> As per the discussions in PR108757, we know this transformation is valid
> >>> only under some conditions.
> >>> For C code, "/" towards zero (trunc_div), and "X - N * M"
> >>> maybe wrap/overflow/underflow. So, it is valid that "X - N * M" does
> >>> not cross zero and does not wrap/overflow/underflow.
> >>>
> >>> This patch also handles the case when "N" is the power of 2, where
> >>> "(X - N * M) / N" is "(X - N * M) >> log2(N)".
> >>>
> >>> Bootstrap & regtest pass on ppc64{,le} and x86_64.
> >>> Is this ok for trunk?
> >>>
> >>> BR,
> >>> Jeff (Jiufu)
> >>>
> >>> PR tree-optimization/108757
> >>>
> >>> gcc/ChangeLog:
> >>>
> >>> * gimple-match-head.cc (optimize_x_minus_NM_div_N_plus_M): New function.
> >>> * match.pd ((X - N * M) / N + M): New pattern.
> >>>
> >>> gcc/testsuite/ChangeLog:
> >>>
> >>> * gcc.dg/pr108757-1.c: New test.
> >>> * gcc.dg/pr108757-2.c: New test.
> >>> * gcc.dg/pr108757.h: New test.
> >>>
> >>> ---
> >>> gcc/gimple-match-head.cc | 54 ++++++++++
> >>> gcc/match.pd | 22 ++++
> >>> gcc/testsuite/gcc.dg/pr108757-1.c | 17 ++++
> >>> gcc/testsuite/gcc.dg/pr108757-2.c | 18 ++++
> >>> gcc/testsuite/gcc.dg/pr108757.h | 160 ++++++++++++++++++++++++++++++
> >>> 5 files changed, 271 insertions(+)
> >>> create mode 100644 gcc/testsuite/gcc.dg/pr108757-1.c
> >>> create mode 100644 gcc/testsuite/gcc.dg/pr108757-2.c
> >>> create mode 100644 gcc/testsuite/gcc.dg/pr108757.h
> >>>
> >>> diff --git a/gcc/gimple-match-head.cc b/gcc/gimple-match-head.cc
> >>> index b08cd891a13..680a4cb2fc6 100644
> >>> --- a/gcc/gimple-match-head.cc
> >>> +++ b/gcc/gimple-match-head.cc
> >>> @@ -224,3 +224,57 @@ optimize_successive_divisions_p (tree divisor, tree inner_div)
> >>> }
> >>> return true;
> >>> }
> >>> +
> >>> +/* Return true if "(X - N * M) / N + M" can be optimized into "X / N".
> >>> + Otherwise return false.
> >>> +
> >>> + For unsigned,
> >>> + If sign bit of M is 0 (clz is 0), valid range is [N*M, MAX].
> >>> + If sign bit of M is 1, valid range is [0, MAX - N*(-M)].
> >>> +
> >>> + For signed,
> >>> + If N*M > 0, valid range: [MIN+N*M, 0] + [N*M, MAX]
> >>> + If N*M < 0, valid range: [MIN, -(-N*M)] + [0, MAX - (-N*M)]. */
> >>> +
> >>> +static bool
> >>> +optimize_x_minus_NM_div_N_plus_M (tree x, wide_int n, wide_int m, tree type)
> >>> +{
> >>> + wide_int max = wi::max_value (type);
> >>> + signop sgn = TYPE_SIGN (type);
> >>> + wide_int nm;
> >>> + wi::overflow_type ovf;
> >>> + if (TYPE_UNSIGNED (type) && wi::clz (m) == 0)
> >>> + nm = wi::mul (n, -m, sgn, &ovf);
> >>> + else
> >>> + nm = wi::mul (n, m, sgn, &ovf);
> >>> +
> >>> + if (ovf != wi::OVF_NONE)
