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/*========================== begin_copyright_notice ============================
Copyright (C) 2017-2021 Intel Corporation
SPDX-License-Identifier: MIT
============================= end_copyright_notice ===========================*/
#include "common/LLVMWarningsPush.hpp"
#include <llvm/Pass.h>
#include <llvm/ADT/SmallVector.h>
#include <llvmWrapper/IR/CallSite.h>
#include <llvm/Transforms/Utils/Cloning.h>
#include "common/LLVMWarningsPop.hpp"
#include "Compiler/CISACodeGen/ShaderCodeGen.hpp"
#include "Compiler/IGCPassSupport.h"
#include "Compiler/MetaDataUtilsWrapper.h"
using namespace llvm;
using namespace IGC;
using namespace IGC::IGCMD;
// OpenCL C specification states that a kernel function is just a regular
// function call if a __kernel function is called by another kernel function.
// But, it doesn't clarify what's the behavior exactly. Under certain
// conditions, such a call may be ambiguous without separating kernel function
// and user functions, e.g.
//
// __kernel __attribute__((reqd_work_group_size(1, 1, 1)))
// void bar(...) {
// ...
// }
//
// __kernel __attribute__((reqd_work_group_size(32, 1, 1)))
// void foo(...) {
// ...
// bar(...);
// ...
// }
//
// Such ambiguity also exists if function call is enabled as well as if there
// are optimizations which may treat kernel function differently from user
// functions, such as inline buffer resolution, which will resolve the first
// local pointer argument at compilation time. If a function is used as both a
// kernel function and a user function. The first local pointer argument is
// ambiguous for optimization to resolve it statically.
//
// OpenCL C++ specification already clarifies the issue and would not allow a
// kernel function to called from another kernel function. However, we still
// need to handle that for OCL 1.2 and OCL 2.0.
//
// This pass is added to clone a kernel function to a user function if it's
// called.
//
namespace {
class KernelFunctionCloning : public ModulePass {
public:
static char ID;
KernelFunctionCloning() : ModulePass(ID) {}
bool runOnModule(Module &) override;
llvm::StringRef getPassName() const override { return "KernelFunctionCloning"; }
private:
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.setPreservesCFG();
AU.addRequired<CodeGenContextWrapper>();
AU.addRequired<MetaDataUtilsWrapper>();
}
};
} // End anonymous namespace
namespace IGC {
ModulePass *createKernelFunctionCloningPass() { return new KernelFunctionCloning(); }
#define PASS_FLAG "igc-kernel-function-cloning"
#define PASS_DESC "Clone kernel functions if it's called."
#define PASS_CFG_ONLY false
#define PASS_ANALYSIS false
IGC_INITIALIZE_PASS_BEGIN(KernelFunctionCloning, PASS_FLAG, PASS_DESC, PASS_CFG_ONLY, PASS_ANALYSIS)
IGC_INITIALIZE_PASS_DEPENDENCY(CodeGenContextWrapper)
IGC_INITIALIZE_PASS_DEPENDENCY(MetaDataUtilsWrapper)
IGC_INITIALIZE_PASS_END(KernelFunctionCloning, PASS_FLAG, PASS_DESC, PASS_CFG_ONLY, PASS_ANALYSIS)
} // namespace IGC
char KernelFunctionCloning::ID = 0;
template <typename PatternTypeFirst, typename... PatternTypeRest> struct PatternChecker {
template <typename Checker> static bool run(User *user, Checker check) {
auto casted = dyn_cast<PatternTypeFirst>(user);
if (!casted)
return false;
if constexpr (sizeof...(PatternTypeRest) > 0) {
for (auto user : casted->users()) {
if (!PatternChecker<PatternTypeRest...>::run(user, check)) {
return false;
}
}
}
return check(casted);
}
};
bool KernelFunctionCloning::runOnModule(Module &M) {
MetaDataUtils *MDU = getAnalysis<MetaDataUtilsWrapper>().getMetaDataUtils();
// Collect kernel functions being called.
SmallVector<Function *, 8> KernelsToClone;
for (auto &F : M) {
auto FII = MDU->findFunctionsInfoItem(&F);
if (FII == MDU->end_FunctionsInfo())
continue;
// Check this kernell function is called.
for (auto *U : F.users()) {
//
// Ignore if it's a user semantic decoration on function.
//
// GlobalVariable("llvm.global.annotations"):
// ConstantArray:
// ConstantStruct:
// BitCastOperator:
// Function = [ANNOTATED_FUNCTION]
// GetElementPtr:
// GlobalVariable = [ANNOTATION]
// ConstantStruct:
// ...
//
bool user_semantic =
PatternChecker<BitCastOperator, ConstantStruct, ConstantArray, GlobalVariable>::run(U, [](User *user) {
if (auto casted = dyn_cast<GlobalVariable>(user)) {
return casted->getName().compare("llvm.global.annotations") == 0;
}
return true;
});
if (user_semantic) {
continue;
}
IGCLLVM::CallSite *call = nullptr;
call = dyn_cast<IGCLLVM::CallSite>(U);
if (!call)
continue;
KernelsToClone.push_back(&F);
break;
}
}
// Clone it
bool Changed = false;
for (auto *F : KernelsToClone) {
ValueToValueMapTy VMap;
auto *NewF = CloneFunction(F, VMap);
NewF->setLinkage(GlobalValue::InternalLinkage);
if (!F->getParent()->getFunction(NewF->getName()))
F->getParent()->getFunctionList().push_back(NewF);
// Collect pointers to users (callsites) of the original kernel
// function and loop through the collection. Otherwise when looping
// through F->users(), calling call->setCalledFunction(NewF) modifies
// the F->users() by removing the very first element (second element
// becomes first) and the loop skips every second element.
SmallVector<User *, 8> originalKernelFunctionUsers;
for (auto *U : F->users()) {
originalKernelFunctionUsers.push_back(U);
}
// Replace the original calls to kernel function with calls to user
// function clone at the callsites.
for (auto &U : originalKernelFunctionUsers) {
IGCLLVM::CallSite *call = nullptr;
call = dyn_cast<IGCLLVM::CallSite>(U);
if (!call)
continue;
if (call->getCalledFunction()->getType() == NewF->getType())
call->setCalledFunction(NewF);
}
Changed = true;
}
return Changed;
}
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