tree-optimization/110496 - TYPE_PRECISION issue with store-merging

When store-merging looks for bswap opportunities we also handle
BIT_FIELD_REFs where we verify the refed object is of scalar
type but we don't check for the result type we eventually use.
That's done later but after we eventually query TYPE_PRECISION.
The following re-orders this.

	PR tree-optimization/110496
	* gimple-ssa-store-merging.cc (find_bswap_or_nop_1): Re-order
	verifying and TYPE_PRECISION query for the BIT_FIELD_REF case.

	* gcc.dg/pr110496.c: New testcase.

2 files changed, 30 insertions, 1 deletions

diff --git a/gcc/gimple-ssa-store-merging.cc b/gcc/gimple-ssa-store-merging.cc
index 401496a..0d19b98 100644
--- a/gcc/gimple-ssa-store-merging.cc
+++ b/gcc/gimple-ssa-store-merging.cc
@@ -650,10 +650,13 @@ find_bswap_or_nop_1 (gimple *stmt, struct symbolic_number *n, int limit)
 
 	  /* Convert.  */
 	  n->type = TREE_TYPE (rhs1);
+	  if (!verify_symbolic_number_p (n, stmt))
+	    return NULL;
+
 	  if (!n->base_addr)
 	    n->range = TYPE_PRECISION (n->type) / BITS_PER_UNIT;
 
-	  return verify_symbolic_number_p (n, stmt) ? stmt : NULL;
+	  return stmt;
 	}
 
       return NULL;
diff --git a/gcc/testsuite/gcc.dg/pr110496.c b/gcc/testsuite/gcc.dg/pr110496.c
new file mode 100644
index 0000000..3c3d12f
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr110496.c
@@ -0,0 +1,26 @@
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+long contents, f_num;
+int decide();
+int f_MV0__x;
+void f() {
+  unsigned char *rptr;
+  unsigned char valbuf[6];
+  rptr = (unsigned char *)contents;
+  if (decide())
+    do {
+      __builtin_memcpy(valbuf, &f_MV0__x, sizeof(int));
+      (&valbuf[0])[4] = (&valbuf[0])[5] = 0;
+    } while (0);
+  else {
+    int MV0__x = f_num;
+    __builtin_memcpy(valbuf, &MV0__x, sizeof(int));
+    (&valbuf[0])[4] = (&valbuf[0])[5] = 0;
+  }
+  rptr[1] = valbuf[4];
+  rptr[2] = valbuf[5];
+  rptr[4] = valbuf[1];
+  rptr[5] = valbuf[2];
+  __builtin_memset(valbuf, 0, 8);
+}