> >>> + return false;
> >>> +
> >>> + value_range vr0;
> >>> + if (!get_range_query (cfun)->range_of_expr (vr0, x) || vr0.varying_p ()
> >>> + || vr0.undefined_p ())
> >>> + return false;
> >>> +
> >>> + wide_int wmin0 = vr0.lower_bound ();
> >>> + wide_int wmax0 = vr0.upper_bound ();
> >>> + wide_int min = wi::min_value (type);
> >>> +
> >>> + /* unsigned */
> >>> + if ((TYPE_UNSIGNED (type)))
> >>> + /* M > 0 (clz != 0): [N*M, MAX], M < 0 : [0, MAX-N*(-M)] */
> >>> + return wi::clz (m) != 0 ? wi::ge_p (wmin0, nm, sgn)
> >>> + : wi::le_p (wmax0, max - nm, sgn);
> >>> +
> >>> + /* signed, N*M > 0 */
> >>> + else if (wi::gt_p (nm, 0, sgn))
> >>> + /* [N*M, MAX] or [MIN+N*M, 0] */
> >>> + return wi::ge_p (wmin0, nm, sgn)
> >>> + || (wi::ge_p (wmin0, min + nm, sgn) && wi::le_p (wmax0, 0, sgn));
> >>> +
> >>> + /* signed, N*M < 0 */
> >>> + /* [MIN, N*M] or [0, MAX + N*M]*/
> >>> + else
> >>> + return wi::le_p (wmax0, nm, sgn)
> >>> + || (wi::ge_p (wmin0, 0, sgn) && wi::le_p (wmax0, max - (-nm), sgn));
> >>> +}
> >>> diff --git a/gcc/match.pd b/gcc/match.pd
> >>> index ceae1c34abc..1aaa5530577 100644
> >>> --- a/gcc/match.pd
> >>> +++ b/gcc/match.pd
> >>> @@ -881,6 +881,28 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
> >>> #endif
> >>> ))))
> >>>
> >>> +#if GIMPLE
> >>> +/* Simplify ((t + -N*M) / N + M) -> t / N. */
> >>> +(for div (trunc_div exact_div)
> >>> + (simplify
> >>> + (plus (div (plus @0 INTEGER_CST@1) INTEGER_CST@2) INTEGER_CST@3)
> >>> + (with {wide_int n = wi::to_wide (@2); wide_int m = wi::to_wide (@3);}
> >>> + (if (INTEGRAL_TYPE_P (type)
> >>> + && n * m == -wi::to_wide (@1)
> >>> + && optimize_x_minus_NM_div_N_plus_M (@0, n, m, type))
> >>> + (div @0 @2)))))
> >>> +
> >>> +/* Simplify ((t + -(M<<N)) >> N + M) -> t >> N. */
> >>> +(simplify
> >>> + (plus (rshift (plus @0 INTEGER_CST@1) INTEGER_CST@2) INTEGER_CST@3)
> >>> + (with {wide_int n = wi::to_wide (@2); wide_int m = wi::to_wide (@3);}
> >>> + (if (INTEGRAL_TYPE_P (type)
> >>> + && (m << n) == -wi::to_wide (@1)
> >>> + && optimize_x_minus_NM_div_N_plus_M (@0,
> >>> + wi::one (TYPE_PRECISION (type)) << n, m, type))
> >>> + (rshift @0 @2))))
> >>> +#endif
> >>> +
> >>> (for op (negate abs)
> >>> /* Simplify cos(-x) and cos(|x|) -> cos(x). Similarly for cosh. */
> >>> (for coss (COS COSH)
> >>> diff --git a/gcc/testsuite/gcc.dg/pr108757-1.c b/gcc/testsuite/gcc.dg/pr108757-1.c
> >>> new file mode 100644
> >>> index 00000000000..349318a7c82
> >>> --- /dev/null
> >>> +++ b/gcc/testsuite/gcc.dg/pr108757-1.c
> >>> @@ -0,0 +1,17 @@
> >>> +/* PR tree-optimization/108757 */
