[gcc r14-7129] middle-end/112740 - vector boolean CTOR expansion issue

[Richard Biener]

https://gcc.gnu.org/g:e1f2d58a1e2536f13d3f2ea2d7373ae62cec9125

commit r14-7129-ge1f2d58a1e2536f13d3f2ea2d7373ae62cec9125
Author: Richard Biener <rguenther@suse.de>
Date:   Wed Jan 10 14:54:10 2024 +0100

    middle-end/112740 - vector boolean CTOR expansion issue
    
    The optimization to expand uniform boolean vectors by sign-extension
    works only for dense masks but it failed to check that.
    
            PR middle-end/112740
            * expr.cc (store_constructor): Check the integer vector
            mask has a single bit per element before using sign-extension
            to expand an uniform vector.
    
            * gcc.dg/pr112740.c: New testcase.

Diff:
---
 gcc/expr.cc                     |  8 +++++---
 gcc/testsuite/gcc.dg/pr112740.c | 19 +++++++++++++++++++
 2 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/gcc/expr.cc b/gcc/expr.cc
index dc816bc20fa..0bf80832fe5 100644
--- a/gcc/expr.cc
+++ b/gcc/expr.cc
@@ -7841,10 +7841,12 @@ store_constructor (tree exp, rtx target, int cleared, poly_int64 size,
 	    break;
 	  }
 	/* Use sign-extension for uniform boolean vectors with
-	   integer modes.  Effectively "vec_duplicate" for bitmasks.  */
-	if (!TREE_SIDE_EFFECTS (exp)
+	   integer modes and single-bit mask entries.
+	   Effectively "vec_duplicate" for bitmasks.  */
+	if (elt_size == 1
+	    && !TREE_SIDE_EFFECTS (exp)
 	    && VECTOR_BOOLEAN_TYPE_P (type)
-	    && SCALAR_INT_MODE_P (mode)
+	    && SCALAR_INT_MODE_P (TYPE_MODE (type))
 	    && (elt = uniform_vector_p (exp))
 	    && !VECTOR_TYPE_P (TREE_TYPE (elt)))
 	  {
diff --git a/gcc/testsuite/gcc.dg/pr112740.c b/gcc/testsuite/gcc.dg/pr112740.c
new file mode 100644
index 00000000000..8250cafd2ff
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr112740.c
@@ -0,0 +1,19 @@
+/* { dg-do run { target { int128 } } } */
+/* { dg-options "" } */
+
+typedef unsigned __int128 __attribute__((__vector_size__ (16))) V;
+
+V
+foo (unsigned c, V v)
+{
+  return (V) (c <= v) == 0;
+}
+
+int
+main (void)
+{
+  V x = foo (0, (V) { });
+  if (x[0])
+    __builtin_abort ();
+  return 0;
+}