On Fri, Jul 26, 2024 at 6:37 AM Andrew Pinski <quic_apin...@quicinc.com> wrote:
>
> While doing cleanups on this code I noticed that we do the duplicate
> of comparisons at -O0. For C and C++ code this makes no difference as
> the gimplifier never produces COND_EXPR. But it could make a difference
> for other front-ends.
> Oh and for -fno-tree-ter, duplicating the comparison is just a waste
> as it is never used for expand.
>
> I also decided to add a few testcases so this is checked in the future.
> Even added one for the duplication itself.
>
> Bootstrapped and tested on x86_64-linux-gnu with no regressions.
OK
> PR tree-optimization/116101
>
> gcc/ChangeLog:
>
> * gimple-isel.cc (maybe_duplicate_comparison): Don't
> do anything for -O0 or -fno-tree-ter.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.dg/tree-ssa/dup_compare_cond-1.c: New test.
> * gcc.dg/tree-ssa/dup_compare_cond-2.c: New test.
> * gcc.dg/tree-ssa/dup_compare_cond-3.c: New test.
>
> Signed-off-by: Andrew Pinski <quic_apin...@quicinc.com>
> ---
> gcc/gimple-isel.cc | 5 +++++
> .../gcc.dg/tree-ssa/dup_compare_cond-1.c | 19 +++++++++++++++++++
> .../gcc.dg/tree-ssa/dup_compare_cond-2.c | 19 +++++++++++++++++++
> .../gcc.dg/tree-ssa/dup_compare_cond-3.c | 19 +++++++++++++++++++
> 4 files changed, 62 insertions(+)
> create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/dup_compare_cond-1.c
> create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/dup_compare_cond-2.c
> create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/dup_compare_cond-3.c
>
> diff --git a/gcc/gimple-isel.cc b/gcc/gimple-isel.cc
> index 99bfc937bd5..2817ab659af 100644
> --- a/gcc/gimple-isel.cc
> +++ b/gcc/gimple-isel.cc
> @@ -407,6 +407,11 @@ maybe_duplicate_comparison (gassign *stmt, basic_block
> bb)
> tree lhs = gimple_assign_lhs (stmt);
> unsigned cnt = 0;
>
> + /* This is should not be used for -O0 nor it is not useful
> + when ter is turned off. */
> + if (!optimize || !flag_tree_ter)
> + return;
> +
> FOR_EACH_IMM_USE_FAST (use_p, imm_iter, lhs)
> {
> if (is_gimple_debug (USE_STMT (use_p)))
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/dup_compare_cond-1.c
> b/gcc/testsuite/gcc.dg/tree-ssa/dup_compare_cond-1.c
> new file mode 100644
> index 00000000000..0321a60b34f
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/dup_compare_cond-1.c
> @@ -0,0 +1,19 @@
> +/* { dg-do compile } */
> +/* { dg-options "-fgimple -O0 -fdump-tree-optimized " } */
> +/* PR tree-optimization/116101 */
> +
> +int __GIMPLE() f(int a, int b, int c, int d, int e)
> +{
> + _Bool t;
> + int ff;
> + int gg;
> + int res;
> + t = a == b;
> + ff = t ? a : e;
> + gg = t ? d : b;
> + res = ff+gg;
> + return res;
> +}
> +
> +/* At -O0 we should not duplicate the comparison. */
> +/* { dg-final { scan-tree-dump-times " == " 1 "optimized" } } */
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/dup_compare_cond-2.c
> b/gcc/testsuite/gcc.dg/tree-ssa/dup_compare_cond-2.c
> new file mode 100644
> index 00000000000..07e2175c612
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/dup_compare_cond-2.c
> @@ -0,0 +1,19 @@
> +/* { dg-do compile } */
> +/* { dg-options "-fgimple -O2 -fdump-tree-optimized " } */
> +/* PR middle-end/105715 */
> +
> +int __GIMPLE() f(int a, int b, int c, int d, int e)
> +{
> + _Bool t;
> + int ff;
> + int gg;
> + int res;
> + t = a == b;
> + ff = t ? a : e;
> + gg = t ? d : b;
> + res = ff+gg;
> + return res;
> +}
> +
> +/* At -O2 we should have duplicate the comparison. */
> +/* { dg-final { scan-tree-dump-times " == " 2 "optimized" } } */
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/dup_compare_cond-3.c
> b/gcc/testsuite/gcc.dg/tree-ssa/dup_compare_cond-3.c
> new file mode 100644
> index 00000000000..88bf19795e0
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/dup_compare_cond-3.c
> @@ -0,0 +1,19 @@
> +/* { dg-do compile } */
> +/* { dg-options "-fgimple -O2 -fno-tree-ter -fdump-tree-optimized " } */
> +/* PR tree-optimization/116101 */
> +
> +int __GIMPLE() f(int a, int b, int c, int d, int e)
> +{
> + _Bool t;
> + int ff;
> + int gg;
> + int res;
> + t = a == b;
> + ff = t ? a : e;
> + gg = t ? d : b;
> + res = ff+gg;
> + return res;
> +}
> +
> +/* With -fno-tree-ter it is not useful to duplicate the comparison. */
> +/* { dg-final { scan-tree-dump-times " == " 1 "optimized" } } */
> --
> 2.43.0
>
