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Cranelift: Rewrite (x>>k)<<k into masking off the bottom k bits (#5673)

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* Cranelift: Rewrite `(x>>k)<<k` into masking off the bottom `k` bits

* Add a runtest for exercising our rewrite of `(x >> k) << k` into masking
This commit is contained in:
Nick Fitzgerald
2023-01-31 13:11:12 -08:00
committed by GitHub
parent 7f2c8e6344
commit 253e28ca4f
3 changed files with 153 additions and 0 deletions
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66
cranelift/filetests/filetests/egraph/algebraic.clif
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@@ -20,3 +20,69 @@ block0:
; check: v2 = iconst.i64 0x9876_5432
; check: return v2 ; v2 = 0x9876_5432
}
function %unsigned_shift_right_shift_left_i8(i8) -> i8 {
block0(v0: i8):
v1 = iconst.i8 5
v2 = ushr v0, v1
v3 = ishl v2, v1
return v3
; check: v4 = iconst.i8 224
; check: v5 = band v0, v4
; return v5
}
function %unsigned_shift_right_shift_left_i32(i32) -> i32 {
block0(v0: i32):
v1 = iconst.i32 5
v2 = ushr v0, v1
v3 = ishl v2, v1
return v3
; check: v4 = iconst.i32 0xffff_ffe0
; check: v5 = band v0, v4
; return v5
}
function %unsigned_shift_right_shift_left_i64(i64) -> i64 {
block0(v0: i64):
v1 = iconst.i64 5
v2 = ushr v0, v1
v3 = ishl v2, v1
return v3
; check: v4 = iconst.i64 -32
; check: v5 = band v0, v4
; return v5
}
function %signed_shift_right_shift_left_i8(i8) -> i8 {
block0(v0: i8):
v1 = iconst.i8 5
v2 = sshr v0, v1
v3 = ishl v2, v1
return v3
; check: v4 = iconst.i8 224
; check: v5 = band v0, v4
; return v5
}
function %signed_shift_right_shift_left_i32(i32) -> i32 {
block0(v0: i32):
v1 = iconst.i32 5
v2 = sshr v0, v1
v3 = ishl v2, v1
return v3
; check: v4 = iconst.i32 0xffff_ffe0
; check: v5 = band v0, v4
; return v5
}
function %signed_shift_right_shift_left_i64(i64) -> i64 {
block0(v0: i64):
v1 = iconst.i64 5
v2 = sshr v0, v1
v3 = ishl v2, v1
return v3
; check: v4 = iconst.i64 -32
; check: v5 = band v0, v4
; return v5
}