forked from OSchip/llvm-project
179 lines
5.6 KiB
C++
179 lines
5.6 KiB
C++
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//===-- NVPTXImageOptimizer.cpp - Image optimization pass -----------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This pass implements IR-level optimizations of image access code,
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// including:
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//
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// 1. Eliminate istypep intrinsics when image access qualifier is known
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//
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//===----------------------------------------------------------------------===//
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#include "NVPTX.h"
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#include "NVPTXUtilities.h"
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#include "llvm/IR/Instructions.h"
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#include "llvm/IR/Intrinsics.h"
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#include "llvm/IR/Module.h"
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#include "llvm/Pass.h"
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#include "llvm/Analysis/ConstantFolding.h"
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using namespace llvm;
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namespace {
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class NVPTXImageOptimizer : public FunctionPass {
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private:
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static char ID;
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SmallVector<Instruction*, 4> InstrToDelete;
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public:
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NVPTXImageOptimizer();
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bool runOnFunction(Function &F);
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private:
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bool replaceIsTypePSampler(Instruction &I);
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bool replaceIsTypePSurface(Instruction &I);
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bool replaceIsTypePTexture(Instruction &I);
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Value *cleanupValue(Value *V);
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void replaceWith(Instruction *From, ConstantInt *To);
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};
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}
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char NVPTXImageOptimizer::ID = 0;
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NVPTXImageOptimizer::NVPTXImageOptimizer()
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: FunctionPass(ID) {}
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bool NVPTXImageOptimizer::runOnFunction(Function &F) {
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bool Changed = false;
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InstrToDelete.clear();
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// Look for call instructions in the function
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for (Function::iterator BI = F.begin(), BE = F.end(); BI != BE;
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++BI) {
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for (BasicBlock::iterator I = (*BI).begin(), E = (*BI).end();
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I != E; ++I) {
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Instruction &Instr = *I;
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if (CallInst *CI = dyn_cast<CallInst>(I)) {
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Function *CalledF = CI->getCalledFunction();
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if (CalledF && CalledF->isIntrinsic()) {
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// This is an intrinsic function call, check if its an istypep
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switch (CalledF->getIntrinsicID()) {
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default: break;
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case Intrinsic::nvvm_istypep_sampler:
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Changed |= replaceIsTypePSampler(Instr);
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break;
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case Intrinsic::nvvm_istypep_surface:
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Changed |= replaceIsTypePSurface(Instr);
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break;
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case Intrinsic::nvvm_istypep_texture:
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Changed |= replaceIsTypePTexture(Instr);
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break;
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}
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}
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}
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}
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}
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// Delete any istypep instances we replaced in the IR
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for (unsigned i = 0, e = InstrToDelete.size(); i != e; ++i)
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InstrToDelete[i]->eraseFromParent();
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return Changed;
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}
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bool NVPTXImageOptimizer::replaceIsTypePSampler(Instruction &I) {
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Value *TexHandle = cleanupValue(I.getOperand(0));
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if (isSampler(*TexHandle)) {
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// This is an OpenCL sampler, so it must be a samplerref
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replaceWith(&I, ConstantInt::getTrue(I.getContext()));
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return true;
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} else if (isImageWriteOnly(*TexHandle) ||
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isImageReadWrite(*TexHandle) ||
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isImageReadOnly(*TexHandle)) {
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// This is an OpenCL image, so it cannot be a samplerref
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replaceWith(&I, ConstantInt::getFalse(I.getContext()));
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return true;
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} else {
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// The image type is unknown, so we cannot eliminate the intrinsic
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return false;
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}
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}
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bool NVPTXImageOptimizer::replaceIsTypePSurface(Instruction &I) {
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Value *TexHandle = cleanupValue(I.getOperand(0));
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if (isImageReadWrite(*TexHandle) ||
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isImageWriteOnly(*TexHandle)) {
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// This is an OpenCL read-only/read-write image, so it must be a surfref
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replaceWith(&I, ConstantInt::getTrue(I.getContext()));
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return true;
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} else if (isImageReadOnly(*TexHandle) ||
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isSampler(*TexHandle)) {
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// This is an OpenCL read-only/ imageor sampler, so it cannot be
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// a surfref
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replaceWith(&I, ConstantInt::getFalse(I.getContext()));
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return true;
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} else {
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// The image type is unknown, so we cannot eliminate the intrinsic
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return false;
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}
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}
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bool NVPTXImageOptimizer::replaceIsTypePTexture(Instruction &I) {
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Value *TexHandle = cleanupValue(I.getOperand(0));
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if (isImageReadOnly(*TexHandle)) {
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// This is an OpenCL read-only image, so it must be a texref
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replaceWith(&I, ConstantInt::getTrue(I.getContext()));
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return true;
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} else if (isImageWriteOnly(*TexHandle) ||
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isImageReadWrite(*TexHandle) ||
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isSampler(*TexHandle)) {
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// This is an OpenCL read-write/write-only image or a sampler, so it
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// cannot be a texref
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replaceWith(&I, ConstantInt::getFalse(I.getContext()));
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return true;
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} else {
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// The image type is unknown, so we cannot eliminate the intrinsic
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return false;
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}
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}
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void NVPTXImageOptimizer::replaceWith(Instruction *From, ConstantInt *To) {
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// We implement "poor man's DCE" here to make sure any code that is no longer
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// live is actually unreachable and can be trivially eliminated by the
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// unreachable block elimiation pass.
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for (CallInst::use_iterator UI = From->use_begin(), UE = From->use_end();
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UI != UE; ++UI) {
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if (BranchInst *BI = dyn_cast<BranchInst>(*UI)) {
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if (BI->isUnconditional()) continue;
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BasicBlock *Dest;
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if (To->isZero())
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// Get false block
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Dest = BI->getSuccessor(1);
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else
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// Get true block
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Dest = BI->getSuccessor(0);
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BranchInst::Create(Dest, BI);
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InstrToDelete.push_back(BI);
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}
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}
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From->replaceAllUsesWith(To);
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InstrToDelete.push_back(From);
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}
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Value *NVPTXImageOptimizer::cleanupValue(Value *V) {
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if (ExtractValueInst *EVI = dyn_cast<ExtractValueInst>(V)) {
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return cleanupValue(EVI->getAggregateOperand());
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}
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return V;
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}
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FunctionPass *llvm::createNVPTXImageOptimizerPass() {
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return new NVPTXImageOptimizer();
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}
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