//===-- SPIRVPrepareFunctions.cpp - modify function signatures --*- C++ -*-===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// This pass modifies function signatures containing aggregate arguments
// and/or return value before IRTranslator. Information about the original
// signatures is stored in metadata. It is used during call lowering to
// restore correct SPIR-V types of function arguments and return values.
// This pass also substitutes some llvm intrinsic calls with calls to newly
// generated functions (as the Khronos LLVM/SPIR-V Translator does).
//
// NOTE: this pass is a module-level one due to the necessity to modify
// GVs/functions.
//
//===----------------------------------------------------------------------===//
#include "SPIRV.h"
#include "SPIRVSubtarget.h"
#include "SPIRVTargetMachine.h"
#include "SPIRVUtils.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/CodeGen/IntrinsicLowering.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/IR/IntrinsicsSPIRV.h"
#include "llvm/Transforms/Utils/Cloning.h"
#include "llvm/Transforms/Utils/LowerMemIntrinsics.h"
#include <charconv>
#include <regex>
using namespace llvm;
namespace llvm {
void initializeSPIRVPrepareFunctionsPass(PassRegistry &);
}
namespace {
class SPIRVPrepareFunctions : public ModulePass {
const SPIRVTargetMachine &TM;
bool substituteIntrinsicCalls(Function *F);
Function *removeAggregateTypesFromSignature(Function *F);
public:
static char ID;
SPIRVPrepareFunctions(const SPIRVTargetMachine &TM) : ModulePass(ID), TM(TM) {
initializeSPIRVPrepareFunctionsPass(*PassRegistry::getPassRegistry());
}
bool runOnModule(Module &M) override;
StringRef getPassName() const override { return "SPIRV prepare functions"; }
void getAnalysisUsage(AnalysisUsage &AU) const override {
ModulePass::getAnalysisUsage(AU);
}
};
} // namespace
char SPIRVPrepareFunctions::ID = 0;
INITIALIZE_PASS(SPIRVPrepareFunctions, "prepare-functions",
"SPIRV prepare functions", false, false)
std::string lowerLLVMIntrinsicName(IntrinsicInst *II) {
Function *IntrinsicFunc = II->getCalledFunction();
assert(IntrinsicFunc && "Missing function");
std::string FuncName = IntrinsicFunc->getName().str();
std::replace(FuncName.begin(), FuncName.end(), '.', '_');
FuncName = "spirv." + FuncName;
return FuncName;
}
static Function *getOrCreateFunction(Module *M, Type *RetTy,
ArrayRef<Type *> ArgTypes,
StringRef Name) {
FunctionType *FT = FunctionType::get(RetTy, ArgTypes, false);
Function *F = M->getFunction(Name);
if (F && F->getFunctionType() == FT)
return F;
Function *NewF = Function::Create(FT, GlobalValue::ExternalLinkage, Name, M);
if (F)
NewF->setDSOLocal(F->isDSOLocal());
NewF->setCallingConv(CallingConv::SPIR_FUNC);
return NewF;
}
static bool lowerIntrinsicToFunction(IntrinsicInst *Intrinsic) {
// For @llvm.memset.* intrinsic cases with constant value and length arguments
// are emulated via "storing" a constant array to the destination. For other
// cases we wrap the intrinsic in @spirv.llvm_memset_* function and expand the
// intrinsic to a loop via expandMemSetAsLoop().
if (auto *MSI = dyn_cast<MemSetInst>(Intrinsic))
if (isa<Constant>(MSI->getValue()) && isa<ConstantInt>(MSI->getLength()))
return false; // It is handled later using OpCopyMemorySized.
Module *M = Intrinsic->getModule();
std::string FuncName = lowerLLVMIntrinsicName(Intrinsic);
if (Intrinsic->isVolatile())
FuncName += ".volatile";
// Redirect @llvm.intrinsic.* call to @spirv.llvm_intrinsic_*
Function *F = M->getFunction(FuncName);
if (F) {
Intrinsic->setCalledFunction(F);
return true;
}
// TODO copy arguments attributes: nocapture writeonly.
