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InstCombine: look for masked compares with subset relation

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Even in cases which aren't universally optimisable like "(A & B) != 0 && (A &
C) != 0", the masks can make one of the comparisons completely redundant. In
this case, since we've gone to the effort of spotting masked comparisons we
should combine them.

rdar://problem/7625728

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@189930 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Tim Northover
2013-09-04 11:57:13 +00:00
parent 19fdc268c3
commit 7bfabdac4e
2 changed files with 197 additions and 11 deletions
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122
test/Transforms/InstCombine/icmp-logical.ll Normal file
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; RUN: opt -instcombine -S -o - %s | FileCheck %s
define i1 @masked_and_notallzeroes(i32 %A) {
; CHECK-LABEL: @masked_and_notallzeroes
; CHECK: [[MASK:%.*]] = and i32 %A, 7
; CHECK: icmp ne i32 [[MASK]], 0
; CHECK-NOT: and i32 %A, 39
; CHECK: ret i1
%mask1 = and i32 %A, 7
%tst1 = icmp ne i32 %mask1, 0
%mask2 = and i32 %A, 39
%tst2 = icmp ne i32 %mask2, 0
%res = and i1 %tst1, %tst2
ret i1 %res
}
define i1 @masked_or_allzeroes(i32 %A) {
; CHECK-LABEL: @masked_or_allzeroes
; CHECK: [[MASK:%.*]] = and i32 %A, 7
; CHECK: icmp eq i32 [[MASK]], 0
; CHECK-NOT: and i32 %A, 39
; CHECK: ret i1
%mask1 = and i32 %A, 7
%tst1 = icmp eq i32 %mask1, 0
%mask2 = and i32 %A, 39
%tst2 = icmp eq i32 %mask2, 0
%res = or i1 %tst1, %tst2
ret i1 %res
}
define i1 @masked_and_notallones(i32 %A) {
; CHECK-LABEL: @masked_and_notallones
; CHECK: [[MASK:%.*]] = and i32 %A, 7
; CHECK: icmp ne i32 [[MASK]], 7
; CHECK-NOT: and i32 %A, 39
; CHECK: ret i1
%mask1 = and i32 %A, 7
%tst1 = icmp ne i32 %mask1, 7
%mask2 = and i32 %A, 39
%tst2 = icmp ne i32 %mask2, 39
%res = and i1 %tst1, %tst2
ret i1 %res
}
define i1 @masked_or_allones(i32 %A) {
; CHECK-LABEL: @masked_or_allones
; CHECK: [[MASK:%.*]] = and i32 %A, 7
; CHECK: icmp eq i32 [[MASK]], 7
; CHECK-NOT: and i32 %A, 39
; CHECK: ret i1
%mask1 = and i32 %A, 7
%tst1 = icmp eq i32 %mask1, 7
%mask2 = and i32 %A, 39
%tst2 = icmp eq i32 %mask2, 39
%res = or i1 %tst1, %tst2
ret i1 %res
}
define i1 @masked_and_notA(i32 %A) {
; CHECK-LABEL: @masked_and_notA
; CHECK: [[MASK:%.*]] = and i32 %A, 39
; CHECK: icmp ne i32 [[MASK]], %A
; CHECK-NOT: and i32 %A, 7
; CHECK: ret i1
%mask1 = and i32 %A, 7
%tst1 = icmp ne i32 %mask1, %A
%mask2 = and i32 %A, 39
%tst2 = icmp ne i32 %mask2, %A
%res = and i1 %tst1, %tst2
ret i1 %res
}
define i1 @masked_or_A(i32 %A) {
; CHECK-LABEL: @masked_or_A
; CHECK: [[MASK:%.*]] = and i32 %A, 39
; CHECK: icmp eq i32 [[MASK]], %A
; CHECK-NOT: and i32 %A, 7
; CHECK: ret i1
%mask1 = and i32 %A, 7
%tst1 = icmp eq i32 %mask1, %A
%mask2 = and i32 %A, 39
%tst2 = icmp eq i32 %mask2, %A
%res = or i1 %tst1, %tst2
ret i1 %res
}
define i1 @masked_or_allzeroes_notoptimised(i32 %A) {
; CHECK-LABEL: @masked_or_allzeroes_notoptimised
; CHECK: [[MASK:%.*]] = and i32 %A, 15
; CHECK: icmp eq i32 [[MASK]], 0
; CHECK: [[MASK:%.*]] = and i32 %A, 39
; CHECK: icmp eq i32 [[MASK]], 0
; CHECK: ret i1
%mask1 = and i32 %A, 15
%tst1 = icmp eq i32 %mask1, 0
%mask2 = and i32 %A, 39
%tst2 = icmp eq i32 %mask2, 0
%res = or i1 %tst1, %tst2
ret i1 %res
}