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X86: Use bitset to manage a bag of bits. NFC.

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Doesn't matter in terms of memory usage or perf here, but it's a neat
simplification.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@229672 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Benjamin Kramer 2015-02-18 14:10:44 +00:00
parent 227affe405
commit e8a0a78bad
1 changed files with 3 additions and 7 deletions
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10
lib/Target/X86/X86ISelLowering.cpp
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@ -5828,13 +5828,12 @@ static SDValue LowerBuildVectorv4x32(SDValue Op, SelectionDAG &DAG,
const X86Subtarget *Subtarget,
const TargetLowering &TLI) {
// Find all zeroable elements.
bool Zeroable[4];
std::bitset<4> Zeroable;
for (int i=0; i < 4; ++i) {
SDValue Elt = Op->getOperand(i);
Zeroable[i] = (Elt.getOpcode() == ISD::UNDEF || X86::isZeroNode(Elt));
}
assert(std::count_if(&Zeroable[0], &Zeroable[4],
[](bool M) { return !M; }) > 1 &&
assert(Zeroable.size() - Zeroable.count() > 1 &&
"We expect at least two non-zero elements!");
// We only know how to deal with build_vector nodes where elements are either
@ -5920,10 +5919,7 @@ static SDValue LowerBuildVectorv4x32(SDValue Op, SelectionDAG &DAG,
V2 = DAG.getNode(ISD::BITCAST, SDLoc(V2), MVT::v4f32, V2);
// Ok, we can emit an INSERTPS instruction.
unsigned ZMask = 0;
for (int i = 0; i < 4; ++i)
if (Zeroable[i])
ZMask |= 1 << i;
unsigned ZMask = Zeroable.to_ulong();
unsigned InsertPSMask = EltMaskIdx << 6 | EltIdx << 4 | ZMask;
assert((InsertPSMask & ~0xFFu) == 0 && "Invalid mask!");