[PATCH V2 1/2] Pass type of comparison operands instead of comparison result to truth_type_for in build_vec_cmp.

[liuhongt]

>I think it's indeed on purpose that the result of v1 < v2 is a signed
>integer vector type.
>But build_vec_cmp should not use the truth type for the result but instead the
>truth type for the comparison, so

Change build_vec_cmp in both c/c++, also notice for jit part, it already uses
type of comparison instead of the result.

gcc/c/ChangeLog:

        * c-typeck.cc (build_vec_cmp): Pass type of arg0 to
        truth_type_for.

gcc/cp/ChangeLog:

        * typeck.cc (build_vec_cmp): Pass type of arg0 to
        truth_type_for.
---
 gcc/c/c-typeck.cc | 2 +-
 gcc/cp/typeck.cc  | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/gcc/c/c-typeck.cc b/gcc/c/c-typeck.cc
index e55e887da14..41ee38368f2 100644
--- a/gcc/c/c-typeck.cc
+++ b/gcc/c/c-typeck.cc
@@ -11982,7 +11982,7 @@ build_vec_cmp (tree_code code, tree type,
 {
   tree zero_vec = build_zero_cst (type);
   tree minus_one_vec = build_minus_one_cst (type);
-  tree cmp_type = truth_type_for (type);
+  tree cmp_type = truth_type_for (TREE_TYPE (arg0));
   tree cmp = build2 (code, cmp_type, arg0, arg1);
   return build3 (VEC_COND_EXPR, type, cmp, minus_one_vec, zero_vec);
 }
diff --git a/gcc/cp/typeck.cc b/gcc/cp/typeck.cc
index 8132bd7fccc..7b2ad51bde7 100644
--- a/gcc/cp/typeck.cc
+++ b/gcc/cp/typeck.cc
@@ -4826,7 +4826,7 @@ build_vec_cmp (tree_code code, tree type,
 {
   tree zero_vec = build_zero_cst (type);
   tree minus_one_vec = build_minus_one_cst (type);
-  tree cmp_type = truth_type_for (type);
+  tree cmp_type = truth_type_for (TREE_TYPE (arg0));
   tree cmp = build2 (code, cmp_type, arg0, arg1);
   return build3 (VEC_COND_EXPR, type, cmp, minus_one_vec, zero_vec);
 }
-- 
2.31.1