On 27/11/14 15:13, Richard Biener wrote:
Bootstrapped and tested on x86_64-unknown-linux-gnu, applied to trunk.
Richard.
2014-11-27 Richard Biener <rguent...@suse.de>
PR tree-optimization/64088
* tree-ssa-tail-merge.c (update_debug_stmt): After resetting
the stmt break from the loop over use operands.
* gcc.dg/torture/pr64091.c: New testcase.
Index: gcc/tree-ssa-tail-merge.c
===================================================================
--- gcc/tree-ssa-tail-merge.c (revision 218117)
+++ gcc/tree-ssa-tail-merge.c (working copy)
@@ -1606,9 +1613,7 @@ update_debug_stmt (gimple stmt)
{
use_operand_p use_p;
ssa_op_iter oi;
- basic_block bbdef, bbuse;
- gimple def_stmt;
- tree name;
+ basic_block bbuse;
if (!gimple_debug_bind_p (stmt))
return;
@@ -1616,19 +1621,16 @@ update_debug_stmt (gimple stmt)
bbuse = gimple_bb (stmt);
FOR_EACH_PHI_OR_STMT_USE (use_p, stmt, oi, SSA_OP_USE)
{
- name = USE_FROM_PTR (use_p);
- gcc_assert (TREE_CODE (name) == SSA_NAME);
-
- def_stmt = SSA_NAME_DEF_STMT (name);
- gcc_assert (def_stmt != NULL);
-
- bbdef = gimple_bb (def_stmt);
+ tree name = USE_FROM_PTR (use_p);
+ gimple def_stmt = SSA_NAME_DEF_STMT (name);
+ basic_block bbdef = gimple_bb (def_stmt);
if (bbdef == NULL || bbuse == bbdef
|| dominated_by_p (CDI_DOMINATORS, bbuse, bbdef))
continue;
gimple_debug_bind_reset_value (stmt);
update_stmt (stmt);
+ break;
}
}
Index: gcc/testsuite/gcc.dg/torture/pr64091.c
===================================================================
--- gcc/testsuite/gcc.dg/torture/pr64091.c (revision 0)
+++ gcc/testsuite/gcc.dg/torture/pr64091.c (working copy)
@@ -0,0 +1,28 @@
+/* { dg-do compile } */
+/* { dg-additional-options "-g" } */
+
+extern int foo(void);
+
+int main(void)
+{
+ int i, a, b;
+
+ if (foo())
+ return 0;
+
+ for (i = 0, a = 0, b = 0; i < 3; i++, a++)
+ {
+ if (foo())
+ break;
+
+ if (b += a)
+ a = 0;
+ }
+
+ if (!a)
+ return 2;
+
+ b += a;
+
+ return 0;
+}
Hi,
the ICE that the patch above fixes does not reproduce on 4.9.
One reason is that an edge_flag EDGE_EXECUTABLE happens to be set, which
prevents tail-merge from doing a merge.
Another reason is that the use that is added to the free_uses freelist
during update_stmt happens to be not immediately reused, so the contents
remains the same.
Using first attached patch, which:
- clears EDGE_EXECUTABLE in tail-merge, and
- clears the contents of a use when adding it to the freelist
we manage to trigger the same problem with 4.9.
Is seems possible to me that the same problem could trigger on 4.9 for a
different example without the trigger patch.
The second attached patch is a minimal version of the above fix.
OK for 4.9?
Thanks,
- Tom
trigger
---
gcc/tree-ssa-operands.c | 6 +++++-
gcc/tree-ssa-tail-merge.c | 1 +
2 files changed, 6 insertions(+), 1 deletion(-)
diff --git a/gcc/tree-ssa-operands.c b/gcc/tree-ssa-operands.c
index 76d04630..d249354 100644
--- a/gcc/tree-ssa-operands.c
+++ b/gcc/tree-ssa-operands.c
@@ -402,7 +402,11 @@ finalize_ssa_uses (struct function *fn, gimple stmt)
if (old_ops)
{
for (ptr = old_ops; ptr; ptr = ptr->next)
- delink_imm_use (USE_OP_PTR (ptr));
+ {
+ delink_imm_use (USE_OP_PTR (ptr));
+ USE_OP_PTR (ptr)->use = NULL;
+ USE_OP_PTR (ptr)->loc.stmt = NULL;
+ }
old_ops->next = gimple_ssa_operands (fn)->free_uses;
gimple_ssa_operands (fn)->free_uses = old_ops;
}
diff --git a/gcc/tree-ssa-tail-merge.c b/gcc/tree-ssa-tail-merge.c
index b5165d5..af2641c 100644
--- a/gcc/tree-ssa-tail-merge.c
+++ b/gcc/tree-ssa-tail-merge.c
@@ -725,6 +725,7 @@ find_same_succ_bb (basic_block bb, same_succ *same_p)
{
int index = e->dest->index;
bitmap_set_bit (same->succs, index);
+ e->flags &= ~EDGE_EXECUTABLE;
same_succ_edge_flags[index] = e->flags;
}
EXECUTE_IF_SET_IN_BITMAP (same->succs, 0, j, bj)
Backport "Fix PR64091"
2016-01-25 Tom de Vries <t...@codesourcery.com>
backport from trunk:
2014-11-27 Richard Biener <rguent...@suse.de>
PR tree-optimization/PR64091
* tree-ssa-tail-merge.c (update_debug_stmt): After resetting
the stmt break from the loop over use operands.
* gcc.dg/torture/pr64091.c: New testcase.
---
gcc/testsuite/gcc.dg/torture/pr64091.c | 28 ++++++++++++++++++++++++++++
gcc/tree-ssa-tail-merge.c | 1 +
2 files changed, 29 insertions(+)
diff --git a/gcc/testsuite/gcc.dg/torture/pr64091.c b/gcc/testsuite/gcc.dg/torture/pr64091.c
new file mode 100644
index 0000000..0cd994a
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr64091.c
@@ -0,0 +1,28 @@
+/* { dg-do compile } */
+/* { dg-additional-options "-g" } */
+
+extern int foo(void);
+
+int main(void)
+{
+ int i, a, b;
+
+ if (foo())
+ return 0;
+
+ for (i = 0, a = 0, b = 0; i < 3; i++, a++)
+ {
+ if (foo())
+ break;
+
+ if (b += a)
+ a = 0;
+ }
+
+ if (!a)
+ return 2;
+
+ b += a;
+
+ return 0;
+}
diff --git a/gcc/tree-ssa-tail-merge.c b/gcc/tree-ssa-tail-merge.c
index af2641c..b3022ff 100644
--- a/gcc/tree-ssa-tail-merge.c
+++ b/gcc/tree-ssa-tail-merge.c
@@ -1619,6 +1619,7 @@ update_debug_stmt (gimple stmt)
gimple_debug_bind_reset_value (stmt);
update_stmt (stmt);
+ break;
}
}
