llvm-6502/test/Transforms/Reassociate/xor_reassoc.ll
Shuxin Yang 2d10010649 Implement XOR reassociation. It is based on following rules:
rule 1: (x | c1) ^ c2 => (x & ~c1) ^ (c1^c2),
     only useful when c1=c2
  rule 2: (x & c1) ^ (x & c2) = (x & (c1^c2))
  rule 3: (x | c1) ^ (x | c2) = (x & c3) ^ c3 where c3 = c1 ^ c2
  rule 4: (x | c1) ^ (x & c2) => (x & c3) ^ c1, where c3 = ~c1 ^ c2

 It reduces an application's size (in terms of # of instructions) by 8.9%.
 Reviwed by Pete Cooper. Thanks a lot!

 rdar://13212115  


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@178409 91177308-0d34-0410-b5e6-96231b3b80d8
2013-03-30 02:15:01 +00:00

152 lines
3.5 KiB
LLVM

;RUN: opt -S -reassociate < %s | FileCheck %s
; ==========================================================================
;
; Xor reassociation general cases
;
; ==========================================================================
; (x | c1) ^ (x | c2) => (x & c3) ^ c3, where c3 = c1^c2
;
define i32 @xor1(i32 %x) {
%or = or i32 %x, 123
%or1 = or i32 %x, 456
%xor = xor i32 %or, %or1
ret i32 %xor
;CHECK: @xor1
;CHECK: %and.ra = and i32 %x, 435
;CHECK: %xor = xor i32 %and.ra, 435
}
; Test rule : (x & c1) ^ (x & c2) = (x & (c1^c2))
; Real testing case : (x & 123) ^ y ^ (x & 345) => (x & 435) ^ y
define i32 @xor2(i32 %x, i32 %y) {
%and = and i32 %x, 123
%xor = xor i32 %and, %y
%and1 = and i32 %x, 456
%xor2 = xor i32 %xor, %and1
ret i32 %xor2
;CHECK: @xor2
;CHECK: %and.ra = and i32 %x, 435
;CHECK: %xor2 = xor i32 %and.ra, %y
}
; Test rule: (x | c1) ^ (x & c2) = (x & c3) ^ c1, where c3 = ~c1 ^ c2
; c3 = ~c1 ^ c2
define i32 @xor3(i32 %x, i32 %y) {
%or = or i32 %x, 123
%xor = xor i32 %or, %y
%and = and i32 %x, 456
%xor1 = xor i32 %xor, %and
ret i32 %xor1
;CHECK: @xor3
;CHECK: %and.ra = and i32 %x, -436
;CHECK: %xor = xor i32 %y, 123
;CHECK: %xor1 = xor i32 %xor, %and.ra
}
; Test rule: (x | c1) ^ c2 = (x & ~c1) ^ (c1 ^ c2)
define i32 @xor4(i32 %x, i32 %y) {
%and = and i32 %x, -124
%xor = xor i32 %y, 435
%xor1 = xor i32 %xor, %and
ret i32 %xor1
; CHECK: @xor4
; CHECK: %and = and i32 %x, -124
; CHECK: %xor = xor i32 %y, 435
; CHECK: %xor1 = xor i32 %xor, %and
}
; ==========================================================================
;
; Xor reassociation special cases
;
; ==========================================================================
; Special case1:
; (x | c1) ^ (x & ~c1) = c1
define i32 @xor_special1(i32 %x, i32 %y) {
%or = or i32 %x, 123
%xor = xor i32 %or, %y
%and = and i32 %x, -124
%xor1 = xor i32 %xor, %and
ret i32 %xor1
; CHECK: @xor_special1
; CHECK: %xor1 = xor i32 %y, 123
; CHECK: ret i32 %xor1
}
; Special case1:
; (x | c1) ^ (x & c1) = x ^ c1
define i32 @xor_special2(i32 %x, i32 %y) {
%or = or i32 %x, 123
%xor = xor i32 %or, %y
%and = and i32 %x, 123
%xor1 = xor i32 %xor, %and
ret i32 %xor1
; CHECK: @xor_special2
; CHECK: %xor = xor i32 %y, 123
; CHECK: %xor1 = xor i32 %xor, %x
; CHECK: ret i32 %xor1
}
; (x | c1) ^ (x | c1) => 0
define i32 @xor_special3(i32 %x) {
%or = or i32 %x, 123
%or1 = or i32 %x, 123
%xor = xor i32 %or, %or1
ret i32 %xor
;CHECK: @xor_special3
;CHECK: ret i32 0
}
; (x & c1) ^ (x & c1) => 0
define i32 @xor_special4(i32 %x) {
%or = and i32 %x, 123
%or1 = and i32 123, %x
%xor = xor i32 %or, %or1
ret i32 %xor
;CHECK: @xor_special4
;CHECK: ret i32 0
}
; ==========================================================================
;
; Xor reassociation curtail code size
;
; ==========================================================================
; (x | c1) ^ (x | c2) => (x & c3) ^ c3
; is enabled if one of operands has multiple uses
;
define i32 @xor_ra_size1(i32 %x) {
%or = or i32 %x, 123
%or1 = or i32 %x, 456
%xor = xor i32 %or, %or1
%add = add i32 %xor, %or
ret i32 %add
;CHECK: @xor_ra_size1
;CHECK: %xor = xor i32 %and.ra, 435
}
; (x | c1) ^ (x | c2) => (x & c3) ^ c3
; is disenabled if bothf operands has multiple uses.
;
define i32 @xor_ra_size2(i32 %x) {
%or = or i32 %x, 123
%or1 = or i32 %x, 456
%xor = xor i32 %or, %or1
%add = add i32 %xor, %or
%add2 = add i32 %add, %or1
ret i32 %add2
;CHECK: @xor_ra_size2
;CHECK: %or1 = or i32 %x, 456
;CHECK: %xor = xor i32 %or, %or1
}