From: Andreas Krebbel <Andreas.Krebbel@de.ibm.com>
Date: Tue, 30 Mar 2010 13:27:36 +0000 (+0000)
Subject: s390.c (s390_emit_prologue): Omit issuing a
X-Git-Tag: releases/gcc-4.3.5~118
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=bff443405d3cc1729b88a3688895e57a4f12cbb0;p=thirdparty%2Fgcc.git

s390.c (s390_emit_prologue): Omit issuing a


2010-03-30  Andreas Krebbel  <Andreas.Krebbel@de.ibm.com>

        * config/s390/s390.c (s390_emit_prologue): Omit issuing a
        * dynamic
        stack check if the mask would be zero.

2010-03-30  Andreas Krebbel  <Andreas.Krebbel@de.ibm.com>

        * gcc.target/s390/stackcheck1.c: New testcase.

From-SVN: r157824
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 838e39de9d34..c68f8bf1983a 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2010-03-30  Andreas Krebbel  <Andreas.Krebbel@de.ibm.com>
+
+	* config/s390/s390.c (s390_emit_prologue): Omit issuing a dynamic
+	stack check if the mask would be zero.
+
 2010-03-27  Uros Bizjak  <ubizjak@gmail.com>
 
 	PR target/42113
diff --git a/gcc/config/s390/s390.c b/gcc/config/s390/s390.c
index 280358c0c3f6..9c806467e9f6 100644
--- a/gcc/config/s390/s390.c
+++ b/gcc/config/s390/s390.c
@@ -7357,20 +7357,37 @@ s390_emit_prologue (void)
 	    }
 	  else
 	    {
-	      HOST_WIDE_INT stack_check_mask = ((s390_stack_size - 1)
-						& ~(stack_guard - 1));
-	      rtx t = gen_rtx_AND (Pmode, stack_pointer_rtx,
-				   GEN_INT (stack_check_mask));
-	      if (TARGET_64BIT)
-		gen_cmpdi (t, const0_rtx);
-	      else
-		gen_cmpsi (t, const0_rtx);
-
-	      emit_insn (gen_conditional_trap (gen_rtx_EQ (CCmode,
-							   gen_rtx_REG (CCmode,
-								     CC_REGNUM),
-							   const0_rtx),
-					       const0_rtx));
+ 	      /* stack_guard has to be smaller than s390_stack_size.
+ 		 Otherwise we would emit an AND with zero which would
+ 		 not match the test under mask pattern.  */
+ 	      if (stack_guard >= s390_stack_size)
+ 		{
+ 		  warning (0, "frame size of function %qs is "
+			   HOST_WIDE_INT_PRINT_DEC
+ 			   " bytes which is more than half the stack size. "
+ 			   "The dynamic check would not be reliable. "
+ 			   "No check emitted for this function.",
+ 			   current_function_name(),
+ 			   cfun_frame_layout.frame_size);
+ 		}
+ 	      else
+ 		{
+		  HOST_WIDE_INT stack_check_mask = ((s390_stack_size - 1)
+						    & ~(stack_guard - 1));
+		  rtx t = gen_rtx_AND (Pmode, stack_pointer_rtx,
+				       GEN_INT (stack_check_mask));
+		  if (TARGET_64BIT)
+		    gen_cmpdi (t, const0_rtx);
+		  else
+		    gen_cmpsi (t, const0_rtx);
+
+		  emit_insn (gen_conditional_trap (
+                               gen_rtx_EQ (CCmode,
+					   gen_rtx_REG (CCmode,
+							CC_REGNUM),
+					   const0_rtx),
+			       const0_rtx));
+		}
 	    }
   	}
 
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index df9456535a45..124ff8367577 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2010-03-30  Andreas Krebbel  <Andreas.Krebbel@de.ibm.com>
+
+	* gcc.target/s390/stackcheck1.c: New testcase.
+
 2010-03-21  Kaveh R. Ghazi  <ghazi@caip.rutgers.edu>
 
 	* gcc.target/powerpc/ppc-sdata-1.c: Require nonpic.
diff --git a/gcc/testsuite/gcc.target/s390/stackcheck1.c b/gcc/testsuite/gcc.target/s390/stackcheck1.c
new file mode 100644
index 000000000000..f588833d899e
--- /dev/null
+++ b/gcc/testsuite/gcc.target/s390/stackcheck1.c
@@ -0,0 +1,14 @@
+/* The automatically chosen stack guard value caused an ICE in that
+   case.  */
+
+/* { dg-do compile } */
+/* { dg-options "-O2 -mstack-size=4096" } */
+
+extern void bar (char *);
+
+void
+foo ()
+{
+  char a[2500];
+  bar (a);
+}