Fix middle-end/103645: empty struct store not removed when using compound literal
Commit Message
From: Andrew Pinski <apinski@marvell.com>
For compound literals empty struct stores are not removed as they go down a
different path of the gimplifier; trying to optimize the init constructor.
This fixes the problem by not adding the gimple assignment at the end
of gimplify_init_constructor if it was an empty type.
Note this updates gcc.dg/pr87052.c where we had:
const char d[0] = { };
And was expecting a store to d but after this, there is no store
as the decl's type is zero in size.
OK? Bootstrapped and tested on x86_64-linux-gnu with no regressions.
gcc/ChangeLog:
PR middle-end/103645
* gimplify.c (gimplify_init_constructor): Don't build/add
gimple assignment of an empty type.
testsuite/ChangeLog:
* gcc.dg/pr87052.c: Update d var to expect nothing.
---
gcc/gimplify.cc | 7 +++++--
gcc/testsuite/gcc.dg/pr87052.c | 6 +++---
2 files changed, 8 insertions(+), 5 deletions(-)
Comments
On Mon, Aug 8, 2022 at 5:38 AM apinski--- via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> From: Andrew Pinski <apinski@marvell.com>
>
> For compound literals empty struct stores are not removed as they go down a
> different path of the gimplifier; trying to optimize the init constructor.
> This fixes the problem by not adding the gimple assignment at the end
> of gimplify_init_constructor if it was an empty type.
>
> Note this updates gcc.dg/pr87052.c where we had:
> const char d[0] = { };
> And was expecting a store to d but after this, there is no store
> as the decl's type is zero in size.
>
> OK? Bootstrapped and tested on x86_64-linux-gnu with no regressions.
OK.
> gcc/ChangeLog:
>
> PR middle-end/103645
> * gimplify.c (gimplify_init_constructor): Don't build/add
> gimple assignment of an empty type.
>
> testsuite/ChangeLog:
> * gcc.dg/pr87052.c: Update d var to expect nothing.
> ---
> gcc/gimplify.cc | 7 +++++--
> gcc/testsuite/gcc.dg/pr87052.c | 6 +++---
> 2 files changed, 8 insertions(+), 5 deletions(-)
>
> diff --git a/gcc/gimplify.cc b/gcc/gimplify.cc
> index 2ac7ca0855e..f0fbdb48012 100644
> --- a/gcc/gimplify.cc
> +++ b/gcc/gimplify.cc
> @@ -5488,8 +5488,11 @@ gimplify_init_constructor (tree *expr_p, gimple_seq *pre_p, gimple_seq *post_p,
> if (ret == GS_ERROR)
> return GS_ERROR;
> /* If we have gimplified both sides of the initializer but have
> - not emitted an assignment, do so now. */
> - if (*expr_p)
> + not emitted an assignment, do so now. */
> + if (*expr_p
> + /* If the type is an empty type, we don't need to emit the
> + assignment. */
> + && !is_empty_type (TREE_TYPE (TREE_OPERAND (*expr_p, 0))))
> {
> tree lhs = TREE_OPERAND (*expr_p, 0);
> tree rhs = TREE_OPERAND (*expr_p, 1);
> diff --git a/gcc/testsuite/gcc.dg/pr87052.c b/gcc/testsuite/gcc.dg/pr87052.c
> index 18e092c4674..796fe6440c1 100644
> --- a/gcc/testsuite/gcc.dg/pr87052.c
> +++ b/gcc/testsuite/gcc.dg/pr87052.c
> @@ -23,8 +23,7 @@ void test (void)
>
> const char d[0] = { };
>
> - /* Expect the following:
> - d = ""; */
> + /* Expect nothing. */
>
> const char e[0] = "";
>
> @@ -36,6 +35,7 @@ void test (void)
> /* { dg-final { scan-tree-dump-times "a = \"\\\\x00ab\";" 1 "gimple" } }
> { dg-final { scan-tree-dump-times "b = \"a\\\\x00bc\";" 1 "gimple" } }
> { dg-final { scan-tree-dump-times "c = \"\";" 1 "gimple" } }
> - { dg-final { scan-tree-dump-times "d = { *};" 1 "gimple" } }
> + { dg-final { scan-tree-dump-times "d = " 1 "gimple" } }
> + { dg-final { scan-tree-dump-times "d = {CLOBBER\\(eol\\)}" 1 "gimple" } }
> { dg-final { scan-tree-dump-times "e = " 1 "gimple" } }
> { dg-final { scan-tree-dump-times "e = {CLOBBER\\(eol\\)}" 1 "gimple" } } */
> --
> 2.27.0
>
@@ -5488,8 +5488,11 @@ gimplify_init_constructor (tree *expr_p, gimple_seq *pre_p, gimple_seq *post_p,
if (ret == GS_ERROR)
return GS_ERROR;
/* If we have gimplified both sides of the initializer but have
- not emitted an assignment, do so now. */
- if (*expr_p)
+ not emitted an assignment, do so now. */
+ if (*expr_p
+ /* If the type is an empty type, we don't need to emit the
+ assignment. */
+ && !is_empty_type (TREE_TYPE (TREE_OPERAND (*expr_p, 0))))
{
tree lhs = TREE_OPERAND (*expr_p, 0);
tree rhs = TREE_OPERAND (*expr_p, 1);
@@ -23,8 +23,7 @@ void test (void)
const char d[0] = { };
- /* Expect the following:
- d = ""; */
+ /* Expect nothing. */
const char e[0] = "";
@@ -36,6 +35,7 @@ void test (void)
/* { dg-final { scan-tree-dump-times "a = \"\\\\x00ab\";" 1 "gimple" } }
{ dg-final { scan-tree-dump-times "b = \"a\\\\x00bc\";" 1 "gimple" } }
{ dg-final { scan-tree-dump-times "c = \"\";" 1 "gimple" } }
- { dg-final { scan-tree-dump-times "d = { *};" 1 "gimple" } }
+ { dg-final { scan-tree-dump-times "d = " 1 "gimple" } }
+ { dg-final { scan-tree-dump-times "d = {CLOBBER\\(eol\\)}" 1 "gimple" } }
{ dg-final { scan-tree-dump-times "e = " 1 "gimple" } }
{ dg-final { scan-tree-dump-times "e = {CLOBBER\\(eol\\)}" 1 "gimple" } } */