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CodeGen_LLVM.cpp
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#include <limits>
#include <memory>
#include <sstream>
#include "CPlusPlusMangle.h"
#include "CSE.h"
#include "CodeGen_Internal.h"
#include "CodeGen_LLVM.h"
#include "CodeGen_Posix.h"
#include "CodeGen_Targets.h"
#include "CompilerLogger.h"
#include "Debug.h"
#include "Deinterleave.h"
#include "EmulateFloat16Math.h"
#include "ExprUsesVar.h"
#include "ExternFuncArgument.h"
#include "FindIntrinsics.h"
#include "IREquality.h"
#include "IROperator.h"
#include "IRPrinter.h"
#include "IntegerDivisionTable.h"
#include "JITModule.h"
#include "LLVM_Headers.h"
#include "LLVM_Runtime_Linker.h"
#include "Lerp.h"
#include "LowerParallelTasks.h"
#include "Pipeline.h"
#include "Simplify.h"
#include "Util.h"
// MSVC won't set __cplusplus correctly unless certain compiler flags are set
// (and CMake doesn't set those flags for you even if you specify C++17),
// so we need to check against _MSVC_LANG as well, for completeness.
#if !(__cplusplus >= 201703L || _MSVC_LANG >= 201703L)
#error "Halide requires C++17 or later; please upgrade your compiler."
#endif
namespace Halide {
std::unique_ptr<llvm::Module> codegen_llvm(const Module &module, llvm::LLVMContext &context) {
std::unique_ptr<Internal::CodeGen_LLVM> cg(Internal::CodeGen_LLVM::new_for_target(module.target(), context));
return cg->compile(module);
}
namespace Internal {
using namespace llvm;
using std::map;
using std::ostringstream;
using std::pair;
using std::string;
using std::vector;
// Define a local empty inline function for each target
// to disable initialization.
#define LLVM_TARGET(target) \
inline void Initialize##target##Target() { \
}
#include <llvm/Config/Targets.def>
#undef LLVM_TARGET
#define LLVM_ASM_PARSER(target) \
inline void Initialize##target##AsmParser() { \
}
#include <llvm/Config/AsmParsers.def>
#undef LLVM_ASM_PARSER
#define LLVM_ASM_PRINTER(target) \
inline void Initialize##target##AsmPrinter() { \
}
#include <llvm/Config/AsmPrinters.def>
#undef LLVM_ASM_PRINTER
#define InitializeTarget(target) \
LLVMInitialize##target##Target(); \
LLVMInitialize##target##TargetInfo(); \
LLVMInitialize##target##TargetMC();
#define InitializeAsmParser(target) \
LLVMInitialize##target##AsmParser();
#define InitializeAsmPrinter(target) \
LLVMInitialize##target##AsmPrinter();
// Override above empty init function with macro for supported targets.
#ifdef WITH_ARM
#define InitializeARMTarget() InitializeTarget(ARM)
#define InitializeARMAsmParser() InitializeAsmParser(ARM)
#define InitializeARMAsmPrinter() InitializeAsmPrinter(ARM)
#endif
#ifdef WITH_NVPTX
#define InitializeNVPTXTarget() InitializeTarget(NVPTX)
// #define InitializeNVPTXAsmParser() InitializeAsmParser(NVPTX) // there is no ASM parser for NVPTX
#define InitializeNVPTXAsmPrinter() InitializeAsmPrinter(NVPTX)
#endif
#ifdef WITH_AARCH64
#define InitializeAArch64Target() InitializeTarget(AArch64)
#define InitializeAArch64AsmParser() InitializeAsmParser(AArch64)
#define InitializeAArch64AsmPrinter() InitializeAsmPrinter(AArch64)
#endif
#ifdef WITH_HEXAGON
#define InitializeHexagonTarget() InitializeTarget(Hexagon)
#define InitializeHexagonAsmParser() InitializeAsmParser(Hexagon)
#define InitializeHexagonAsmPrinter() InitializeAsmPrinter(Hexagon)
#endif
#ifdef WITH_POWERPC
#define InitializePowerPCTarget() InitializeTarget(PowerPC)
#define InitializePowerPCAsmParser() InitializeAsmParser(PowerPC)
#define InitializePowerPCAsmPrinter() InitializeAsmPrinter(PowerPC)
#endif
#ifdef WITH_RISCV
#define InitializeRISCVTarget() InitializeTarget(RISCV)
#define InitializeRISCVAsmParser() InitializeAsmParser(RISCV)
#define InitializeRISCVAsmPrinter() InitializeAsmPrinter(RISCV)
#endif
#ifdef WITH_X86
#define InitializeX86Target() InitializeTarget(X86)
#define InitializeX86AsmParser() InitializeAsmParser(X86)
#define InitializeX86AsmPrinter() InitializeAsmPrinter(X86)
#endif
#ifdef WITH_WEBASSEMBLY
#define InitializeWebAssemblyTarget() InitializeTarget(WebAssembly)
#define InitializeWebAssemblyAsmParser() InitializeAsmParser(WebAssembly)
#define InitializeWebAssemblyAsmPrinter() InitializeAsmPrinter(WebAssembly)
#endif
namespace {
llvm::Value *CreateConstGEP1_32(IRBuilderBase *builder, llvm::Type *gep_type,
Value *ptr, unsigned index) {
return builder->CreateConstGEP1_32(gep_type, ptr, index);
}
llvm::Value *CreateInBoundsGEP(IRBuilderBase *builder, llvm::Type *gep_type,
Value *ptr, ArrayRef<Value *> index_list) {
return builder->CreateInBoundsGEP(gep_type, ptr, index_list);
}
// Get the LLVM linkage corresponding to a Halide linkage type.
