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[PATCH, PR 42703] Check whether we can construct a reference to the original before creating a SRA replacement
- From: Martin Jambor <mjambor at suse dot cz>
- To: GCC Patches <gcc-patches at gcc dot gnu dot org>
- Cc: Richard Guenther <rguenther at suse dot de>
- Date: Wed, 13 Jan 2010 12:06:46 +0100
- Subject: [PATCH, PR 42703] Check whether we can construct a reference to the original before creating a SRA replacement
Hi,
PR 42703 contains an out of bounds reference to an array within a
union. When SRA tries to load data from that piece of memory, it
cannot find a field which conforms to offset and size requirements and
thus unexpectedly fails, hitting an assert.
This patch avoids that by checking that we can create a reference
expression to access the original data within the aggregate before
deciding to create each individual replacement.
Bootstrapped and tested on x86_64-linux. OK for trunk?
Thanks,
Martin
2010-01-13 Martin Jambor <mjambor@suse.cz>
PR tree-optimization/42703
* tree-sra.c (analyze_access_subtree): Check that we can vuild a
reference to the original data within the aggregate.
* testsuite/gcc.c-torture/compile/pr42703.c: New test.
Index: mine/gcc/tree-sra.c
===================================================================
--- mine.orig/gcc/tree-sra.c
+++ mine/gcc/tree-sra.c
@@ -1659,7 +1659,13 @@ analyze_access_subtree (struct access *r
if (allow_replacements && scalar && !root->first_child
&& (root->grp_hint
- || (direct_read && root->grp_write)))
+ || (direct_read && root->grp_write))
+ /* We must not ICE later on when trying to build an access to the
+ original data within the aggregate even when it is impossible to do in
+ a defined way like in the PR 42703 testcase. Therefore we check
+ pre-emptively here that we will be able to do that. */
+ && build_ref_for_offset (NULL, TREE_TYPE (root->base), root->offset,
+ root->type, false))
{
if (dump_file && (dump_flags & TDF_DETAILS))
{
Index: mine/gcc/testsuite/gcc.c-torture/compile/pr42703.c
===================================================================
--- /dev/null
+++ mine/gcc/testsuite/gcc.c-torture/compile/pr42703.c
@@ -0,0 +1,12 @@
+__extension__ typedef unsigned long long int uint64_t;
+typedef uint64_t ScmUInt64;
+void swapb64(ScmUInt64 *loc)
+{
+ union {
+ ScmUInt64 l;
+ unsigned char c[4];
+ } dd;
+ unsigned char t;
+ dd.l = *loc;
+ (t = dd.c[3], dd.c[3] = dd.c[4], dd.c[4] = t);
+}