[llvm-mca] Delay calculation of Cycles per Resources, separate the cycles and resource quantities.

Summary:
This patch removes the storing of accumulated floating point data 
within the llvm-mca library.

This patch splits-up the two quantities: cycles and number of resource units.
By splitting-up these two quantities, we delay the calculation of "cycles per resource unit"
until that value is read, reducing the chance of accumulating floating point error. 

I considered using the APFloat, but after measuring performance, for a large (many iteration)
sample, I decided to go with this faster solution.

Reviewers: andreadb, courbet, RKSimon

Reviewed By: andreadb

Subscribers: llvm-commits, javed.absar, tschuett, gbedwell

Differential Revision: https://reviews.llvm.org/D51903

llvm-svn: 341980

2 files changed, 8 insertions, 6 deletions

diff --git a/llvm/tools/llvm-mca/include/HardwareUnits/ResourceManager.h b/llvm/tools/llvm-mca/include/HardwareUnits/ResourceManager.h
index c3f893660eb..dfac15f53fc 100644
--- a/llvm/tools/llvm-mca/include/HardwareUnits/ResourceManager.h
+++ b/llvm/tools/llvm-mca/include/HardwareUnits/ResourceManager.h
@@ -17,6 +17,7 @@
 #define LLVM_TOOLS_LLVM_MCA_RESOURCE_MANAGER_H
 
 #include "Instruction.h"
+#include "Support.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/SmallVector.h"
@@ -344,7 +345,7 @@ public:
 
   void issueInstruction(
       const InstrDesc &Desc,
-      llvm::SmallVectorImpl<std::pair<ResourceRef, double>> &Pipes);
+      llvm::SmallVectorImpl<std::pair<ResourceRef, ResourceCycles>> &Pipes);
 
   void cycleEvent(llvm::SmallVectorImpl<ResourceRef> &ResourcesFreed);
 
diff --git a/llvm/tools/llvm-mca/include/HardwareUnits/Scheduler.h b/llvm/tools/llvm-mca/include/HardwareUnits/Scheduler.h
index 61bbf3fcf36..db124958ee5 100644
--- a/llvm/tools/llvm-mca/include/HardwareUnits/Scheduler.h
+++ b/llvm/tools/llvm-mca/include/HardwareUnits/Scheduler.h
@@ -18,6 +18,7 @@
 #include "HardwareUnits/HardwareUnit.h"
 #include "HardwareUnits/LSUnit.h"
 #include "ResourceManager.h"
+#include "Support.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/MC/MCSchedule.h"
 
@@ -103,7 +104,7 @@ class Scheduler : public HardwareUnit {
   /// Issue an instruction without updating the ready queue.
   void issueInstructionImpl(
       InstRef &IR,
-      llvm::SmallVectorImpl<std::pair<ResourceRef, double>> &Pipes);
+      llvm::SmallVectorImpl<std::pair<ResourceRef, ResourceCycles>> &Pipes);
 
   // Identify instructions that have finished executing, and remove them from
   // the IssuedSet. References to executed instructions are added to input
@@ -164,10 +165,10 @@ public:
   /// Issue an instruction and populates a vector of used pipeline resources,
   /// and a vector of instructions that transitioned to the ready state as a
   /// result of this event.
-  void
-  issueInstruction(InstRef &IR,
-                   llvm::SmallVectorImpl<std::pair<ResourceRef, double>> &Used,
-                   llvm::SmallVectorImpl<InstRef> &Ready);
+  void issueInstruction(
+      InstRef &IR,
+      llvm::SmallVectorImpl<std::pair<ResourceRef, ResourceCycles>> &Used,
+      llvm::SmallVectorImpl<InstRef> &Ready);
 
   /// Returns true if IR has to be issued immediately, or if IR is a zero
   /// latency instruction.