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use the valuetracking isPowerOfTwo function, which is more powerful than checking

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for a constant directly.  Thanks to Duncan for pointing this out.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@131885 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2011-05-23 00:09:55 +00:00
parent b3f0673d52
commit 6083bb9353
1 changed files with 4 additions and 4 deletions
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8
lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
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@ -31,13 +31,13 @@ static Value *simplifyValueKnownNonZero(Value *V, InstCombiner &IC) {
// ((1 << A) >>u B) --> (1 << (A-B))
// Because V cannot be zero, we know that B is less than A.
Value *A = 0, *B = 0; ConstantInt *One = 0;
if (match(V, m_LShr(m_OneUse(m_Shl(m_ConstantInt(One), m_Value(A))),
Value *A = 0, *B = 0, *PowerOf2 = 0;
if (match(V, m_LShr(m_OneUse(m_Shl(m_Value(PowerOf2), m_Value(A))),
m_Value(B))) &&
// The "1" can be any value known to be a power of 2.
One->getValue().isPowerOf2()) {
isPowerOfTwo(PowerOf2, IC.getTargetData())) {
A = IC.Builder->CreateSub(A, B, "tmp");
return IC.Builder->CreateShl(One, A);
return IC.Builder->CreateShl(PowerOf2, A);
}
// TODO: Lots more we could do here: