[PATCH, ARM] Fix unrecognizable vector comparisons

[Zhenqiang Chen]

Hi,

During expand, function vcond<mode><mode> inverses some CMP, e.g.

   a LE b -> b GE a

But if "b" is "CONST0_RTX", "b GE a" will be an illegal insn.

(insn 933 932 934 113 (set (reg:V4SI 1027)
        (unspec:V4SI [
                (const_vector:V4SI [
                        (const_int 0 [0])
                        (const_int 0 [0])
                        (const_int 0 [0])
                        (const_int 0 [0])
                    ])
                (reg:V4SI 1023 [ vect_var_.49 ])
                (const_int 1 [0x1])
            ] UNSPEC_VCGE)) PUGHSlab/Mapping.c:567 -1
     (nil))

Refer https://bugs.launchpad.net/linaro-toolchain-binaries/+bug/1189445
for more. And the bug also happens for FSF trunk.

The similar issue
(https://bugs.launchpad.net/linaro-toolchain-binaries/+bug/1163942)
had fixed on AARCH64:
http://gcc.gnu.org/ml/gcc-patches/2013-04/msg00581.html

The patch is similar to the fix for aarch64.

Bootstrap and no make check regression on Panda Board.

Is it OK for trunk and 4.8?

Thanks!
-Zhenqiang

ChangeLog:

2013-06-18  Zhenqiang Chen  <zhenqiang.c...@linaro.org>

        * config/arm/neon.md (vcond): Fix floating-point vector
        comparisons against 0.

diff --git a/gcc/config/arm/neon.md b/gcc/config/arm/neon.md
index e814df0..9299ae5 100644
--- a/gcc/config/arm/neon.md
+++ b/gcc/config/arm/neon.md
@@ -1671,6 +1671,7 @@
                             ? 3 : 1;
   rtx magic_rtx = GEN_INT (magic_word);
   int inverse = 0;
+  int use_zero_form = 0;
   int swap_bsl_operands = 0;
   rtx mask = gen_reg_rtx (<V_cmp_result>mode);
   rtx tmp = gen_reg_rtx (<V_cmp_result>mode);
@@ -1681,12 +1682,16 @@
   switch (GET_CODE (operands[3]))
     {
     case GE:
+    case GT:
     case LE:
+    case LT:
     case EQ:
-      if (!REG_P (operands[5])
-         && (operands[5] != CONST0_RTX (<MODE>mode)))
-       operands[5] = force_reg (<MODE>mode, operands[5]);
-      break;
+      if (operands[5] == CONST0_RTX (<MODE>mode))
+       {
+         use_zero_form = 1;
+         break;
+       }
+      /* Fall through.  */
     default:
       if (!REG_P (operands[5]))
        operands[5] = force_reg (<MODE>mode, operands[5]);
@@ -1737,7 +1742,26 @@
         a GT b -> a GT b
         a LE b -> b GE a
         a LT b -> b GT a
-        a EQ b -> a EQ b  */
+        a EQ b -> a EQ b
+        Note that there also exist direct comparison against 0 forms,
+        so catch those as a special case.  */
+      if (use_zero_form)
+       {
+         inverse = 0;
+         switch (GET_CODE (operands[3]))
+           {
+           case LT:
+             base_comparison = gen_neon_vclt<mode>;
+             break;
+           case LE:
+             base_comparison = gen_neon_vcle<mode>;
+             break;
+           default:
+             /* Do nothing, other zero form cases already have the correct
+                base_comparison.  */
+             break;
+           }
+       }

       if (!inverse)
        emit_insn (base_comparison (mask, operands[4], operands[5], magic_rtx));