On Sat, Jan 28, 2023 at 11:25 PM Andrew Pinski via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> This patch adds a check in match_simplify_replacement to make sure the
> middlebb
> does not have any phi-nodes as we don't currently move those.
> This was just a thinko from before.
>
> Ok? Bootstrapped and tested on x86_64-linux-gnu with no regressions?
OK.
> PR tree-optimization/108582
>
> gcc/ChangeLog:
>
> * tree-ssa-phiopt.cc (match_simplify_replacement): Add check
> for middlebb to have no phi nodes.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.dg/pr108582-1.c: New test.
> ---
> gcc/testsuite/gcc.dg/pr108582-1.c | 58 +++++++++++++++++++++++++++++++
> gcc/tree-ssa-phiopt.cc | 5 +++
> 2 files changed, 63 insertions(+)
> create mode 100644 gcc/testsuite/gcc.dg/pr108582-1.c
>
> diff --git a/gcc/testsuite/gcc.dg/pr108582-1.c
> b/gcc/testsuite/gcc.dg/pr108582-1.c
> new file mode 100644
> index 00000000000..88c2de369ad
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/pr108582-1.c
> @@ -0,0 +1,58 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O3 -fno-tree-ccp -fno-tree-dce" } */
> +
> +/*
> + PHI-OPT via match_simplify_replacement used to transform:
> + if (_25 != 0)
> + goto <bb 8>; [25.00%]
> + else
> + goto <bb 9>; [75.00%]
> +
> + <bb 8> [local count: 11649864]:
> + # iftmp.5_13 = PHI <2(7)>
> + k_22 = k_11 | iftmp.5_13;
> +
> + <bb 9> [local count: 105655256]:
> + # g_9 = PHI <1(2), 0(8), g_8(7)>
> + # k_12 = PHI <k_20(D)(2), k_22(8), k_11(7)>
> +
> +into:
> +
> + _15 = (int) _25;
> + _28 = -_15;
> + _4 = _13 & _28;
> + _6 = _4 | k_11;
> +
> + <bb 8> [local count: 105655256]:
> + # g_9 = PHI <1(2), g_8(7)>
> + # k_12 = PHI <k_20(D)(2), _6(7)>
> +
> +Removing the phi-node/assignment of _13.
> +
> + */
> +
> +int a, c, d, e, f;
> +char b;
> +int main() {
> + int g = 1;
> + char h[1] = {0};
> + while (a) {
> + if (f) {
> + b = 0;
> + if (d)
> + continue;
> + }
> + if (a < 1) {
> + g = 0;
> + goto L;
> + }
> + }
> + while (c) {
> + char *j = h;
> + int k;
> + L:
> + if (e && !g)
> + k |= 2 | (*j < 0);
> + }
> + return 0;
> +}
> diff --git a/gcc/tree-ssa-phiopt.cc b/gcc/tree-ssa-phiopt.cc
> index c3a889dc593..a7ab6ce4ad9 100644
> --- a/gcc/tree-ssa-phiopt.cc
> +++ b/gcc/tree-ssa-phiopt.cc
> @@ -1002,6 +1002,11 @@ match_simplify_replacement (basic_block cond_bb,
> basic_block middle_bb,
> if (!single_pred_p (middle_bb))
> return false;
>
> + /* The middle bb cannot have phi nodes as we don't
> + move those assignments yet. */
> + if (!gimple_seq_empty_p (phi_nodes (middle_bb)))
> + return false;
> +
> stmt_to_move = last_and_only_stmt (middle_bb);
> if (!stmt_to_move)
> return false;
> --
> 2.31.1
>
