[llvm] r335977 - [llvm-mca] Remove field HasReadAdvanceEntries from class ReadDescriptor.

[Andrea Di Biagio via llvm-commits]

Author: adibiagio
Date: Fri Jun 29 07:24:46 2018
New Revision: 335977

URL: http://llvm.org/viewvc/llvm-project?rev=335977&view=rev
Log:
[llvm-mca] Remove field HasReadAdvanceEntries from class ReadDescriptor.

This simplifies the logic that updates RAW dependencies in the DispatchStage.
There is no advantage in storing that flag in the ReadDescriptor; we should
simply rely on the call to `STI.getReadAdvanceCycles()` to obtain the
ReadAdvance cycles. If there are no read-advance entries, then method
`getReadAdvanceCycles()` quickly returns 0.

No functional change intended.

Modified:
    llvm/trunk/tools/llvm-mca/DispatchStage.cpp
    llvm/trunk/tools/llvm-mca/InstrBuilder.cpp
    llvm/trunk/tools/llvm-mca/Instruction.h

Modified: llvm/trunk/tools/llvm-mca/DispatchStage.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/llvm-mca/DispatchStage.cpp?rev=335977&r1=335976&r2=335977&view=diff
==============================================================================
--- llvm/trunk/tools/llvm-mca/DispatchStage.cpp (original)
+++ llvm/trunk/tools/llvm-mca/DispatchStage.cpp Fri Jun 29 07:24:46 2018
@@ -82,12 +82,6 @@ void DispatchStage::updateRAWDependencie
   // For each write, check if we have ReadAdvance information, and use it
   // to figure out in how many cycles this read becomes available.
   const ReadDescriptor &RD = RS.getDescriptor();
-  if (!RD.HasReadAdvanceEntries) {
-    for (WriteRef &WR : DependentWrites)
-      WR.getWriteState()->addUser(&RS, /* ReadAdvance */ 0);
-    return;
-  }
-
   const MCSchedModel &SM = STI.getSchedModel();
   const MCSchedClassDesc *SC = SM.getSchedClassDesc(RD.SchedClassID);
   for (WriteRef &WR : DependentWrites) {

Modified: llvm/trunk/tools/llvm-mca/InstrBuilder.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/llvm-mca/InstrBuilder.cpp?rev=335977&r1=335976&r2=335977&view=diff
==============================================================================
--- llvm/trunk/tools/llvm-mca/InstrBuilder.cpp (original)
+++ llvm/trunk/tools/llvm-mca/InstrBuilder.cpp Fri Jun 29 07:24:46 2018
@@ -265,8 +265,6 @@ static void populateReads(InstrDesc &ID,
                           const MCSchedClassDesc &SCDesc,
                           const MCSubtargetInfo &STI) {
   unsigned SchedClassID = MCDesc.getSchedClass();
-  bool HasReadAdvanceEntries = SCDesc.NumReadAdvanceEntries > 0;
-
   unsigned i = 0;
   unsigned NumExplicitDefs = MCDesc.getNumDefs();
   // Skip explicit definitions.
@@ -295,7 +293,6 @@ static void populateReads(InstrDesc &ID,
     ReadDescriptor &Read = ID.Reads[CurrentUse];
     Read.OpIndex = i + CurrentUse;
     Read.UseIndex = CurrentUse;
-    Read.HasReadAdvanceEntries = HasReadAdvanceEntries;
     Read.SchedClassID = SchedClassID;
     LLVM_DEBUG(dbgs() << "\t\tOpIdx=" << Read.OpIndex);
   }
@@ -305,7 +302,6 @@ static void populateReads(InstrDesc &ID,
     Read.OpIndex = ~CurrentUse;
     Read.UseIndex = NumExplicitUses + CurrentUse;
     Read.RegisterID = MCDesc.getImplicitUses()[CurrentUse];
-    Read.HasReadAdvanceEntries = HasReadAdvanceEntries;
     Read.SchedClassID = SchedClassID;
     LLVM_DEBUG(dbgs() << "\t\tOpIdx=" << Read.OpIndex
                       << ", RegisterID=" << Read.RegisterID << '\n');

Modified: llvm/trunk/tools/llvm-mca/Instruction.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/llvm-mca/Instruction.h?rev=335977&r1=335976&r2=335977&view=diff
==============================================================================
--- llvm/trunk/tools/llvm-mca/Instruction.h (original)
+++ llvm/trunk/tools/llvm-mca/Instruction.h Fri Jun 29 07:24:46 2018
@@ -77,11 +77,6 @@ struct ReadDescriptor {
   // Scheduling Class Index. It is used to query the scheduling model for the
   // MCSchedClassDesc object.
   unsigned SchedClassID;
-  // True if there may be a local forwarding logic in hardware to serve a
-  // write used by this read. This information, along with SchedClassID, is
-  // used to dynamically check at Instruction creation time, if the input
-  // operands can benefit from a ReadAdvance bonus.
-  bool HasReadAdvanceEntries;
 
   bool isImplicitRead() const { return OpIndex < 0; };
 };