* [PATCH] tree-optimization/110491 - PHI-OPT and undefs
@ 2023-07-04 12:16 Richard Biener
0 siblings, 0 replies; only message in thread
From: Richard Biener @ 2023-07-04 12:16 UTC (permalink / raw)
To: gcc-patches; +Cc: pinskia
The following makes sure to not make conditional undefs in PHI arguments
unconditional by folding cond ? arg1 : arg2.
Bootstrapped and tested on x86_64-unknown-linux-gnu, pushed.
This might become redundant with the pending fix to reset
flow-sensitive info.
Richard.
PR tree-optimization/110491
* tree-ssa-phiopt.cc (match_simplify_replacement): Check
whether the PHI args are possibly undefined before folding
the COND_EXPR.
* gcc.dg/torture/pr110491.c: New testcase.
---
gcc/testsuite/gcc.dg/torture/pr110491.c | 29 +++++++++++++++++++++++++
gcc/tree-ssa-phiopt.cc | 7 ++++++
2 files changed, 36 insertions(+)
create mode 100644 gcc/testsuite/gcc.dg/torture/pr110491.c
diff --git a/gcc/testsuite/gcc.dg/torture/pr110491.c b/gcc/testsuite/gcc.dg/torture/pr110491.c
new file mode 100644
index 00000000000..00b3bdfc122
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr110491.c
@@ -0,0 +1,29 @@
+/* { dg-do run } */
+
+int a, c, d, e;
+short b;
+void f(int *g) { c &= *g; }
+void h(void);
+void i() {
+ a = 1;
+ h();
+ f(&a);
+}
+void h() {
+ int *j = &c;
+ *j = 5;
+k:
+ for (; 4 + b <= 0;)
+ ;
+ for (; d;) {
+ c = e == 0;
+ goto k;
+ }
+}
+int main()
+{
+ i();
+ if (c != 1)
+ __builtin_abort ();
+ return 0;
+}
diff --git a/gcc/tree-ssa-phiopt.cc b/gcc/tree-ssa-phiopt.cc
index 31a7c39e405..467c9fd108a 100644
--- a/gcc/tree-ssa-phiopt.cc
+++ b/gcc/tree-ssa-phiopt.cc
@@ -785,6 +785,13 @@ match_simplify_replacement (basic_block cond_bb, basic_block middle_bb,
arg_false = arg0;
}
+ /* Do not make conditional undefs unconditional. */
+ if ((TREE_CODE (arg_true) == SSA_NAME
+ && ssa_name_maybe_undef_p (arg_true))
+ || (TREE_CODE (arg_false) == SSA_NAME
+ && ssa_name_maybe_undef_p (arg_false)))
+ return false;
+
tree type = TREE_TYPE (gimple_phi_result (phi));
result = gimple_simplify_phiopt (early_p, type, stmt,
arg_true, arg_false,
--
2.35.3
^ permalink raw reply [flat|nested] only message in thread
only message in thread, other threads:[~2023-07-04 12:16 UTC | newest]
Thread overview: (only message) (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2023-07-04 12:16 [PATCH] tree-optimization/110491 - PHI-OPT and undefs Richard Biener
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).