FunctionCallee FC =
M->getOrInsertFunction(FuncName, Intrinsic->getFunctionType());
auto IntrinsicID = Intrinsic->getIntrinsicID();
Intrinsic->setCalledFunction(FC);
F = dyn_cast<Function>(FC.getCallee());
assert(F && "Callee must be a function");
switch (IntrinsicID) {
case Intrinsic::memset: {
auto *MSI = static_cast<MemSetInst *>(Intrinsic);
Argument *Dest = F->getArg(0);
Argument *Val = F->getArg(1);
Argument *Len = F->getArg(2);
Argument *IsVolatile = F->getArg(3);
Dest->setName("dest");
Val->setName("val");
Len->setName("len");
IsVolatile->setName("isvolatile");
BasicBlock *EntryBB = BasicBlock::Create(M->getContext(), "entry", F);
IRBuilder<> IRB(EntryBB);
auto *MemSet = IRB.CreateMemSet(Dest, Val, Len, MSI->getDestAlign(),
MSI->isVolatile());
IRB.CreateRetVoid();
expandMemSetAsLoop(cast<MemSetInst>(MemSet));
MemSet->eraseFromParent();
break;
}
case Intrinsic::bswap: {
BasicBlock *EntryBB = BasicBlock::Create(M->getContext(), "entry", F);
IRBuilder<> IRB(EntryBB);
auto *BSwap = IRB.CreateIntrinsic(Intrinsic::bswap, Intrinsic->getType(),
F->getArg(0));
IRB.CreateRet(BSwap);
IntrinsicLowering IL(M->getDataLayout());
IL.LowerIntrinsicCall(BSwap);
break;
}
default:
break;
}
return true;
}
static std::string getAnnotation(Value *AnnoVal, Value *OptAnnoVal) {
if (auto *Ref = dyn_cast_or_null<GetElementPtrInst>(AnnoVal))
AnnoVal = Ref->getOperand(0);
if (auto *Ref = dyn_cast_or_null<BitCastInst>(OptAnnoVal))
OptAnnoVal = Ref->getOperand(0);
std::string Anno;
if (auto *C = dyn_cast_or_null<Constant>(AnnoVal)) {
StringRef Str;
if (getConstantStringInfo(C, Str))
Anno = Str;
}
// handle optional annotation parameter in a way that Khronos Translator do
// (collect integers wrapped in a struct)
if (auto *C = dyn_cast_or_null<Constant>(OptAnnoVal);
C && C->getNumOperands()) {
Value *MaybeStruct = C->getOperand(0);
if (auto *Struct = dyn_cast<ConstantStruct>(MaybeStruct)) {
for (unsigned I = 0, E = Struct->getNumOperands(); I != E; ++I) {
if (auto *CInt = dyn_cast<ConstantInt>(Struct->getOperand(I)))
Anno += (I == 0 ? ": " : ", ") +
std::to_string(CInt->getType()->getIntegerBitWidth() == 1
? CInt->getZExtValue()
: CInt->getSExtValue());
}
} else if (auto *Struct = dyn_cast<ConstantAggregateZero>(MaybeStruct)) {
// { i32 i32 ... } zeroinitializer
for (unsigned I = 0, E = Struct->getType()->getStructNumElements();
I != E; ++I)
Anno += I == 0 ? ": 0" : ", 0";
}
}
return Anno;
}
static SmallVector<Metadata *> parseAnnotation(Value *I,
const std::string &Anno,
LLVMContext &Ctx,
Type *Int32Ty) {
// Try to parse the annotation string according to the following rules:
// annotation := ({kind} | {kind:value,value,...})+
// kind := number
// value := number | string
static const std::regex R(
"\\{(\\d+)(?:[:,](\\d+|\"[^\"]*\")(?:,(\\d+|\"[^\"]*\"))*)?\\}");
SmallVector<Metadata *> MDs;
int Pos = 0;
for (std::sregex_iterator
It = std::sregex_iterator(Anno.begin(), Anno.end(), R),
ItEnd = std::sregex_iterator();
It != ItEnd; ++It) {
if (It->position() != Pos)
return SmallVector<Metadata *>{};
Pos = It->position() + It->length();
std::smatch Match = *It;
SmallVector<Metadata *> MDsItem;
for (std::size_t i = 1; i < Match.size(); ++i) {
std::ssub_match SMatch = Match[i];
std::string Item = SMatch.str();
if (Item.length() == 0)
break;
if (Item[0] == '"') {
Item = Item.substr(1, Item.length() - 2);
// Acceptable format of the string snippet is:
static const std::regex RStr("^(\\d+)(?:,(\\d+))*$");
if (std::smatch MatchStr; std::regex_match(Item, MatchStr, RStr)) {
for (std::size_t SubIdx = 1; SubIdx < MatchStr.size(); ++SubIdx)
if (std::string SubStr = MatchStr[SubIdx].str(); SubStr.length())
MDsItem.push_back(ConstantAsMetadata::get(
ConstantInt::get(Int32Ty, std::stoi(SubStr))));
} else {
MDsItem.push_back(MDString::get(Ctx, Item));
}
} else if (int32_t Num;
std::from_chars(Item.data(), Item.data() + Item.size(), Num)
.ec == std::errc{}) {
MDsItem.push_back(
ConstantAsMetadata::get(ConstantInt::get(Int32Ty, Num)));
} else {
MDsItem.push_back(MDString::get(Ctx, Item));
}
}
if (MDsItem.size() == 0)
return SmallVector<Metadata *>{};
MDs.push_back(MDNode::get(Ctx, MDsItem));
}
return Pos == static_cast<int>(Anno.length()) ? MDs
: SmallVector<Metadata *>{};
}
static void lowerPtrAnnotation(IntrinsicInst *II) {
LLVMContext &Ctx = II->getContext();
Type *Int32Ty = Type::getInt32Ty(Ctx);
// Retrieve an annotation string from arguments.
