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https://github.com/c64scene-ar/llvm-6502.git
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fdb19e5887
disproving a condition. This actually compiles the existing testcase
(udiv_select_to_select_shift) to:
define i64 @test(i64 %X, i1 %Cond) {
entry:
%divisor1.t = lshr i64 %X, 3 ; <i64> [#uses=1]
%quotient2 = lshr i64 %X, 3 ; <i64> [#uses=1]
%sum = add i64 %divisor1.t, %quotient2 ; <i64> [#uses=1]
ret i64 %sum
}
instead of:
define i64 @test(i64 %X, i1 %Cond) {
entry:
%quotient1.v = select i1 %Cond, i64 3, i64 4 ; <i64> [#uses=1]
%quotient1 = lshr i64 %X, %quotient1.v ; <i64> [#uses=1]
%quotient2 = lshr i64 %X, 3 ; <i64> [#uses=1]
%sum = add i64 %quotient1, %quotient2 ; <i64> [#uses=1]
ret i64 %sum
}
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@53534 91177308-0d34-0410-b5e6-96231b3b80d8
18 lines
559 B
LLVM
18 lines
559 B
LLVM
; Test that this transform works:
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; udiv X, (Select Cond, C1, C2) --> Select Cond, (shr X, C1), (shr X, C2)
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;
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; RUN: llvm-as < %s | opt -instcombine | llvm-dis -f -o %t
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; RUN: not grep select %t
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; RUN: grep lshr %t | count 2
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; RUN: not grep udiv %t
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define i64 @test(i64 %X, i1 %Cond ) {
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entry:
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%divisor1 = select i1 %Cond, i64 16, i64 8
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%quotient1 = udiv i64 %X, %divisor1
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%divisor2 = select i1 %Cond, i64 8, i64 0
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%quotient2 = udiv i64 %X, %divisor2
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%sum = add i64 %quotient1, %quotient2
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ret i64 %sum
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}
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