llvm-project/llvm/lib/Target/AArch64/SVEIntrinsicOpts.cpp

266 lines
8.1 KiB
C++

//===----- SVEIntrinsicOpts - SVE ACLE Intrinsics Opts --------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// Performs general IR level optimizations on SVE intrinsics.
//
// The main goal of this pass is to remove unnecessary reinterpret
// intrinsics (llvm.aarch64.sve.convert.[to|from].svbool), e.g:
//
// %1 = @llvm.aarch64.sve.convert.to.svbool.nxv4i1(<vscale x 4 x i1> %a)
// %2 = @llvm.aarch64.sve.convert.from.svbool.nxv4i1(<vscale x 16 x i1> %1)
//
// This pass also looks for ptest intrinsics & phi instructions where the
// operands are being needlessly converted to and from svbool_t.
//
//===----------------------------------------------------------------------===//
#include "Utils/AArch64BaseInfo.h"
#include "llvm/ADT/PostOrderIterator.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/IntrinsicsAArch64.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/PatternMatch.h"
#include "llvm/InitializePasses.h"
#include "llvm/Support/Debug.h"
using namespace llvm;
using namespace llvm::PatternMatch;
#define DEBUG_TYPE "aarch64-sve-intrinsic-opts"
namespace llvm {
void initializeSVEIntrinsicOptsPass(PassRegistry &);
}
namespace {
struct SVEIntrinsicOpts : public ModulePass {
static char ID; // Pass identification, replacement for typeid
SVEIntrinsicOpts() : ModulePass(ID) {
initializeSVEIntrinsicOptsPass(*PassRegistry::getPassRegistry());
}
bool runOnModule(Module &M) override;
void getAnalysisUsage(AnalysisUsage &AU) const override;
private:
static IntrinsicInst *isReinterpretToSVBool(Value *V);
static bool optimizeIntrinsic(Instruction *I);
bool optimizeFunctions(SmallSetVector<Function *, 4> &Functions);
static bool optimizeConvertFromSVBool(IntrinsicInst *I);
static bool optimizePTest(IntrinsicInst *I);
static bool processPhiNode(IntrinsicInst *I);
};
} // end anonymous namespace
void SVEIntrinsicOpts::getAnalysisUsage(AnalysisUsage &AU) const {
AU.addRequired<DominatorTreeWrapperPass>();
AU.setPreservesCFG();
}
char SVEIntrinsicOpts::ID = 0;
static const char *name = "SVE intrinsics optimizations";
INITIALIZE_PASS_BEGIN(SVEIntrinsicOpts, DEBUG_TYPE, name, false, false)
INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass);
INITIALIZE_PASS_END(SVEIntrinsicOpts, DEBUG_TYPE, name, false, false)
namespace llvm {
ModulePass *createSVEIntrinsicOptsPass() { return new SVEIntrinsicOpts(); }
} // namespace llvm
/// Returns V if it's a cast from <n x 16 x i1> (aka svbool_t), nullptr
/// otherwise.
IntrinsicInst *SVEIntrinsicOpts::isReinterpretToSVBool(Value *V) {
IntrinsicInst *I = dyn_cast<IntrinsicInst>(V);
if (!I)
return nullptr;
if (I->getIntrinsicID() != Intrinsic::aarch64_sve_convert_to_svbool)
return nullptr;
return I;
}
/// The function will remove redundant reinterprets casting in the presence
/// of the control flow
bool SVEIntrinsicOpts::processPhiNode(IntrinsicInst *X) {
SmallVector<Instruction *, 32> Worklist;
auto RequiredType = X->getType();
auto *PN = dyn_cast<PHINode>(X->getArgOperand(0));
assert(PN && "Expected Phi Node!");
// Don't create a new Phi unless we can remove the old one.
