On 16/08/18 23:12, Luc Van Oostenryck wrote:
> If the effective mask (C & M) is different than the outer mask C,
> then this later can be replaced by the smaller (C & M), giving:
> OP((x | M'), K) with M' == (C & M).
>
> For example, code like:
> int foo(int x)
> {
> return (x | 0xfffffff0) & 0xfff;
> }
C = 0xfffffff0, OP = &, K = 0xfff, (C & K) = 0xff0, so
OP((x | M'), K) where M' = (C & K).
ATB,
Ramsay Jones
>
> is now simplified into:
> foo:
> or.32 %r2 <- %arg1, $0xff0
> and.32 %r3 <- %r2, $0xfff
> ret.32 %r3
>
> while previously, the constant was not reduced:
> foo:
> or.32 %r2 <- %arg1, $0xfffffff0
> and.32 %r3 <- %r2, $0xfff
> ret.32 %r3
>
> Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@xxxxxxxxx>
> ---
> simplify.c | 4 ++++
> validation/optim/and-or-constant2.c | 1 -
> 2 files changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/simplify.c b/simplify.c
> index 755371002..5a802d207 100644
> --- a/simplify.c
> +++ b/simplify.c
> @@ -622,6 +622,10 @@ static int simplify_mask_or(struct instruction *insn, unsigned long long mask, s
> // if (C & M) == M: OR(x, C) -> (C & M)
> return replace_pseudo(insn, &insn->src1, value_pseudo(nval));
> }
> + if (nval != oval && !multi_users(or->target)) {
> + // if (C & M) != C: OR(x, C) -> OR(x, (C & M))
> + return replace_pseudo(or, &or->src2, value_pseudo(nval));
> + }
> }
> return 0;
> }
> diff --git a/validation/optim/and-or-constant2.c b/validation/optim/and-or-constant2.c
> index 82e0d3c69..d7e66f9c0 100644
> --- a/validation/optim/and-or-constant2.c
> +++ b/validation/optim/and-or-constant2.c
> @@ -6,7 +6,6 @@ int foo(int x)
> /*
> * check-name: and-or-constant2
> * check-command: test-linearize -Wno-decl $file
> - * check-known-to-fail
> *
> * check-output-ignore
> * check-output-contains: or\\..*\\$0xff0
>