> >>> +/* { dg-do compile } */
> >>> +/* { dg-options "-O2 -fdump-tree-optimized" } */
> >>> +
> >>> +#include <limits.h>
> >>> +#define N 4
> >>> +#define M 3
> >>> +#define GAP 0
> >>> +typedef unsigned int UINT;
> >>> +typedef int INT;
> >>> +#define UMAX UINT_MAX
> >>> +#define IMAX INT_MAX
> >>> +#define IMIN INT_MIN
> >>> +#include "pr108757.h"
> >>> +
> >>> +/* { dg-final { scan-tree-dump-not " = x_\[0-9\]\\(D\\) \\+ " "optimized" } } */
> >>> +/* { dg-final { scan-tree-dump-not " = b_\[0-9\] \\+ " "optimized" } } */
> >>> diff --git a/gcc/testsuite/gcc.dg/pr108757-2.c b/gcc/testsuite/gcc.dg/pr108757-2.c
> >>> new file mode 100644
> >>> index 00000000000..7302e9c606c
> >>> --- /dev/null
> >>> +++ b/gcc/testsuite/gcc.dg/pr108757-2.c
> >>> @@ -0,0 +1,18 @@
> >>> +/* PR tree-optimization/108757 */
> >>> +/* { dg-do compile } */
> >>> +/* { dg-options "-O2 -fdump-tree-optimized" } */
> >>> +
> >>> +#include <limits.h>
> >>> +#define N 4
> >>> +#define M 3
> >>> +#define GAP 2
> >>> +typedef unsigned int UINT;
> >>> +typedef int INT;
> >>> +#define UMAX UINT_MAX
> >>> +#define IMAX INT_MAX
> >>> +#define IMIN INT_MIN
> >>> +#include "pr108757.h"
> >>> +
> >>> +/* { dg-final { scan-tree-dump-times " = x_\[0-9\]\\(D\\) \\+ " 16 "optimized" } } */
> >>> +/* { dg-final { scan-tree-dump-times " = b_\[0-9\] \\+ " 16 "optimized" } } */
> >>> +
> >>> diff --git a/gcc/testsuite/gcc.dg/pr108757.h b/gcc/testsuite/gcc.dg/pr108757.h
> >>> new file mode 100644
> >>> index 00000000000..9e12d106aad
> >>> --- /dev/null
> >>> +++ b/gcc/testsuite/gcc.dg/pr108757.h
> >>> @@ -0,0 +1,160 @@
> >>> +#define NOINLINE __attribute__ ((noinline))
> >>> +UINT NOINLINE
> >>> +opt_u1 (UINT x)
> >>> +{
> >>> + if (x < (M * N) - GAP)
> >>> + return 0;
> >>> + UINT a = x - (M * N);
> >>> + UINT b = a / N;
> >>> + return b + M;
> >>> +}
> >>> +
> >>> +UINT NOINLINE
> >>> +opt_u2 (UINT x)
> >>> +{
> >>> + if (x > (UMAX - (M * N) + GAP))
> >>> + return 0;
> >>> + UINT a = x + (M * N);
> >>> + UINT b = a / N;
> >>> + return b - M;
> >>> +}
> >>> +
> >>> +INT NOINLINE
> >>> +opt_s1 (INT x)
> >>> +{
> >>> + if (x < (M * N) - GAP)
> >>> + return 0;
> >>> + INT a = x - (M * N);
> >>> + INT b = a / N;
> >>> + return b + M;
> >>> +}
> >>> +
> >>> +INT NOINLINE
> >>> +opt_s2 (INT x)
> >>> +{
> >>> + if (x < IMIN + (M * N) - GAP || x > 0)
> >>> + return 0;
> >>> + INT a = x - (M * N);
> >>> + INT b = a / N;
> >>> + return b + M;
> >>> +}
> >>> +
> >>> +INT NOINLINE
> >>> +opt_s3 (INT x)
> >>> +{
> >>> + if (x < (M * N) - GAP)
> >>> + return 0;
> >>> + INT a = x - (M * N);
> >>> + INT b = a / -N;
> >>> + return b + -M;
