[v3] LoongArch: Replace -mexplicit-relocs=auto simple-used address peephole2 with combine
Checks
Commit Message
The problem with peephole2 is it uses a naive sliding-window algorithm
and misses many cases. For example:
float a[10000];
float t() { return a[0] + a[8000]; }
is compiled to:
la.local $r13,a
la.local $r12,a+32768
fld.s $f1,$r13,0
fld.s $f0,$r12,-768
fadd.s $f0,$f1,$f0
by trunk. But as we've explained in r14-4851, the following would be
better with -mexplicit-relocs=auto:
pcalau12i $r13,%pc_hi20(a)
pcalau12i $r12,%pc_hi20(a+32000)
fld.s $f1,$r13,%pc_lo12(a)
fld.s $f0,$r12,%pc_lo12(a+32000)
fadd.s $f0,$f1,$f0
However the sliding-window algorithm just won't detect the pcalau12i/fld
pair to be optimized. Use a define_insn_and_split in combine pass will
work around the issue.
gcc/ChangeLog:
* config/loongarch/predicates.md
(symbolic_pcrel_offset_operand): New define_predicate.
(mem_simple_ldst_operand): Likewise.
* config/loongarch/loongarch-protos.h
(loongarch_rewrite_mem_for_simple_ldst): Declare.
* config/loongarch/loongarch.cc
(loongarch_rewrite_mem_for_simple_ldst): Implement.
* config/loongarch/loongarch.md (simple_load<mode>): New
define_insn_and_rewrite.
(simple_load_<su>ext<SUBDI:mode><GPR:mode>): Likewise.
(simple_store<mode>): Likewise.
(define_peephole2): Remove la.local/[f]ld peepholes.
gcc/testsuite/ChangeLog:
* gcc.target/loongarch/explicit-relocs-auto-single-load-store-2.c:
New test.
* gcc.target/loongarch/explicit-relocs-auto-single-load-store-3.c:
New test.
---
Changes from [v2]:
- Match (mem (symbol_ref ...)) instead of (symbol_ref ...) to retain the
attributes of the MEM.
- Add a test to make sure the attributes of the MEM is retained.
[v2]:https://gcc.gnu.org/pipermail/gcc-patches/2023-December/641430.html
Bootstrapped & regtestd on loongarch64-linux-gnu. Ok for trunk?
gcc/config/loongarch/loongarch-protos.h | 1 +
gcc/config/loongarch/loongarch.cc | 16 +++
gcc/config/loongarch/loongarch.md | 114 +++++-------------
gcc/config/loongarch/predicates.md | 13 ++
...explicit-relocs-auto-single-load-store-2.c | 11 ++
...explicit-relocs-auto-single-load-store-3.c | 18 +++
6 files changed, 86 insertions(+), 87 deletions(-)
create mode 100644 gcc/testsuite/gcc.target/loongarch/explicit-relocs-auto-single-load-store-2.c
create mode 100644 gcc/testsuite/gcc.target/loongarch/explicit-relocs-auto-single-load-store-3.c
Comments
在 2023/12/29 上午12:11, Xi Ruoyao 写道:
> The problem with peephole2 is it uses a naive sliding-window algorithm
> and misses many cases. For example:
>
> float a[10000];
> float t() { return a[0] + a[8000]; }
>
> is compiled to:
>
> la.local $r13,a
> la.local $r12,a+32768
> fld.s $f1,$r13,0
> fld.s $f0,$r12,-768
> fadd.s $f0,$f1,$f0
>
> by trunk. But as we've explained in r14-4851, the following would be
> better with -mexplicit-relocs=auto:
>
> pcalau12i $r13,%pc_hi20(a)
> pcalau12i $r12,%pc_hi20(a+32000)
> fld.s $f1,$r13,%pc_lo12(a)
> fld.s $f0,$r12,%pc_lo12(a+32000)
> fadd.s $f0,$f1,$f0
>
> However the sliding-window algorithm just won't detect the pcalau12i/fld
> pair to be optimized. Use a define_insn_and_split in combine pass will
> work around the issue.
>
> gcc/ChangeLog:
>
> * config/loongarch/predicates.md
> (symbolic_pcrel_offset_operand): New define_predicate.
