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suspension points inside branching control flow

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This commit is contained in:
Andrew Kelley
2019-08-04 18:24:10 -04:00
parent 12924477a5
commit fa30ebfbe5
6 changed files with 161 additions and 83 deletions
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165
src/codegen.cpp
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@@ -1997,7 +1997,9 @@ static LLVMValueRef ir_render_save_err_ret_addr(CodeGen *g, IrExecutable *execut
return call_instruction;
}
static LLVMValueRef ir_render_return(CodeGen *g, IrExecutable *executable, IrInstructionReturn *return_instruction) {
static LLVMValueRef ir_render_return(CodeGen *g, IrExecutable *executable,
IrInstructionReturn *return_instruction)
{
if (fn_is_async(g->cur_fn)) {
LLVMTypeRef usize_type_ref = g->builtin_types.entry_usize->llvm_type;
LLVMValueRef locals_ptr = g->cur_ret_ptr;
@@ -2006,12 +2008,10 @@ static LLVMValueRef ir_render_return(CodeGen *g, IrExecutable *executable, IrIns
ZigType *ret_type = ret_type_has_bits ? return_instruction->value->value.type : nullptr;
if (ir_want_runtime_safety(g, &return_instruction->base)) {
LLVMValueRef resume_index_ptr = LLVMBuildStructGEP(g->builder, locals_ptr, coro_fn_ptr_index, "");
LLVMValueRef new_resume_fn = g->cur_fn->resume_blocks.last()->split_llvm_fn;
LLVMBuildStore(g->builder, new_resume_fn, resume_index_ptr);
LLVMValueRef new_resume_index = LLVMConstAllOnes(usize_type_ref);
LLVMBuildStore(g->builder, new_resume_index, g->cur_async_resume_index_ptr);
}
LLVMValueRef awaiter_ptr = LLVMBuildStructGEP(g->builder, locals_ptr, coro_awaiter_index, "");
LLVMValueRef result_ptr_as_usize;
if (ret_type_has_bits) {
LLVMValueRef result_ptr_ptr = LLVMBuildStructGEP(g->builder, locals_ptr, coro_arg_start, "");
@@ -2029,8 +2029,8 @@ static LLVMValueRef ir_render_return(CodeGen *g, IrExecutable *executable, IrIns
}
LLVMValueRef zero = LLVMConstNull(usize_type_ref);
LLVMValueRef all_ones = LLVMConstAllOnes(usize_type_ref);
LLVMValueRef prev_val = LLVMBuildAtomicRMW(g->builder, LLVMAtomicRMWBinOpXchg, awaiter_ptr,
all_ones, LLVMAtomicOrderingSequentiallyConsistent, g->is_single_threaded);
LLVMValueRef prev_val = LLVMBuildAtomicRMW(g->builder, LLVMAtomicRMWBinOpXchg, g->cur_async_awaiter_ptr,
all_ones, LLVMAtomicOrderingMonotonic, g->is_single_threaded);
LLVMBasicBlockRef bad_return_block = LLVMAppendBasicBlock(g->cur_fn_val, "BadReturn");
LLVMBasicBlockRef early_return_block = LLVMAppendBasicBlock(g->cur_fn_val, "EarlyReturn");
@@ -3453,7 +3453,6 @@ static void render_async_spills(CodeGen *g) {
}
static void render_async_var_decls(CodeGen *g, Scope *scope) {
render_async_spills(g);
for (;;) {
switch (scope->id) {
case ScopeIdCImport:
@@ -3573,6 +3572,14 @@ static LLVMValueRef ir_render_call(CodeGen *g, IrExecutable *executable, IrInstr
if (instruction->is_async || callee_is_async) {
assert(frame_result_loc != nullptr);
LLVMValueRef fn_ptr_ptr = LLVMBuildStructGEP(g->builder, frame_result_loc, coro_fn_ptr_index, "");