llvm::GlobalValue::LinkageTypes llvm_linkage(LinkageType t) {
// TODO(dsharlet): For some reason, marking internal functions as
// private linkage on OSX is causing some of the static tests to
// fail. Figure out why so we can remove this.
return llvm::GlobalValue::ExternalLinkage;
// switch (t) {
// case LinkageType::ExternalPlusArgv:
// case LinkageType::ExternalPlusMetadata:
// case LinkageType::External:
// return llvm::GlobalValue::ExternalLinkage;
// default:
// return llvm::GlobalValue::PrivateLinkage;
// }
}
} // namespace
CodeGen_LLVM::CodeGen_LLVM(const Target &t)
: builder(nullptr),
target(t),
wild_u1x_(Variable::make(UInt(1, 0), "*")),
wild_i8x_(Variable::make(Int(8, 0), "*")),
wild_u8x_(Variable::make(UInt(8, 0), "*")),
wild_i16x_(Variable::make(Int(16, 0), "*")),
wild_u16x_(Variable::make(UInt(16, 0), "*")),
wild_i32x_(Variable::make(Int(32, 0), "*")),
wild_u32x_(Variable::make(UInt(32, 0), "*")),
wild_i64x_(Variable::make(Int(64, 0), "*")),
wild_u64x_(Variable::make(UInt(64, 0), "*")),
wild_f32x_(Variable::make(Float(32, 0), "*")),
wild_f64x_(Variable::make(Float(64, 0), "*")),
wild_u1_(Variable::make(UInt(1), "*")),
wild_i8_(Variable::make(Int(8), "*")),
wild_u8_(Variable::make(UInt(8), "*")),
wild_i16_(Variable::make(Int(16), "*")),
wild_u16_(Variable::make(UInt(16), "*")),
wild_i32_(Variable::make(Int(32), "*")),
wild_u32_(Variable::make(UInt(32), "*")),
wild_i64_(Variable::make(Int(64), "*")),
wild_u64_(Variable::make(UInt(64), "*")),
wild_f32_(Variable::make(Float(32), "*")),
wild_f64_(Variable::make(Float(64), "*")),
strict_float(t.has_feature(Target::StrictFloat)),
llvm_large_code_model(t.has_feature(Target::LLVMLargeCodeModel)) {
initialize_llvm();
}
void CodeGen_LLVM::set_context(llvm::LLVMContext &context) {
this->context = &context;
effective_vscale = target_vscale();
}
std::unique_ptr<CodeGen_LLVM> CodeGen_LLVM::new_for_target(const Target &target, llvm::LLVMContext &context) {
std::unique_ptr<CodeGen_LLVM> result;
if (target.arch == Target::X86) {
result = new_CodeGen_X86(target);
} else if (target.arch == Target::ARM) {
result = new_CodeGen_ARM(target);
} else if (target.arch == Target::POWERPC) {
result = new_CodeGen_PowerPC(target);
} else if (target.arch == Target::Hexagon) {
result = new_CodeGen_Hexagon(target);
} else if (target.arch == Target::WebAssembly) {
result = new_CodeGen_WebAssembly(target);
} else if (target.arch == Target::RISCV) {
result = new_CodeGen_RISCV(target);
}
user_assert(result) << "Unknown target architecture: " << target.to_string() << "\n";
result->set_context(context);
return result;
}
void CodeGen_LLVM::initialize_llvm() {
static std::once_flag init_llvm_once;
std::call_once(init_llvm_once, []() {
// You can hack in command-line args to llvm with the
// environment variable HL_LLVM_ARGS, e.g. HL_LLVM_ARGS="-print-after-all"
std::string args = get_env_variable("HL_LLVM_ARGS");
if (!args.empty()) {
vector<std::string> arg_vec = split_string(args, " ");
vector<const char *> c_arg_vec;
c_arg_vec.push_back("llc");
for (const std::string &s : arg_vec) {
c_arg_vec.push_back(s.c_str());
}
cl::ParseCommandLineOptions((int)(c_arg_vec.size()), &c_arg_vec[0], "Halide compiler\n");
}
InitializeNativeTarget();
InitializeNativeTargetAsmPrinter();
InitializeNativeTargetAsmParser();
#define LLVM_TARGET(target) \
Initialize##target##Target();
#include <llvm/Config/Targets.def>
#undef LLVM_TARGET
#define LLVM_ASM_PARSER(target) \
Initialize##target##AsmParser();
#include <llvm/Config/AsmParsers.def>
#undef LLVM_ASM_PARSER
#define LLVM_ASM_PRINTER(target) \
Initialize##target##AsmPrinter();
#include <llvm/Config/AsmPrinters.def>
#undef LLVM_ASM_PRINTER
});
}
void CodeGen_LLVM::init_context() {
// Ensure our IRBuilder is using the current context.
builder = std::make_unique<IRBuilder<>>(*context);
// Branch weights for very likely branches
llvm::MDBuilder md_builder(*context);
very_likely_branch = md_builder.createBranchWeights(1 << 30, 0);
default_fp_math_md = md_builder.createFPMath(0.0);
strict_fp_math_md = md_builder.createFPMath(0.0);
builder->setDefaultFPMathTag(default_fp_math_md);
llvm::FastMathFlags fast_flags;
fast_flags.setNoNaNs();
fast_flags.setNoInfs();
fast_flags.setNoSignedZeros();
// Don't use approximate reciprocals for division. It's too inaccurate even for Halide.
