[llvm-mca] Remove flag -max-retire-per-cycle, and update the docs.

This is done in preparation for D45259.
With D45259, models can specify the size of the reorder buffer, and the retire
throughput directly via tablegen.

llvm-svn: 329274

docs/CommandGuide/llvm-mca.rst

@@ -68,11 +68,6 @@ option specifies "``-``", then the output will also be sent to standard output.
  defaults to the 'IssueWidth' specified by the processor scheduling model.
  If width is zero, then the default dispatch width is used.
 
-.. option:: -max-retire-per-cycle=<retire throughput>
-
- Specify the retire throughput (i.e. how many instructions can be retired by the
- retire control unit every cycle).
-
 .. option:: -register-file-size=<size>
 
  Specify the size of the register file. When specified, this flag limits

tools/llvm-mca/Backend.h

@@ -62,15 +62,15 @@ public:
   Backend(const llvm::MCSubtargetInfo &Subtarget,
           const llvm::MCRegisterInfo &MRI, InstrBuilder &B, SourceMgr &Source,
           unsigned DispatchWidth = 0, unsigned RegisterFileSize = 0,
-          unsigned MaxRetirePerCycle = 0, unsigned LoadQueueSize = 0,
-          unsigned StoreQueueSize = 0, bool AssumeNoAlias = false)
+          unsigned LoadQueueSize = 0, unsigned StoreQueueSize = 0,
+          bool AssumeNoAlias = false)
       : STI(Subtarget), IB(B),
         HWS(llvm::make_unique<Scheduler>(this, Subtarget.getSchedModel(),
                                          LoadQueueSize, StoreQueueSize,
                                          AssumeNoAlias)),
         DU(llvm::make_unique<DispatchUnit>(
             this, STI, MRI, Subtarget.getSchedModel().MicroOpBufferSize,
-            RegisterFileSize, MaxRetirePerCycle, DispatchWidth, HWS.get())),
+            RegisterFileSize, DispatchWidth, HWS.get())),
         SM(Source), Cycles(0) {
     HWS->setDispatchUnit(DU.get());
   }

tools/llvm-mca/Dispatch.h

@@ -192,9 +192,9 @@ private:
   DispatchUnit *Owner;
 
 public:
-  RetireControlUnit(unsigned NumSlots, unsigned RPC, DispatchUnit *DU)
+  RetireControlUnit(unsigned NumSlots, DispatchUnit *DU)
       : NextAvailableSlotIdx(0), CurrentInstructionSlotIdx(0),
-        AvailableSlots(NumSlots), MaxRetirePerCycle(RPC), Owner(DU) {
+        AvailableSlots(NumSlots), MaxRetirePerCycle(0), Owner(DU) {
     assert(NumSlots && "Expected at least one slot!");
     Queue.resize(NumSlots);
   }
@@ -266,14 +266,13 @@ class DispatchUnit {
 public:
   DispatchUnit(Backend *B, const llvm::MCSubtargetInfo &STI,
                const llvm::MCRegisterInfo &MRI, unsigned MicroOpBufferSize,
-               unsigned RegisterFileSize, unsigned MaxRetirePerCycle,
-               unsigned MaxDispatchWidth, Scheduler *Sched)
+               unsigned RegisterFileSize, unsigned MaxDispatchWidth,
+               Scheduler *Sched)
       : DispatchWidth(MaxDispatchWidth), AvailableEntries(MaxDispatchWidth),
         CarryOver(0U), SC(Sched),
         RAT(llvm::make_unique<RegisterFile>(STI.getSchedModel(), MRI,
                                             RegisterFileSize)),
-        RCU(llvm::make_unique<RetireControlUnit>(MicroOpBufferSize,
-                                                 MaxRetirePerCycle, this)),
+        RCU(llvm::make_unique<RetireControlUnit>(MicroOpBufferSize, this)),
         Owner(B) {}
 
   unsigned getDispatchWidth() const { return DispatchWidth; }

tools/llvm-mca/llvm-mca.cpp

@@ -81,11 +81,6 @@ static cl::opt<unsigned> DispatchWidth(
     cl::desc("Dispatch Width. By default it is set equal to IssueWidth"),
     cl::init(0));
 
-static cl::opt<unsigned> MaxRetirePerCycle(
-    "max-retire-per-cycle",
-    cl::desc("Maximum number of instructions that can be retired in one cycle"),
-    cl::init(0));
-
 static cl::opt<unsigned>
     RegisterFileSize("register-file-size",
                      cl::desc("Maximum number of temporary registers which can "
@@ -361,8 +356,8 @@ int main(int argc, char **argv) {
   }
 
   std::unique_ptr<mca::Backend> B = llvm::make_unique<mca::Backend>(
-      *STI, *MRI, *IB, *S, Width, RegisterFileSize, MaxRetirePerCycle,
-      LoadQueueSize, StoreQueueSize, AssumeNoAlias);
+      *STI, *MRI, *IB, *S, Width, RegisterFileSize, LoadQueueSize,
+      StoreQueueSize, AssumeNoAlias);
 
   std::unique_ptr<mca::BackendPrinter> Printer =
       llvm::make_unique<mca::BackendPrinter>(*B);