From b2b9806fed69015f45bb5cecd5d5aba361a954c8 Mon Sep 17 00:00:00 2001 From: Andrea Di Biagio Date: Mon, 11 Feb 2019 17:55:47 +0000 Subject: [PATCH] [MCA][Scheduler] Track resources that were found busy when issuing an instruction. This is a follow up of r353706. When the scheduler fails to issue a ready instruction to the underlying pipelines, it now updates a mask of 'busy resource units'. That information will be used in future to obtain the set of "problematic" resources in the case of bottlenecks caused by resource pressure. No functional change intended. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@353728 91177308-0d34-0410-b5e6-96231b3b80d8 --- include/llvm/MCA/HardwareUnits/Scheduler.h | 13 ++++++++++++- lib/MCA/HardwareUnits/Scheduler.cpp | 3 +++ 2 files changed, 15 insertions(+), 1 deletion(-) diff --git a/include/llvm/MCA/HardwareUnits/Scheduler.h b/include/llvm/MCA/HardwareUnits/Scheduler.h index 53e416b1643..6e1d68020fe 100644 --- a/include/llvm/MCA/HardwareUnits/Scheduler.h +++ b/include/llvm/MCA/HardwareUnits/Scheduler.h @@ -96,6 +96,13 @@ class Scheduler : public HardwareUnit { std::vector ReadySet; std::vector IssuedSet; + // A mask of busy resource units. It defaults to the empty set (i.e. a zero + // mask), and it is cleared at the beginning of every cycle. + // It is updated every time the scheduler fails to issue an instruction from + // the ready set due to unavailable pipeline resources. + // Each bit of the mask represents an unavailable resource. + uint64_t BusyResourceUnits; + /// Verify the given selection strategy and set the Strategy member /// accordingly. If no strategy is provided, the DefaultSchedulerStrategy is /// used. @@ -126,7 +133,7 @@ public: Scheduler(std::unique_ptr RM, LSUnit &Lsu, std::unique_ptr SelectStrategy) - : LSU(Lsu), Resources(std::move(RM)) { + : LSU(Lsu), Resources(std::move(RM)), BusyResourceUnits(0) { initializeStrategy(std::move(SelectStrategy)); } @@ -194,6 +201,10 @@ public: /// resources are not available. InstRef select(); + /// Returns a mask of busy resources. Each bit of the mask identifies a unique + /// processor resource unit. In the absence of bottlenecks caused by resource + /// pressure, the mask value returned by this method is always zero. + uint64_t getBusyResourceUnits() const { return BusyResourceUnits; } bool arePipelinesFullyUsed() const { return !Resources->getAvailableProcResUnits(); } diff --git a/lib/MCA/HardwareUnits/Scheduler.cpp b/lib/MCA/HardwareUnits/Scheduler.cpp index fb1080dc02c..b8cd62f8bd4 100644 --- a/lib/MCA/HardwareUnits/Scheduler.cpp +++ b/lib/MCA/HardwareUnits/Scheduler.cpp @@ -140,6 +140,7 @@ InstRef Scheduler::select() { Strategy->compare(IR, ReadySet[QueueIndex])) { const InstrDesc &D = IR.getInstruction()->getDesc(); uint64_t BusyResourceMask = Resources->checkAvailability(D); + BusyResourceUnits |= BusyResourceMask; if (!BusyResourceMask) QueueIndex = I; } @@ -196,6 +197,8 @@ void Scheduler::cycleEvent(SmallVectorImpl &Freed, IR.getInstruction()->cycleEvent(); promoteToReadySet(Ready); + + BusyResourceUnits = 0; } bool Scheduler::mustIssueImmediately(const InstRef &IR) const { -- 2.50.1