// fast_flags.setAllowReciprocal();
// Theoretically, setAllowReassoc could be setUnsafeAlgebra for earlier versions, but that
// turns on all the flags.
fast_flags.setAllowReassoc();
fast_flags.setAllowContract(true);
fast_flags.setApproxFunc();
builder->setFastMathFlags(fast_flags);
// Define some types
void_t = llvm::Type::getVoidTy(*context);
i1_t = llvm::Type::getInt1Ty(*context);
i8_t = llvm::Type::getInt8Ty(*context);
i16_t = llvm::Type::getInt16Ty(*context);
i32_t = llvm::Type::getInt32Ty(*context);
i64_t = llvm::Type::getInt64Ty(*context);
f16_t = llvm::Type::getHalfTy(*context);
f32_t = llvm::Type::getFloatTy(*context);
f64_t = llvm::Type::getDoubleTy(*context);
// Ensure no Value pointers carry over from previous context.
struct_type_recovery.clear();
}
void CodeGen_LLVM::init_module() {
init_context();
// Start with a module containing the initial module for this target.
module = get_initial_module_for_target(target, context);
}
namespace {
struct MangledNames {
string simple_name;
string extern_name;
string argv_name;
string metadata_name;
};
MangledNames get_mangled_names(const std::string &name,
LinkageType linkage,
NameMangling mangling,
const std::vector<LoweredArgument> &args,
const Target &target) {
std::vector<std::string> namespaces;
MangledNames names;
names.simple_name = extract_namespaces(name, namespaces);
names.extern_name = names.simple_name;
names.argv_name = names.simple_name + "_argv";
names.metadata_name = names.simple_name + "_metadata";
if (linkage != LinkageType::Internal &&
((mangling == NameMangling::Default &&
target.has_feature(Target::CPlusPlusMangling)) ||
mangling == NameMangling::CPlusPlus)) {
std::vector<ExternFuncArgument> mangle_args;
for (const auto &arg : args) {
if (arg.kind == Argument::InputScalar) {
mangle_args.emplace_back(make_zero(arg.type));
} else if (arg.kind == Argument::InputBuffer ||
arg.kind == Argument::OutputBuffer) {
mangle_args.emplace_back(Buffer<>());
}
}
names.extern_name = cplusplus_function_mangled_name(names.simple_name, namespaces, type_of<int>(), mangle_args, target);
halide_handle_cplusplus_type inner_type(halide_cplusplus_type_name(halide_cplusplus_type_name::Simple, "void"), {}, {},
{halide_handle_cplusplus_type::Pointer, halide_handle_cplusplus_type::Pointer});
Type void_star_star(Handle(1, &inner_type));
names.argv_name = cplusplus_function_mangled_name(names.argv_name, namespaces, type_of<int>(), {ExternFuncArgument(make_zero(void_star_star))}, target);
names.metadata_name = cplusplus_function_mangled_name(names.metadata_name, namespaces, type_of<const struct halide_filter_metadata_t *>(), {}, target);
}
return names;
}
MangledNames get_mangled_names(const LoweredFunc &f, const Target &target) {
return get_mangled_names(f.name, f.linkage, f.name_mangling, f.args, target);
}
} // namespace
llvm::FunctionType *CodeGen_LLVM::signature_to_type(const ExternSignature &signature) {
internal_assert(void_t != nullptr && halide_buffer_t_type != nullptr);
llvm::Type *ret_type =
signature.is_void_return() ? void_t : llvm_type_of(upgrade_type_for_argument_passing(signature.ret_type()));
std::vector<llvm::Type *> llvm_arg_types;
for (const Type &t : signature.arg_types()) {
if (t == type_of<struct halide_buffer_t *>()) {
llvm_arg_types.push_back(PointerType::get(halide_buffer_t_type, 0));
} else {
llvm_arg_types.push_back(llvm_type_of(upgrade_type_for_argument_passing(t)));
}
}
return llvm::FunctionType::get(ret_type, llvm_arg_types, false);
}
/*static*/
std::unique_ptr<llvm::Module> CodeGen_LLVM::compile_trampolines(
const Target &target,
llvm::LLVMContext &context,
const std::string &suffix,
const std::vector<std::pair<std::string, ExternSignature>> &externs) {
std::unique_ptr<CodeGen_LLVM> codegen(new_for_target(target, context));
codegen->init_codegen("trampolines" + suffix);
for (const std::pair<std::string, ExternSignature> &e : externs) {
const std::string &callee_name = e.first;
const std::string wrapper_name = callee_name + suffix;
llvm::FunctionType *fn_type = codegen->signature_to_type(e.second);
// callee might already be present for builtins, e.g. halide_print
llvm::Function *callee = codegen->module->getFunction(callee_name);
if (!callee) {
callee = llvm::Function::Create(fn_type, llvm::Function::ExternalLinkage, callee_name, codegen->module.get());
}
std::vector<bool> buffer_args(e.second.arg_types().size());
size_t index = 0;
for (const Type &t : e.second.arg_types()) {
buffer_args[index++] = (t == type_of<struct halide_buffer_t *>());
}
codegen->add_argv_wrapper(callee, wrapper_name, /*result_in_argv*/ true, buffer_args);
}
return codegen->finish_codegen();
}
void CodeGen_LLVM::init_codegen(const std::string &name, bool any_strict_float) {
init_module();
internal_assert(module && context);
#if LLVM_VERSION >= 210
debug(1) << "Target triple of initial module: " << module->getTargetTriple().str() << "\n";
#else
debug(1) << "Target triple of initial module: " << module->getTargetTriple() << "\n";
#endif
module->setModuleIdentifier(name);
// Add some target specific info to the module as metadata.
