[patch][middle-end/PR102359]Not add initialization for DECL_VALUE_EXPR variables with -ftrivial-auto-var-init

[Qing Zhao]

This is the updated patch, I will push it after done with testing.

Let me know if you see any issue.

Thanks.

Qing.

============================

>From 1f07c20ecdc9a015369c8bb472ebbd3bcaabdf17 Mon Sep 17 00:00:00 2001
From: qing zhao <qing.zhao@oracle.com>
Date: Tue, 5 Oct 2021 08:10:02 -0700
Subject: [PATCH] middle-end/102359 Not add initialization for variables that
 have been  initialized by FEs.

C++ FE creates proxy variables, which have associated DECL_VALUE_EXPR
and have been initialized by FE. For such auto variable, we should not
add initialization when -ftrivial-auto-var-init presents.

gcc/ChangeLog:

2021-10-05  qing zhao  <qing.zhao@oracle.com>

	* gimplify.c (gimplify_decl_expr): Not add initialization for an
	auto variable when it has been initialized by frontend.

gcc/testsuite/ChangeLog:

2021-10-05  qing zhao  <qing.zhao@oracle.com>

	* g++.dg/pr102359_1.C: New test.
	* g++.dg/pr102359_2.C: New test.
---
 gcc/gimplify.c                    |  9 ++++++++-
 gcc/testsuite/g++.dg/pr102359_1.C | 13 +++++++++++++
 gcc/testsuite/g++.dg/pr102359_2.C | 13 +++++++++++++
 3 files changed, 34 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/g++.dg/pr102359_1.C
 create mode 100644 gcc/testsuite/g++.dg/pr102359_2.C

diff --git a/gcc/gimplify.c b/gcc/gimplify.c
index b27776a..d96fca4 100644
--- a/gcc/gimplify.c
+++ b/gcc/gimplify.c
@@ -1872,6 +1872,9 @@ gimplify_decl_expr (tree *stmt_p, gimple_seq *seq_p)
     {
       tree init = DECL_INITIAL (decl);
       bool is_vla = false;
+      /* Check whether a decl has FE created VALUE_EXPR here BEFORE
+	 gimplify_vla_decl creates VALUE_EXPR for a vla decl.  */
+      bool decl_had_value_expr_p = DECL_HAS_VALUE_EXPR_P (decl);
 
       poly_uint64 size;
       if (!poly_int_tree_p (DECL_SIZE_UNIT (decl), &size)
@@ -1934,7 +1937,11 @@ gimplify_decl_expr (tree *stmt_p, gimple_seq *seq_p)
       /* When there is no explicit initializer, if the user requested,
 	 We should insert an artifical initializer for this automatic
 	 variable.  */
-      else if (is_var_need_auto_init (decl))
+      else if (is_var_need_auto_init (decl)
+	       /* If the decl has VALUE_EXPR that was created by FE (usually
+		  C++FE), it's a proxy varaible, and FE already initialized
+		  the VALUE_EXPR of it, we should not initialize it here.  */
+	       && !decl_had_value_expr_p)
 	{
 	  gimple_add_init_for_auto_var (decl,
 					flag_auto_var_init,
diff --git a/gcc/testsuite/g++.dg/pr102359_1.C b/gcc/testsuite/g++.dg/pr102359_1.C
new file mode 100644
index 0000000..da643cd
--- /dev/null
+++ b/gcc/testsuite/g++.dg/pr102359_1.C
@@ -0,0 +1,13 @@
+/* PR middle-end/102359 ICE gimplification failed since
+   r12-3433-ga25e0b5e6ac8a77a.  */
+/* { dg-do compile } */
+/* { dg-options "-ftrivial-auto-var-init=zero" } */
+/* { dg-require-effective-target c++17 } */
+
+struct A {
+  double a = 111;
+  auto foo() {
+    return [*this] { return a; };
+  }
+};
+int X = A{}.foo()();
diff --git a/gcc/testsuite/g++.dg/pr102359_2.C b/gcc/testsuite/g++.dg/pr102359_2.C
new file mode 100644
index 0000000..d026d72
--- /dev/null
+++ b/gcc/testsuite/g++.dg/pr102359_2.C
@@ -0,0 +1,13 @@
+/* PR middle-end/102359 ICE gimplification failed since
+   r12-3433-ga25e0b5e6ac8a77a.  */
+/* { dg-do run} */
+/* { dg-options "-ftrivial-auto-var-init=zero" } */
+/* { dg-require-effective-target c++17 } */
+
+int main()
+{
+ int i = 42;
+ auto l = [=]() mutable { return i; };
+ if (l() != i)
+   __builtin_abort ();
+}
-- 
1.9.1