[gcc r14-9487] vect: Call vect_convert_output with the right vecitype [PR114108]

[gcc r14-9487] vect: Call vect_convert_output with the right vecitype [PR114108]

[Tejas Belagod]

https://gcc.gnu.org/g:81f3d963e05de8b17d4ccc7667ead9ed156193a4

commit r14-9487-g81f3d963e05de8b17d4ccc7667ead9ed156193a4
Author: Tejas Belagod <tejas.belagod@arm.com>
Date:   Wed Mar 6 15:30:26 2024 +0530

    vect: Call vect_convert_output with the right vecitype [PR114108]
    
    This patch fixes a bug where vect_recog_abd_pattern called vect_convert_output
    with the incorrect vecitype for the corresponding pattern_stmt.
    vect_convert_output expects vecitype to be the vector form of the scalar type
    of the LHS of pattern_stmt, but we were passing in the vector form of the LHS
    of the new impending conversion statement.  This caused a skew in ABD's
    pattern_stmt having the vectype of the following gimple pattern_stmt.
    
            2024-03-06  Tejas Belagod  <tejas.belagod@arm.com>
    
    gcc/ChangeLog:
    
            PR middle-end/114108
            * tree-vect-patterns.cc (vect_recog_abd_pattern): Call
            vect_convert_output with the correct vecitype.
    
    gcc/testsuite/ChangeLog:
            * gcc.dg/vect/pr114108.c: New test.

Diff:
---
 gcc/testsuite/gcc.dg/vect/pr114108.c | 19 +++++++++++++++++++
 gcc/tree-vect-patterns.cc            |  5 ++---
 2 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/gcc/testsuite/gcc.dg/vect/pr114108.c b/gcc/testsuite/gcc.dg/vect/pr114108.c
new file mode 100644
index 00000000000..b3075d41398
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/pr114108.c
@@ -0,0 +1,19 @@
+/* { dg-do compile } */
+
+#include "tree-vect.h"
+
+typedef signed char schar;
+
+__attribute__((noipa, noinline, optimize("O3")))
+void foo(const schar *a, const schar *b, schar *c, int n)
+{
+  for (int i = 0; i < n; i++)
+    {   
+      unsigned u = __builtin_abs (a[i] - b[i]);
+      c[i] = u <= 7U ? u : 7U; 
+    }   
+}
+
+
+/* { dg-final { scan-tree-dump "LOOP VECTORIZED" "vect" { target aarch64*-*-* } } } */
+/* { dg-final { scan-tree-dump "vect_recog_abd_pattern: detected" "vect" { target aarch64*-*-* } } } */
diff --git a/gcc/tree-vect-patterns.cc b/gcc/tree-vect-patterns.cc
index d562f57920f..4f491c6b833 100644
--- a/gcc/tree-vect-patterns.cc
+++ b/gcc/tree-vect-patterns.cc
@@ -1576,9 +1576,8 @@ vect_recog_abd_pattern (vec_info *vinfo,
       && !TYPE_UNSIGNED (abd_out_type))
     {
       tree unsign = unsigned_type_for (abd_out_type);
-      tree unsign_vectype = get_vectype_for_scalar_type (vinfo, unsign);
-      stmt = vect_convert_output (vinfo, stmt_vinfo, unsign, stmt,
-				  unsign_vectype);
+      stmt = vect_convert_output (vinfo, stmt_vinfo, unsign, stmt, vectype_out);
+      vectype_out = get_vectype_for_scalar_type (vinfo, unsign);
     }
 
   return vect_convert_output (vinfo, stmt_vinfo, out_type, stmt, vectype_out);