[llvm] r333892 - [llvm-mca] Track cycles contributed by resources that are in a 'Super' relationship.

[Andrea Di Biagio via llvm-commits]

Author: adibiagio
Date: Mon Jun  4 05:23:07 2018
New Revision: 333892

URL: http://llvm.org/viewvc/llvm-project?rev=333892&view=rev
Log:
[llvm-mca] 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 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.


Modified:
    llvm/trunk/tools/llvm-mca/InstrBuilder.cpp

Modified: llvm/trunk/tools/llvm-mca/InstrBuilder.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/llvm-mca/InstrBuilder.cpp?rev=333892&r1=333891&r2=333892&view=diff
==============================================================================
--- llvm/trunk/tools/llvm-mca/InstrBuilder.cpp (original)
+++ llvm/trunk/tools/llvm-mca/InstrBuilder.cpp Mon Jun  4 05:23:07 2018
@@ -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(Inst
   // 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(Inst
       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(Inst
     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++;
       }