[PATCH V2] Restrict the two sources of vect_recog_cond_expr_convert_pattern to be of the same type when convert is extension.

[liuhongt via Gcc-patches]

> I find this quite unreadable, it looks like if @2 and @3 are treated
> differently.  I think keeping the old 3 lines and just adding
>       && (TYPE_PRECISION (TREE_TYPE (@0)) >= TYPE_PRECISION (type)
>           || (TYPE_UNSIGNED (TREE_TYPE (@2))
>               == TYPE_UNSIGNED (TREE_TYPE (@3))))
> after it ideally with a comment why would be better.
Update patch.

gcc/ChangeLog:

        PR tree-optimization/104551
        PR tree-optimization/103771
        * match.pd (cond_expr_convert_p): Add types_match check when
        convert is extension.
        * tree-vect-patterns.cc
        (gimple_cond_expr_convert_p): Adjust comments.
        (vect_recog_cond_expr_convert_pattern): Ditto.

gcc/testsuite/ChangeLog:

        * gcc.target/i386/pr104551.c: New test.
---
 gcc/match.pd                             |  6 ++++++
 gcc/testsuite/gcc.target/i386/pr104551.c | 24 ++++++++++++++++++++++++
 gcc/tree-vect-patterns.cc                |  6 ++++--
 3 files changed, 34 insertions(+), 2 deletions(-)
 create mode 100644 gcc/testsuite/gcc.target/i386/pr104551.c

diff --git a/gcc/match.pd b/gcc/match.pd
index 05a10ab6bfd..8b6f22f1065 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -7698,5 +7698,11 @@ and,
          == TYPE_PRECISION (TREE_TYPE (@2))
        && TYPE_PRECISION (TREE_TYPE (@0))
          == TYPE_PRECISION (TREE_TYPE (@3))
+       /* For vect_recog_cond_expr_convert_pattern, @2 and @3 can differ in
+         signess when convert is truncation, but not ok for extension since
+         it's sign_extend vs zero_extend.  */
+       && (TYPE_PRECISION (TREE_TYPE (@0)) > TYPE_PRECISION (type)
+          || (TYPE_UNSIGNED (TREE_TYPE (@2))
+              == TYPE_UNSIGNED (TREE_TYPE (@3))))
        && single_use (@4)
        && single_use (@5))))
diff --git a/gcc/testsuite/gcc.target/i386/pr104551.c 
b/gcc/testsuite/gcc.target/i386/pr104551.c
new file mode 100644
index 00000000000..6300f25c0d5
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr104551.c
@@ -0,0 +1,24 @@
+/* { dg-do run } */
+/* { dg-options "-O3 -mavx2" } */
+/* { dg-require-effective-target avx2 } */
+
+unsigned int
+__attribute__((noipa))
+test(unsigned int a, unsigned char p[16]) {
+  unsigned int res = 0;
+  for (unsigned b = 0; b < a; b += 1)
+    res = p[b] ? p[b] : (char) b;
+  return res;
+}
+
+int main ()
+{
+  unsigned int a = 16U;
+  unsigned char p[16];
+  for (int i = 0; i != 16; i++)
+    p[i] = (unsigned char)128;
+  unsigned int res = test (a, p);
+  if (res != 128)
+    __builtin_abort ();
+  return 0;
+}
diff --git a/gcc/tree-vect-patterns.cc b/gcc/tree-vect-patterns.cc
index a8f96d59643..217bdfd7045 100644
--- a/gcc/tree-vect-patterns.cc
+++ b/gcc/tree-vect-patterns.cc
@@ -929,8 +929,10 @@ vect_reassociating_reduction_p (vec_info *vinfo,
    with conditions:
    1) @1, @2, c, d, a, b are all integral type.
    2) There's single_use for both @1 and @2.
-   3) a, c and d have same precision.
+   3) a, c have same precision.
    4) c and @1 have different precision.
+   5) c, d are the same type or they can differ in sign when convert is
+   truncation.
 
    record a and c and d and @3.  */
 
@@ -952,7 +954,7 @@ extern bool gimple_cond_expr_convert_p (tree, tree*, tree 
(*)(tree));
    TYPE_PRECISION (TYPE_E) != TYPE_PRECISION (TYPE_CD);
    TYPE_PRECISION (TYPE_AB) == TYPE_PRECISION (TYPE_CD);
    single_use of op_true and op_false.
-   TYPE_AB could differ in sign.
+   TYPE_AB could differ in sign when (TYPE_E) A is a truncation.
 
    Input:
 
-- 
2.18.1