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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
17 lines
660 B
LLVM
17 lines
660 B
LLVM
; RUN: llvm-as < %s | opt -instcombine | llvm-dis | grep {lshr.*3}
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; RUN: llvm-as < %s | opt -instcombine | llvm-dis | grep {call .*%cond}
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; PR2506
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; We can simplify the operand of udiv to '8', but not the operand to the
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; call. If the callee never returns, we can't assume the div is reachable.
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define i32 @a(i32 %x, i32 %y) {
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entry:
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%tobool = icmp ne i32 %y, 0 ; <i1> [#uses=1]
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%cond = select i1 %tobool, i32 8, i32 0 ; <i32> [#uses=2]
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%call = call i32 @b( i32 %cond ) ; <i32> [#uses=0]
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%div = udiv i32 %x, %cond ; <i32> [#uses=1]
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ret i32 %div
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}
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declare i32 @b(i32)
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