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* [gcc r13-2926] tree-optimization/105646 - re-interpret always executed in uninit diag
@ 2022-09-29 8:24 Richard Biener
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From: Richard Biener @ 2022-09-29 8:24 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:a1cd4d52d6ef90b977fb2d80c1cf17f3efa5b01d
commit r13-2926-ga1cd4d52d6ef90b977fb2d80c1cf17f3efa5b01d
Author: Richard Biener <rguenther@suse.de>
Date: Fri Aug 19 15:11:14 2022 +0200
tree-optimization/105646 - re-interpret always executed in uninit diag
The following fixes PR105646, not diagnosing
int f1();
int f3(){
auto const & a = f1();
bool v3{v3};
return a;
}
with optimization because the early uninit diagnostic pass only
diagnoses always executed cases. The patch does this by
re-interpreting what always executed means and choosing to
ignore exceptional and abnormal control flow for this. At the
same time it improves things as suggested in a comment - when
the value-numbering run done without optimizing figures there's
a fallthru path, consider blocks on it as always executed.
PR tree-optimization/105646
* tree-ssa-uninit.cc (warn_uninitialized_vars): Pre-compute
the set of fallthru reachable blocks from function entry
and use that to determine wlims.always_executed.
* g++.dg/uninit-pr105646.C: New testcase.
Diff:
---
gcc/testsuite/g++.dg/uninit-pr105646.C | 17 +++++++++++++++++
gcc/tree-ssa-uninit.cc | 10 ++++++++--
2 files changed, 25 insertions(+), 2 deletions(-)
diff --git a/gcc/testsuite/g++.dg/uninit-pr105646.C b/gcc/testsuite/g++.dg/uninit-pr105646.C
new file mode 100644
index 00000000000..48ceb986ec6
--- /dev/null
+++ b/gcc/testsuite/g++.dg/uninit-pr105646.C
@@ -0,0 +1,17 @@
+// { dg-do compile }
+// { dg-require-effective-target c++11 }
+// { dg-options "-O2 -Wuninitialized" }
+
+int f1();
+int f2(){
+ bool v2{v2}; // { dg-warning "is used uninitialized" }
+ auto const & a = f1();
+ return a;
+}
+int f3(){
+ auto const & a = f1();
+ // Diagnose the following when optimizing and as unconditional
+ // uninitialized use despite f1 possibly throwing
+ bool v3{v3}; // { dg-warning "is used uninitialized" }
+ return a;
+}
diff --git a/gcc/tree-ssa-uninit.cc b/gcc/tree-ssa-uninit.cc
index eae29f88f9d..bde23997a0a 100644
--- a/gcc/tree-ssa-uninit.cc
+++ b/gcc/tree-ssa-uninit.cc
@@ -991,14 +991,20 @@ warn_uninitialized_vars (bool wmaybe_uninit)
auto_bb_flag ft_reachable (cfun);
/* Mark blocks that are always executed when we ignore provably
- not executed edges. */
+ not executed and EH and abnormal edges. */
basic_block bb = single_succ (ENTRY_BLOCK_PTR_FOR_FN (cfun));
while (!(bb->flags & ft_reachable))
{
bb->flags |= ft_reachable;
+ edge e = find_fallthru_edge (bb->succs);
+ if (e && e->flags & EDGE_EXECUTABLE)
+ {
+ bb = e->dest;
+ continue;
+ }
/* Find a single executable edge. */
edge_iterator ei;
- edge e, ee = NULL;
+ edge ee = NULL;
FOR_EACH_EDGE (e, ei, bb->succs)
if (e->flags & EDGE_EXECUTABLE)
{
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