> >>> +}
> >>> +
> >>> +INT NOINLINE
> >>> +opt_s4 (INT x)
> >>> +{
> >>> + if (x < IMIN + (M * N) - GAP || x > 0)
> >>> + return 0;
> >>> + INT a = x - (M * N);
> >>> + INT b = a / -N;
> >>> + return b + -M;
> >>> +}
> >>> +
> >>> +INT NOINLINE
> >>> +opt_s5 (INT x)
> >>> +{
> >>> + if (x > (-M * N) + GAP)
> >>> + return 0;
> >>> + INT a = x - (-M * N);
> >>> + INT b = a / N;
> >>> + return b + -M;
> >>> +}
> >>> +
> >>> +INT NOINLINE
> >>> +opt_s6 (INT x)
> >>> +{
> >>> + if (x > IMAX - (M * N) + GAP || x < 0)
> >>> + return 0;
> >>> + INT a = x - (-M * N);
> >>> + INT b = a / N;
> >>> + return b + -M;
> >>> +}
> >>> +
> >>> +INT NOINLINE
> >>> +opt_s7 (INT x)
> >>> +{
> >>> + if (x > (M * -N) + GAP)
> >>> + return 0;
> >>> + INT a = x - (M * -N);
> >>> + INT b = a / -N;
> >>> + return b + M;
> >>> +}
> >>> +
> >>> +INT NOINLINE
> >>> +opt_s8 (INT x)
> >>> +{
> >>> + if (x > IMAX - (M * N) + GAP || x < 0)
> >>> + return 0;
> >>> + INT a = x - (M * -N);
> >>> + INT b = a / -N;
> >>> + return b + M;
> >>> +}
> >>> +
> >>> +UINT NOINLINE
> >>> +opt_u3 (UINT x)
> >>> +{
> >>> + if (x < (M << N) - GAP)
> >>> + return 0;
> >>> + UINT a = x - (M << N);
> >>> + UINT b = a >> N;
> >>> + return b + M;
> >>> +}
> >>> +
> >>> +UINT NOINLINE
> >>> +opt_u4 (UINT x)
> >>> +{
> >>> + if (x > (UMAX - (M << N)) + GAP)
> >>> + return 0;
> >>> + UINT a = x + (M << N);
> >>> + UINT b = a >> N;
> >>> + return b - M;
> >>> +}
> >>> +
> >>> +INT NOINLINE
> >>> +opt_s9 (INT x)
> >>> +{
> >>> + if (x < (M << N) - GAP)
> >>> + return 0;
> >>> + INT a = x - (M << N);
> >>> + INT b = a >> N;
> >>> + return b + M;
> >>> +}
> >>> +
> >>> +INT NOINLINE
> >>> +opt_s10 (INT x)
> >>> +{
> >>> + if (x < IMIN + (M << N) - GAP || x > 0)
> >>> + return 0;
> >>> + INT a = x - (M << N);
> >>> + INT b = a >> N;
> >>> + return b + M;
> >>> +}
> >>> +
> >>> +INT NOINLINE
> >>> +opt_s11 (INT x)
> >>> +{
> >>> + if (x > (-M << N) + GAP)
> >>> + return 0;
> >>> + INT a = x - (-M << N);
> >>> + INT b = a >> N;
> >>> + return b + -M;
> >>> +}
> >>> +
> >>> +INT NOINLINE
> >>> +opt_s12 (INT x)
> >>> +{
> >>> + if (x > IMAX - (M << N) + GAP || x < 0)
> >>> + return 0;
> >>> + INT a = x - (-M << N);
> >>> + INT b = a >> N;
> >>> + return b + -M;
> >>> +}
> >>>
>
@@ -224,3 +224,57 @@ optimize_successive_divisions_p (tree divisor, tree inner_div)
}
return true;
}
+
+/* Return true if "(X - N * M) / N + M" can be optimized into "X / N".
+ Otherwise return false.
+
+ For unsigned,
+ If sign bit of M is 0 (clz is 0), valid range is [N*M, MAX].
+ If sign bit of M is 1, valid range is [0, MAX - N*(-M)].
