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[llvm-mca] Track cycles contributed by resources that are in a 'Super' relationship.

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This is required if we want to correctly match the behavior of method
SubtargetEmitter::ExpandProcResource() in Tablegen. When computing the set of
"consumed" processor resources and resource cycles, the logic in
ExpandProcResource() doesn't update the number of resource cycles contributed by
a "Super" resource to a group.  We need to take this into account when a model
declares a processor resource which is part of a 'processor resource group', and
it is also used as the "Super" of other resources.

llvm-svn: 333892
This commit is contained in:
Andrea Di Biagio 2018-06-04 12:23:07 +00:00
parent 98a53476a7
commit 9cf08c77bf
1 changed files with 19 additions and 1 deletions
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20
tools/llvm-mca/InstrBuilder.cpp
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@ -13,6 +13,7 @@
//===----------------------------------------------------------------------===//
#include "InstrBuilder.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/MC/MCInst.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
@ -33,6 +34,19 @@ static void initializeUsedResources(InstrDesc &ID,
// Populate resources consumed.
using ResourcePlusCycles = std::pair<uint64_t, ResourceUsage>;
std::vector<ResourcePlusCycles> Worklist;
// Track cycles contributed by resources that are in a "Super" relationship.
// This is required if we want to correctly match the behavior of method
// SubtargetEmitter::ExpandProcResource() in Tablegen. When computing the set
// of "consumed" processor resources and resource cycles, the logic in
// ExpandProcResource() doesn't update the number of resource cycles
// contributed by a "Super" resource to a group.
// We need to take this into account when we find that a processor resource is
// part of a group, and it is also used as the "Super" of other resources.
// This map stores the number of cycles contributed by sub-resources that are
// part of a "Super" resource. The key value is the "Super" resource mask ID.
DenseMap<uint64_t, unsigned> SuperResources;
for (unsigned I = 0, E = SCDesc.NumWriteProcResEntries; I < E; ++I) {
const MCWriteProcResEntry *PRE = STI.getWriteProcResBegin(&SCDesc) + I;
const MCProcResourceDesc &PR = *SM.getProcResource(PRE->ProcResourceIdx);
@ -41,6 +55,10 @@ static void initializeUsedResources(InstrDesc &ID,
ID.Buffers.push_back(Mask);
CycleSegment RCy(0, PRE->Cycles, false);
Worklist.emplace_back(ResourcePlusCycles(Mask, ResourceUsage(RCy)));
if (PR.SuperIdx) {
uint64_t Super = ProcResourceMasks[PR.SuperIdx];
SuperResources[Super] += PRE->Cycles;
}
}
// Sort elements by mask popcount, so that we prioritize resource units over
@ -80,7 +98,7 @@ static void initializeUsedResources(InstrDesc &ID,
for (unsigned J = I + 1; J < E; ++J) {
ResourcePlusCycles &B = Worklist[J];
if ((NormalizedMask & B.first) == NormalizedMask) {
B.second.CS.Subtract(A.second.size());
B.second.CS.Subtract(A.second.size() - SuperResources[A.first]);
if (countPopulation(B.first) > 1)
B.second.NumUnits++;
}