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[PATCH] Fix PR80334
- From: Richard Biener <rguenther at suse dot de>
- To: gcc-patches at gcc dot gnu dot org
- Date: Thu, 6 Apr 2017 14:40:08 +0200 (CEST)
- Subject: [PATCH] Fix PR80334
- Authentication-results: sourceware.org; auth=none
The following patch makes sure to preserve (mis-)alignment of memory
references when IVOPTs generates TARGET_MEM_REFs for them.
Bootstrapped on x86_64-unknown-linux-gnu, testing in progress.
Richard.
2017-04-06 Richard Biener <rguenther@suse.de>
PR tree-optimization/80334
* tree-ssa-loop-ivopts.c (rewrite_use_address): Properly
preserve alignment of accesses.
* g++.dg/torture/pr80334.C: New testcase.
Index: gcc/tree-ssa-loop-ivopts.c
===================================================================
--- gcc/tree-ssa-loop-ivopts.c (revision 246724)
+++ gcc/tree-ssa-loop-ivopts.c (working copy)
@@ -7396,7 +7396,11 @@ rewrite_use_address (struct ivopts_data
base_hint = var_at_stmt (data->current_loop, cand, use->stmt);
iv = var_at_stmt (data->current_loop, cand, use->stmt);
- ref = create_mem_ref (&bsi, TREE_TYPE (*use->op_p), &aff,
+ tree type = TREE_TYPE (*use->op_p);
+ unsigned int align = get_object_alignment (*use->op_p);
+ if (align != TYPE_ALIGN (type))
+ type = build_aligned_type (type, align);
+ ref = create_mem_ref (&bsi, type, &aff,
reference_alias_ptr_type (*use->op_p),
iv, base_hint, data->speed);
copy_ref_info (ref, *use->op_p);
Index: gcc/testsuite/g++.dg/torture/pr80334.C
===================================================================
--- gcc/testsuite/g++.dg/torture/pr80334.C (nonexistent)
+++ gcc/testsuite/g++.dg/torture/pr80334.C (working copy)
@@ -0,0 +1,18 @@
+// { dg-do run }
+
+struct A { alignas(16) char c; };
+struct B { A unpacked; char d; } __attribute__((packed));
+
+char x;
+
+int
+main()
+{
+ alignas(16) B b[3];
+ for (int i = 0; i < 3; i++) b[i].unpacked.c = 'a' + i;
+ for (int i = 0; i < 3; i++)
+ {
+ auto a = new A(b[i].unpacked);
+ x = a->c;
+ }
+}