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* [gcc r12-5411] Use modref even for nested functions in ref_maybe_used_by_call_p_1
@ 2021-11-19 17:09 Jan Hubicka
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From: Jan Hubicka @ 2021-11-19 17:09 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:ada63d56beb0e535d35b165b55f85e29a0b36929
commit r12-5411-gada63d56beb0e535d35b165b55f85e29a0b36929
Author: Jan Hubicka <jh@suse.cz>
Date: Fri Nov 19 18:09:13 2021 +0100
Use modref even for nested functions in ref_maybe_used_by_call_p_1
Remove test for function not having call chain guarding modref use in
ref_maybe_used_by_call_p_1. It never made sense since modref treats call chain
accesses explicitly. It was however copied from earlier check for ECF_CONST
(which seems dubious too, but I would like to discuss it independelty).
This enables us to detect that memory pointed to static chain (or parts of it)
are unused by the function.
lto-bootstrapped-regtested all lanugages on x86_64-linux.
gcc/ChangeLog:
2021-11-19 Jan Hubicka <hubicka@ucw.cz>
* tree-ssa-alias.c (ref_maybe_used_by_call_p_1): Do not guard modref
by !gimple_call_chain.
gcc/testsuite/ChangeLog:
2021-11-19 Jan Hubicka <hubicka@ucw.cz>
* gcc.dg/tree-ssa/modref-dse-6.c: New test.
Diff:
---
gcc/testsuite/gcc.dg/tree-ssa/modref-dse-6.c | 23 +++++++++++++++++++++++
gcc/tree-ssa-alias.c | 2 +-
2 files changed, 24 insertions(+), 1 deletion(-)
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/modref-dse-6.c b/gcc/testsuite/gcc.dg/tree-ssa/modref-dse-6.c
new file mode 100644
index 00000000000..d1e45a893ad
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/modref-dse-6.c
@@ -0,0 +1,23 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+int
+main()
+{
+ int a,b;
+ __attribute__ ((noinline))
+ void kill_me()
+ {
+ a=1234;
+ b=2234;
+ }
+ a=0;
+ b=1234;
+ __attribute__ ((noinline))
+ int reta()
+ {
+ return a;
+ }
+ return reta();
+}
+/* { dg-final { scan-tree-dump-not "kill_me" "optimized" } } */
+/* { dg-final { scan-tree-dump-not "1234" "optimized" } } */
diff --git a/gcc/tree-ssa-alias.c b/gcc/tree-ssa-alias.c
index 02bbc87b597..cd6a0b2f67b 100644
--- a/gcc/tree-ssa-alias.c
+++ b/gcc/tree-ssa-alias.c
@@ -2755,7 +2755,7 @@ ref_maybe_used_by_call_p_1 (gcall *call, ao_ref *ref, bool tbaa_p)
callee = gimple_call_fndecl (call);
- if (!gimple_call_chain (call) && callee != NULL_TREE)
+ if (callee != NULL_TREE)
{
struct cgraph_node *node = cgraph_node::get (callee);
/* We can not safely optimize based on summary of calle if it does
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