Ping: [PATCH 1/2] Fold plusminus_mult expr with multi-use operands (PR 94234)

[Richard Biener]

On Mon, Sep 14, 2020 at 5:17 AM Feng Xue OS via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> Thanks,

@@ -3426,8 +3426,16 @@ dt_simplify::gen_1 (FILE *f, int indent, bool
gimple, operand *result)
          /* Re-fold the toplevel result.  It's basically an embedded
             gimple_build w/o actually building the stmt.  */
          if (!is_predicate)
-           fprintf_indent (f, indent,
-                           "res_op->resimplify (lseq, valueize);\n");
+           {
+             fprintf_indent (f, indent,
+                             "res_op->resimplify (lseq, valueize);\n");
+             if (e->force_leaf)
+               {
+                 fprintf_indent (f, indent,
+                     "if (!maybe_push_res_to_seq (res_op, NULL))\n");
+                 fprintf_indent (f, indent + 2, "return false;\n");

please use "goto %s;\n", fail_label)  here.  OK with that change.

I've tried again to think about sth prettier to cover these kind of
single-use checks but failed to come up with sth.

Thanks and sorry for the delay,
Richard.

> Feng
>
> ________________________________________
> From: Feng Xue OS
> Sent: Thursday, September 3, 2020 2:06 PM
> To: gcc-patches@gcc.gnu.org
> Subject: [PATCH 1/2] Fold plusminus_mult expr with multi-use operands (PR 94234)
>
> For pattern A * C +- B * C -> (A +- B) * C, simplification is disabled
> when A and B are not single-use. This patch is a minor enhancement
> on the pattern, which allows folding if final result is found to be a
> simple gimple value (constant/existing SSA).
>
> Bootstrapped/regtested on x86_64-linux and aarch64-linux.
>
> Feng
> ---
> 2020-09-03  Feng Xue  <fxue@os.amperecomputing.com>
>
> gcc/
>         PR tree-optimization/94234
>         * genmatch.c (dt_simplify::gen_1): Emit check on final simplification
>         result when "!" is specified on toplevel output expr.
>         * match.pd ((A * C) +- (B * C) -> (A +- B) * C): Allow folding for
>         expr with multi-use operands if final result is a simple gimple value.
>
> gcc/testsuite/
>         PR tree-optimization/94234
>         * gcc.dg/pr94234-2.c: New test.
> ---