[gcc r13-2493] tree-optimization/106844 - fix ICE in init_use_preds

[gcc r13-2493] tree-optimization/106844 - fix ICE in init_use_preds

[Richard Biener]

https://gcc.gnu.org/g:1a4e1425f8498580994e32ceb3c50bd52616a82d

commit r13-2493-g1a4e1425f8498580994e32ceb3c50bd52616a82d
Author: Richard Biener <rguenther@suse.de>
Date:   Tue Sep 6 10:42:50 2022 +0200

    tree-optimization/106844 - fix ICE in init_use_preds
    
    The following fixes an oversight in the last change to
    compute_control_dep_chain where we have to return whether we found
    a chain.
    
            PR tree-optimization/106844
            * gimple-predicate-analysis.cc (compute_control_dep_chain):
            Return whether we found a chain.
    
            * gcc.dg/pr106844.c: New testcase.

Diff:
---
 gcc/gimple-predicate-analysis.cc |  2 +-
 gcc/testsuite/gcc.dg/pr106844.c  | 16 ++++++++++++++++
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/gcc/gimple-predicate-analysis.cc b/gcc/gimple-predicate-analysis.cc
index 681047deee7..ef2906ebc51 100644
--- a/gcc/gimple-predicate-analysis.cc
+++ b/gcc/gimple-predicate-analysis.cc
@@ -1077,7 +1077,7 @@ compute_control_dep_chain (basic_block dom_bb, const_basic_block dep_bb,
 	      if (dump_file)
 		fprintf (dump_file, "param_uninit_control_dep_attempts "
 			 "exceeded: %u\n", *num_calls);
-	      return false;
+	      break;
 	    }
 	  ++*num_calls;
 
diff --git a/gcc/testsuite/gcc.dg/pr106844.c b/gcc/testsuite/gcc.dg/pr106844.c
new file mode 100644
index 00000000000..df68d76f257
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr106844.c
@@ -0,0 +1,16 @@
+/* { dg-do compile } */
+/* { dg-options "-O -Wuninitialized --param uninit-control-dep-attempts=1" } */
+
+struct {
+  int count;
+  int array[8];
+} fde_merge_v1;
+
+void
+fde_merge_i2() {
+  unsigned i1;
+  do
+    while (i1 && fde_merge_v1.array[i1 - 1]) /* { dg-warning "uninitialized" } */
+      i1--;
+  while (fde_merge_i2);
+}