> (mem_simple_ldst_operand): Likewise.
> * config/loongarch/loongarch-protos.h
> (loongarch_rewrite_mem_for_simple_ldst): Declare.
> * config/loongarch/loongarch.cc
> (loongarch_rewrite_mem_for_simple_ldst): Implement.
> * config/loongarch/loongarch.md (simple_load<mode>): New
> define_insn_and_rewrite.
> (simple_load_<su>ext<SUBDI:mode><GPR:mode>): Likewise.
> (simple_store<mode>): Likewise.
> (define_peephole2): Remove la.local/[f]ld peepholes.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.target/loongarch/explicit-relocs-auto-single-load-store-2.c:
> New test.
> * gcc.target/loongarch/explicit-relocs-auto-single-load-store-3.c:
> New test.
> ---
>
> Changes from [v2]:
> - Match (mem (symbol_ref ...)) instead of (symbol_ref ...) to retain the
> attributes of the MEM.
> - Add a test to make sure the attributes of the MEM is retained.
>
> [v2]:https://gcc.gnu.org/pipermail/gcc-patches/2023-December/641430.html
>
> Bootstrapped & regtestd on loongarch64-linux-gnu. Ok for trunk?
>
> gcc/config/loongarch/loongarch-protos.h | 1 +
> gcc/config/loongarch/loongarch.cc | 16 +++
> gcc/config/loongarch/loongarch.md | 114 +++++-------------
> gcc/config/loongarch/predicates.md | 13 ++
> ...explicit-relocs-auto-single-load-store-2.c | 11 ++
> ...explicit-relocs-auto-single-load-store-3.c | 18 +++
> 6 files changed, 86 insertions(+), 87 deletions(-)
> create mode 100644 gcc/testsuite/gcc.target/loongarch/explicit-relocs-auto-single-load-store-2.c
> create mode 100644 gcc/testsuite/gcc.target/loongarch/explicit-relocs-auto-single-load-store-3.c
>
> diff --git a/gcc/config/loongarch/loongarch-protos.h b/gcc/config/loongarch/loongarch-protos.h
/* snip */
>
> diff --git a/gcc/config/loongarch/loongarch.md b/gcc/config/loongarch/loongarch.md
/* snip */
> +(define_insn_and_rewrite "simple_load<mode>"
> + [(set (match_operand:LD_AT_LEAST_32_BIT 0 "register_operand" "=r,f")
> + (match_operand:LD_AT_LEAST_32_BIT 1 "mem_simple_ldst_operand" ""))]
> + "loongarch_pre_reload_split () \
> + && la_opt_explicit_relocs == EXPLICIT_RELOCS_AUTO \
Is the '\' here dispensable? I don't seem to have added it when I wrote
the conditions.
> + && (TARGET_CMODEL_NORMAL || TARGET_CMODEL_MEDIUM)"
> + "#"
> + "&& true"
> {
> - emit_insn (gen_pcalau12i_gr<P:mode> (operands[0], operands[1]));
> + operands[1] = loongarch_rewrite_mem_for_simple_ldst (operands[1]);
> })
/* snip */
> ;; Synchronization instructions.
> diff --git a/gcc/config/loongarch/predicates.md b/gcc/config/loongarch/predicates.md
> index 83fea08315c..2158fe7538c 100644
> --- a/gcc/config/loongarch/predicates.md
> +++ b/gcc/config/loongarch/predicates.md
> @@ -579,6 +579,19 @@ (define_predicate "symbolic_pcrel_operand"
> return loongarch_symbolic_constant_p (op, &type) && type == SYMBOL_PCREL;
> })
>
> +(define_predicate "symbolic_pcrel_offset_operand"
> + (and (match_code "plus")
> + (match_operand 0 "symbolic_pcrel_operand")
> + (match_operand 1 "const_int_operand")))
> +
> +(define_predicate "mem_simple_ldst_operand"
> + (match_code "mem")
> +{
> + op = XEXP (op, 0);
> + return symbolic_pcrel_operand (op, Pmode) ||
> + symbolic_pcrel_offset_operand (op, Pmode);
> +})
> +
>
Symbol '||' It shouldn't be at the end of the line.
