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[InstCombine] Add tests to demonstrate the miscompile in PR33078. 

llvm-svn: 303445
This commit is contained in:
Davide Italiano 2017-05-19 19:23:24 +00:00
parent b527b2cf13
commit d837b0f9b9
1 changed files with 39 additions and 0 deletions
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39
llvm/test/Transforms/InstCombine/cast.ll
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@ -1470,3 +1470,42 @@ define i32 @test93(i32 %A) {
%D = trunc i96 %C to i32
ret i32 %D
}
; The following three tests show a miscompile of sext + lshr + trunc patterns.
; PR33078
define i8 @pr33078_1(i8 %A) {
; CHECK-LABEL: @pr33078_1(
; CHECK-NEXT: [[C:%.*]] = ashr i8 [[A:%.*]], 7
; CHECK-NEXT: ret i8 [[C]]
;
%B = sext i8 %A to i16
%C = lshr i16 %B, 8
%D = trunc i16 %C to i8
ret i8 %D
}
define i12 @pr33078_2(i8 %A) {
; CHECK-LABEL: @pr33078_2(
; CHECK-NEXT: [[C:%.*]] = ashr i8 [[A:%.*]], 4
; CHECK-NEXT: [[D:%.*]] = sext i8 [[C]] to i12
; CHECK-NEXT: ret i12 [[D]]
;
%B = sext i8 %A to i16
%C = lshr i16 %B, 4
%D = trunc i16 %C to i12
ret i12 %D
}
define i4 @pr33078_3(i8 %A) {
; CHECK-LABEL: @pr33078_3(
; CHECK-NEXT: [[B:%.*]] = sext i8 [[A:%.*]] to i16
; CHECK-NEXT: [[C:%.*]] = lshr i16 [[B]], 12
; CHECK-NEXT: [[D:%.*]] = trunc i16 [[C]] to i4
; CHECK-NEXT: ret i4 [[D]]
;
%B = sext i8 %A to i16
%C = lshr i16 %B, 12
%D = trunc i16 %C to i4
ret i4 %D
}