if (!PN->hasOneUse())
return false;
for (Value *IncValPhi : PN->incoming_values()) {
auto *Reinterpret = isReinterpretToSVBool(IncValPhi);
if (!Reinterpret ||
RequiredType != Reinterpret->getArgOperand(0)->getType())
return false;
}
// Create the new Phi
LLVMContext &Ctx = PN->getContext();
IRBuilder<> Builder(Ctx);
Builder.SetInsertPoint(PN);
PHINode *NPN = Builder.CreatePHI(RequiredType, PN->getNumIncomingValues());
Worklist.push_back(PN);
for (unsigned I = 0; I < PN->getNumIncomingValues(); I++) {
auto *Reinterpret = cast<Instruction>(PN->getIncomingValue(I));
NPN->addIncoming(Reinterpret->getOperand(0), PN->getIncomingBlock(I));
Worklist.push_back(Reinterpret);
}
// Cleanup Phi Node and reinterprets
X->replaceAllUsesWith(NPN);
X->eraseFromParent();
for (auto &I : Worklist)
if (I->use_empty())
I->eraseFromParent();
return true;
}
bool SVEIntrinsicOpts::optimizePTest(IntrinsicInst *I) {
IntrinsicInst *Op1 = dyn_cast<IntrinsicInst>(I->getArgOperand(0));
IntrinsicInst *Op2 = dyn_cast<IntrinsicInst>(I->getArgOperand(1));
if (Op1 && Op2 &&
Op1->getIntrinsicID() == Intrinsic::aarch64_sve_convert_to_svbool &&
Op2->getIntrinsicID() == Intrinsic::aarch64_sve_convert_to_svbool &&
Op1->getArgOperand(0)->getType() == Op2->getArgOperand(0)->getType()) {
Value *Ops[] = {Op1->getArgOperand(0), Op2->getArgOperand(0)};
Type *Tys[] = {Op1->getArgOperand(0)->getType()};
Module *M = I->getParent()->getParent()->getParent();
auto Fn = Intrinsic::getDeclaration(M, I->getIntrinsicID(), Tys);
auto CI = CallInst::Create(Fn, Ops, I->getName(), I);
I->replaceAllUsesWith(CI);
I->eraseFromParent();
if (Op1->use_empty())
Op1->eraseFromParent();
if (Op1 != Op2 && Op2->use_empty())
Op2->eraseFromParent();
return true;
}
return false;
}
bool SVEIntrinsicOpts::optimizeConvertFromSVBool(IntrinsicInst *I) {
assert(I->getIntrinsicID() == Intrinsic::aarch64_sve_convert_from_svbool &&
"Unexpected opcode");
// If the reinterpret instruction operand is a PHI Node
if (isa<PHINode>(I->getArgOperand(0)))
return processPhiNode(I);
// If we have a reinterpret intrinsic I of type A which is converting from
// another reinterpret Y of type B, and the source type of Y is A, then we can
// elide away both reinterprets if there are no other users of Y.
auto *Y = isReinterpretToSVBool(I->getArgOperand(0));
if (!Y)
return false;
Value *SourceVal = Y->getArgOperand(0);
if (I->getType() != SourceVal->getType())
return false;
I->replaceAllUsesWith(SourceVal);
I->eraseFromParent();
if (Y->use_empty())
Y->eraseFromParent();
return true;
}
bool SVEIntrinsicOpts::optimizeIntrinsic(Instruction *I) {
IntrinsicInst *IntrI = dyn_cast<IntrinsicInst>(I);
if (!IntrI)
return false;
switch (IntrI->getIntrinsicID()) {
case Intrinsic::aarch64_sve_convert_from_svbool:
return optimizeConvertFromSVBool(IntrI);
case Intrinsic::aarch64_sve_ptest_any:
case Intrinsic::aarch64_sve_ptest_first:
case Intrinsic::aarch64_sve_ptest_last:
return optimizePTest(IntrI);
default:
return false;
}
return true;
}
bool SVEIntrinsicOpts::optimizeFunctions(
SmallSetVector<Function *, 4> &Functions) {
bool Changed = false;
for (auto *F : Functions) {
DominatorTree *DT = &getAnalysis<DominatorTreeWrapperPass>(*F).getDomTree();
// Traverse the DT with an rpo walk so we see defs before uses, allowing
// simplification to be done incrementally.
BasicBlock *Root = DT->getRoot();
ReversePostOrderTraversal<BasicBlock *> RPOT(Root);
for (auto *BB : RPOT)
for (Instruction &I : make_early_inc_range(*BB))
Changed |= optimizeIntrinsic(&I);
}
return Changed;
}
bool SVEIntrinsicOpts::runOnModule(Module &M) {
bool Changed = false;
SmallSetVector<Function *, 4> Functions;
// Check for SVE intrinsic declarations first so that we only iterate over
// relevant functions. Where an appropriate declaration is found, store the
// function(s) where it is used so we can target these only.
for (auto &F : M.getFunctionList()) {
if (!F.isDeclaration())
continue;
switch (F.getIntrinsicID()) {
case Intrinsic::aarch64_sve_convert_from_svbool:
case Intrinsic::aarch64_sve_ptest_any:
case Intrinsic::aarch64_sve_ptest_first:
case Intrinsic::aarch64_sve_ptest_last:
for (auto I = F.user_begin(), E = F.user_end(); I != E;) {
auto *Inst = dyn_cast<Instruction>(*I++);
Functions.insert(Inst->getFunction());
}
break;
default:
break;
}
}
if (!Functions.empty())
Changed |= optimizeFunctions(Functions);
return Changed;
}