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//===-- AMDGPUAlwaysInlinePass.cpp - Promote Allocas ----------------------===//
//
// 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 pass marks all internal functions as always_inline and creates
/// duplicates of all other functions and marks the duplicates as always_inline.
//
//===----------------------------------------------------------------------===//
#include "AMDGPU.h"
#include "AMDGPUTargetMachine.h"
#include "Utils/AMDGPUBaseInfo.h"
#include "llvm/CodeGen/CommandFlags.h"
#include "llvm/IR/Module.h"
#include "llvm/Pass.h"
#include "llvm/Support/CommandLine.h"
using namespace llvm;
namespace {
static cl::opt<bool> StressCalls(
"amdgpu-stress-function-calls",
cl::Hidden,
cl::desc("Force all functions to be noinline"),
cl::init(false));
class AMDGPUAlwaysInline : public ModulePass {
bool GlobalOpt;
public:
static char ID;
AMDGPUAlwaysInline(bool GlobalOpt = false) :
ModulePass(ID), GlobalOpt(GlobalOpt) { }
bool runOnModule(Module &M) override;
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.setPreservesAll();
}
};
} // End anonymous namespace
INITIALIZE_PASS(AMDGPUAlwaysInline, "amdgpu-always-inline",
"AMDGPU Inline All Functions", false, false)
char AMDGPUAlwaysInline::ID = 0;
static void
recursivelyVisitUsers(GlobalValue &GV,
SmallPtrSetImpl<Function *> &FuncsToAlwaysInline) {
SmallVector<User *, 16> Stack(GV.users());
SmallPtrSet<const Value *, 8> Visited;
while (!Stack.empty()) {
User *U = Stack.pop_back_val();
if (!Visited.insert(U).second)
continue;
if (Instruction *I = dyn_cast<Instruction>(U)) {
Function *F = I->getParent()->getParent();
if (!AMDGPU::isEntryFunctionCC(F->getCallingConv())) {
// FIXME: This is a horrible hack. We should always respect noinline,
// and just let us hit the error when we can't handle this.
//
// Unfortunately, clang adds noinline to all functions at -O0. We have
// to override this here until that's fixed.
F->removeFnAttr(Attribute::NoInline);
FuncsToAlwaysInline.insert(F);
Stack.push_back(F);
}
// No need to look at further users, but we do need to inline any callers.
continue;
}
append_range(Stack, U->users());
}
}
static bool alwaysInlineImpl(Module &M, bool GlobalOpt) {
std::vector<GlobalAlias*> AliasesToRemove;
SmallPtrSet<Function *, 8> FuncsToAlwaysInline;
SmallPtrSet<Function *, 8> FuncsToNoInline;
Triple TT(M.getTargetTriple());
for (GlobalAlias &A : M.aliases()) {
if (Function* F = dyn_cast<Function>(A.getAliasee())) {
if (TT.getArch() == Triple::amdgcn &&
A.getLinkage() != GlobalValue::InternalLinkage)
continue;
A.replaceAllUsesWith(F);
AliasesToRemove.push_back(&A);
}
// FIXME: If the aliasee isn't a function, it's some kind of constant expr
// cast that won't be inlined through.
}
if (GlobalOpt) {
for (GlobalAlias* A : AliasesToRemove) {
A->eraseFromParent();
}
}
// Always force inlining of any function that uses an LDS global address. This
// is something of a workaround because we don't have a way of supporting LDS
// objects defined in functions. LDS is always allocated by a kernel, and it
// is difficult to manage LDS usage if a function may be used by multiple
// kernels.
//
// OpenCL doesn't allow declaring LDS in non-kernels, so in practice this
// should only appear when IPO passes manages to move LDs defined in a kernel
// into a single user function.
for (GlobalVariable &GV : M.globals()) {
// TODO: Region address
unsigned AS = GV.getAddressSpace();
if ((AS == AMDGPUAS::REGION_ADDRESS) ||
(AS == AMDGPUAS::LOCAL_ADDRESS &&
(!AMDGPUTargetMachine::EnableLowerModuleLDS)))
recursivelyVisitUsers(GV, FuncsToAlwaysInline);
}
if (!AMDGPUTargetMachine::EnableFunctionCalls || StressCalls) {
auto IncompatAttr
= StressCalls ? Attribute::AlwaysInline : Attribute::NoInline;
for (Function &F : M) {
if (!F.isDeclaration() && !F.use_empty() &&
!F.hasFnAttribute(IncompatAttr)) {
if (StressCalls) {
if (!FuncsToAlwaysInline.count(&F))
FuncsToNoInline.insert(&F);
} else
FuncsToAlwaysInline.insert(&F);
}
}
}
for (Function *F : FuncsToAlwaysInline)
F->addFnAttr(Attribute::AlwaysInline);
for (Function *F : FuncsToNoInline)
F->addFnAttr(Attribute::NoInline);
return !FuncsToAlwaysInline.empty() || !FuncsToNoInline.empty();
}
bool AMDGPUAlwaysInline::runOnModule(Module &M) {
return alwaysInlineImpl(M, GlobalOpt);
}
ModulePass *llvm::createAMDGPUAlwaysInlinePass(bool GlobalOpt) {
return new AMDGPUAlwaysInline(GlobalOpt);
}
PreservedAnalyses AMDGPUAlwaysInlinePass::run(Module &M,
ModuleAnalysisManager &AM) {
alwaysInlineImpl(M, GlobalOpt);
return PreservedAnalyses::all();
}
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