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[InstCombine] add test to show missed bswap; NFC 

D41353 / D41233 are proposing to alter the shl/and canonicalization,
but I think that would just move an existing pattern-matching hole
to a different place.

llvm-svn: 322206
This commit is contained in:
Sanjay Patel 2018-01-10 18:47:21 +00:00
parent 79390ad709
commit d04026ea43
1 changed files with 91 additions and 12 deletions
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103
llvm/test/Transforms/InstCombine/bswap.ll
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@ -95,21 +95,100 @@ define i32 @test6(i32 %x) nounwind readnone {
ret i32 %tmp7
}
; PR23863
define i32 @test7(i32 %x) {
; CHECK-LABEL: @test7(
; CHECK-NEXT: [[OR6:%.*]] = call i32 @llvm.bswap.i32(i32 %x)
; CHECK-NEXT: ret i32 [[OR6]]
declare void @extra_use(i32)
; swaphalf = (x << 16 | x >> 16)
; ((swaphalf & 0x00ff00ff) << 8) | ((swaphalf >> 8) & 0x00ff00ff)
define i32 @bswap32_and_first(i32 %x) {
; CHECK-LABEL: @bswap32_and_first(
; CHECK-NEXT: [[BSWAP:%.*]] = call i32 @llvm.bswap.i32(i32 %x)
; CHECK-NEXT: ret i32 [[BSWAP]]
;
%shl = shl i32 %x, 16
%shr = lshr i32 %x, 16
%or = or i32 %shl, %shr
%and2 = shl i32 %or, 8
%shl3 = and i32 %and2, -16711936
%and4 = lshr i32 %or, 8
%shr5 = and i32 %and4, 16711935
%or6 = or i32 %shl3, %shr5
ret i32 %or6
%swaphalf = or i32 %shl, %shr
%t = and i32 %swaphalf, 16711935
%tshl = shl nuw i32 %t, 8
%b = lshr i32 %swaphalf, 8
%band = and i32 %b, 16711935
%bswap = or i32 %tshl, %band
ret i32 %bswap
}
; FIXME: Extra use should not prevent matching to bswap.
; swaphalf = (x << 16 | x >> 16)
; ((swaphalf & 0x00ff00ff) << 8) | ((swaphalf >> 8) & 0x00ff00ff)
define i32 @bswap32_and_first_extra_use(i32 %x) {
; CHECK-LABEL: @bswap32_and_first_extra_use(
; CHECK-NEXT: [[SHL:%.*]] = shl i32 %x, 16
; CHECK-NEXT: [[SHR:%.*]] = lshr i32 %x, 16
; CHECK-NEXT: [[SWAPHALF:%.*]] = or i32 [[SHL]], [[SHR]]
; CHECK-NEXT: [[T:%.*]] = and i32 [[SWAPHALF]], 16711935
; CHECK-NEXT: [[TSHL:%.*]] = shl nuw i32 [[T]], 8
; CHECK-NEXT: [[B:%.*]] = lshr i32 [[SWAPHALF]], 8
; CHECK-NEXT: [[BAND:%.*]] = and i32 [[B]], 16711935
; CHECK-NEXT: [[BSWAP:%.*]] = or i32 [[TSHL]], [[BAND]]
; CHECK-NEXT: call void @extra_use(i32 [[T]])
; CHECK-NEXT: ret i32 [[BSWAP]]
;
%shl = shl i32 %x, 16
%shr = lshr i32 %x, 16
%swaphalf = or i32 %shl, %shr
%t = and i32 %swaphalf, 16711935
%tshl = shl nuw i32 %t, 8
%b = lshr i32 %swaphalf, 8
%band = and i32 %b, 16711935
%bswap = or i32 %tshl, %band
call void @extra_use(i32 %t)
ret i32 %bswap
}
; swaphalf = (x << 16 | x >> 16)
; ((swaphalf << 8) & 0xff00ff00) | ((swaphalf >> 8) & 0x00ff00ff)
; PR23863
define i32 @bswap32_shl_first(i32 %x) {
; CHECK-LABEL: @bswap32_shl_first(
; CHECK-NEXT: [[BSWAP:%.*]] = call i32 @llvm.bswap.i32(i32 %x)
; CHECK-NEXT: ret i32 [[BSWAP]]
;
%shl = shl i32 %x, 16
%shr = lshr i32 %x, 16
%swaphalf = or i32 %shl, %shr
%t = shl i32 %swaphalf, 8
%tand = and i32 %t, -16711936
%b = lshr i32 %swaphalf, 8
%band = and i32 %b, 16711935
%bswap = or i32 %tand, %band
ret i32 %bswap
}
; Extra use should not prevent matching to bswap.
; swaphalf = (x << 16 | x >> 16)
; ((swaphalf << 8) & 0xff00ff00) | ((swaphalf >> 8) & 0x00ff00ff)
define i32 @bswap32_shl_first_extra_use(i32 %x) {
; CHECK-LABEL: @bswap32_shl_first_extra_use(
; CHECK-NEXT: [[SHL:%.*]] = shl i32 %x, 16
; CHECK-NEXT: [[SHR:%.*]] = lshr i32 %x, 16
; CHECK-NEXT: [[SWAPHALF:%.*]] = or i32 [[SHL]], [[SHR]]
; CHECK-NEXT: [[T:%.*]] = shl i32 [[SWAPHALF]], 8
; CHECK-NEXT: [[BSWAP:%.*]] = call i32 @llvm.bswap.i32(i32 %x)
; CHECK-NEXT: call void @extra_use(i32 [[T]])
; CHECK-NEXT: ret i32 [[BSWAP]]
;
%shl = shl i32 %x, 16
%shr = lshr i32 %x, 16
%swaphalf = or i32 %shl, %shr
%t = shl i32 %swaphalf, 8
%tand = and i32 %t, -16711936
%b = lshr i32 %swaphalf, 8
%band = and i32 %b, 16711935
%bswap = or i32 %tand, %band
call void @extra_use(i32 %t)
ret i32 %bswap
}
define i16 @test8(i16 %a) {