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[MCA] Improve code comment and reuse an helper function in ResourceManager. NFCI

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llvm-svn: 350322
This commit is contained in:
Andrea Di Biagio 2019-01-03 14:47:46 +00:00
parent b19ee4bbeb
commit 79e68d2ba7
2 changed files with 18 additions and 15 deletions
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14
include/llvm/MCA/HardwareUnits/ResourceManager.h
View File

@ -144,12 +144,14 @@ class ResourceState {
/// A ProcResource can have multiple units.
///
/// For processor resource groups,
/// this field default to the value of field `ResourceMask`; the number of
/// bits set is equal to the cardinality of the group. For normal (i.e.
/// non-group) resources, the number of bits set in this mask is equivalent
/// to the number of units declared by the processor model (see field
/// 'NumUnits' in 'ProcResourceUnits').
/// For processor resource groups this field is a mask of contained resource
/// units. It is obtained from ResourceMask by clearing the highest set bit.
/// The number of resource units in a group can be simply computed as the
/// population count of this field.
///
/// For normal (i.e. non-group) resources, the number of bits set in this mask
/// is equivalent to the number of units declared by the processor model (see
/// field 'NumUnits' in 'ProcResourceUnits').
uint64_t ResourceSizeMask;
/// A mask of ready units.

19
lib/MCA/HardwareUnits/ResourceManager.cpp
View File

@ -24,11 +24,17 @@ namespace mca {
#define DEBUG_TYPE "llvm-mca"
ResourceStrategy::~ResourceStrategy() = default;
// Returns the index of the highest bit set. For resource masks, the position of
// the highest bit set can be used to construct a resource mask identifier.
static unsigned getResourceStateIndex(uint64_t Mask) {
return std::numeric_limits<uint64_t>::digits - countLeadingZeros(Mask);
}
static uint64_t selectImpl(uint64_t CandidateMask,
uint64_t &NextInSequenceMask) {
CandidateMask = 1ULL << (countLeadingZeros(CandidateMask) ^
(std::numeric_limits<uint64_t>::digits - 1));
NextInSequenceMask &= (CandidateMask ^ (CandidateMask - 1));
// The upper bit set in CandidateMask identifies our next candidate resource.
CandidateMask = 1ULL << (getResourceStateIndex(CandidateMask) - 1);
NextInSequenceMask &= (CandidateMask | (CandidateMask - 1));
return CandidateMask;
}
@ -69,8 +75,7 @@ ResourceState::ResourceState(const MCProcResourceDesc &Desc, unsigned Index,
BufferSize(Desc.BufferSize), IsAGroup(countPopulation(ResourceMask) > 1) {
if (IsAGroup) {
ResourceSizeMask =
ResourceMask ^ (1ULL << (countLeadingZeros(ResourceMask) ^
(std::numeric_limits<uint64_t>::digits - 1)));
ResourceMask ^ 1ULL << (getResourceStateIndex(ResourceMask) - 1);
} else {
ResourceSizeMask = (1ULL << Desc.NumUnits) - 1;
}
@ -103,10 +108,6 @@ void ResourceState::dump() const {
}
#endif
static unsigned getResourceStateIndex(uint64_t Mask) {
return std::numeric_limits<uint64_t>::digits - countLeadingZeros(Mask);
}
static std::unique_ptr<ResourceStrategy>
getStrategyFor(const ResourceState &RS) {
if (RS.isAResourceGroup() || RS.getNumUnits() > 1)