tree-ssa-math-opts: Fix up ICE in match_uaddc_usubc [PR110508]

The match_uaddc_usubc matching doesn't require that the second
.{ADD,SUB}_OVERFLOW has REALPART_EXPR of its lhs used, only that there is
at most one.  So, in the weird case where the REALPART_EXPR of it isn't
present, we shouldn't ICE trying to replace that REALPART_EXPR with
REALPART_EXPR of .U{ADD,SUB}C result.

2023-07-02  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/110508
	* tree-ssa-math-opts.cc (match_uaddc_usubc): Only replace re2 with
	REALPART_EXPR opf nlhs if re2 is non-NULL.

	* gcc.dg/pr110508.c: New test.

diff --git a/gcc/testsuite/gcc.dg/pr110508.c b/gcc/testsuite/gcc.dg/pr110508.c
new file mode 100644 (file)
index 0000000..a1f8f55
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr110508.c
@@ -0,0 +1,9 @@
+/* PR tree-optimization/110508 */
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+void
+foo (unsigned a, unsigned b, unsigned *c, _Bool d)
+{
+  __builtin_addc (a, b, d, c);
+}

diff --git a/gcc/tree-ssa-math-opts.cc b/gcc/tree-ssa-math-opts.cc
index 701fce2ab612a41e9f730ef84c95231078d4cbbd..68fc518b1abe2719f109fe0a077813672e4faf08 100644 (file)
--- a/gcc/tree-ssa-math-opts.cc
+++ b/gcc/tree-ssa-math-opts.cc
@@ -4861,11 +4861,14 @@ match_uaddc_usubc (gimple_stmt_iterator *gsi, gimple *stmt, tree_code code)
   gsi_remove (&gsi2, true);
   /* Replace the re2 statement with __real__ of the newly added
      .UADDC/.USUBC call.  */
-  gsi2 = gsi_for_stmt (re2);
-  tree rlhs = gimple_assign_lhs (re2);
-  g = gimple_build_assign (rlhs, REALPART_EXPR,
-                          build1 (REALPART_EXPR, TREE_TYPE (rlhs), nlhs));
-  gsi_replace (&gsi2, g, true);
+  if (re2)
+    {
+      gsi2 = gsi_for_stmt (re2);
+      tree rlhs = gimple_assign_lhs (re2);
+      g = gimple_build_assign (rlhs, REALPART_EXPR,
+                              build1 (REALPART_EXPR, TREE_TYPE (rlhs), nlhs));
+      gsi_replace (&gsi2, g, true);
+    }
   if (rhs[2])
     {
       /* If this is the arg1 + arg2 + (ovf1 + ovf2) or