+
+ For signed,
+ If N*M > 0, valid range: [MIN+N*M, 0] + [N*M, MAX]
+ If N*M < 0, valid range: [MIN, -(-N*M)] + [0, MAX - (-N*M)]. */
+
+static bool
+optimize_x_minus_NM_div_N_plus_M (tree x, wide_int n, wide_int m, tree type)
+{
+ wide_int max = wi::max_value (type);
+ signop sgn = TYPE_SIGN (type);
+ wide_int nm;
+ wi::overflow_type ovf;
+ if (TYPE_UNSIGNED (type) && wi::clz (m) == 0)
+ nm = wi::mul (n, -m, sgn, &ovf);
+ else
+ nm = wi::mul (n, m, sgn, &ovf);
+
+ if (ovf != wi::OVF_NONE)
+ return false;
+
+ value_range vr0;
+ if (!get_range_query (cfun)->range_of_expr (vr0, x) || vr0.varying_p ()
+ || vr0.undefined_p ())
+ return false;
+
+ wide_int wmin0 = vr0.lower_bound ();
+ wide_int wmax0 = vr0.upper_bound ();
+ wide_int min = wi::min_value (type);
+
+ /* unsigned */
+ if ((TYPE_UNSIGNED (type)))
+ /* M > 0 (clz != 0): [N*M, MAX], M < 0 : [0, MAX-N*(-M)] */
+ return wi::clz (m) != 0 ? wi::ge_p (wmin0, nm, sgn)
+ : wi::le_p (wmax0, max - nm, sgn);
+
+ /* signed, N*M > 0 */
+ else if (wi::gt_p (nm, 0, sgn))
+ /* [N*M, MAX] or [MIN+N*M, 0] */
+ return wi::ge_p (wmin0, nm, sgn)
+ || (wi::ge_p (wmin0, min + nm, sgn) && wi::le_p (wmax0, 0, sgn));
+
+ /* signed, N*M < 0 */
+ /* [MIN, N*M] or [0, MAX + N*M]*/
+ else
+ return wi::le_p (wmax0, nm, sgn)
+ || (wi::ge_p (wmin0, 0, sgn) && wi::le_p (wmax0, max - (-nm), sgn));
+}
@@ -881,6 +881,28 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
#endif
))))
+#if GIMPLE
+/* Simplify ((t + -N*M) / N + M) -> t / N. */
+(for div (trunc_div exact_div)
+ (simplify
+ (plus (div (plus @0 INTEGER_CST@1) INTEGER_CST@2) INTEGER_CST@3)
+ (with {wide_int n = wi::to_wide (@2); wide_int m = wi::to_wide (@3);}
+ (if (INTEGRAL_TYPE_P (type)
+ && n * m == -wi::to_wide (@1)
+ && optimize_x_minus_NM_div_N_plus_M (@0, n, m, type))
+ (div @0 @2)))))
+
+/* Simplify ((t + -(M<<N)) >> N + M) -> t >> N. */
+(simplify
+ (plus (rshift (plus @0 INTEGER_CST@1) INTEGER_CST@2) INTEGER_CST@3)
+ (with {wide_int n = wi::to_wide (@2); wide_int m = wi::to_wide (@3);}
+ (if (INTEGRAL_TYPE_P (type)
+ && (m << n) == -wi::to_wide (@1)
+ && optimize_x_minus_NM_div_N_plus_M (@0,
+ wi::one (TYPE_PRECISION (type)) << n, m, type))
+ (rshift @0 @2))))
+#endif
+
(for op (negate abs)
/* Simplify cos(-x) and cos(|x|) -> cos(x). Similarly for cosh. */
(for coss (COS COSH)
new file mode 100644
@@ -0,0 +1,17 @@
+/* PR tree-optimization/108757 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+
+#include <limits.h>
+#define N 4
+#define M 3
+#define GAP 0
+typedef unsigned int UINT;
+typedef int INT;
+#define UMAX UINT_MAX
+#define IMAX INT_MAX
+#define IMIN INT_MIN
+#include "pr108757.h"
+
+/* { dg-final { scan-tree-dump-not " = x_\[0-9\]\\(D\\) \\+ " "optimized" } } */
+/* { dg-final { scan-tree-dump-not " = b_\[0-9\] \\+ " "optimized" } } */
new file mode 100644
