[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

1 files changed, 2 insertions, 1 deletions

diff --git a/llvm/tools/llvm-mca/Views/ResourcePressureView.cpp b/llvm/tools/llvm-mca/Views/ResourcePressureView.cpp
index 75f5261b954..bba1e70bc26 100644
--- a/llvm/tools/llvm-mca/Views/ResourcePressureView.cpp
+++ b/llvm/tools/llvm-mca/Views/ResourcePressureView.cpp
@@ -46,7 +46,8 @@ void ResourcePressureView::onEvent(const HWInstructionEvent &Event) {
     return;
   const auto &IssueEvent = static_cast<const HWInstructionIssuedEvent &>(Event);
   const unsigned SourceIdx = Event.IR.getSourceIndex() % Source.size();
-  for (const std::pair<ResourceRef, double> &Use : IssueEvent.UsedResources) {
+  for (const std::pair<ResourceRef, ResourceCycles> &Use :
+       IssueEvent.UsedResources) {
     const ResourceRef &RR = Use.first;
     assert(Resource2VecIndex.find(RR.first) != Resource2VecIndex.end());
     unsigned R2VIndex = Resource2VecIndex[RR.first];