module->addModuleFlag(llvm::Module::Warning, "halide_use_soft_float_abi", use_soft_float_abi() ? 1 : 0);
module->addModuleFlag(llvm::Module::Warning, "halide_mcpu_target", MDString::get(*context, mcpu_target()));
module->addModuleFlag(llvm::Module::Warning, "halide_mcpu_tune", MDString::get(*context, mcpu_tune()));
module->addModuleFlag(llvm::Module::Warning, "halide_mattrs", MDString::get(*context, mattrs()));
module->addModuleFlag(llvm::Module::Warning, "halide_mabi", MDString::get(*context, mabi()));
module->addModuleFlag(llvm::Module::Warning, "halide_use_pic", use_pic() ? 1 : 0);
module->addModuleFlag(llvm::Module::Warning, "halide_use_large_code_model", llvm_large_code_model ? 1 : 0);
module->addModuleFlag(llvm::Module::Warning, "halide_per_instruction_fast_math_flags", any_strict_float);
if (effective_vscale != 0) {
module->addModuleFlag(llvm::Module::Warning, "halide_effective_vscale", effective_vscale);
}
// Ensure some types we need are defined
halide_buffer_t_type = get_llvm_struct_type_by_name(module.get(), "struct.halide_buffer_t");
internal_assert(halide_buffer_t_type) << "Did not find halide_buffer_t in initial module";
type_t_type = get_llvm_struct_type_by_name(module.get(), "struct.halide_type_t");
internal_assert(type_t_type) << "Did not find halide_type_t in initial module";
dimension_t_type = get_llvm_struct_type_by_name(module.get(), "struct.halide_dimension_t");
internal_assert(dimension_t_type) << "Did not find halide_dimension_t in initial module";
metadata_t_type = get_llvm_struct_type_by_name(module.get(), "struct.halide_filter_metadata_t");
internal_assert(metadata_t_type) << "Did not find halide_filter_metadata_t in initial module";
argument_t_type = get_llvm_struct_type_by_name(module.get(), "struct.halide_filter_argument_t");
internal_assert(argument_t_type) << "Did not find halide_filter_argument_t in initial module";
scalar_value_t_type = get_llvm_struct_type_by_name(module.get(), "struct.halide_scalar_value_t");
internal_assert(scalar_value_t_type) << "Did not find halide_scalar_value_t in initial module";
device_interface_t_type = get_llvm_struct_type_by_name(module.get(), "struct.halide_device_interface_t");
internal_assert(device_interface_t_type) << "Did not find halide_device_interface_t in initial module";
pseudostack_slot_t_type = get_llvm_struct_type_by_name(module.get(), "struct.halide_pseudostack_slot_t");
internal_assert(pseudostack_slot_t_type) << "Did not find halide_pseudostack_slot_t in initial module";
semaphore_t_type = get_llvm_struct_type_by_name(module.get(), "struct.halide_semaphore_t");
internal_assert(semaphore_t_type) << "Did not find halide_semaphore_t in initial module";
}
std::unique_ptr<llvm::Module> CodeGen_LLVM::compile(const Module &input) {
init_codegen(input.name(), input.any_strict_float());
internal_assert(module && context && builder)
<< "The CodeGen_LLVM subclass should have made an initial module before calling CodeGen_LLVM::compile\n";
// Generate the code for this module.
debug(1) << "Generating llvm bitcode...\n";
for (const auto &b : input.buffers()) {
compile_buffer(b);
}
vector<MangledNames> function_names;
// Declare all functions
for (const auto &f : input.functions()) {
const auto names = get_mangled_names(f, get_target());
function_names.push_back(names);
// Deduce the types of the arguments to our function
vector<llvm::Type *> arg_types(f.args.size());
for (size_t i = 0; i < f.args.size(); i++) {
if (f.args[i].is_buffer()) {
arg_types[i] = PointerType::get(halide_buffer_t_type, 0);
} else {
arg_types[i] = llvm_type_of(upgrade_type_for_argument_passing(f.args[i].type));
}
}
FunctionType *func_t = FunctionType::get(i32_t, arg_types, false);
function = llvm::Function::Create(func_t, llvm_linkage(f.linkage), names.extern_name, module.get());
set_function_attributes_from_halide_target_options(*function);
// Mark the buffer args as no alias and save indication for add_argv_wrapper if needed
std::vector<bool> buffer_args(f.args.size());
for (size_t i = 0; i < f.args.size(); i++) {
bool is_buffer = f.args[i].is_buffer();
buffer_args[i] = is_buffer;
if (is_buffer) {
function->addParamAttr(i, Attribute::NoAlias);
}
}
// sym_push helpfully calls setName, which we don't want
symbol_table.push("::" + f.name, function);
// If the Func is externally visible, also create the argv wrapper and metadata.
