The optimization to expand uniform boolean vectors by sign-extension
works only for dense masks but it failed to check that.

Bootstrap and regtest running on x86_64-unknown-linux-gnu, I've
checked aarch64 RTL expansion for the testcase.  Will push tomorrow.

Richard.

        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.
---
 gcc/expr.cc                     |  8 +++++---
 gcc/testsuite/gcc.dg/pr112740.c | 19 +++++++++++++++++++
 2 files changed, 24 insertions(+), 3 deletions(-)
 create mode 100644 gcc/testsuite/gcc.dg/pr112740.c

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;
+}
-- 
2.35.3

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