hardcmp: split before dispatch edge

If we harden a compare at the end of a block with an edge to the
abnormal dispatch block, it won't have a single successor.  Arrange to
split the block at its final stmt so as to have a single succ.

for  gcc/ChangeLog

	PR middle-end/104975
	* gimple-harden-conditionals.cc
	(pass_harden_compares::execute): Force split in case of
	multiple edges.

for  gcc/testsuite/ChangeLog

	PR middle-end/104975
	* gcc.dg/pr104975.c: New.

diff --git a/gcc/gimple-harden-conditionals.cc b/gcc/gimple-harden-conditionals.cc
index 6a5fc3fb9e1a27c4feaf0df70374210b5b3b5260..be01f3ea8c44af2e1f3d9429698d9902aa421257 100644 (file)
--- a/gcc/gimple-harden-conditionals.cc
+++ b/gcc/gimple-harden-conditionals.cc
@@ -509,10 +509,16 @@ pass_harden_compares::execute (function *fun)
        gsi_insert_before (&gsi_split, asgnck, GSI_SAME_STMT);
 
        /* We wish to insert a cond_expr after the compare, so arrange
-          for it to be at the end of a block if it isn't.  */
-       if (!gsi_end_p (gsi_split))
+          for it to be at the end of a block if it isn't, and for it
+          to have a single successor in case there's more than
+          one, as in PR104975.  */
+       if (!gsi_end_p (gsi_split)
+           || !single_succ_p (gsi_bb (gsi_split)))
          {
-           gsi_prev (&gsi_split);
+           if (!gsi_end_p (gsi_split))
+             gsi_prev (&gsi_split);
+           else
+             gsi_split = gsi_last_bb (gsi_bb (gsi_split));
            basic_block obb = gsi_bb (gsi_split);
            basic_block nbb = split_block (obb, gsi_stmt (gsi_split))->dest;
            gsi_next (&gsi_split);

diff --git a/gcc/testsuite/gcc.dg/pr104975.c b/gcc/testsuite/gcc.dg/pr104975.c
new file mode 100644 (file)
index 0000000..04532fc
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr104975.c
@@ -0,0 +1,20 @@
+/* { dg-do compile } */
+/* { dg-options "-O1 -fharden-compares -fno-inline -fno-ipa-pure-const" } */
+
+__attribute__ ((pure, returns_twice)) int
+bar (int);
+
+int
+quux (void)
+{
+  return 0;
+}
+
+int
+foo (short int x)
+{
+  x = !x;
+  bar (quux ());
+
+  return x;
+}