On Tue, 10 May 2016, Richard Biener wrote:
>
> ifcvt is confused about fake edges not being loop exits which the
> following fixes.
>
> Bootstrap / regtest pending on x86_64-unknown-linux-gnu.
Didn't fare well. The following patch mitigates the issue as well
but in the end make it just latent - it is still sth I wanted
to persue anyway seeing the sometimes odd choices for added
fake edges. The patch reduces the number from two to one
and adds it to the real dead-end infinite loop only for the
testcases.
2016-05-11 Richard Biener <rguent...@suse.de>
PR tree-optimization/70986
* cfganal.c (dfs_find_deadend): Prefer to take edges exiting
loops.
* gcc.dg/torture/pr70986-1.c: New testcase.
* gcc.dg/torture/pr70986-2.c: Likewise.
* gcc.dg/torture/pr70986-3.c: Likewise.
Index: gcc/testsuite/gcc.dg/torture/pr70986-1.c
===================================================================
--- gcc/testsuite/gcc.dg/torture/pr70986-1.c (revision 0)
+++ gcc/testsuite/gcc.dg/torture/pr70986-1.c (working copy)
@@ -0,0 +1,22 @@
+/* { dg-do compile } */
+
+int a, g;
+char b, c;
+short d, e, f;
+
+char
+fn1 ()
+{
+ return a ? a : 1;
+}
+
+void
+fn2 ()
+{
+ char h;
+ for (; d;)
+ for (; e; e++)
+ c = (fn1 () && h) & !(f |= 9 ^ (b > (g = c)));
+ for (;;)
+ ;
+}
Index: gcc/testsuite/gcc.dg/torture/pr70986-2.c
===================================================================
--- gcc/testsuite/gcc.dg/torture/pr70986-2.c (revision 0)
+++ gcc/testsuite/gcc.dg/torture/pr70986-2.c (working copy)
@@ -0,0 +1,20 @@
+/* { dg-do compile } */
+
+int gi, dg;
+
+void
+fe (void)
+{
+ int ka = gi;
+
+ for (;;)
+ {
+ if (ka != 0)
+ {
+ if (dg != 0)
+ gi = 0;
+ ++ka;
+ }
+ ++dg;
+ }
+}
Index: gcc/testsuite/gcc.dg/torture/pr70986-3.c
===================================================================
--- gcc/testsuite/gcc.dg/torture/pr70986-3.c (revision 0)
+++ gcc/testsuite/gcc.dg/torture/pr70986-3.c (working copy)
@@ -0,0 +1,18 @@
+/* { dg-do compile } */
+
+int a, b;
+int
+fn1 (int p1)
+{
+ return p1 < 0 ? p1 : a;
+}
+
+void
+fn2 ()
+{
+lbl_100:
+ b = 1;
+ for (; b != 21; b = fn1 (b))
+ ;
+ goto lbl_100;
+}
Index: gcc/cfganal.c
===================================================================
*** gcc/cfganal.c (revision 236069)
--- gcc/cfganal.c (working copy)
*************** dfs_find_deadend (basic_block bb)
*** 747,753 ****
return bb;
}
! bb = EDGE_SUCC (bb, 0)->dest;
}
gcc_unreachable ();
--- 751,771 ----
return bb;
}
! /* If we are in an analyzed cycle make sure to try exiting it.
! Note this is a heuristic only and expected to work when loop
! fixup is needed as well. */
! if (! bb->loop_father
! || ! loop_outer (bb->loop_father))
! bb = EDGE_SUCC (bb, 0)->dest;
! else
! {
! edge_iterator ei;
! edge e;
! FOR_EACH_EDGE (e, ei, bb->succs)
! if (bb->loop_father != e->dest->loop_father)
! break;
! bb = e ? e->dest : EDGE_SUCC (bb, 0)->dest;
! }
}
gcc_unreachable ();
