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Cranelift: Rewrite or(and(x, y), not(y)) => or(x, not(y)) again (#5684)

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This rewrite was introduced in #5676 and then reverted in #5682 due to a footgun
where we accidentally weren't actually checking the `y == !z` precondition. This
commit fixes the precondition check. It also fixes the arithmetic to be
correctly masked to the value type's width.

This reverts commit 268f6bfc1d.
This commit is contained in:
Nick Fitzgerald
2023-02-01 12:53:22 -08:00
committed by GitHub
parent 91b8a2c527
commit ffbbfbffce
5 changed files with 177 additions and 1 deletions
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34
cranelift/filetests/filetests/runtests/or-and-y-with-not-y.clif Normal file
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@@ -0,0 +1,34 @@
;; Test the rewrite: `or(and(x, y), not(y)) => or(x, not(y))`
test interpret
test run
target aarch64
target x86_64
target riscv64
target s390x
function %or_and_y_with_not_y(i8, i8) -> i8 {
block0(v0: i8, v1: i8):
v2 = band v0, v1
v3 = bnot v1
v4 = bor v2, v3
return v4
}
; run: %or_and_y_with_not_y(0xff, 0x0a) == 0xff
; run: %or_and_y_with_not_y(0xff, 0xb0) == 0xff
; run: %or_and_y_with_not_y(0xaa, 0x0a) == 0xff
; run: %or_and_y_with_not_y(0xaa, 0xb0) == 0xef
; run: %or_and_y_with_not_y(0x00, 0x0a) == 0xf5
; run: %or_and_y_with_not_y(0x00, 0xb0) == 0x4f
function %or_and_constant_with_not_constant(i8) -> i8 {
block0(v0: i8):
v1 = iconst.i8 -4
v2 = band v0, v1
v3 = iconst.i8 3
v4 = bor v2, v3
return v4
}
; run: %or_and_constant_with_not_constant(0xff) == 0xff
; run: %or_and_constant_with_not_constant(0xaa) == 0xab
; run: %or_and_constant_with_not_constant(0x00) == 0x03