From 21c7aab09805d0c8c7695c8a69c8715d673a739a Mon Sep 17 00:00:00 2001
From: Andrew Pinski <apinski@marvell.com>
Date: Mon, 20 Dec 2021 20:27:33 -0800
Subject: [PATCH] Fix middle-end/103645: empty struct store not removed when
using compound literal
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.cc (gimplify_init_constructor): Don't build/add
gimple assignment of an empty type.
gcc/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 2ac7ca0855e5..f0fbdb48012b 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 18e092c46744..796fe6440c17 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" } } */
--
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