Hi all,
Store merging ICEs on this invalid testcase because it trips up on the negative
bitposition to store to.
It doesn't really expect to handle negative offsets and I believe they won't
occur very often in valid code anyway.
Filling out structs/bitfields/class members involves positive offsets.
I can look into removing all the assumptions about positive offsets if folks
want me to (should involve removing
some 'unsigned' modifiers from HOST_WIDE_INTs and double-checking some range
checks), but for now
this patch just fixes the ICE by rejecting negative offsets early on.
Bootstrapped and tested on aarch64-none-linux-gnu and x86_64.
Ok for trunk?
Thanks,
Kyrill
2016-11-01 Kyrylo Tkachov <kyrylo.tkac...@arm.com>
PR tree-optimization/78162
* gimple-ssa-store-merging.c (execute): Mark stores with bitpos < 0
as invalid.
2016-11-01 Kyrylo Tkachov <kyrylo.tkac...@arm.com>
PR tree-optimization/78162
* gcc.c-torture/compile/pr78162.c: New test.
diff --git a/gcc/gimple-ssa-store-merging.c b/gcc/gimple-ssa-store-merging.c
index f82cad35afbc10eea76957d38100acdce137d271..4dbf03f61ab5ed4e33481d53cc3c2dee1a457f8f 100644
--- a/gcc/gimple-ssa-store-merging.c
+++ b/gcc/gimple-ssa-store-merging.c
@@ -1371,7 +1371,7 @@ pass_store_merging::execute (function *fun)
&unsignedp, &reversep, &volatilep);
/* As a future enhancement we could handle stores with the same
base and offset. */
- bool invalid = offset || reversep
+ bool invalid = offset || reversep || bitpos < 0
|| ((bitsize > MAX_BITSIZE_MODE_ANY_INT)
&& (TREE_CODE (rhs) != INTEGER_CST))
|| !rhs_valid_for_store_merging_p (rhs)
diff --git a/gcc/testsuite/gcc.c-torture/compile/pr78162.c b/gcc/testsuite/gcc.c-torture/compile/pr78162.c
new file mode 100644
index 0000000000000000000000000000000000000000..743d4e678b5b8c9a7ee6fb45254f86212523d59c
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/compile/pr78162.c
@@ -0,0 +1,10 @@
+/* PR tree-optimization/78162.
+ Handle negative offsets in store merging gracefully. */
+
+int a, b[1][2];
+
+void fn1()
+{
+ for (a = 0; a < 2; a++)
+ b[-1][a] = 0;
+}