+ return symbolic_pcrel_operand (op, Pmode)
+ || symbolic_pcrel_offset_operand (op, Pmode);
Others LGTM.
Thanks!
/* snip */
On Fri, 2023-12-29 at 15:57 +0800, chenglulu wrote:
/* snip */
> > diff --git a/gcc/config/loongarch/loongarch.md b/gcc/config/loongarch/loongarch.md
> /* snip */
> > +(define_insn_and_rewrite "simple_load<mode>"
> > + [(set (match_operand:LD_AT_LEAST_32_BIT 0 "register_operand" "=r,f")
> > + (match_operand:LD_AT_LEAST_32_BIT 1 "mem_simple_ldst_operand" ""))]
> > + "loongarch_pre_reload_split () \
> > + && la_opt_explicit_relocs == EXPLICIT_RELOCS_AUTO \
> Is the '\' here dispensable? I don't seem to have added it when I wrote
> the conditions.
It seems '\' is not needed, I'll drop them.
/* snip */
>
> > +(define_predicate "mem_simple_ldst_operand"
> > + (match_code "mem")
> > +{
> > + op = XEXP (op, 0);
> > + return symbolic_pcrel_operand (op, Pmode) ||
> > + symbolic_pcrel_offset_operand (op, Pmode);
> > +})
> > +
> >
> Symbol '||' It shouldn't be at the end of the line.
Indeed.
>
> + return symbolic_pcrel_operand (op, Pmode)
> + || symbolic_pcrel_offset_operand (op, Pmode);
>
> Others LGTM.
> Thanks!
>
> /* snip */
>
@@ -163,6 +163,7 @@ extern bool loongarch_use_ins_ext_p (rtx, HOST_WIDE_INT, HOST_WIDE_INT);
extern bool loongarch_check_zero_div_p (void);
extern bool loongarch_pre_reload_split (void);
extern int loongarch_use_bstrins_for_ior_with_mask (machine_mode, rtx *);
+extern rtx loongarch_rewrite_mem_for_simple_ldst (rtx);
union loongarch_gen_fn_ptrs
{
@@ -5717,6 +5717,22 @@ loongarch_use_bstrins_for_ior_with_mask (machine_mode mode, rtx *op)
return 0;
}
+/* Rewrite a MEM for simple load/store under -mexplicit-relocs=auto
+ -mcmodel={normal/medium}. */
+rtx
+loongarch_rewrite_mem_for_simple_ldst (rtx mem)
+{
+ rtx addr = XEXP (mem, 0);
+ rtx hi = gen_rtx_UNSPEC (Pmode, gen_rtvec (1, addr),
+ UNSPEC_PCALAU12I_GR);
+ rtx new_mem;
+
+ addr = gen_rtx_LO_SUM (Pmode, force_reg (Pmode, hi), addr);
+ new_mem = gen_rtx_MEM (GET_MODE (mem), addr);
+ MEM_COPY_ATTRIBUTES (new_mem, mem);
+ return new_mem;
+}
+
/* Print the text for PRINT_OPERAND punctation character CH to FILE.
The punctuation characters are:
@@ -4135,101 +4135,41 @@ (define_insn "loongarch_crcc_w_<size>_w"
;;
;; And if the pseudo op cannot be relaxed, we'll get a worse result (with
;; 3 instructions).
