From: Alexandre Oliva <oliva@adacore.com>
Date: Wed, 10 Jun 2020 20:56:36 +0000 (-0300)
Subject: [PR51447] restore the global reg var before returning from main
X-Git-Tag: basepoints/gcc-12~7072
X-Git-Url: https://gcc.gnu.org/git/?a=commitdiff_plain;h=06ef9c119c56568e5f77a5189aa382cb97c95a9e;hp=a9eec9625ea7165292958be04899b057804192fb;p=gcc.git

[PR51447] restore the global reg var before returning from main

A runtime system might legitimately hold in rbx a value expected to be
preserved across the call to main, but its use as a global register
variable stops main from preserving it.


for  gcc/testsuite/ChangeLog

	PR rtl-optimization/51447
	* gcc.c-torture/execute/pr51447.c (main): Preserve call-saved
	register.
---

diff --git a/gcc/testsuite/gcc.c-torture/execute/pr51447.c b/gcc/testsuite/gcc.c-torture/execute/pr51447.c
index 887ddb7d0677..1d00953af3aa 100644
--- a/gcc/testsuite/gcc.c-torture/execute/pr51447.c
+++ b/gcc/testsuite/gcc.c-torture/execute/pr51447.c
@@ -14,6 +14,9 @@ int
 main (void)
 {
   __label__ nonlocal_lab;
+#ifdef __x86_64__
+  void *save = ptr;
+#endif
   __attribute__((noinline, noclone)) void
     bar (void *func)
       {
@@ -25,5 +28,8 @@ main (void)
 nonlocal_lab:
   if (ptr != &&nonlocal_lab)
     abort ();
+#ifdef __x86_64__
+  ptr = save; /* Restore the call-saved register.  */
+#endif
   return 0;
 }