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* [gcc r12-6643] c++: Fix cp_genericize_target_expr for TARGET_EXPRs created for global initialization [PR104031]
@ 2022-01-17 17:11 Jakub Jelinek
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From: Jakub Jelinek @ 2022-01-17 17:11 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:aeca44768d54b089243004d1ef00d34dfa9f6530
commit r12-6643-gaeca44768d54b089243004d1ef00d34dfa9f6530
Author: Jakub Jelinek <jakub@redhat.com>
Date: Mon Jan 17 18:10:34 2022 +0100
c++: Fix cp_genericize_target_expr for TARGET_EXPRs created for global initialization [PR104031]
The following patch is miscompiled, cp_genericize_target_expr expects
that for the constant part split_nonconstant_init will emit an INIT_EXPR
that will initialize it, but that doesn't happen and instead we get
DECL_INITIAL on the TARGET_EXPR_SLOT that isn't initialized anywhere
in the IL.
The problem is that the TARGET_EXPR has been created while
current_function_decl was NULL, it is inside a global var initializer.
That means the build_local_temp created VAR_DECL has NULL DECL_CONTEXT.
Later on when genericizing the ssdf (current_function_decl is already
non-NULL), the new cp_genericize_target_expr is called and during
split_nonconstant_init it checks is_local_temp, but that due to the NULL
DECL_CONTEXT returns false. DECL_CONTEXT is set only later on during
gimplification.
The following patch fixes it by setting DECL_CONTEXT also inside of
cp_genericize_target_expr, which fixes the testcase. But if there are
better spots to do that, please let me know...
2022-01-17 Jakub Jelinek <jakub@redhat.com>
PR c++/104031
* cp-gimplify.c (cp_genericize_target_expr): Set DECL_CONTEXT of
TARGET_EXPR_SLOT to current_function_decl if it was NULL.
* g++.dg/cpp1y/pr104031.C: New test.
Diff:
---
gcc/cp/cp-gimplify.c | 9 +++++++--
gcc/testsuite/g++.dg/cpp1y/pr104031.C | 23 +++++++++++++++++++++++
2 files changed, 30 insertions(+), 2 deletions(-)
diff --git a/gcc/cp/cp-gimplify.c b/gcc/cp/cp-gimplify.c
index b80010e0983..ad610309953 100644
--- a/gcc/cp/cp-gimplify.c
+++ b/gcc/cp/cp-gimplify.c
@@ -930,9 +930,14 @@ cp_genericize_init_expr (tree *stmt_p)
static void
cp_genericize_target_expr (tree *stmt_p)
{
+ tree slot = TARGET_EXPR_SLOT (*stmt_p);
+ /* If TARGET_EXPR is created for some global var initializer, the slot
+ will have NULL and so is_local_temp will return false for it. If
+ this is a ssdf, set DECL_CONTEXT now. */
+ if (DECL_CONTEXT (slot) == NULL_TREE)
+ DECL_CONTEXT (slot) = current_function_decl;
cp_genericize_init (&TARGET_EXPR_INITIAL (*stmt_p),
- TARGET_EXPR_INITIAL (*stmt_p),
- TARGET_EXPR_SLOT (*stmt_p));
+ TARGET_EXPR_INITIAL (*stmt_p), slot);
}
/* Genericization context. */
diff --git a/gcc/testsuite/g++.dg/cpp1y/pr104031.C b/gcc/testsuite/g++.dg/cpp1y/pr104031.C
new file mode 100644
index 00000000000..5f736621ae1
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1y/pr104031.C
@@ -0,0 +1,23 @@
+// PR c++/104031
+// { dg-do run { target c++14 } }
+// { dg-options "-O2" }
+
+struct A {
+ A () {}
+ ~A () {}
+};
+struct B {
+ A a;
+ int b = 0;
+};
+struct C
+{
+ [[gnu::noipa]]
+ C (B x) { if (x.b != 42) __builtin_abort (); }
+};
+static C c ({ .a = A{}, .b = 42 });
+
+int
+main ()
+{
+}
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