morestack.S (__morestack_non_split): Check whether caller is varargs and needs…

morestack.S (__morestack_non_split): Check whether caller is varargs and needs %bp to hold the stack frame on return.

libgcc/:
	* config/i386/morestack.S (__morestack_non_split): Check whether
	caller is varargs and needs %bp to hold the stack frame on return.
gcc/testsuite/:
	* gcc.dg/split-6.c: New test.

From-SVN: r187894

gcc/testsuite/ChangeLog

+2012-05-25  Ian Lance Taylor  <iant@google.com>
+
+	* gcc.dg/split-6.c: New test.
+
 2012-05-25  Eric Botcazou  <ebotcazou@adacore.com>
 
 	* gnat.dg/lto14.adb: New test.

gcc/testsuite/gcc.dg/split-6.c

+/* { dg-do run } */
+/* { dg-require-effective-target split_stack } */
+/* { dg-options "-fsplit-stack" } */
+
+/* This test is like split-3.c, but tests with a smaller stack frame,
+   since that uses a different prologue.  */
+
+#include <stdarg.h>
+#include <stdlib.h>
+
+/* Use a noinline function to ensure that the buffer is not removed
+   from the stack.  */
+static void use_buffer (char *buf) __attribute__ ((noinline));
+static void
+use_buffer (char *buf)
+{
+  buf[0] = '\0';
+}
+
+/* When using gold, the call to abort will force a stack split.  */
+
+static void
+down (int i, ...)
+{
+  char buf[1];
+  va_list ap;
+
+  va_start (ap, i);
+  if (va_arg (ap, int) != 1
+      || va_arg (ap, int) != 2
+      || va_arg (ap, int) != 3
+      || va_arg (ap, int) != 4
+      || va_arg (ap, int) != 5
+      || va_arg (ap, int) != 6
+      || va_arg (ap, int) != 7
+      || va_arg (ap, int) != 8
+      || va_arg (ap, int) != 9
+      || va_arg (ap, int) != 10)
+    abort ();
+
+  if (i > 0)
+    {
+      use_buffer (buf);
+      down (i - 1, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10);
+    }
+}
+
+int
+main (void)
+{
+  down (1000, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10);
+  return 0;
+}

libgcc/ChangeLog

+2012-05-25  Ian Lance Taylor  <iant@google.com>
+
+	* config/i386/morestack.S (__morestack_non_split): Check whether
+	caller is varargs and needs %bp to hold the stack frame on return.
+
 2012-05-25  Olivier Hainque  <hainque@adacore.com>
 
 	* config/rs6000/vxworks/tramp.S (trampoline_setup): Use a longcall
@@ -80,9 +85,9 @@
 
 2012-04-28  Aurelien Jarno  <aurelien@aurel32.net>
 
-	* config.host (mips64*-*-linux*, mipsisa64*-*-linux*): Remove. 
-	(mips*-*-linux*): Include mips/t-tpbit when long double is 
-	16 bytes long. 
+	* config.host (mips64*-*-linux*, mipsisa64*-*-linux*): Remove.
+	(mips*-*-linux*): Include mips/t-tpbit when long double is
+	16 bytes long.
 
 2012-04-25  Sriraman Tallam  <tmsriram@google.com>
 

libgcc/config/i386/morestack.S

 # x86/x86_64 support for -fsplit-stack.
-# Copyright (C) 2009, 2010, 2011 Free Software Foundation, Inc.
+# Copyright (C) 2009, 2010, 2011, 2012 Free Software Foundation, Inc.
 # Contributed by Ian Lance Taylor <iant@google.com>.
 
 # This file is part of GCC.
@@ -138,6 +138,24 @@ __morestack_non_split:
 	je	1f			# see above.
 	addl	$2,%eax
 1:	inc	%eax
+
+	# If the instruction that we return to is
+	#   leal  20(%ebp),{%eax,%ecx,%edx}
+	# then we have been called by a varargs function that expects
+	# %ebp to hold a real value.  That can only work if we do the
+	# full stack split routine.  FIXME: This is fragile.
+	cmpb	$0x8d,(%eax)
+	jne	3f
+	cmpb	$0x14,2(%eax)
+	jne	3f
+	cmpb	$0x45,1(%eax)
+	je	2f
+	cmpb	$0x4d,1(%eax)
+	je	2f
+	cmpb	$0x55,1(%eax)
+	je	2f
+
+3:	
 	movl	%eax,4(%esp)		# Update return address.
 
 	popl	%eax			# Restore %eax and stack.
@@ -175,18 +193,32 @@ __morestack_non_split:
 #else
 	cmpl	%fs:0x40,%eax
 #endif
-	popq	%rax			# Restore register.
-
-	.cfi_adjust_cfa_offset -8	# Adjust for popped register.
 
 	jb	2f			# Get more space if we need it.
 
 	# This breaks call/return prediction, as described above.
-	incq	(%rsp)			# Increment the return address.
+	incq	8(%rsp)			# Increment the return address.
+
+	# If the instruction that we return to is
+	#   leaq  24(%rbp), %r11n
+	# then we have been called by a varargs function that expects
+	# %ebp to hold a real value.  That can only work if we do the
+	# full stack split routine.  FIXME: This is fragile.
+	movq	8(%rsp),%rax
+	cmpl	$0x185d8d4c,(%rax)
+	je	2f
+
+	popq	%rax			# Restore register.
+
+	.cfi_adjust_cfa_offset -8	# Adjust for popped register.
 
 	ret				# Return to caller.
 
 2:
+	popq	%rax			# Restore register.
+
+	.cfi_adjust_cfa_offset -8	# Adjust for popped register.
+
 	addq	$0x5000+BACKOFF,%r10	# Increment space we request.
 
 	# Fall through into morestack.