Value *PtrArg = nullptr;
if (auto *BI = dyn_cast<BitCastInst>(II->getArgOperand(0)))
PtrArg = BI->getOperand(0);
else
PtrArg = II->getOperand(0);
std::string Anno =
getAnnotation(II->getArgOperand(1),
4 < II->arg_size() ? II->getArgOperand(4) : nullptr);
// Parse the annotation.
SmallVector<Metadata *> MDs = parseAnnotation(II, Anno, Ctx, Int32Ty);
// If the annotation string is not parsed successfully we don't know the
// format used and output it as a general UserSemantic decoration.
// Otherwise MDs is a Metadata tuple (a decoration list) in the format
// expected by `spirv.Decorations`.
if (MDs.size() == 0) {
auto UserSemantic = ConstantAsMetadata::get(ConstantInt::get(
Int32Ty, static_cast<uint32_t>(SPIRV::Decoration::UserSemantic)));
MDs.push_back(MDNode::get(Ctx, {UserSemantic, MDString::get(Ctx, Anno)}));
}
// Build the internal intrinsic function.
IRBuilder<> IRB(II->getParent());
IRB.SetInsertPoint(II);
IRB.CreateIntrinsic(
Intrinsic::spv_assign_decoration, {PtrArg->getType()},
{PtrArg, MetadataAsValue::get(Ctx, MDNode::get(Ctx, MDs))});
II->replaceAllUsesWith(II->getOperand(0));
}
static void lowerFunnelShifts(IntrinsicInst *FSHIntrinsic) {
// Get a separate function - otherwise, we'd have to rework the CFG of the
// current one. Then simply replace the intrinsic uses with a call to the new
// function.
// Generate LLVM IR for i* @spirv.llvm_fsh?_i* (i* %a, i* %b, i* %c)
Module *M = FSHIntrinsic->getModule();
FunctionType *FSHFuncTy = FSHIntrinsic->getFunctionType();
Type *FSHRetTy = FSHFuncTy->getReturnType();
const std::string FuncName = lowerLLVMIntrinsicName(FSHIntrinsic);
Function *FSHFunc =
getOrCreateFunction(M, FSHRetTy, FSHFuncTy->params(), FuncName);
if (!FSHFunc->empty()) {
FSHIntrinsic->setCalledFunction(FSHFunc);
return;
}
BasicBlock *RotateBB = BasicBlock::Create(M->getContext(), "rotate", FSHFunc);
IRBuilder<> IRB(RotateBB);
Type *Ty = FSHFunc->getReturnType();
// Build the actual funnel shift rotate logic.
// In the comments, "int" is used interchangeably with "vector of int
// elements".
FixedVectorType *VectorTy = dyn_cast<FixedVectorType>(Ty);
Type *IntTy = VectorTy ? VectorTy->getElementType() : Ty;
unsigned BitWidth = IntTy->getIntegerBitWidth();
ConstantInt *BitWidthConstant = IRB.getInt({BitWidth, BitWidth});
Value *BitWidthForInsts =
VectorTy
? IRB.CreateVectorSplat(VectorTy->getNumElements(), BitWidthConstant)
: BitWidthConstant;
Value *RotateModVal =
IRB.CreateURem(/*Rotate*/ FSHFunc->getArg(2), BitWidthForInsts);
Value *FirstShift = nullptr, *SecShift = nullptr;
if (FSHIntrinsic->getIntrinsicID() == Intrinsic::fshr) {
// Shift the less significant number right, the "rotate" number of bits
// will be 0-filled on the left as a result of this regular shift.