@@ -0,0 +1,18 @@
+/* PR tree-optimization/108757 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+
+#include <limits.h>
+#define N 4
+#define M 3
+#define GAP 2
+typedef unsigned int UINT;
+typedef int INT;
+#define UMAX UINT_MAX
+#define IMAX INT_MAX
+#define IMIN INT_MIN
+#include "pr108757.h"
+
+/* { dg-final { scan-tree-dump-times " = x_\[0-9\]\\(D\\) \\+ " 16 "optimized" } } */
+/* { dg-final { scan-tree-dump-times " = b_\[0-9\] \\+ " 16 "optimized" } } */
+
new file mode 100644
@@ -0,0 +1,160 @@
+#define NOINLINE __attribute__ ((noinline))
+UINT NOINLINE
+opt_u1 (UINT x)
+{
+ if (x < (M * N) - GAP)
+ return 0;
+ UINT a = x - (M * N);
+ UINT b = a / N;
+ return b + M;
+}
+
+UINT NOINLINE
+opt_u2 (UINT x)
+{
+ if (x > (UMAX - (M * N) + GAP))
+ return 0;
+ UINT a = x + (M * N);
+ UINT b = a / N;
+ return b - M;
+}
+
+INT NOINLINE
+opt_s1 (INT x)
+{
+ if (x < (M * N) - GAP)
+ return 0;
+ INT a = x - (M * N);
+ INT b = a / N;
+ return b + M;
+}
+
+INT NOINLINE
+opt_s2 (INT x)
+{
+ if (x < IMIN + (M * N) - GAP || x > 0)
+ return 0;
+ INT a = x - (M * N);
+ INT b = a / N;
+ return b + M;
+}
+
+INT NOINLINE
+opt_s3 (INT x)
+{
+ if (x < (M * N) - GAP)
+ return 0;
+ INT a = x - (M * N);
+ INT b = a / -N;
+ return b + -M;
+}
+
+INT NOINLINE
+opt_s4 (INT x)
+{
+ if (x < IMIN + (M * N) - GAP || x > 0)
+ return 0;
+ INT a = x - (M * N);
+ INT b = a / -N;
+ return b + -M;
+}
+
+INT NOINLINE
+opt_s5 (INT x)
+{
+ if (x > (-M * N) + GAP)
+ return 0;
+ INT a = x - (-M * N);
+ INT b = a / N;
+ return b + -M;
+}
+
+INT NOINLINE
+opt_s6 (INT x)
+{
+ if (x > IMAX - (M * N) + GAP || x < 0)
+ return 0;
+ INT a = x - (-M * N);
+ INT b = a / N;
+ return b + -M;
+}
+
+INT NOINLINE
+opt_s7 (INT x)
+{
+ if (x > (M * -N) + GAP)
+ return 0;
+ INT a = x - (M * -N);
+ INT b = a / -N;
+ return b + M;
+}
+
+INT NOINLINE
+opt_s8 (INT x)
+{
+ if (x > IMAX - (M * N) + GAP || x < 0)
+ return 0;
+ INT a = x - (M * -N);
+ INT b = a / -N;
+ return b + M;
+}
+
+UINT NOINLINE
+opt_u3 (UINT x)
+{
+ if (x < (M << N) - GAP)
+ return 0;
+ UINT a = x - (M << N);
+ UINT b = a >> N;
+ return b + M;
+}
+
+UINT NOINLINE
+opt_u4 (UINT x)
+{
+ if (x > (UMAX - (M << N)) + GAP)
+ return 0;
+ UINT a = x + (M << N);
+ UINT b = a >> N;
+ return b - M;
+}
+
+INT NOINLINE
+opt_s9 (INT x)
+{
+ if (x < (M << N) - GAP)
+ return 0;
+ INT a = x - (M << N);
+ INT b = a >> N;
+ return b + M;
+}
+
+INT NOINLINE
+opt_s10 (INT x)
+{
+ if (x < IMIN + (M << N) - GAP || x > 0)
+ return 0;
+ INT a = x - (M << N);
+ INT b = a >> N;
+ return b + M;
+}
+
+INT NOINLINE
+opt_s11 (INT x)
+{
+ if (x > (-M << N) + GAP)
+ return 0;
+ INT a = x - (-M << N);
+ INT b = a >> N;
+ return b + -M;
+}
+
+INT NOINLINE
+opt_s12 (INT x)
+{
+ if (x > IMAX - (M << N) + GAP || x < 0)
+ return 0;
+ INT a = x - (-M << N);
+ INT b = a >> N;
+ return b + -M;
+}