[PATCH, i386]: Fix PR44578, GCC generates MMX instructions but fails to generate "emms"

[Uros Bizjak]

Hello!

Attached patch fixes PR44578, where MMX register was allocated for
zero_extendsidi2 RTX. The patch adds "!" to the interfering
alternative, so RA won't choose alternative involving MMX register
unless absolute necessary.

2013-04-29  Uros Bizjak  <ubiz...@gmail.com>

    PR target/44578
    * config/i386/i386.md (*zero_extendisid2): Add "!" to m->?*y
    alternative.

testsuite/ChangeLog:

2013-04-29  Uros Bizjak  <ubiz...@gmail.com>

    PR target/44578
    * gcc.target/i386/pr44578.c: New test.

Patch was bootstrapped and regression tested on x86_64-pc-linux-gnu
{,-m32} and was committed to mainline SVN.

The patch will be backported to 4.7 and 4.8 branches.

Uros.

Index: config/i386/i386.md
===================================================================
--- config/i386/i386.md (revision 198401)
+++ config/i386/i386.md (working copy)
@@ -3049,10 +3049,10 @@
 
 (define_insn "*zero_extendsidi2"
   [(set (match_operand:DI 0 "nonimmediate_operand"
-                       "=r,?r,?o,r   ,o,?*Ym,?*y,?*Yi,?*x")
+                       "=r,?r,?o,r   ,o,?*Ym,?!*y,?*Yi,?*x")
        (zero_extend:DI
         (match_operand:SI 1 "x86_64_zext_operand"
-                       "0 ,rm,r ,rmWz,0,r   ,m  ,r   ,m")))]
+                       "0 ,rm,r ,rmWz,0,r   ,m   ,r   ,m")))]
   ""
 {
   switch (get_attr_type (insn))
Index: testsuite/gcc.target/i386/pr44578.c
===================================================================
--- testsuite/gcc.target/i386/pr44578.c (revision 0)
+++ testsuite/gcc.target/i386/pr44578.c (working copy)
@@ -0,0 +1,31 @@
+/* { dg-do run } */
+/* { dg-options "-O2 -mtune=athlon64" } */
+
+extern void abort (void);
+
+long double
+__attribute__((noinline, noclone))
+test (float num)
+{
+  unsigned int i;
+
+  if (num < 0.0)
+    num = 0.0;
+
+  __builtin_memcpy (&i, &num, sizeof(unsigned int));
+
+  return (long double)(unsigned long long) i;
+}
+
+int
+main ()
+{
+  long double x;
+
+  x = test (0.0);
+
+  if (x != 0.0)
+    abort ();
+
+  return 0;
+}