FirstShift = IRB.CreateLShr(FSHFunc->getArg(1), RotateModVal);
} else {
// Shift the more significant number left, the "rotate" number of bits
// will be 0-filled on the right as a result of this regular shift.
FirstShift = IRB.CreateShl(FSHFunc->getArg(0), RotateModVal);
}
// We want the "rotate" number of the more significant int's LSBs (MSBs) to
// occupy the leftmost (rightmost) "0 space" left by the previous operation.
// Therefore, subtract the "rotate" number from the integer bitsize...
Value *SubRotateVal = IRB.CreateSub(BitWidthForInsts, RotateModVal);
if (FSHIntrinsic->getIntrinsicID() == Intrinsic::fshr) {
// ...and left-shift the more significant int by this number, zero-filling
// the LSBs.
SecShift = IRB.CreateShl(FSHFunc->getArg(0), SubRotateVal);
} else {
// ...and right-shift the less significant int by this number, zero-filling
// the MSBs.
SecShift = IRB.CreateLShr(FSHFunc->getArg(1), SubRotateVal);
}
// A simple binary addition of the shifted ints yields the final result.
IRB.CreateRet(IRB.CreateOr(FirstShift, SecShift));
FSHIntrinsic->setCalledFunction(FSHFunc);
}
static void lowerExpectAssume(IntrinsicInst *II) {
// If we cannot use the SPV_KHR_expect_assume extension, then we need to
// ignore the intrinsic and move on. It should be removed later on by LLVM.
// Otherwise we should lower the intrinsic to the corresponding SPIR-V
// instruction.
// For @llvm.assume we have OpAssumeTrueKHR.
// For @llvm.expect we have OpExpectKHR.
//
// We need to lower this into a builtin and then the builtin into a SPIR-V
// instruction.
if (II->getIntrinsicID() == Intrinsic::assume) {
Function *F = Intrinsic::getOrInsertDeclaration(
II->getModule(), Intrinsic::SPVIntrinsics::spv_assume);
II->setCalledFunction(F);
} else if (II->getIntrinsicID() == Intrinsic::expect) {
Function *F = Intrinsic::getOrInsertDeclaration(
II->getModule(), Intrinsic::SPVIntrinsics::spv_expect,
{II->getOperand(0)->getType()});
II->setCalledFunction(F);
} else {
llvm_unreachable("Unknown intrinsic");
}
return;
}
static bool toSpvOverloadedIntrinsic(IntrinsicInst *II, Intrinsic::ID NewID,
ArrayRef<unsigned> OpNos) {
Function *F = nullptr;
if (OpNos.empty()) {
F = Intrinsic::getOrInsertDeclaration(II->getModule(), NewID);
} else {
SmallVector<Type *, 4> Tys;
for (unsigned OpNo : OpNos)
Tys.push_back(II->getOperand(OpNo)->getType());
F = Intrinsic::getOrInsertDeclaration(II->getModule(), NewID, Tys);
}
II->setCalledFunction(F);
return true;
}
// Substitutes calls to LLVM intrinsics with either calls to SPIR-V intrinsics
// or calls to proper generated functions. Returns True if F was modified.
bool SPIRVPrepareFunctions::substituteIntrinsicCalls(Function *F) {
bool Changed = false;
for (BasicBlock &BB : *F) {
for (Instruction &I : BB) {
auto Call = dyn_cast<CallInst>(&I);
if (!Call)
continue;
Function *CF = Call->getCalledFunction();
if (!CF || !CF->isIntrinsic())
continue;
auto *II = cast<IntrinsicInst>(Call);
switch (II->getIntrinsicID()) {
case Intrinsic::memset:
case Intrinsic::bswap:
Changed |= lowerIntrinsicToFunction(II);
break;
case Intrinsic::fshl:
case Intrinsic::fshr:
lowerFunnelShifts(II);
Changed = true;
break;
case Intrinsic::assume:
case Intrinsic::expect: {
const SPIRVSubtarget &STI = TM.getSubtarget<SPIRVSubtarget>(*F);
if (STI.canUseExtension(SPIRV::Extension::SPV_KHR_expect_assume))
lowerExpectAssume(II);
Changed = true;
} break;
case Intrinsic::lifetime_start:
Changed |= toSpvOverloadedIntrinsic(
II, Intrinsic::SPVIntrinsics::spv_lifetime_start, {1});
break;
case Intrinsic::lifetime_end:
Changed |= toSpvOverloadedIntrinsic(
II, Intrinsic::SPVIntrinsics::spv_lifetime_end, {1});
break;
case Intrinsic::ptr_annotation:
lowerPtrAnnotation(II);
Changed = true;
break;
}
}
}
return Changed;
}
// Returns F if aggregate argument/return types are not present or cloned F
// function with the types replaced by i32 types. The change in types is
// noted in 'spv.cloned_funcs' metadata for later restoration.
