gimple-fold: Fix the recent ifcombine optimization for _BitInt [PR118023]

The BIT_FIELD_REF verifier has:
          if (INTEGRAL_TYPE_P (TREE_TYPE (op))
              && !type_has_mode_precision_p (TREE_TYPE (op)))
            {
              error ("%qs of non-mode-precision operand", code_name);
              return true;
            }
check among other things, so one can't extract something out of say
_BitInt(63) or _BitInt(4096).
The new ifcombine optimization happily creates such BIT_FIELD_REFs
and ICEs during their verification.

The following patch fixes that by rejecting those in decode_field_reference.

2024-12-14  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/118023
	* gimple-fold.cc (decode_field_reference): Return NULL_TREE if
	inner has non-type_has_mode_precision_p integral type.

	* gcc.dg/bitint-119.c: New test.

diff --git a/gcc/gimple-fold.cc b/gcc/gimple-fold.cc
index e1b4b65dd662f6cded0c15105c9f0bb8e98e807c..6c11654a2c65b54500d44f5077716929593224c0 100644 (file)
--- a/gcc/gimple-fold.cc
+++ b/gcc/gimple-fold.cc
@@ -7643,7 +7643,9 @@ decode_field_reference (tree *pexp, HOST_WIDE_INT *pbitsize,
       /* Reject out-of-bound accesses (PR79731).  */
       || (! AGGREGATE_TYPE_P (TREE_TYPE (inner))
          && compare_tree_int (TYPE_SIZE (TREE_TYPE (inner)),
-                              bp + bs) < 0))
+                              bp + bs) < 0)
+      || (INTEGRAL_TYPE_P (TREE_TYPE (inner))
+         && !type_has_mode_precision_p (TREE_TYPE (inner))))
     return NULL_TREE;
 
   *pbitsize = bs;

diff --git a/gcc/testsuite/gcc.dg/bitint-119.c b/gcc/testsuite/gcc.dg/bitint-119.c
new file mode 100644 (file)
index 0000000..8283d50
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/bitint-119.c
@@ -0,0 +1,11 @@
+/* PR tree-optimization/118023 */
+/* { dg-do compile { target bitint } } */
+/* { dg-options "-O2" } */
+
+_BitInt(63) b;
+
+int
+foo (void)
+{
+  return !*(_Complex char *) &b;
+}