ssa: Fix up maybe_rewrite_mem_ref_base complex type handling [PR116034]

The folding into REALPART_EXPR is correct, used only when the mem_offset
is zero, but for IMAGPART_EXPR it didn't check the exact offset value (just
that it is not 0).
The following patch fixes that by using IMAGPART_EXPR only if the offset
is right and using BITFIELD_REF or whatever else otherwise.

2024-07-23  Jakub Jelinek  <jakub@redhat.com>
	    Andrew Pinski  <quic_apinski@quicinc.com>

	PR tree-optimization/116034
	* tree-ssa.cc (maybe_rewrite_mem_ref_base): Only use IMAGPART_EXPR
	if MEM_REF offset is equal to element type size.

	* gcc.dg/pr116034.c: New test.

(cherry picked from commit b9cefd67a2a464a3c9413e6b3f28e7dc7a9ef162)

diff --git a/gcc/testsuite/gcc.dg/pr116034.c b/gcc/testsuite/gcc.dg/pr116034.c
new file mode 100644 (file)
index 0000000..9a31de0
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr116034.c
@@ -0,0 +1,22 @@
+/* PR tree-optimization/116034 */
+/* { dg-do run } */
+/* { dg-options "-O1 -fno-strict-aliasing" } */
+
+int g;
+
+static inline int
+foo (_Complex unsigned short c)
+{
+  __builtin_memmove (&g, 1 + (char *) &c, 2);
+  return g;
+}
+
+int
+main ()
+{
+  if (__SIZEOF_SHORT__ == 2
+      && __CHAR_BIT__ == 8
+      && (foo (__BYTE_ORDER__ != __ORDER_BIG_ENDIAN__ ? 0x100 : 1)
+         != (__BYTE_ORDER__ != __ORDER_BIG_ENDIAN__ ? 1 : 0x100)))
+    __builtin_abort ();
+}

diff --git a/gcc/tree-ssa.cc b/gcc/tree-ssa.cc
index 491a5fa9565ecea1aca97d309d143d61616e6e9c..7fdf9d1b9aabfed98bfeefb3500fc751f1b47a43 100644 (file)
--- a/gcc/tree-ssa.cc
+++ b/gcc/tree-ssa.cc
@@ -1527,7 +1527,10 @@ maybe_rewrite_mem_ref_base (tree *tp, bitmap suitable_for_renaming)
        }
       else if (TREE_CODE (TREE_TYPE (sym)) == COMPLEX_TYPE
               && useless_type_conversion_p (TREE_TYPE (*tp),
-                                            TREE_TYPE (TREE_TYPE (sym))))
+                                            TREE_TYPE (TREE_TYPE (sym)))
+              && (integer_zerop (TREE_OPERAND (*tp, 1))
+                  || tree_int_cst_equal (TREE_OPERAND (*tp, 1),
+                                         TYPE_SIZE_UNIT (TREE_TYPE (*tp)))))
        {
          *tp = build1 (integer_zerop (TREE_OPERAND (*tp, 1))
                        ? REALPART_EXPR : IMAGPART_EXPR,