Function *
SPIRVPrepareFunctions::removeAggregateTypesFromSignature(Function *F) {
bool IsRetAggr = F->getReturnType()->isAggregateType();
// Allow intrinsics with aggregate return type to reach GlobalISel
if (F->isIntrinsic() && IsRetAggr)
return F;
IRBuilder<> B(F->getContext());
bool HasAggrArg =
std::any_of(F->arg_begin(), F->arg_end(), [](Argument &Arg) {
return Arg.getType()->isAggregateType();
});
bool DoClone = IsRetAggr || HasAggrArg;
if (!DoClone)
return F;
SmallVector<std::pair<int, Type *>, 4> ChangedTypes;
Type *RetType = IsRetAggr ? B.getInt32Ty() : F->getReturnType();
if (IsRetAggr)
ChangedTypes.push_back(std::pair<int, Type *>(-1, F->getReturnType()));
SmallVector<Type *, 4> ArgTypes;
for (const auto &Arg : F->args()) {
if (Arg.getType()->isAggregateType()) {
ArgTypes.push_back(B.getInt32Ty());
ChangedTypes.push_back(
std::pair<int, Type *>(Arg.getArgNo(), Arg.getType()));
} else
ArgTypes.push_back(Arg.getType());
}
FunctionType *NewFTy =
FunctionType::get(RetType, ArgTypes, F->getFunctionType()->isVarArg());
Function *NewF =
Function::Create(NewFTy, F->getLinkage(), F->getName(), *F->getParent());
ValueToValueMapTy VMap;
auto NewFArgIt = NewF->arg_begin();
for (auto &Arg : F->args()) {
StringRef ArgName = Arg.getName();
NewFArgIt->setName(ArgName);
VMap[&Arg] = &(*NewFArgIt++);
}
SmallVector<ReturnInst *, 8> Returns;
CloneFunctionInto(NewF, F, VMap, CloneFunctionChangeType::LocalChangesOnly,
Returns);
NewF->takeName(F);
NamedMDNode *FuncMD =
F->getParent()->getOrInsertNamedMetadata("spv.cloned_funcs");
SmallVector<Metadata *, 2> MDArgs;
MDArgs.push_back(MDString::get(B.getContext(), NewF->getName()));
for (auto &ChangedTyP : ChangedTypes)
MDArgs.push_back(MDNode::get(
B.getContext(),
{ConstantAsMetadata::get(B.getInt32(ChangedTyP.first)),
ValueAsMetadata::get(Constant::getNullValue(ChangedTyP.second))}));
MDNode *ThisFuncMD = MDNode::get(B.getContext(), MDArgs);
FuncMD->addOperand(ThisFuncMD);
for (auto *U : make_early_inc_range(F->users())) {
if (auto *CI = dyn_cast<CallInst>(U))
CI->mutateFunctionType(NewF->getFunctionType());
U->replaceUsesOfWith(F, NewF);
}
// register the mutation
if (RetType != F->getReturnType())
TM.getSubtarget<SPIRVSubtarget>(*F).getSPIRVGlobalRegistry()->addMutated(
NewF, F->getReturnType());
return NewF;
}
bool SPIRVPrepareFunctions::runOnModule(Module &M) {
bool Changed = false;
for (Function &F : M) {
Changed |= substituteIntrinsicCalls(&F);
Changed |= sortBlocks(F);
}
std::vector<Function *> FuncsWorklist;
for (auto &F : M)
FuncsWorklist.push_back(&F);
for (auto *F : FuncsWorklist) {
Function *NewF = removeAggregateTypesFromSignature(F);
if (NewF != F) {
F->eraseFromParent();
Changed = true;
}
}
return Changed;
}
ModulePass *
llvm::createSPIRVPrepareFunctionsPass(const SPIRVTargetMachine &TM) {
return new SPIRVPrepareFunctions(TM);
}
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