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authorDimitry Andric <dim@FreeBSD.org>2019-12-20 19:53:05 +0000
committerDimitry Andric <dim@FreeBSD.org>2019-12-20 19:53:05 +0000
commit0b57cec536236d46e3dba9bd041533462f33dbb7 (patch)
tree56229dbdbbf76d18580f72f789003db17246c8d9 /contrib/llvm-project/llvm/lib/Target/AMDGPU/AMDGPUInline.cpp
parent718ef55ec7785aae63f98f8ca05dc07ed399c16d (diff)
Notes
Diffstat (limited to 'contrib/llvm-project/llvm/lib/Target/AMDGPU/AMDGPUInline.cpp')
-rw-r--r--contrib/llvm-project/llvm/lib/Target/AMDGPU/AMDGPUInline.cpp228
1 files changed, 228 insertions, 0 deletions
diff --git a/contrib/llvm-project/llvm/lib/Target/AMDGPU/AMDGPUInline.cpp b/contrib/llvm-project/llvm/lib/Target/AMDGPU/AMDGPUInline.cpp
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+//===- AMDGPUInline.cpp - Code to perform simple function inlining --------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+/// \file
+/// This is AMDGPU specific replacement of the standard inliner.
+/// The main purpose is to account for the fact that calls not only expensive
+/// on the AMDGPU, but much more expensive if a private memory pointer is
+/// passed to a function as an argument. In this situation, we are unable to
+/// eliminate private memory in the caller unless inlined and end up with slow
+/// and expensive scratch access. Thus, we boost the inline threshold for such
+/// functions here.
+///
+//===----------------------------------------------------------------------===//
+
+
+#include "AMDGPU.h"
+#include "llvm/Transforms/IPO.h"
+#include "llvm/Analysis/AssumptionCache.h"
+#include "llvm/Analysis/CallGraph.h"
+#include "llvm/Analysis/InlineCost.h"
+#include "llvm/Analysis/ValueTracking.h"
+#include "llvm/Analysis/TargetTransformInfo.h"
+#include "llvm/IR/CallSite.h"
+#include "llvm/IR/DataLayout.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/Module.h"
+#include "llvm/IR/Type.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Transforms/IPO/Inliner.h"
+
+using namespace llvm;
+
+#define DEBUG_TYPE "inline"
+
+static cl::opt<int>
+ArgAllocaCost("amdgpu-inline-arg-alloca-cost", cl::Hidden, cl::init(1500),
+ cl::desc("Cost of alloca argument"));
+
+// If the amount of scratch memory to eliminate exceeds our ability to allocate
+// it into registers we gain nothing by aggressively inlining functions for that
+// heuristic.
+static cl::opt<unsigned>
+ArgAllocaCutoff("amdgpu-inline-arg-alloca-cutoff", cl::Hidden, cl::init(256),
+ cl::desc("Maximum alloca size to use for inline cost"));
+
+// Inliner constraint to achieve reasonable compilation time
+static cl::opt<size_t>
+MaxBB("amdgpu-inline-max-bb", cl::Hidden, cl::init(300),
+ cl::desc("Maximum BB number allowed in a function after inlining"
+ " (compile time constraint)"));
+
+namespace {
+
+class AMDGPUInliner : public LegacyInlinerBase {
+
+public:
+ AMDGPUInliner() : LegacyInlinerBase(ID) {
+ initializeAMDGPUInlinerPass(*PassRegistry::getPassRegistry());
+ Params = getInlineParams();
+ }
+
+ static char ID; // Pass identification, replacement for typeid
+
+ unsigned getInlineThreshold(CallSite CS) const;
+
+ InlineCost getInlineCost(CallSite CS) override;
+
+ bool runOnSCC(CallGraphSCC &SCC) override;
+
+ void getAnalysisUsage(AnalysisUsage &AU) const override;
+
+private:
+ TargetTransformInfoWrapperPass *TTIWP;
+
+ InlineParams Params;
+};
+
+} // end anonymous namespace
+
+char AMDGPUInliner::ID = 0;
+INITIALIZE_PASS_BEGIN(AMDGPUInliner, "amdgpu-inline",
+ "AMDGPU Function Integration/Inlining", false, false)
+INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
+INITIALIZE_PASS_DEPENDENCY(CallGraphWrapperPass)
+INITIALIZE_PASS_DEPENDENCY(ProfileSummaryInfoWrapperPass)
+INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass)
+INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
+INITIALIZE_PASS_END(AMDGPUInliner, "amdgpu-inline",
+ "AMDGPU Function Integration/Inlining", false, false)
+
+Pass *llvm::createAMDGPUFunctionInliningPass() { return new AMDGPUInliner(); }
+
+bool AMDGPUInliner::runOnSCC(CallGraphSCC &SCC) {
+ TTIWP = &getAnalysis<TargetTransformInfoWrapperPass>();
+ return LegacyInlinerBase::runOnSCC(SCC);
+}
+
+void AMDGPUInliner::getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.addRequired<TargetTransformInfoWrapperPass>();
+ LegacyInlinerBase::getAnalysisUsage(AU);
+}
+
+unsigned AMDGPUInliner::getInlineThreshold(CallSite CS) const {
+ int Thres = Params.DefaultThreshold;
+
+ Function *Caller = CS.getCaller();
+ // Listen to the inlinehint attribute when it would increase the threshold
+ // and the caller does not need to minimize its size.
