[gcc r12-6917] tree-optimization/104263 - avoid retaining abnormal edges for non-call/goto stmts

[gcc r12-6917] tree-optimization/104263 - avoid retaining abnormal edges for non-call/goto stmts

[Richard Biener]

https://gcc.gnu.org/g:5b6f04276e3d1f20817ed37b2e26e43bd12cc0d2

commit r12-6917-g5b6f04276e3d1f20817ed37b2e26e43bd12cc0d2
Author: Richard Biener <rguenther@suse.de>
Date:   Fri Jan 28 10:55:29 2022 +0100

    tree-optimization/104263 - avoid retaining abnormal edges for non-call/goto stmts
    
    This removes a premature optimization from
    gimple_purge_dead_abnormal_call_edges which, after eliding the
    last setjmp (or computed goto) statement from a function and
    thus clearing cfun->calls_setjmp, leaves us with the abnormal
    edges from other calls that are elided for example via inlining
    or DCE.  That's a CFG / IL combination that should be impossible
    (not addressing the fact that with cfun->calls_setjmp and
    cfun->has_nonlocal_label cleared we should not have any abnormal
    edge at all).
    
    For the testcase in the PR this means that IPA inlining will
    remove the abormal edges from the block after inlining the call
    the edge was coming from.
    
    2022-01-28  Richard Biener  <rguenther@suse.de>
    
            PR tree-optimization/104263
            * tree-cfg.cc (gimple_purge_dead_abnormal_call_edges):
            Purge edges also when !cfun->has_nonlocal_label
            and !cfun->calls_setjmp.
    
            * gcc.dg/tree-ssa/inline-13.c: New testcase.

Diff:
---
 gcc/testsuite/gcc.dg/tree-ssa/inline-13.c | 27 +++++++++++++++++++++++++++
 gcc/tree-cfg.cc                           |  4 ----
 2 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/gcc/testsuite/gcc.dg/tree-ssa/inline-13.c b/gcc/testsuite/gcc.dg/tree-ssa/inline-13.c
new file mode 100644
index 00000000000..94d8a9c709e
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/inline-13.c
@@ -0,0 +1,27 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fno-early-inlining -fdump-tree-fixup_cfg3" } */
+
+int n;
+
+static int
+bar (void)
+{
+  int a;
+
+  n = 0;
+  a = 0;
+
+  return n;
+}
+
+__attribute__ ((pure, returns_twice)) int
+foo (void)
+{
+  n = bar () + 1;
+  foo ();
+
+  return 0;
+}
+
+/* Abnormal edges should be properly elided after IPA inlining of bar.  */
+/* { dg-final { scan-tree-dump-times "bb" 1 "fixup_cfg3" } } */
diff --git a/gcc/tree-cfg.cc b/gcc/tree-cfg.cc
index 77178a6bf69..efd10332c53 100644
--- a/gcc/tree-cfg.cc
+++ b/gcc/tree-cfg.cc
@@ -8915,10 +8915,6 @@ gimple_purge_dead_abnormal_call_edges (basic_block bb)
   edge_iterator ei;
   gimple *stmt = last_stmt (bb);
 
-  if (!cfun->has_nonlocal_label
-      && !cfun->calls_setjmp)
-    return false;
-
   if (stmt && stmt_can_make_abnormal_goto (stmt))
     return false;