On Tue, 6 Oct 2015, Richard Biener wrote:
>
> This fixes an ICE in SCCVN - not sure how we got away with not clearing
> new slots... possibly SSA name recycling triggered.
Ah, it's not supposed to happen. Bisection shows the cause, fixed
with the following instead.
Bootstrap / regtest pending on x86_64-unknown-linux-gnu.
Richard.
2015-10-06 Richard Biener <rguent...@suse.de>
PR tree-optimization/67859
* tree-ssa-pre.c (create_expression_by_pieces): Properly
discard not inserted stmts.
* gcc.dg/torture/pr67859.c: New testcase.
Index: gcc/testsuite/gcc.dg/torture/pr67859.c
===================================================================
--- gcc/testsuite/gcc.dg/torture/pr67859.c (revision 0)
+++ gcc/testsuite/gcc.dg/torture/pr67859.c (working copy)
@@ -0,0 +1,15 @@
+/* { dg-do compile } */
+
+int a, b, c;
+
+void
+fn1 ()
+{
+ b = c ? 0 : 1 << a;
+ b |= 0x9D7A5FD9;
+ for (;;)
+ {
+ int d = 1;
+ b &= (unsigned) d;
+ }
+}
Index: gcc/tree-ssa-pre.c
===================================================================
*** gcc/tree-ssa-pre.c (revision 228514)
--- gcc/tree-ssa-pre.c (working copy)
*************** create_expression_by_pieces (basic_block
*** 2897,2907 ****
folded = gimple_convert (&forced_stmts, exprtype, folded);
! /* If everything simplified to an exisiting SSA name or constant just
! return that. */
! if (gimple_seq_empty_p (forced_stmts)
! || is_gimple_min_invariant (folded))
return folded;
gcc_assert (TREE_CODE (folded) == SSA_NAME);
--- 2897,2912 ----
folded = gimple_convert (&forced_stmts, exprtype, folded);
! /* If there is nothing to insert, return the simplified result. */
! if (gimple_seq_empty_p (forced_stmts))
return folded;
+ /* If we simplified to a constant return it and discard eventually
+ built stmts. */
+ if (is_gimple_min_invariant (folded))
+ {
+ gimple_seq_discard (forced_stmts);
+ return folded;
+ }
gcc_assert (TREE_CODE (folded) == SSA_NAME);
