[gcc r15-6775] [ifcombine] fix mask variable test to match use [PR118344]

[Alexandre Oliva via Gcc-cvs]

https://gcc.gnu.org/g:fd4e979d0c66567c2cb89f97b51abd35a8773d88

commit r15-6775-gfd4e979d0c66567c2cb89f97b51abd35a8773d88
Author: Alexandre Oliva <ol...@adacore.com>
Date:   Fri Jan 10 09:32:43 2025 -0300

    [ifcombine] fix mask variable test to match use [PR118344]
    
    There was a cut&pasto in the rr_and_mask's adjustment to match the
    combined type: the test on whether there was a mask already was
    testing the wrong variable, and then it might crash or otherwise fail
    accessing an undefined mask.  This only hit with checking enabled,
    and rarely at that.
    
    
    for  gcc/ChangeLog
    
            PR tree-optimization/118344
            * gimple-fold.cc (fold_truth_andor_for_ifcombine): Fix typo in
            rr_and_mask's type adjustment test.
    
    for  gcc/testsuite/ChangeLog
    
            PR tree-optimization/118344
            * gcc.dg/field-merge-19.c: New.

Diff:
---
 gcc/gimple-fold.cc                    |  2 +-
 gcc/testsuite/gcc.dg/field-merge-19.c | 41 +++++++++++++++++++++++++++++++++++
 2 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/gcc/gimple-fold.cc b/gcc/gimple-fold.cc
index 0ad92de3a218..20b5024d861d 100644
--- a/gcc/gimple-fold.cc
+++ b/gcc/gimple-fold.cc
@@ -8644,7 +8644,7 @@ fold_truth_andor_for_ifcombine (enum tree_code code, tree 
truth_type,
                          xlr_bitpos);
       else
        lr_mask = wi::shifted_mask (xlr_bitpos, lr_bitsize, false, rnprec);
-      if (rl_and_mask.get_precision ())
+      if (rr_and_mask.get_precision ())
        rr_mask = wi::lshift (wide_int::from (rr_and_mask, rnprec, UNSIGNED),
                              xrr_bitpos);
       else
diff --git a/gcc/testsuite/gcc.dg/field-merge-19.c 
b/gcc/testsuite/gcc.dg/field-merge-19.c
new file mode 100644
index 000000000000..5622baa52b0a
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/field-merge-19.c
@@ -0,0 +1,41 @@
+/* { dg-do compile } */
+/* { dg-options "-O3 -fchecking" } */
+
+/* PR tree-optimization/118344 */
+
+/* This used to ICE attempting to extend a mask variable after testing the
+   wrong mask variable.  */
+
+int d, e, g, h, i, c, j;
+static short k;
+char o;
+static int *p;
+static long *a;
+int b[0];
+int q(int s, int t, int *u, int *v) {
+  for (int f = 0; f < s; f++)
+    if ((t & v[f]) != u[f])
+      return 0;
+  return 1;
+}
+int w(int s, int t) {
+  int l[] = {t, t, t, t}, m[] = {e, e, 3, 1};
+  int n = q(s, d, l, m);
+  return n;
+}
+int x(unsigned s) {
+  unsigned r;
+  if (s >= -1)
+    return 1;
+  r = 10000000;
+  while (s > 1 / r)
+    r /= 2;
+  return g ? 2 : 0;
+}
+void y() {
+  for (;;) {
+    b[w(8, *p)] = h;
+    for (; a + k; j = o)
+      i &= c = x(6) < 0;
+  }
+}