[gcc r14-8985] Fix ICE in loop splitting with -fno-guess-branch-probability

[gcc r14-8985] Fix ICE in loop splitting with -fno-guess-branch-probability

[Jan Hubicka]

https://gcc.gnu.org/g:8d51bfe0f97a27c749c36003867901338833340a

commit r14-8985-g8d51bfe0f97a27c749c36003867901338833340a
Author: Jan Hubicka <jh@suse.cz>
Date:   Wed Feb 14 17:37:34 2024 +0100

    Fix ICE in loop splitting with -fno-guess-branch-probability
    
            PR tree-optimization/111054
    
    gcc/ChangeLog:
    
            * tree-ssa-loop-split.cc (split_loop): Check for profile being present.
    
    gcc/testsuite/ChangeLog:
    
            * gcc.c-torture/compile/pr111054.c: New test.

Diff:
---
 gcc/testsuite/gcc.c-torture/compile/pr111054.c | 11 +++++++++++
 gcc/tree-ssa-loop-split.cc                     |  3 ++-
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/gcc/testsuite/gcc.c-torture/compile/pr111054.c b/gcc/testsuite/gcc.c-torture/compile/pr111054.c
new file mode 100644
index 000000000000..3c0d6e816b97
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/compile/pr111054.c
@@ -0,0 +1,11 @@
+/* { dg-additional-options "-fno-guess-branch-probability" } */
+void *p, *q;
+int i, j;
+
+void
+foo (void)
+{
+  for (i = 0; i < 20; i++)
+    if (i < j)
+      p = q;
+}
diff --git a/gcc/tree-ssa-loop-split.cc b/gcc/tree-ssa-loop-split.cc
index 04215fe7937e..c0bb1b71d17c 100644
--- a/gcc/tree-ssa-loop-split.cc
+++ b/gcc/tree-ssa-loop-split.cc
@@ -712,7 +712,8 @@ split_loop (class loop *loop1)
 			  ? true_edge->probability.to_sreal () : (sreal)1;
 	    sreal scale2 = false_edge->probability.reliable_p ()
 			  ? false_edge->probability.to_sreal () : (sreal)1;
-	    sreal div1 = loop1_prob.to_sreal ();
+	    sreal div1 = loop1_prob.initialized_p ()
+			 ? loop1_prob.to_sreal () : (sreal)1/(sreal)2;
 	    /* +1 to get header interations rather than latch iterations and then
 	       -1 to convert back.  */
 	    if (div1 != 0)