re PR rtl-optimization/6842 (internal compiler error using MMX intrinsics with optimization)

	PR optimization/6842
	* combine.c (combine_simplify_rtx) [SUBREG]: Don't ICE if VOIDmode
	operand subreg cannot be simplified.

	* gcc.dg/20020531-1.c: New test.

From-SVN: r54462

gcc/ChangeLog

 2002-06-10  Jakub Jelinek  <jakub@redhat.com>
 
+	PR optimization/6842
+	* combine.c (combine_simplify_rtx) [SUBREG]: Don't ICE if VOIDmode
+	operand subreg cannot be simplified.
+
+2002-06-10  Jakub Jelinek  <jakub@redhat.com>
+
 	* varasm.c (const_hash): Handle FDESC_EXPR like ADDR_EXPR.
 	(compare_constant): Likewise.
 	(output_addressed_constants): Likewise.

gcc/combine.c

@@ -3866,7 +3866,12 @@ combine_simplify_rtx (x, op0_mode, last, in_dest)
 
       /* simplify_subreg can't use gen_lowpart_for_combine.  */
       if (CONSTANT_P (SUBREG_REG (x))
-	  && subreg_lowpart_offset (mode, op0_mode) == SUBREG_BYTE (x))
+	  && subreg_lowpart_offset (mode, op0_mode) == SUBREG_BYTE (x)
+	     /* Don't call gen_lowpart_for_combine if the inner mode
+		is VOIDmode and we cannot simplify it, as SUBREG without
+		inner mode is invalid.  */
+	  && (GET_MODE (SUBREG_REG (x)) != VOIDmode
+	      || gen_lowpart_common (mode, SUBREG_REG (x))))
 	return gen_lowpart_for_combine (mode, SUBREG_REG (x));
 
       if (GET_MODE_CLASS (GET_MODE (SUBREG_REG (x))) == MODE_CC)

gcc/testsuite/ChangeLog

@@ -4,6 +4,8 @@
 
 	* g++.dg/opt/vt1.C: New test.
 
+	* gcc.dg/20020531-1.c: New test.
+
 2002-06-07  Roger Sayle  <roger@eyesopen.com>
 
 	* gcc.dg/20020607-2.c: New test case.

gcc/testsuite/gcc.dg/20020531-1.c

+/* PR optimization/6842
+   This testcase caused ICE when trying to optimize V8QI subreg of VOIDmode
+   CONST_DOUBLE.  */
+/* { dg-do compile { target i?86-*-* } } */
+/* { dg-options "-O2 -mmmx" } */
+
+typedef int __v8qi __attribute__ ((__mode__ (__V8QI__)));
+extern void abort (void);
+extern void exit (int);
+
+void foo (void)
+{
+  unsigned long long a = 0x0102030405060708LL;
+  unsigned long long b = 0x1020304050607080LL;
+  unsigned long long c;
+
+  c = (unsigned long long) __builtin_ia32_paddusb ((__v8qi) a, (__v8qi) b);
+  __builtin_ia32_emms ();
+  if (c != 0x1122334455667788)
+    abort ();
+}