Patchwork [PR,46226] asm goto may leave stack pointer invalid

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Submitter Richard Henderson
Date Oct. 29, 2010, 5:08 p.m.
Message ID <4CCAFF7E.5080807@redhat.com>
Download mbox | patch
Permalink /patch/69612/
State New
Headers show

Comments

Richard Henderson - Oct. 29, 2010, 5:08 p.m.
An asm goto is a jump instruction, therefore we must ensure a
consistent stack wrt pending adjustments beforehand.

Tested on i486 and x86_64-linux, committed to 4.5 and head.


r~
PR rtl-opt/46226
	* stmt.c (expand_asm_operands): Call do_pending_stack_adjust
	for asm goto.
Richard Henderson - Oct. 29, 2010, 5:14 p.m.
On 10/29/2010 10:08 AM, Richard Henderson wrote:
> An asm goto is a jump instruction, therefore we must ensure a
> consistent stack wrt pending adjustments beforehand.
> 
> Tested on i486 and x86_64-linux, committed to 4.5 and head.

Arg!  -ENOCOFFEE.  I put the testcase in the wrong directory.
It should have been x86-specific, since it does use a "jmp"
insn in the asm goto.

I've moved it from gcc.dg/ to gcc.target/i386/.


r~

Patch

diff --git a/gcc/stmt.c b/gcc/stmt.c
index 9096d83..c8f56f5 100644
--- a/gcc/stmt.c
+++ b/gcc/stmt.c
@@ -776,6 +776,10 @@  expand_asm_operands (tree string, tree outputs, tree inputs,
 
   /* Second pass evaluates arguments.  */
 
+  /* Make sure stack is consistent for asm goto.  */
+  if (nlabels > 0)
+    do_pending_stack_adjust ();
+
   ninout = 0;
   for (i = 0, tail = outputs; tail; tail = TREE_CHAIN (tail), i++)
     {
diff --git a/gcc/testsuite/gcc.dg/pr46226.c b/gcc/testsuite/gcc.dg/pr46226.c
new file mode 100644
index 0000000..9934a4f
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr46226.c
@@ -0,0 +1,36 @@ 
+/* { dg-do run } */
+/* { dg-options "-Os -fomit-frame-pointer" } */
+/* { dg-options "-Os -fomit-frame-pointer -mno-accumulate-outgoing-args -fno-asynchronous-unwind-tables" { target { i?86-*-* x86_64-*-* } } } */
+
+extern void abort(void);
+
+static void *p[2];
+
+void __attribute__((noinline))
+g(int x, ...)
+{
+  asm volatile ("" : : "g"(x));
+}
+
+void __attribute__((noinline))
+f(int x)
+{
+  p[0] = __builtin_return_address (0);
+  if (x == 0)
+    g(0);
+  g(1, 2, 3, 4, 5, 6, 7);
+
+  asm goto ("jmp %l0" : : : : label);
+  abort ();
+
+ label:
+  p[1] = __builtin_return_address (0);
+}
+
+int main()
+{
+  f(1);
+  if (p[0] != p[1])
+    abort ();
+  return 0;
+}