From: Jakub Jelinek <jakub@redhat.com>
Date: Thu, 11 Feb 2016 09:09:58 +0000 (+0100)
Subject: backport: re PR tree-optimization/68680 (On-stack VLA does not cause instrumentation... 
X-Git-Tag: releases/gcc-4.9.4~342
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2f5dd203e0ee48d1e0e57eab25d8aad0f2206504;p=thirdparty%2Fgcc.git

backport: re PR tree-optimization/68680 (On-stack VLA does not cause instrumentation with -fstack-protector)

	Backported from mainline
	2015-12-04  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/68680
	* calls.c (special_function_p): Return ECF_MAY_BE_ALLOCA for
	BUILT_IN_ALLOCA{,_WITH_ALIGN}.  Don't check for __builtin_alloca
	by name.

	* gcc.target/i386/pr68680.c: New test.

From-SVN: r233322
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 7508126e52f9..091289fb107d 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,6 +1,13 @@
 2016-02-11  Jakub Jelinek  <jakub@redhat.com>
 
 	Backported from mainline
+	2015-12-04  Jakub Jelinek  <jakub@redhat.com>
+
+	PR tree-optimization/68680
+	* calls.c (special_function_p): Return ECF_MAY_BE_ALLOCA for
+	BUILT_IN_ALLOCA{,_WITH_ALIGN}.  Don't check for __builtin_alloca
+	by name.
+
 	2015-11-21  Jakub Jelinek  <jakub@redhat.com>
 
 	PR debug/66432
diff --git a/gcc/calls.c b/gcc/calls.c
index 8ada78fba7f0..3cfb34446fda 100644
--- a/gcc/calls.c
+++ b/gcc/calls.c
@@ -521,12 +521,9 @@ special_function_p (const_tree fndecl, int flags)
       /* We assume that alloca will always be called by name.  It
 	 makes no sense to pass it as a pointer-to-function to
 	 anything that does not understand its behavior.  */
-      if (((IDENTIFIER_LENGTH (DECL_NAME (fndecl)) == 6
-	    && name[0] == 'a'
-	    && ! strcmp (name, "alloca"))
-	   || (IDENTIFIER_LENGTH (DECL_NAME (fndecl)) == 16
-	       && name[0] == '_'
-	       && ! strcmp (name, "__builtin_alloca"))))
+      if (IDENTIFIER_LENGTH (DECL_NAME (fndecl)) == 6
+	  && name[0] == 'a'
+	  && ! strcmp (name, "alloca"))
 	flags |= ECF_MAY_BE_ALLOCA;
 
       /* Disregard prefix _, __, __x or __builtin_.  */
@@ -572,6 +569,17 @@ special_function_p (const_tree fndecl, int flags)
 	flags |= ECF_NORETURN;
     }
 
+  if (DECL_BUILT_IN_CLASS (fndecl) == BUILT_IN_NORMAL)
+    switch (DECL_FUNCTION_CODE (fndecl))
+      {
+      case BUILT_IN_ALLOCA:
+      case BUILT_IN_ALLOCA_WITH_ALIGN:
+	flags |= ECF_MAY_BE_ALLOCA;
+	break;
+      default:
+	break;
+      }
+
   return flags;
 }
 
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 3db0586c4bfe..4a724f722b08 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,6 +1,11 @@
 2016-02-11  Jakub Jelinek  <jakub@redhat.com>
 
 	Backported from mainline
+	2015-12-04  Jakub Jelinek  <jakub@redhat.com>
+
+	PR tree-optimization/68680
+	* gcc.target/i386/pr68680.c: New test.
+
 	2015-12-03  Jakub Jelinek  <jakub@redhat.com>
 
 	PR preprocessor/57580
diff --git a/gcc/testsuite/gcc.target/i386/pr68680.c b/gcc/testsuite/gcc.target/i386/pr68680.c
new file mode 100644
index 000000000000..5524e156362e
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr68680.c
@@ -0,0 +1,15 @@
+/* PR tree-optimization/68680 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -fstack-protector-strong" } */
+
+int foo (char *);
+
+int
+bar (unsigned long x)
+{
+  char a[x];
+  return foo (a);
+}
+
+/* Verify that this function is stack protected.  */
+/* { dg-final { scan-assembler "stack_chk_fail" } } */