[Bug rtl-optimization/41833] vec_splat followed by vec_splat could be improved

[pinskia at gcc dot gnu dot org]

------- Comment #2 from pinskia at gcc dot gnu dot org  2009-10-27 16:37 -------
Patch which I am testing:
Index: testsuite/gcc.target/powerpc/altivec-33.c
===================================================================
--- testsuite/gcc.target/powerpc/altivec-33.c   (revision 0)
+++ testsuite/gcc.target/powerpc/altivec-33.c   (revision 0)
@@ -0,0 +1,16 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target powerpc_altivec_ok } */
+/* { dg-options "-O2 -maltivec" } */
+
+/* We should only produce one vspltw as we already splatted the value.  */
+/* { dg-final { scan-assembler-times "vspltw" 1 } } */
+
+#include <altivec.h>
+
+vector float f(vector float a)
+{
+  vector float b = vec_splat (a, 2);
+  return vec_splat (b, 0);
+}
+
+
Index: simplify-rtx.c
===================================================================
--- simplify-rtx.c      (revision 153603)
+++ simplify-rtx.c      (working copy)
@@ -2946,6 +2946,9 @@ simplify_binary_operation_1 (enum rtx_co
                                    tmp_op, gen_rtx_PARALLEL (VOIDmode, vec));
              return tmp;
            }
+         if (GET_CODE (trueop0) == VEC_DUPLICATE
+             && GET_MODE (XEXP (trueop0, 0)) == mode)
+           return XEXP (trueop0, 0);
        }
       else
        {


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41833