[PATCH] volatile not taken into account for local variables

[Jakub Jelinek]

Hi!

Since

Wed May 31 08:07:52 2000  Richard Kenner  <kenner@vlsi1.ultra.nyu.edu>

	* stmt.c (expand_decl): Call set_mem_attributes.

patch volatile modifier is not considered for local variables as can be seen
in the test below on ia32 or e.g. in the testcase below the patch (but as it
uses signals, alarm and also if not successful loops forever, I don't think
it can go into the testsuite). I understand mem_set_attributes cannot be
called on assign_temp because assign_temp code does not consider MEM flags
when looking for reusable slots yet, so for now I think we should just set
MEM_VOLATILE_P and later on if assign_temp is changed call here full
mem_set_attributes.

2000-11-22  Jakub Jelinek  <jakub@redhat.com>

	* stmt.c (expand_decl): Set MEM_VOLATILE_P of stack temp for
	volatile trees.

	* gcc.c-torture/execute/ieee/20001122-1.c: New test.

--- gcc/stmt.c.jj	Mon Nov 20 16:27:21 2000
+++ gcc/stmt.c	Wed Nov 22 13:03:05 2000
@@ -3877,6 +3877,8 @@ expand_decl (decl)
 	}
 
       DECL_RTL (decl) = assign_temp (TREE_TYPE (decl), 1, 1, 1);
+      if (TREE_THIS_VOLATILE (decl))
+	MEM_VOLATILE_P (DECL_RTL (decl)) = 1;
 
       /* Set alignment we actually gave this decl.  */
       DECL_ALIGN (decl) = (DECL_MODE (decl) == BLKmode ? BIGGEST_ALIGNMENT
--- gcc/testsuite/gcc.c-torture/execute/ieee/20001122-1.c.jj	Wed Nov 22 13:19:38 2000
+++ gcc/testsuite/gcc.c-torture/execute/ieee/20001122-1.c	Wed Nov 22 13:22:02 2000
@@ -0,0 +1,22 @@
+volatile double a, *p;
+
+int main ()
+{
+  double c, d;
+  volatile double b;
+
+  d = 1.0;
+  p = &b;
+  do
+  {
+    c = d;
+    d = c * 0.5;
+    b = 1 + d;
+  } while (b != 1.0);
+
+  a = 1.0 + c;
+  if (a == 1.0)
+    abort();
+
+  exit (0);
+}

#include <unistd.h>
#include <signal.h>

volatile int *dp;

void
dosig (int n)
{
   *dp = 0;
}

int
main ()
{
   volatile int d;

   signal (SIGALRM, dosig);
   alarm(2);
   d = 1;
   dp = &d;
   while (d);
   return 0;
}


	Jakub