Hi Richard,
It looks like this patch result in one ICE for RISC-V backend for case
tree-ssa.exp=ssa-sink-16.c, could you please help to double check about it?
Any more information required please feel free to let me know. Thanks.
compiler error: Segmentation fault
0x1903067 crash_signal
../../../../gcc/gcc/toplev.cc:316
0x111a24e loop_outer(loop const*)
../../../../gcc/gcc/cfgloop.h:549
0x1ac2143 find_uses_to_rename_use
../../../../gcc/gcc/tree-ssa-loop-manip.cc:424
0x1ac2295 find_uses_to_rename_stmt
../../../../gcc/gcc/tree-ssa-loop-manip.cc:464
0x1ac2456 find_uses_to_rename_bb
../../../../gcc/gcc/tree-ssa-loop-manip.cc:495
0x1ac2585 find_uses_to_rename
../../../../gcc/gcc/tree-ssa-loop-manip.cc:521
0x1ac267c rewrite_into_loop_closed_ssa_1
../../../../gcc/gcc/tree-ssa-loop-manip.cc:588
0x1ac2735 rewrite_into_loop_closed_ssa(bitmap_head*, unsigned int)
../../../../gcc/gcc/tree-ssa-loop-manip.cc:628
0x19682a3 repair_loop_structures
../../../../gcc/gcc/tree-cfgcleanup.cc:1190
0x196831d cleanup_tree_cfg(unsigned int)
../../../../gcc/gcc/tree-cfgcleanup.cc:1209
0x16e654b execute_function_todo
../../../../gcc/gcc/passes.cc:2057
0x16e534d do_per_function
../../../../gcc/gcc/passes.cc:1687
0x16e68b0 execute_todo
../../../../gcc/gcc/passes.cc:2142
Pan
-----Original Message-----
From: Richard Biener <rguent...@suse.de>
Sent: Monday, December 4, 2023 7:54 PM
To: gcc-patches@gcc.gnu.org
Subject: [PATCH] tree-optimization/112827 - corrupt SCEV cache during SCCP
The following avoids corrupting the SCEV cache by my last change
to propagate constant final values immediately. The easiest fix
is to keep a dead initialization around.
Bootstrapped and tested on x86_64-unknown-linux-gnu, pushed.
PR tree-optimization/112827
* tree-scalar-evolution.cc (final_value_replacement_loop):
Do not release SSA name but keep a dead initialization around.
* gcc.dg/torture/pr112827-1.c: New testcase.
* gcc.dg/torture/pr112827-2.c: Likewise.
---
gcc/testsuite/gcc.dg/torture/pr112827-1.c | 14 ++++++++++++++
gcc/testsuite/gcc.dg/torture/pr112827-2.c | 18 ++++++++++++++++++
gcc/tree-scalar-evolution.cc | 9 +++------
3 files changed, 35 insertions(+), 6 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/torture/pr112827-1.c
create mode 100644 gcc/testsuite/gcc.dg/torture/pr112827-2.c
diff --git a/gcc/testsuite/gcc.dg/torture/pr112827-1.c
b/gcc/testsuite/gcc.dg/torture/pr112827-1.c
new file mode 100644
index 00000000000..6838cbbe62f
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr112827-1.c
@@ -0,0 +1,14 @@
+/* { dg-do compile } */
+
+int a, b, c, d, e;
+int main() {
+ for (; c; c++) {
+ for (a = 0; a < 2; a++)
+ ;
+ for (; b; b++) {
+ e = d;
+ d = a;
+ }
+ }
+ return 0;
+}
diff --git a/gcc/testsuite/gcc.dg/torture/pr112827-2.c
b/gcc/testsuite/gcc.dg/torture/pr112827-2.c
new file mode 100644
index 00000000000..a7a2a70211b
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr112827-2.c
@@ -0,0 +1,18 @@
+/* { dg-do compile } */
+
+short a, b[1], f;
+char c, g;
+int d, e;
+int main() {
+ for (; f; f++) {
+ for (d = 0; d < 2; d++)
+ ;
+ if (a)
+ for (g = 0; g < 2; g++)
+ for (c = 0; c < 2; c += b[d+g])
+ ;
+ for (; e; e++)
+ ;
+ }
+ return 0;
+}
diff --git a/gcc/tree-scalar-evolution.cc b/gcc/tree-scalar-evolution.cc
index 065bcd0743d..7556d89e9f8 100644
--- a/gcc/tree-scalar-evolution.cc
+++ b/gcc/tree-scalar-evolution.cc
@@ -3847,13 +3847,10 @@ final_value_replacement_loop (class loop *loop)
def = unshare_expr (def);
remove_phi_node (&psi, false);
- /* Propagate constants immediately. */
+ /* Propagate constants immediately, but leave an unused initialization
+ around to avoid invalidating the SCEV cache. */
if (CONSTANT_CLASS_P (def))
- {
- replace_uses_by (rslt, def);
- release_ssa_name (rslt);
- continue;
- }
+ replace_uses_by (rslt, def);
/* Create the replacement statements. */
gimple_seq stmts;
--
2.35.3