-(define_peephole2
- [(set (match_operand:P 0 "register_operand")
- (match_operand:P 1 "symbolic_pcrel_operand"))
- (set (match_operand:LD_AT_LEAST_32_BIT 2 "register_operand")
- (mem:LD_AT_LEAST_32_BIT (match_dup 0)))]
- "la_opt_explicit_relocs == EXPLICIT_RELOCS_AUTO \
- && (TARGET_CMODEL_NORMAL || TARGET_CMODEL_MEDIUM) \
- && (peep2_reg_dead_p (2, operands[0]) \
- || REGNO (operands[0]) == REGNO (operands[2]))"
- [(set (match_dup 2)
- (mem:LD_AT_LEAST_32_BIT (lo_sum:P (match_dup 0) (match_dup 1))))]
- {
- emit_insn (gen_pcalau12i_gr<P:mode> (operands[0], operands[1]));
- })
-
-(define_peephole2
- [(set (match_operand:P 0 "register_operand")
- (match_operand:P 1 "symbolic_pcrel_operand"))
- (set (match_operand:LD_AT_LEAST_32_BIT 2 "register_operand")
- (mem:LD_AT_LEAST_32_BIT (plus (match_dup 0)
- (match_operand 3 "const_int_operand"))))]
- "la_opt_explicit_relocs == EXPLICIT_RELOCS_AUTO \
- && (TARGET_CMODEL_NORMAL || TARGET_CMODEL_MEDIUM) \
- && (peep2_reg_dead_p (2, operands[0]) \
- || REGNO (operands[0]) == REGNO (operands[2]))"
- [(set (match_dup 2)
- (mem:LD_AT_LEAST_32_BIT (lo_sum:P (match_dup 0) (match_dup 1))))]
- {
- operands[1] = plus_constant (Pmode, operands[1], INTVAL (operands[3]));
- emit_insn (gen_pcalau12i_gr<P:mode> (operands[0], operands[1]));
- })
-
-(define_peephole2
- [(set (match_operand:P 0 "register_operand")
- (match_operand:P 1 "symbolic_pcrel_operand"))
- (set (match_operand:GPR 2 "register_operand")
- (any_extend:GPR (mem:SUBDI (match_dup 0))))]
- "la_opt_explicit_relocs == EXPLICIT_RELOCS_AUTO \
- && (TARGET_CMODEL_NORMAL || TARGET_CMODEL_MEDIUM) \
- && (peep2_reg_dead_p (2, operands[0]) \
- || REGNO (operands[0]) == REGNO (operands[2]))"
- [(set (match_dup 2)
- (any_extend:GPR (mem:SUBDI (lo_sum:P (match_dup 0)
- (match_dup 1)))))]
+(define_insn_and_rewrite "simple_load<mode>"
+ [(set (match_operand:LD_AT_LEAST_32_BIT 0 "register_operand" "=r,f")
+ (match_operand:LD_AT_LEAST_32_BIT 1 "mem_simple_ldst_operand" ""))]
+ "loongarch_pre_reload_split () \
+ && la_opt_explicit_relocs == EXPLICIT_RELOCS_AUTO \
+ && (TARGET_CMODEL_NORMAL || TARGET_CMODEL_MEDIUM)"
+ "#"
+ "&& true"
{
- emit_insn (gen_pcalau12i_gr<P:mode> (operands[0], operands[1]));
+ operands[1] = loongarch_rewrite_mem_for_simple_ldst (operands[1]);
})
-(define_peephole2
- [(set (match_operand:P 0 "register_operand")
- (match_operand:P 1 "symbolic_pcrel_operand"))
- (set (match_operand:GPR 2 "register_operand")
+(define_insn_and_rewrite "simple_load_<su>ext<SUBDI:mode><GPR:mode>"
+ [(set (match_operand:GPR 0 "register_operand" "=r")
(any_extend:GPR
- (mem:SUBDI (plus (match_dup 0)
- (match_operand 3 "const_int_operand")))))]
- "la_opt_explicit_relocs == EXPLICIT_RELOCS_AUTO \
- && (TARGET_CMODEL_NORMAL || TARGET_CMODEL_MEDIUM) \
- && (peep2_reg_dead_p (2, operands[0]) \
- || REGNO (operands[0]) == REGNO (operands[2]))"
- [(set (match_dup 2)
- (any_extend:GPR (mem:SUBDI (lo_sum:P (match_dup 0)
- (match_dup 1)))))]
- {
- operands[1] = plus_constant (Pmode, operands[1], INTVAL (operands[3]));
- emit_insn (gen_pcalau12i_gr<P:mode> (operands[0], operands[1]));
- })
-