// (useful for calling from JIT and other machine interfaces).
if (f.linkage == LinkageType::ExternalPlusArgv || f.linkage == LinkageType::ExternalPlusMetadata) {
add_argv_wrapper(function, names.argv_name, false, buffer_args);
if (f.linkage == LinkageType::ExternalPlusMetadata) {
embed_metadata_getter(names.metadata_name,
names.simple_name, f.args, input.get_metadata_name_map());
}
}
// Workaround for https://github.com/halide/Halide/issues/635:
// For historical reasons, Halide-generated AOT code
// defines user_context as `void const*`, but expects all
// define_extern code with user_context usage to use `void *`. This
// usually isn't an issue, but if both the caller and callee of the
// pass a user_context, *and* c_plus_plus_name_mangling is enabled,
// we get link errors because of this dichotomy. Fixing this
// "correctly" (ie so that everything always uses identical types for
// user_context in all cases) will require a *lot* of downstream
// churn (see https://github.com/halide/Halide/issues/7298),
// so this is a workaround: Add a wrapper with `void*`
// ucon -> `void const*` ucon. In most cases this will be ignored
// (and probably dead-stripped), but in these cases it's critical.
//
// (Note that we don't check to see if c_plus_plus_name_mangling is
// enabled, since that would have to be done on the caller side, and
// this is purely a callee-side fix.)
if (f.linkage != LinkageType::Internal &&
target.has_feature(Target::CPlusPlusMangling) &&
target.has_feature(Target::UserContext)) {
int wrapper_ucon_index = -1;
auto wrapper_args = f.args; // make a copy
auto wrapper_llvm_arg_types = arg_types; // make a copy
for (int i = 0; i < (int)wrapper_args.size(); i++) {
if (wrapper_args[i].name == "__user_context" && wrapper_args[i].type == type_of<void const *>()) {
// Update the type of the user_context argument to be void* rather than void const*
wrapper_args[i].type = type_of<void *>();
wrapper_llvm_arg_types[i] = llvm_type_of(upgrade_type_for_argument_passing(wrapper_args[i].type));
wrapper_ucon_index = i;
}
}
if (wrapper_ucon_index >= 0) {
const auto wrapper_names = get_mangled_names(f.name, f.linkage, f.name_mangling, wrapper_args, target);
FunctionType *wrapper_func_t = FunctionType::get(i32_t, wrapper_llvm_arg_types, false);
llvm::Function *wrapper_func = llvm::Function::Create(wrapper_func_t,
llvm::GlobalValue::ExternalLinkage,
wrapper_names.extern_name,
module.get());
set_function_attributes_from_halide_target_options(*wrapper_func);
llvm::BasicBlock *wrapper_block = llvm::BasicBlock::Create(module->getContext(), "entry", wrapper_func);
builder->SetInsertPoint(wrapper_block);
std::vector<llvm::Value *> wrapper_call_args;
for (auto &arg : wrapper_func->args()) {
wrapper_call_args.push_back(&arg);
}
wrapper_call_args[wrapper_ucon_index] = builder->CreatePointerCast(wrapper_call_args[wrapper_ucon_index],
llvm_type_of(type_of<void const *>()));
llvm::CallInst *wrapper_result = builder->CreateCall(function, wrapper_call_args);
// This call should never inline
wrapper_result->setIsNoInline();
builder->CreateRet(wrapper_result);
internal_assert(!verifyFunction(*wrapper_func, &llvm::errs()));
}
}
}
// Define all functions
int idx = 0;
for (const auto &f : input.functions()) {
const auto &names = function_names[idx++];
run_with_large_stack([&]() {
compile_func(f, names.simple_name, names.extern_name);
});
}
debug(2) << "llvm::Module pointer: " << module.get() << "\n";
return finish_codegen();
}
std::unique_ptr<llvm::Module> CodeGen_LLVM::finish_codegen() {
llvm::for_each(*module, set_function_attributes_from_halide_target_options);
// Verify the module is ok
internal_assert(!verifyModule(*module, &llvm::errs()));
debug(2) << "Done generating llvm bitcode\n";
// Optimize
CodeGen_LLVM::optimize_module();
if (target.has_feature(Target::EmbedBitcode)) {
std::string halide_command = "halide target=" + target.to_string();
embed_bitcode(module.get(), halide_command);
}
// Disown the module and return it.
return std::move(module);
}
void CodeGen_LLVM::begin_func(LinkageType linkage, const std::string &name,
const std::string &extern_name, const std::vector<LoweredArgument> &args) {
current_function_args = args;
function = module->getFunction(extern_name);
if (!function) {
internal_assert(function) << "Could not find a function of name " << extern_name << " in module\n";
}
debug(1) << "Generating llvm bitcode prolog for function " << name << "...\n";
// Null out the destructor block.
