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InstCombine: Replace a hand-rolled version of isKnownToBeAPowerOfTwo with the real thing. 

llvm-svn: 199604
This commit is contained in:
Benjamin Kramer 2014-01-19 16:48:41 +00:00
parent 72196f3ae5
commit 7a74bd4703
2 changed files with 6 additions and 23 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

25
llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
View File

@ -1543,23 +1543,6 @@ static Instruction *MatchSelectFromAndOr(Value *A, Value *B,
return 0;
}
/// IsOneHotValue - Returns true for "one-hot" values (values where at most
/// one bit can be set).
static bool IsOneHotValue(Value *V) {
// Match 1<<K.
if (BinaryOperator *BO = dyn_cast<BinaryOperator>(V))
if (BO->getOpcode() == Instruction::Shl) {
ConstantInt *One = dyn_cast<ConstantInt>(BO->getOperand(0));
return One && One->isOne();
}
// Check for power of two integer constants.
if (ConstantInt *K = dyn_cast<ConstantInt>(V))
return K->getValue().isPowerOf2();
return false;
}
/// FoldOrOfICmps - Fold (icmp)|(icmp) if possible.
Value *InstCombiner::FoldOrOfICmps(ICmpInst *LHS, ICmpInst *RHS) {
ICmpInst::Predicate LHSCC = LHS->getPredicate(), RHSCC = RHS->getPredicate();
@ -1581,13 +1564,13 @@ Value *InstCombiner::FoldOrOfICmps(ICmpInst *LHS, ICmpInst *RHS) {
Value *Mask = 0;
Value *Masked = 0;
if (LAnd->getOperand(0) == RAnd->getOperand(0) &&
IsOneHotValue(LAnd->getOperand(1)) &&
IsOneHotValue(RAnd->getOperand(1))) {
isKnownToBeAPowerOfTwo(LAnd->getOperand(1)) &&
isKnownToBeAPowerOfTwo(RAnd->getOperand(1))) {
Mask = Builder->CreateOr(LAnd->getOperand(1), RAnd->getOperand(1));
Masked = Builder->CreateAnd(LAnd->getOperand(0), Mask);
} else if (LAnd->getOperand(1) == RAnd->getOperand(1) &&
IsOneHotValue(LAnd->getOperand(0)) &&
IsOneHotValue(RAnd->getOperand(0))) {
isKnownToBeAPowerOfTwo(LAnd->getOperand(0)) &&
isKnownToBeAPowerOfTwo(RAnd->getOperand(0))) {
Mask = Builder->CreateOr(LAnd->getOperand(0), RAnd->getOperand(0));
Masked = Builder->CreateAnd(LAnd->getOperand(1), Mask);
}

4
llvm/test/Transforms/InstCombine/onehot_merge.ll
View File

@ -16,7 +16,7 @@ bb:
;CHECK: @foo1_and
;CHECK: shl i32 1, %c1
;CHECK-NEXT: shl i32 1, %c2
;CHECK-NEXT: lshr i32 -2147483648, %c2
;CHECK-NEXT: or i32
;CHECK-NEXT: and i32
;CHECK-NEXT: icmp ne i32 %1, %0
@ -24,7 +24,7 @@ bb:
define i1 @foo1_and(i32 %k, i32 %c1, i32 %c2) {
bb:
%tmp = shl i32 1, %c1
%tmp4 = shl i32 1, %c2
%tmp4 = lshr i32 -2147483648, %c2
%tmp1 = and i32 %tmp, %k
%tmp2 = icmp eq i32 %tmp1, 0
%tmp5 = and i32 %tmp4, %k