+ Function *Callee = CS.getCalledFunction();
+ bool InlineHint = Callee && !Callee->isDeclaration() &&
+ Callee->hasFnAttribute(Attribute::InlineHint);
+ if (InlineHint && Params.HintThreshold && Params.HintThreshold > Thres
+ && !Caller->hasFnAttribute(Attribute::MinSize))
+ Thres = Params.HintThreshold.getValue() *
+ TTIWP->getTTI(*Callee).getInliningThresholdMultiplier();
+
+ const DataLayout &DL = Caller->getParent()->getDataLayout();
+ if (!Callee)
+ return (unsigned)Thres;
+
+ // If we have a pointer to private array passed into a function
+ // it will not be optimized out, leaving scratch usage.
+ // Increase the inline threshold to allow inliniting in this case.
+ uint64_t AllocaSize = 0;
+ SmallPtrSet<const AllocaInst *, 8> AIVisited;
+ for (Value *PtrArg : CS.args()) {
+ PointerType *Ty = dyn_cast<PointerType>(PtrArg->getType());
+ if (!Ty || (Ty->getAddressSpace() != AMDGPUAS::PRIVATE_ADDRESS &&
+ Ty->getAddressSpace() != AMDGPUAS::FLAT_ADDRESS))
+ continue;
+
+ PtrArg = GetUnderlyingObject(PtrArg, DL);
+ if (const AllocaInst *AI = dyn_cast<AllocaInst>(PtrArg)) {
+ if (!AI->isStaticAlloca() || !AIVisited.insert(AI).second)
+ continue;
+ AllocaSize += DL.getTypeAllocSize(AI->getAllocatedType());
+ // If the amount of stack memory is excessive we will not be able
+ // to get rid of the scratch anyway, bail out.
+ if (AllocaSize > ArgAllocaCutoff) {
+ AllocaSize = 0;
+ break;
+ }
+ }
+ }
+ if (AllocaSize)
+ Thres += ArgAllocaCost;
+
+ return (unsigned)Thres;
+}
+
+// Check if call is just a wrapper around another call.
+// In this case we only have call and ret instructions.
+static bool isWrapperOnlyCall(CallSite CS) {
+ Function *Callee = CS.getCalledFunction();
+ if (!Callee || Callee->size() != 1)
+ return false;
+ const BasicBlock &BB = Callee->getEntryBlock();
+ if (const Instruction *I = BB.getFirstNonPHI()) {
+ if (!isa<CallInst>(I)) {
+ return false;
+ }
+ if (isa<ReturnInst>(*std::next(I->getIterator()))) {
+ LLVM_DEBUG(dbgs() << " Wrapper only call detected: "
+ << Callee->getName() << '\n');
+ return true;
+ }
+ }
+ return false;
+}
+
+InlineCost AMDGPUInliner::getInlineCost(CallSite CS) {
+ Function *Callee = CS.getCalledFunction();
+ Function *Caller = CS.getCaller();
+
+ if (!Callee || Callee->isDeclaration())
+ return llvm::InlineCost::getNever("undefined callee");
+
+ if (CS.isNoInline())
+ return llvm::InlineCost::getNever("noinline");
+
+ TargetTransformInfo &TTI = TTIWP->getTTI(*Callee);
+ if (!TTI.areInlineCompatible(Caller, Callee))
+ return llvm::InlineCost::getNever("incompatible");
+
+ if (CS.hasFnAttr(Attribute::AlwaysInline)) {
+ auto IsViable = isInlineViable(*Callee);
+ if (IsViable)
+ return llvm::InlineCost::getAlways("alwaysinline viable");
+ return llvm::InlineCost::getNever(IsViable.message);
+ }
+
+ if (isWrapperOnlyCall(CS))
+ return llvm::InlineCost::getAlways("wrapper-only call");
+
+ InlineParams LocalParams = Params;
+ LocalParams.DefaultThreshold = (int)getInlineThreshold(CS);
+ bool RemarksEnabled = false;
+ const auto &BBs = Caller->getBasicBlockList();
+ if (!BBs.empty()) {
+ auto DI = OptimizationRemark(DEBUG_TYPE, "", DebugLoc(), &BBs.front());
+ if (DI.isEnabled())
+ RemarksEnabled = true;
+ }
+
+ OptimizationRemarkEmitter ORE(Caller);
+ std::function<AssumptionCache &(Function &)> GetAssumptionCache =
+ [this](Function &F) -> AssumptionCache & {
+ return ACT->getAssumptionCache(F);
+ };
+
+ auto IC = llvm::getInlineCost(cast<CallBase>(*CS.getInstruction()), Callee,
+ LocalParams, TTI, GetAssumptionCache, None, PSI,
+ RemarksEnabled ? &ORE : nullptr);
+
+ if (IC && !IC.isAlways() && !Callee->hasFnAttribute(Attribute::InlineHint)) {
+ // Single BB does not increase total BB amount, thus subtract 1
+ size_t Size = Caller->size() + Callee->size() - 1;
+ if (MaxBB && Size > MaxBB)
+ return llvm::InlineCost::getNever("max number of bb exceeded");
+ }
+ return IC;
+}