-(define_peephole2
- [(set (match_operand:P 0 "register_operand")
- (match_operand:P 1 "symbolic_pcrel_operand"))
- (set (mem:ST_ANY (match_dup 0))
- (match_operand:ST_ANY 2 "register_operand"))]
- "la_opt_explicit_relocs == EXPLICIT_RELOCS_AUTO \
- && (TARGET_CMODEL_NORMAL || TARGET_CMODEL_MEDIUM) \
- && (peep2_reg_dead_p (2, operands[0])) \
- && REGNO (operands[0]) != REGNO (operands[2])"
- [(set (mem:ST_ANY (lo_sum:P (match_dup 0) (match_dup 1))) (match_dup 2))]
+ (match_operand:SUBDI 1 "mem_simple_ldst_operand" "")))]
+ "loongarch_pre_reload_split () \
+ && la_opt_explicit_relocs == EXPLICIT_RELOCS_AUTO \
+ && (TARGET_CMODEL_NORMAL || TARGET_CMODEL_MEDIUM)"
+ "#"
+ "&& true"
{
- emit_insn (gen_pcalau12i_gr<P:mode> (operands[0], operands[1]));
+ operands[1] = loongarch_rewrite_mem_for_simple_ldst (operands[1]);
})
-(define_peephole2
- [(set (match_operand:P 0 "register_operand")
- (match_operand:P 1 "symbolic_pcrel_operand"))
- (set (mem:ST_ANY (plus (match_dup 0)
- (match_operand 3 "const_int_operand")))
- (match_operand:ST_ANY 2 "register_operand"))]
- "la_opt_explicit_relocs == EXPLICIT_RELOCS_AUTO \
- && (TARGET_CMODEL_NORMAL || TARGET_CMODEL_MEDIUM) \
- && (peep2_reg_dead_p (2, operands[0])) \
- && REGNO (operands[0]) != REGNO (operands[2])"
- [(set (mem:ST_ANY (lo_sum:P (match_dup 0) (match_dup 1))) (match_dup 2))]
+(define_insn_and_rewrite "simple_store<mode>"
+ [(set (match_operand:ST_ANY 0 "mem_simple_ldst_operand" "")
+ (match_operand:ST_ANY 1 "reg_or_0_operand" "r,f"))]
+ "loongarch_pre_reload_split () \
+ && la_opt_explicit_relocs == EXPLICIT_RELOCS_AUTO \
+ && (TARGET_CMODEL_NORMAL || TARGET_CMODEL_MEDIUM)"
+ "#"
+ "&& true"
{
- operands[1] = plus_constant (Pmode, operands[1], INTVAL (operands[3]));
- emit_insn (gen_pcalau12i_gr<P:mode> (operands[0], operands[1]));
+ operands[0] = loongarch_rewrite_mem_for_simple_ldst (operands[0]);
})
;; Synchronization instructions.
@@ -579,6 +579,19 @@ (define_predicate "symbolic_pcrel_operand"
return loongarch_symbolic_constant_p (op, &type) && type == SYMBOL_PCREL;
})
+(define_predicate "symbolic_pcrel_offset_operand"
+ (and (match_code "plus")
+ (match_operand 0 "symbolic_pcrel_operand")
+ (match_operand 1 "const_int_operand")))
+
+(define_predicate "mem_simple_ldst_operand"
+ (match_code "mem")
+{
+ op = XEXP (op, 0);
+ return symbolic_pcrel_operand (op, Pmode) ||
+ symbolic_pcrel_offset_operand (op, Pmode);
+})
+
(define_predicate "equality_operator"
(match_code "eq,ne"))
new file mode 100644
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -march=loongarch64 -mabi=lp64d -mexplicit-relocs=auto" } */
+
+float a[8001];
+float
+t (void)
+{
+ return a[0] + a[8000];
+}
+
+/* { dg-final { scan-assembler-not "la.local" } } */
new file mode 100644
@@ -0,0 +1,18 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -mexplicit-relocs=auto -fdump-rtl-final" } */
+/* { dg-final { scan-rtl-dump-times "mem/v/c" 2 "final" } } */
+/* { dg-final { scan-assembler-not "la\\.local" } } */
+
+volatile unsigned long counter;
+
+unsigned long
+read (void)
+{
+ return counter;
+}
+
+void
+clear (void)
+{
+ counter = 0;
+}