The following fixes another alignment preserving bug in folding.
Bootstrap / regtest running on x86_64-unknown-linux-gnu.
Richard.
2016-06-10 Richard Biener <rguent...@suse.de>
PR middle-end/64516
* fold-const.c (fold_unary_loc): Preserve alignment when
folding a VIEW_CONVERT_EXPR into a MEM_REF.
* gcc.dg/align-3.c: New testcase.
Index: gcc/fold-const.c
===================================================================
*** gcc/fold-const.c (revision 237286)
--- gcc/fold-const.c (working copy)
*************** fold_unary_loc (location_t loc, enum tre
*** 7964,7969 ****
--- 7974,7981 ----
case VIEW_CONVERT_EXPR:
if (TREE_CODE (op0) == MEM_REF)
{
+ if (TYPE_ALIGN (TREE_TYPE (op0)) != TYPE_ALIGN (type))
+ type = build_aligned_type (type, TYPE_ALIGN (TREE_TYPE (op0)));
tem = fold_build2_loc (loc, MEM_REF, type,
TREE_OPERAND (op0, 0), TREE_OPERAND (op0, 1));
REF_REVERSE_STORAGE_ORDER (tem) = REF_REVERSE_STORAGE_ORDER (op0);
Index: gcc/testsuite/gcc.dg/align-3.c
===================================================================
--- gcc/testsuite/gcc.dg/align-3.c (revision 0)
+++ gcc/testsuite/gcc.dg/align-3.c (working copy)
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-rtl-expand" } */
+
+typedef struct { char a[2]; } __attribute__((__packed__)) TU2;
+unsigned short get16_unaligned(const void *p) {
+ unsigned short v;
+ *(TU2 *)(void *)(&v) = *(const TU2 *)p;
+ return v;
+}
+
+/* { dg-final { scan-rtl-dump "MEM\[^\n\r\]*A8\\\]" "expand" } } */
