I am testing the following patch to fix wrong-debug creatd by
loop-distribution simply dropping debug stmts on the floor
making earlier ones with bogus value live.
Bootstrap & regtest running on x86_64-unknown-linux-gnu.
Richard.
2019-04-15 Richard Biener <rguent...@suse.de>
PR debug/90074
* tree-loop-distribution.c (destroy_loop): Preserve correct
debug info.
* gcc.dg/guality/pr90074.c: New testcase.
Index: gcc/tree-loop-distribution.c
===================================================================
--- gcc/tree-loop-distribution.c (revision 270358)
+++ gcc/tree-loop-distribution.c (working copy)
@@ -1094,12 +1094,8 @@ destroy_loop (struct loop *loop)
bbs = get_loop_body_in_dom_order (loop);
- redirect_edge_pred (exit, src);
- exit->flags &= ~(EDGE_TRUE_VALUE|EDGE_FALSE_VALUE);
- exit->flags |= EDGE_FALLTHRU;
- cancel_loop_tree (loop);
- rescan_loop_exit (exit, false, true);
-
+ gimple_stmt_iterator dst_gsi = gsi_after_labels (exit->dest);
+ bool safe_p = single_pred_p (exit->dest);
i = nbbs;
do
{
@@ -1116,14 +1112,45 @@ destroy_loop (struct loop *loop)
if (virtual_operand_p (gimple_phi_result (phi)))
mark_virtual_phi_result_for_renaming (phi);
}
- for (gimple_stmt_iterator gsi = gsi_start_bb (bbs[i]); !gsi_end_p (gsi);
- gsi_next (&gsi))
+ for (gimple_stmt_iterator gsi = gsi_start_bb (bbs[i]); !gsi_end_p (gsi);)
{
gimple *stmt = gsi_stmt (gsi);
tree vdef = gimple_vdef (stmt);
if (vdef && TREE_CODE (vdef) == SSA_NAME)
mark_virtual_operand_for_renaming (vdef);
+ /* Also move and eventually reset debug stmts. We can leave
+ constant values in place in case the stmt dominates the exit.
+ ??? Non-constant values from the last iteration can be
+ replaced with final values if we can compute them. */
+ if (gimple_debug_bind_p (stmt))
+ {
+ tree val = gimple_debug_bind_get_value (stmt);
+ gsi_move_before (&gsi, &dst_gsi);
+ if (val
+ && (!safe_p
+ || !is_gimple_min_invariant (val)
+ || !dominated_by_p (CDI_DOMINATORS, exit->src, bbs[i])))
+ {
+ gimple_debug_bind_reset_value (stmt);
+ update_stmt (stmt);
+ }
+ }
+ else
+ gsi_next (&gsi);
}
+ }
+ while (i != 0);
+
+ redirect_edge_pred (exit, src);
+ exit->flags &= ~(EDGE_TRUE_VALUE|EDGE_FALSE_VALUE);
+ exit->flags |= EDGE_FALLTHRU;
+ cancel_loop_tree (loop);
+ rescan_loop_exit (exit, false, true);
+
+ i = nbbs;
+ do
+ {
+ --i;
delete_basic_block (bbs[i]);
}
while (i != 0);
Index: gcc/testsuite/gcc.dg/guality/pr90074.c
===================================================================
--- gcc/testsuite/gcc.dg/guality/pr90074.c (nonexistent)
+++ gcc/testsuite/gcc.dg/guality/pr90074.c (working copy)
@@ -0,0 +1,31 @@
+/* { dg-do run } */
+/* { dg-options "-g" } */
+
+void __attribute__((noinline))
+optimize_me_not ()
+{
+ __asm__ volatile ("" : : : "memory");
+}
+char a;
+short b[7][1];
+int main()
+{
+ int i, c;
+ a = 0;
+ i = 0;
+ for (; i < 7; i++) {
+ c = 0;
+ for (; c < 1; c++)
+ b[i][c] = 0;
+ }
+ /* i may very well be optimized out, so we cannot test for i == 7.
+ Instead test i + 1 which will make the test UNSUPPORTED if i
+ is optimized out. Since the test previously had wrong debug
+ with i == 0 this is acceptable. Optimally we'd produce a
+ debug stmt for the final value of the loop during loop distribution
+ which would fix the UNSUPPORTED cases.
+ c is optimized out at -Og for no obvious reason. */
+ optimize_me_not(); /* { dg-final { gdb-test . "i + 1" "8" } } */
+ /* { dg-final { gdb-test .-1 "c + 1" "2" } } */
+ return 0;
+}
