If the effective mask (M) corresponding to OP(_, K) is different
than the combined mask (C & M), then the inner mask (C) 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;
}
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 a36083789..fce99551a 100644
--- a/simplify.c
+++ b/simplify.c
@@ -626,6 +626,10 @@ static int simplify_mask_or(struct instruction *insn, unsigned long long mask, s
// if (C & M) == M: OR(x, C) -> M
return replace_pseudo(insn, &insn->src1, value_pseudo(mask));
}
+ 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
--
2.18.0
