Bootstrapped and tested on x86_64-unknown-linux-gnu, applied to trunk.
Richard.
2016-09-15 Richard Biener <rguent...@suse.de>
PR tree-optimization/77514
* tree-ssa-pre.c (create_expression_by_pieces): Handle garbage
only forced_stmts sequence.
* gcc.dg/torture/pr77514.c: New testcase.
Index: gcc/tree-ssa-pre.c
===================================================================
--- gcc/tree-ssa-pre.c (revision 240133)
+++ gcc/tree-ssa-pre.c (working copy)
@@ -2879,7 +2879,21 @@ create_expression_by_pieces (basic_block
gimple_seq_discard (forced_stmts);
return folded;
}
-
+ /* Likewise if we simplified to sth not queued for insertion. */
+ bool found = false;
+ gsi = gsi_start (forced_stmts);
+ for (; !gsi_end_p (gsi); gsi_next (&gsi))
+ {
+ gimple *stmt = gsi_stmt (gsi);
+ tree forcedname = gimple_get_lhs (stmt);
+ if (forcedname == folded)
+ found = true;
+ }
+ if (! found)
+ {
+ gimple_seq_discard (forced_stmts);
+ return folded;
+ }
gcc_assert (TREE_CODE (folded) == SSA_NAME);
/* If we have any intermediate expressions to the value sets, add them
Index: gcc/testsuite/gcc.dg/torture/pr77514.c
===================================================================
--- gcc/testsuite/gcc.dg/torture/pr77514.c (revision 0)
+++ gcc/testsuite/gcc.dg/torture/pr77514.c (working copy)
@@ -0,0 +1,21 @@
+/* { dg-do compile } */
+
+void
+m1 (char l0, char e8, int hw)
+{
+ char *rs = &l0;
+
+yu:
+ l0 = 1;
+ while (l0 != 0)
+ {
+ l0 = -l0;
+ l0 += (*rs ^ (l0 &= 1));
+ }
+ for (;;)
+ {
+ if (hw != 0)
+ goto yu;
+ rs = &e8;
+ }
+}