destructor_block = nullptr;
// Make the initial basic block
BasicBlock *block = BasicBlock::Create(*context, "entry", function);
builder->SetInsertPoint(block);
// Put the arguments in the symbol table
{
size_t i = 0;
for (auto &arg : function->args()) {
if (args[i].is_buffer()) {
sym_push(args[i].name + ".buffer", &arg);
} else {
Type passed_type = upgrade_type_for_argument_passing(args[i].type);
if (args[i].type != passed_type) {
llvm::Value *a = builder->CreateBitCast(&arg, llvm_type_of(args[i].type));
sym_push(args[i].name, a);
} else {
sym_push(args[i].name, &arg);
}
}
i++;
}
}
}
void CodeGen_LLVM::end_func(const std::vector<LoweredArgument> &args) {
return_with_error_code(ConstantInt::get(i32_t, 0));
// Remove the arguments from the symbol table
for (const auto &arg : args) {
if (arg.is_buffer()) {
sym_pop(arg.name + ".buffer");
} else {
sym_pop(arg.name);
}
}
bool valid = !verifyFunction(*function, &llvm::errs());
if (!valid) {
function->print(dbgs());
}
internal_assert(valid) << "Generated function does not pass LLVM's verifyFunction.\n";
current_function_args.clear();
}
void CodeGen_LLVM::compile_func(const LoweredFunc &f, const std::string &simple_name,
const std::string &extern_name) {
// Generate the function declaration and argument unpacking code.
begin_func(f.linkage, simple_name, extern_name, f.args);
// If building with MSAN, ensure that calls to halide_msan_annotate_buffer_is_initialized()
// happen for every output buffer if the function succeeds.
if (f.linkage != LinkageType::Internal &&
target.has_feature(Target::MSAN)) {
llvm::Function *annotate_buffer_fn =
module->getFunction("halide_msan_annotate_buffer_is_initialized_as_destructor");
internal_assert(annotate_buffer_fn)
<< "Could not find halide_msan_annotate_buffer_is_initialized_as_destructor in module\n";
annotate_buffer_fn->addParamAttr(0, Attribute::NoAlias);
for (const auto &arg : f.args) {
if (arg.kind == Argument::OutputBuffer) {
register_destructor(annotate_buffer_fn, sym_get(arg.name + ".buffer"), OnSuccess);
}
}
}
// Generate the function body.
debug(1) << "Generating llvm bitcode for function " << f.name << "...\n";
f.body.accept(this);
// Show one time warning and clear it.
for (auto it = onetime_warnings.begin(); it != onetime_warnings.end(); it = onetime_warnings.erase(it)) {
user_warning << "In function " << f.name << ", " << it->second;
}
// Clean up and return.
end_func(f.args);
}
// Given a range of iterators of constant ints, get a corresponding vector of llvm::Constant.
template<typename It>
std::vector<llvm::Constant *> get_constants(llvm::Type *t, It begin, It end) {
std::vector<llvm::Constant *> ret;
for (It i = begin; i != end; i++) {
ret.push_back(ConstantInt::get(t, *i));
}
return ret;
}
BasicBlock *CodeGen_LLVM::get_destructor_block() {
if (!destructor_block) {
// Create it if it doesn't exist.
IRBuilderBase::InsertPoint here = builder->saveIP();
destructor_block = BasicBlock::Create(*context, "destructor_block", function);
builder->SetInsertPoint(destructor_block);
// The first instruction in the destructor block is a phi node
// that collects the error code.
PHINode *error_code = builder->CreatePHI(i32_t, 0);
// Calls to destructors will get inserted here.
// The last instruction is the return op that returns it.
builder->CreateRet(error_code);
// Jump back to where we were.
builder->restoreIP(here);
}
internal_assert(destructor_block->getParent() == function);
return destructor_block;
}
Value *CodeGen_LLVM::register_destructor(llvm::Function *destructor_fn, Value *obj, DestructorType when) {
// Create a null-initialized stack slot to track this object
llvm::Type *void_ptr = PointerType::get(i8_t, 0);
llvm::Value *stack_slot = create_alloca_at_entry(void_ptr, 1, true);
// Cast the object to llvm's representation of void *
obj = builder->CreatePointerCast(obj, void_ptr);
// Put it in the stack slot
builder->CreateStore(obj, stack_slot);
// Passing the constant null as the object means the destructor
// will never get called.
{
llvm::Constant *c = dyn_cast<llvm::Constant>(obj);
if (c && c->isNullValue()) {
internal_error << "Destructors must take a non-null object\n";
}
}
// Switch to the destructor block, and add code that cleans up
// this object if the contents of the stack slot is not nullptr.
