From: Andrea Di Biagio <Andrea_DiBiagio@sn.scee.net>
Date: Fri, 15 Feb 2019 18:05:59 +0000 (+0000)
Subject: [MCA][LSUnit] Return the ID of the dependent memory operation from method
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=8dbb7788550dda4b19b6889fbb8fea7fad92051d;p=llvm

[MCA][LSUnit] Return the ID of the dependent memory operation from method
isReady(). NFCI

This is yet another change in preparation for a fix for PR37494.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@354150 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/include/llvm/MCA/HardwareUnits/LSUnit.h b/include/llvm/MCA/HardwareUnits/LSUnit.h
index b8a9f2755b0..5ed2b5bc814 100644
--- a/include/llvm/MCA/HardwareUnits/LSUnit.h
+++ b/include/llvm/MCA/HardwareUnits/LSUnit.h
@@ -187,7 +187,11 @@ public:
   // 4. A store may not pass a previous load (regardless of flag 'NoAlias').
   // 5. A load has to wait until an older load barrier is fully executed.
   // 6. A store has to wait until an older store barrier is fully executed.
-  virtual bool isReady(const InstRef &IR) const;
+  //
+  // Returns an instruction identifier. If IR is ready, then this method returns
+  // `IR.getSourceIndex()`. Otherwise it returns the instruction ID of the
+  // dependent (i.e. conflicting) memory instruction.
+  virtual unsigned isReady(const InstRef &IR) const;
 
   // Load and store instructions are tracked by their corresponding queues from
   // dispatch until the "instruction executed" event.
diff --git a/lib/MCA/HardwareUnits/LSUnit.cpp b/lib/MCA/HardwareUnits/LSUnit.cpp
index 2adc20f8255..4f49fbd2bb4 100644
--- a/lib/MCA/HardwareUnits/LSUnit.cpp
+++ b/lib/MCA/HardwareUnits/LSUnit.cpp
@@ -93,7 +93,7 @@ LSUnit::Status LSUnit::isAvailable(const InstRef &IR) const {
   return LSUnit::LSU_AVAILABLE;
 }
 
-bool LSUnit::isReady(const InstRef &IR) const {
+unsigned LSUnit::isReady(const InstRef &IR) const {
   const InstrDesc &Desc = IR.getInstruction()->getDesc();
   const unsigned Index = IR.getSourceIndex();
   bool IsALoad = Desc.MayLoad;
@@ -106,49 +106,52 @@ bool LSUnit::isReady(const InstRef &IR) const {
     unsigned LoadBarrierIndex = *LoadBarriers.begin();
     // A younger load cannot pass a older load barrier.
     if (Index > LoadBarrierIndex)
-      return false;
+      return LoadBarrierIndex;
     // A load barrier cannot pass a older load.
     if (Index == LoadBarrierIndex && Index != *LoadQueue.begin())
-      return false;
+      return *LoadQueue.begin();
   }
 
   if (IsAStore && !StoreBarriers.empty()) {
     unsigned StoreBarrierIndex = *StoreBarriers.begin();
     // A younger store cannot pass a older store barrier.
     if (Index > StoreBarrierIndex)
-      return false;
+      return StoreBarrierIndex;
     // A store barrier cannot pass a older store.
     if (Index == StoreBarrierIndex && Index != *StoreQueue.begin())
-      return false;
+      return *StoreQueue.begin();
   }
 
   // A load may not pass a previous store unless flag 'NoAlias' is set.
   // A load may pass a previous load.
   if (NoAlias && IsALoad)
-    return true;
+    return Index;
 
   if (StoreQueue.size()) {
     // A load may not pass a previous store.
     // A store may not pass a previous store.
     if (Index > *StoreQueue.begin())
-      return false;
+      return *StoreQueue.begin();
   }
 
   // Okay, we are older than the oldest store in the queue.
   // If there are no pending loads, then we can say for sure that this
   // instruction is ready.
   if (isLQEmpty())
-    return true;
+    return Index;
 
   // Check if there are no older loads.
   if (Index <= *LoadQueue.begin())
-    return true;
+    return Index;
 
   // There is at least one younger load.
   //
-  // A store may not pass a previous load.
   // A load may pass a previous load.
-  return !IsAStore;
+  if (IsALoad)
+    return Index;
+
+  // A store may not pass a previous load.
+  return *LoadQueue.begin();
 }
 
 void LSUnit::onInstructionExecuted(const InstRef &IR) {
diff --git a/lib/MCA/HardwareUnits/Scheduler.cpp b/lib/MCA/HardwareUnits/Scheduler.cpp
index a7a6ed9570f..b5f3617b08f 100644
--- a/lib/MCA/HardwareUnits/Scheduler.cpp
+++ b/lib/MCA/HardwareUnits/Scheduler.cpp
@@ -288,7 +288,8 @@ void Scheduler::dispatch(const InstRef &IR) {
 bool Scheduler::isReady(const InstRef &IR) const {
   const InstrDesc &Desc = IR.getInstruction()->getDesc();
   bool IsMemOp = Desc.MayLoad || Desc.MayStore;
-  return IR.getInstruction()->isReady() && (!IsMemOp || LSU.isReady(IR));
+  return IR.getInstruction()->isReady() &&
+         (!IsMemOp || LSU.isReady(IR) == IR.getSourceIndex());
 }
 
 } // namespace mca