re PR target/5755 (-mregparm=3 and -fomit-frame-pointer corrupt esp register)

	PR target/5755
	* config/i386/i386.c (ix86_return_pops_args): Only pop
	fake structure return argument if it was passed on the stack.

	* gcc.dg/20020224-1.c: New test.

From-SVN: r50028

gcc/ChangeLog

+2002-02-25  Jakub Jelinek  <jakub@redhat.com>
+
+	PR target/5755
+	* config/i386/i386.c (ix86_return_pops_args): Only pop
+	fake structure return argument if it was passed on the stack.
+
 2002-02-25  Jason Merrill  <jason@redhat.com>
 
 	* attribs.c (decl_attributes): Also re-layout PARM_DECL and

gcc/config/i386/i386.c

@@ -1466,12 +1466,25 @@ ix86_return_pops_args (fundecl, funtype, size)
       return size;
   }
 
-  /* Lose any fake structure return argument.  */
+  /* Lose any fake structure return argument if it is passed on the stack.  */
   if (aggregate_value_p (TREE_TYPE (funtype))
       && !TARGET_64BIT)
-    return GET_MODE_SIZE (Pmode);
+    {
+      int nregs = ix86_regparm;
 
-    return 0;
+      if (funtype)
+	{
+	  tree attr = lookup_attribute ("regparm", TYPE_ATTRIBUTES (funtype));
+
+	  if (attr)
+	    nregs = TREE_INT_CST_LOW (TREE_VALUE (TREE_VALUE (attr)));
+	}
+
+      if (!nregs)
+	return GET_MODE_SIZE (Pmode);
+    }
+
+  return 0;
 }
 
 /* Argument support functions.  */

gcc/testsuite/ChangeLog

+2002-02-25  Jakub Jelinek  <jakub@redhat.com>
+
+	* gcc.dg/20020224-1.c: New test.
+
 2002-02-25  Alan Modra  <amodra@bigpond.net.au>
 
 	* gcc.c-torture/execute/20020225-1.c: New.

gcc/testsuite/gcc.dg/20020224-1.c

+/* PR target/5755
+   This testcase failed because the caller of a function returning struct
+   expected the callee to pop up the hidden return structure pointer,
+   while callee was actually not poping it up (as the hidden argument
+   was passed in register).  */
+/* { dg-do run { target i?86-*-* } } */
+/* { dg-options "-O2 -fomit-frame-pointer" } */
+
+extern void abort (void);
+extern void exit (int);
+
+typedef struct {
+   int a1, a2;
+} A;
+
+A a;
+
+A __attribute__ ((regparm (2)))
+foo (int x)
+{
+  return a;
+}
+
+int __attribute__ ((regparm (2)))
+bar (int x)
+{
+  int r = foo(0).a2;
+  return r;
+}
+
+int
+main ()
+{
+  int f;
+  a.a1 = 530;
+  a.a2 = 980;
+  f = bar (0);
+  if (f != 980)
+    abort ();
+  exit (0);
+}