middle-end/108625 - wrong folding due to misinterpreted !

The following fixes a problem with ! handling in genmatch which isn't
conservative enough when intermediate simplifications push to the
sequence but the final operation appears to just pick an existing
(but in this case newly defined in the sequence) operand.  The easiest
fix is to disallow adding to the sequence when processing !.

	PR middle-end/108625
	* genmatch.cc (expr::gen_transform): Also disallow resimplification
	from pushing to lseq with force_leaf.
	(dt_simplify::gen_1): Likewise.

	* gcc.dg/pr108625.c: New testcase.

diff --git a/gcc/genmatch.cc b/gcc/genmatch.cc
index e147ab9db7ad07b545246c180dd3b8fc49d9ce4f..43bd0212d0e205a8b73ba95fe44d83a193ae922e 100644 (file)
--- a/gcc/genmatch.cc
+++ b/gcc/genmatch.cc
@@ -2541,7 +2541,8 @@ expr::gen_transform (FILE *f, int indent, const char *dest, bool gimple,
       for (unsigned i = 0; i < ops.length (); ++i)
        fprintf (f, ", _o%d[%u]", depth, i);
       fprintf (f, ");\n");
-      fprintf_indent (f, indent, "tem_op.resimplify (lseq, valueize);\n");
+      fprintf_indent (f, indent, "tem_op.resimplify (%s, valueize);\n",
+                     !force_leaf ? "lseq" : "NULL");
       fprintf_indent (f, indent,
                      "_r%d = maybe_push_res_to_seq (&tem_op, %s);\n", depth,
                      !force_leaf ? "lseq" : "NULL");
@@ -3451,7 +3452,8 @@ dt_simplify::gen_1 (FILE *f, int indent, bool gimple, operand *result)
          if (!is_predicate)
            {
              fprintf_indent (f, indent,
-                             "res_op->resimplify (lseq, valueize);\n");
+                             "res_op->resimplify (%s, valueize);\n",
+                             !e->force_leaf ? "lseq" : "NULL");
              if (e->force_leaf)
                fprintf_indent (f, indent,
                                "if (!maybe_push_res_to_seq (res_op, NULL)) "

diff --git a/gcc/testsuite/gcc.dg/pr108625.c b/gcc/testsuite/gcc.dg/pr108625.c
new file mode 100644 (file)
index 0000000..03fc288
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr108625.c
@@ -0,0 +1,14 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-forwprop1 -fdump-tree-optimized" } */
+
+unsigned char foo(int x)
+{
+  int t = -x;
+  unsigned char t1 = t;
+  unsigned char t2 = t;
+  /* We may not rewrite this as (unsigned char)(t - x).  */
+  return t1 + t2;
+}
+
+/* { dg-final { scan-tree-dump-times "x_" 1 "forwprop1" } } */
+/* { dg-final { scan-tree-dump-times "x_" 1 "optimized" } } */