From aeca44768d54b089243004d1ef00d34dfa9f6530 Mon Sep 17 00:00:00 2001 From: Jakub Jelinek Date: Mon, 17 Jan 2022 18:10:34 +0100 Subject: [PATCH] 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 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. --- gcc/cp/cp-gimplify.c | 9 +++++++-- gcc/testsuite/g++.dg/cpp1y/pr104031.C | 23 +++++++++++++++++++++++ 2 files changed, 30 insertions(+), 2 deletions(-) create mode 100644 gcc/testsuite/g++.dg/cpp1y/pr104031.C diff --git a/gcc/cp/cp-gimplify.c b/gcc/cp/cp-gimplify.c index b80010e..ad61030 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 0000000..5f73662 --- /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 () +{ +} -- 2.7.4