re PR middle-end/18548 (Miscompiles code generated by Gambit-C Scheme->C compiler)

	PR middle-end/18548
	* expr.c (expand_expr_real_1) <MAX_EXPR>: Ensure that target, op0
	and op1 are all registers (or constants) before expanding the RTL
	comparison sequence [to avoid reg_overlap_mentioned (target, op1)].

	* gcc.dg/max-1.c: New test case.

From-SVN: r92351

gcc/ChangeLog

+2004-12-18  Roger Sayle  <roger@eyesopen.com>
+
+	PR middle-end/18548
+	* expr.c (expand_expr_real_1) <MAX_EXPR>: Ensure that target, op0
+	and op1 are all registers (or constants) before expanding the RTL
+	comparison sequence [to avoid reg_overlap_mentioned (target, op1)].
+
 2004-12-18  Eric Botcazou  <ebotcazou@libertysurf.fr>
 
 	PR rtl-optimization/16968

gcc/expr.c

@@ -7671,7 +7671,7 @@ expand_expr_real_1 (tree exp, rtx target, enum machine_mode tmode,
       /* At this point, a MEM target is no longer useful; we will get better
 	 code without it.  */
 
-      if (MEM_P (target))
+      if (! REG_P (target))
 	target = gen_reg_rtx (mode);
 
       /* If op1 was placed in target, swap op0 and op1.  */
@@ -7682,6 +7682,11 @@ expand_expr_real_1 (tree exp, rtx target, enum machine_mode tmode,
 	  op1 = tem;
 	}
 
+      /* We generate better code and avoid problems with op1 mentioning
+	 target by forcing op1 into a pseudo if it isn't a constant.  */
+      if (! CONSTANT_P (op1))
+	op1 = force_reg (mode, op1);
+
       if (target != op0)
 	emit_move_insn (target, op0);
 

gcc/testsuite/ChangeLog

+2004-12-18  Roger Sayle  <roger@eyesopen.com>
+
+	PR middle-end/18548
+	* gcc.dg/max-1.c: New test case.
+
 2004-12-18  Jakub Jelinek  <jakub@redhat.com>
 
 	* gcc.c-torture/execute/20041218-1.c: New test.

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

+/* PR middle-end/18548 */
+/* Test case reduced by Andrew Pinski <pinskia@physics.uc.edu> */
+/* { dg-do run } */
+/* { dg-options "-O1 -fno-tree-lrs" } */
+
+extern void abort (void);
+
+long fff[10];
+
+void f(long a, long b)
+{
+  long crcc = b;
+  long d = *((long*)(a+1));
+  int i;
+
+  a = d >= b? d:b;
+
+
+  for(i=0;i<10;i++)
+   fff[i] = a;
+}
+
+int main(void)
+{
+  int i;
+  long a = 10;
+  f((long)(&a)-1,0);
+  for(i = 0;i<10;i++)
+   if (fff[i]!=10)
+    abort ();
+  return 0;
+}
+