IRBuilderBase::InsertPoint here = builder->saveIP();
BasicBlock *dtors = get_destructor_block();
builder->SetInsertPoint(dtors->getFirstNonPHIIt());
PHINode *error_code = dyn_cast<PHINode>(dtors->begin());
internal_assert(error_code) << "The destructor block is supposed to start with a phi node\n";
llvm::Value *should_call = nullptr;
switch (when) {
case Always:
should_call = ConstantInt::get(i1_t, 1);
break;
case OnError:
should_call = builder->CreateIsNotNull(error_code);
break;
case OnSuccess:
should_call = builder->CreateIsNull(error_code);
break;
}
llvm::Function *call_destructor = module->getFunction("call_destructor");
internal_assert(call_destructor);
internal_assert(destructor_fn);
internal_assert(should_call);
Value *args[] = {get_user_context(), destructor_fn, stack_slot, should_call};
builder->CreateCall(call_destructor, args);
// Switch back to the original location
builder->restoreIP(here);
// Return the stack slot so that it's possible to cleanup the object early.
return stack_slot;
}
void CodeGen_LLVM::trigger_destructor(llvm::Function *destructor_fn, Value *stack_slot) {
llvm::Function *call_destructor = module->getFunction("call_destructor");
internal_assert(call_destructor);
internal_assert(destructor_fn);
stack_slot = builder->CreatePointerCast(stack_slot, PointerType::get(PointerType::get(i8_t, 0), 0));
Value *should_call = ConstantInt::get(i1_t, 1);
Value *args[] = {get_user_context(), destructor_fn, stack_slot, should_call};
builder->CreateCall(call_destructor, args);
}
void CodeGen_LLVM::compile_buffer(const Buffer<> &buf) {
// Embed the buffer declaration as a global.
internal_assert(buf.defined());
user_assert(buf.data())
<< "Can't embed buffer " << buf.name() << " because it has a null host pointer.\n";
user_assert(!buf.device_dirty())
<< "Can't embed Image \"" << buf.name() << "\""
<< " because it has a dirty device pointer\n";
Constant *type_fields[] = {
ConstantInt::get(i8_t, buf.type().code()),
ConstantInt::get(i8_t, buf.type().bits()),
ConstantInt::get(i16_t, buf.type().lanes())};
Constant *shape = nullptr;
if (buf.dimensions()) {
size_t shape_size = buf.dimensions() * sizeof(halide_dimension_t);
vector<char> shape_blob((char *)buf.raw_buffer()->dim, (char *)buf.raw_buffer()->dim + shape_size);
shape = create_binary_blob(shape_blob, buf.name() + ".shape");
shape = ConstantExpr::getPointerCast(shape, PointerType::get(dimension_t_type, 0));
} else {
shape = ConstantPointerNull::get(PointerType::get(dimension_t_type, 0));
}
// For now, we assume buffers that aren't scalar are constant,
// while scalars can be mutated. This accommodates all our existing
// use cases, which is that all buffers are constant, except those
// used to store stateful module information in offloading runtimes.
bool constant = buf.dimensions() != 0;
vector<char> data_blob((const char *)buf.data(), (const char *)buf.data() + buf.size_in_bytes());
Constant *fields[] = {
ConstantInt::get(i64_t, 0), // device
ConstantPointerNull::get(PointerType::get(device_interface_t_type, 0)), // device_interface
create_binary_blob(data_blob, buf.name() + ".data", constant), // host
ConstantInt::get(i64_t, halide_buffer_flag_host_dirty), // flags
ConstantStruct::get(type_t_type, type_fields), // type
ConstantInt::get(i32_t, buf.dimensions()), // dimensions
shape, // dim
ConstantPointerNull::get(PointerType::get(i8_t, 0)), // padding
};
Constant *buffer_struct = ConstantStruct::get(halide_buffer_t_type, fields);
// Embed the halide_buffer_t and make it point to the data array.
GlobalVariable *global = new GlobalVariable(*module, halide_buffer_t_type,
false, GlobalValue::PrivateLinkage,
nullptr, buf.name() + ".buffer");
global->setInitializer(buffer_struct);
// Finally, dump it in the symbol table
Constant *zero[] = {ConstantInt::get(i32_t, 0)};
Constant *global_ptr = ConstantExpr::getInBoundsGetElementPtr(halide_buffer_t_type, global, zero);
sym_push(buf.name() + ".buffer", global_ptr);
}
Constant *CodeGen_LLVM::embed_constant_scalar_value_t(const Expr &e) {
if (!e.defined()) {
return Constant::getNullValue(PointerType::get(scalar_value_t_type, 0));
}
internal_assert(!e.type().is_handle()) << "Should never see Handle types here.";
llvm::Value *val = codegen(e);
llvm::Constant *constant = dyn_cast<llvm::Constant>(val);
internal_assert(constant);
// Verify that the size of the LLVM value is the size we expected.
internal_assert((uint64_t)constant->getType()->getPrimitiveSizeInBits() == (uint64_t)e.type().bits());
// It's important that we allocate a full scalar_value_t_type here,
// even if the type of the value is smaller; downstream consumers should
// be able to correctly load an entire scalar_value_t_type regardless of its
// type, and if we emit just (say) a uint8 value here, the pointer may be
// misaligned and/or the storage after may be unmapped. LLVM doesn't support
// unions directly, so we'll fake it by making a constant array of the elements
// we need, setting the first to the constant we want, and setting the rest
// to all-zeros. (This happens to work because sizeof(halide_scalar_value_t) is evenly
// divisible by sizeof(any-union-field.)
