Hi!
When the return value of a builtin is ignored, it is being expanded with
target const0_rtx and VOIDmode, but deeper in the builtin expansion routines
the const0_rtx target is actually transformed into NULL target (if it is
figured out that the builtin just can't be optimized away completely).
ix86_expand_builtin for target == NULL creates a pseudo with mode to store
the result to though, which is fine for const/pure builtins because they
won't make it through without the return value being actually used (tested
say __builtin_nanq () and others), but for non-const/pure builtins it
results in ICEs. Fixed thusly, bootstrapped/regtested on x86_64-linux and
i686-linux, ok for trunk/4.8?
2013-06-27 Jakub Jelinek <ja...@redhat.com>
PR target/57736
* config/i386/i386.c (ix86_expand_builtin): If target == NULL
and mode is VOIDmode, don't create a VOIDmode pseudo to copy result
into.
* gcc.target/i386/pr57736.c: New test.
--- gcc/config/i386/i386.c.jj 2013-06-23 20:43:36.000000000 +0200
+++ gcc/config/i386/i386.c 2013-06-27 21:01:16.464580253 +0200
@@ -32222,7 +32222,13 @@ ix86_expand_builtin (tree exp, rtx targe
}
if (target == 0)
- target = gen_reg_rtx (mode);
+ {
+ /* mode is VOIDmode if __builtin_rd* has been called
+ without lhs. */
+ if (mode == VOIDmode)
+ return target;
+ target = gen_reg_rtx (mode);
+ }
if (TARGET_64BIT)
{
--- gcc/testsuite/gcc.target/i386/pr57736.c.jj 2013-06-27 21:14:26.448580682
+0200
+++ gcc/testsuite/gcc.target/i386/pr57736.c 2013-06-27 21:15:52.575039737
+0200
@@ -0,0 +1,41 @@
+/* PR target/57736 */
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+#include <x86intrin.h>
+
+unsigned long long
+f1 (void)
+{
+ return __rdtsc ();
+}
+
+unsigned long long
+f2 (unsigned int *x)
+{
+ return __rdtscp (x);
+}
+
+unsigned long long
+f3 (unsigned int x)
+{
+ return __rdpmc (x);
+}
+
+void
+f4 (void)
+{
+ __rdtsc ();
+}
+
+void
+f5 (unsigned int *x)
+{
+ __rdtscp (x);
+}
+
+void
+f6 (unsigned int x)
+{
+ __rdpmc (x);
+}
Jakub