const size_t value_size = e.type().bytes();
internal_assert(value_size > 0 && value_size <= sizeof(halide_scalar_value_t));
const size_t array_size = sizeof(halide_scalar_value_t) / value_size;
internal_assert(array_size * value_size == sizeof(halide_scalar_value_t));
vector<Constant *> array_entries(array_size, Constant::getNullValue(constant->getType()));
array_entries[0] = constant;
llvm::ArrayType *array_type = ArrayType::get(constant->getType(), array_size);
GlobalVariable *storage = new GlobalVariable(
*module,
array_type,
/*isConstant*/ true,
GlobalValue::PrivateLinkage,
ConstantArray::get(array_type, array_entries));
// Ensure that the storage is aligned for halide_scalar_value_t
storage->setAlignment(llvm::Align((int)sizeof(halide_scalar_value_t)));
Constant *zero[] = {ConstantInt::get(i32_t, 0)};
return ConstantExpr::getBitCast(
ConstantExpr::getInBoundsGetElementPtr(array_type, storage, zero),
PointerType::get(scalar_value_t_type, 0));
}
Constant *CodeGen_LLVM::embed_constant_expr(Expr e, llvm::Type *t) {
internal_assert(t != scalar_value_t_type);
if (!e.defined()) {
return Constant::getNullValue(PointerType::get(t, 0));
}
internal_assert(!e.type().is_handle()) << "Should never see Handle types here.";
if (!is_const(e)) {
e = simplify(e);
internal_assert(is_const(e)) << "Should only see constant values for estimates.";
}
llvm::Value *val = codegen(e);
llvm::Constant *constant = dyn_cast<llvm::Constant>(val);
internal_assert(constant);
GlobalVariable *storage = new GlobalVariable(
*module,
constant->getType(),
/*isConstant*/ true,
GlobalValue::PrivateLinkage,
constant);
Constant *zero[] = {ConstantInt::get(i32_t, 0)};
return ConstantExpr::getBitCast(
ConstantExpr::getInBoundsGetElementPtr(constant->getType(), storage, zero),
PointerType::get(t, 0));
}
// Make a wrapper to call the function with an array of pointer
// args. This is easier for the JIT to call than a function with an
// unknown (at compile time) argument list. If result_in_argv is false,
// the internal function result is returned as the wrapper function
// result; if result_in_argv is true, the internal function result
// is stored as the last item in the argv list (which must be one
// longer than the number of arguments), and the wrapper's actual
// return type is always 'void'.
llvm::Function *CodeGen_LLVM::add_argv_wrapper(llvm::Function *fn,
const std::string &name,
bool result_in_argv,
std::vector<bool> &arg_is_buffer) {
llvm::Type *wrapper_result_type = result_in_argv ? void_t : i32_t;
llvm::Type *wrapper_args_t[] = {PointerType::get(PointerType::get(i8_t, 0), 0)};
llvm::FunctionType *wrapper_func_t = llvm::FunctionType::get(wrapper_result_type, wrapper_args_t, false);
llvm::Function *wrapper_func = llvm::Function::Create(wrapper_func_t, llvm::GlobalValue::ExternalLinkage, name, module.get());
llvm::BasicBlock *wrapper_block = llvm::BasicBlock::Create(module->getContext(), "entry", wrapper_func);
builder->SetInsertPoint(wrapper_block);
llvm::Value *arg_array = iterator_to_pointer(wrapper_func->arg_begin());
std::vector<llvm::Value *> wrapper_args;
for (llvm::Function::arg_iterator i = fn->arg_begin(); i != fn->arg_end(); i++) {
// Get the address of the nth argument
llvm::Value *ptr = CreateConstGEP1_32(builder.get(), PointerType::get(i8_t, 0),
arg_array, wrapper_args.size());
ptr = builder->CreateLoad(PointerType::get(i8_t, 0), ptr);
if (arg_is_buffer[i->getArgNo()]) {
// Cast the argument to a halide_buffer_t *
wrapper_args.push_back(builder->CreatePointerCast(ptr, PointerType::get(halide_buffer_t_type, 0)));
} else {
// Cast to the appropriate type and load
ptr = builder->CreatePointerCast(ptr, PointerType::get(i->getType(), 0));
wrapper_args.push_back(builder->CreateLoad(i->getType(), ptr));
}
}
debug(4) << "Creating call from wrapper to actual function\n";
llvm::CallInst *result = builder->CreateCall(fn, wrapper_args);
// This call should never inline
result->setIsNoInline();
if (result_in_argv) {
llvm::Value *result_in_argv_ptr = CreateConstGEP1_32(builder.get(), PointerType::get(i8_t, 0),
arg_array, wrapper_args.size());
if (fn->getReturnType() != void_t) {
result_in_argv_ptr = builder->CreateLoad(PointerType::get(i8_t, 0), result_in_argv_ptr);
// Cast to the appropriate type and store
result_in_argv_ptr = builder->CreatePointerCast(result_in_argv_ptr, PointerType::get(fn->getReturnType(), 0));
builder->CreateStore(result, result_in_argv_ptr);
}
builder->CreateRetVoid();
} else {
// We could probably support other types as return values,
// but int32 results are all that have actually been tested.
internal_assert(fn->getReturnType() == i32_t);
builder->CreateRet(result);
}
internal_assert(!verifyFunction(*wrapper_func, &llvm::errs()));
return wrapper_func;
}
llvm::Function *CodeGen_LLVM::embed_metadata_getter(const std::string &metadata_name,
const std::string &function_name, const std::vector<LoweredArgument> &args,
const MetadataNameMap &metadata_name_map) {
Constant *zero = ConstantInt::get(i32_t, 0);
const int num_args = (int)args.size();
auto map_string = [&metadata_name_map](const std::string &from) -> std::string {