LLVMValueRef bitcasted_fn_val = LLVMBuildBitCast(g->builder, fn_val,
LLVMGetElementType(LLVMTypeOf(fn_ptr_ptr)), "");
LLVMBuildStore(g->builder, bitcasted_fn_val, fn_ptr_ptr);
LLVMValueRef resume_index_ptr = LLVMBuildStructGEP(g->builder, frame_result_loc, coro_resume_index, "");
LLVMBuildStore(g->builder, zero, resume_index_ptr);
if (prefix_arg_err_ret_stack) {
zig_panic("TODO");
}
@@ -3652,23 +3659,24 @@ static LLVMValueRef ir_render_call(CodeGen *g, IrExecutable *executable, IrInstr
return nullptr;
} else if (callee_is_async) {
ZigType *ptr_result_type = get_pointer_to_type(g, src_return_type, true);
LLVMValueRef split_llvm_fn = make_fn_llvm_value(g, g->cur_fn);
LLVMValueRef fn_ptr_ptr = LLVMBuildStructGEP(g->builder, g->cur_ret_ptr, coro_fn_ptr_index, "");
LLVMBuildStore(g->builder, split_llvm_fn, fn_ptr_ptr);
LLVMBasicBlockRef call_bb = LLVMAppendBasicBlock(g->cur_fn_val, "CallResume");
size_t new_block_index = g->cur_fn->resume_blocks.length + coro_extra_resume_block_count;
g->cur_fn->resume_blocks.append(nullptr);
LLVMValueRef new_block_index_val = LLVMConstInt(usize_type_ref, new_block_index, false);
LLVMAddCase(g->cur_async_switch_instr, new_block_index_val, call_bb);
LLVMBuildStore(g->builder, new_block_index_val, g->cur_async_resume_index_ptr);
LLVMValueRef args[] = {frame_result_loc, LLVMGetUndef(usize_type_ref)};
LLVMValueRef call_inst = ZigLLVMBuildCall(g->builder, fn_val, args, 2, llvm_cc, fn_inline, "");
ZigLLVMSetTailCall(call_inst);
LLVMBuildRetVoid(g->builder);
g->cur_fn_val = split_llvm_fn;
g->cur_ret_ptr = LLVMGetParam(split_llvm_fn, 0);
LLVMBasicBlockRef call_bb = LLVMAppendBasicBlock(split_llvm_fn, "CallResume");
LLVMPositionBuilderAtEnd(g->builder, call_bb);
if (ir_want_runtime_safety(g, &instruction->base)) {
LLVMBasicBlockRef bad_resume_block = LLVMAppendBasicBlock(split_llvm_fn, "BadResume");
LLVMBasicBlockRef ok_resume_block = LLVMAppendBasicBlock(split_llvm_fn, "OkResume");
LLVMValueRef arg_val = LLVMGetParam(split_llvm_fn, 1);
LLVMBasicBlockRef bad_resume_block = LLVMAppendBasicBlock(g->cur_fn_val, "BadResume");
LLVMBasicBlockRef ok_resume_block = LLVMAppendBasicBlock(g->cur_fn_val, "OkResume");
LLVMValueRef arg_val = LLVMGetParam(g->cur_fn_val, 1);
LLVMValueRef all_ones = LLVMConstAllOnes(usize_type_ref);
LLVMValueRef ok_bit = LLVMBuildICmp(g->builder, LLVMIntNE, arg_val, all_ones, "");
LLVMBuildCondBr(g->builder, ok_bit, ok_resume_block, bad_resume_block);
@@ -5144,10 +5152,9 @@ static LLVMValueRef ir_render_assert_non_null(CodeGen *g, IrExecutable *executab
static LLVMValueRef ir_render_suspend_begin(CodeGen *g, IrExecutable *executable,
IrInstructionSuspendBegin *instruction)
{
LLVMValueRef locals_ptr = g->cur_ret_ptr;
LLVMValueRef fn_ptr_ptr = LLVMBuildStructGEP(g->builder, locals_ptr, coro_fn_ptr_index, "");
LLVMValueRef new_fn_ptr = instruction->resume_block->split_llvm_fn;
LLVMBuildStore(g->builder, new_fn_ptr, fn_ptr_ptr);
LLVMTypeRef usize_type_ref = g->builtin_types.entry_usize->llvm_type;
LLVMValueRef new_resume_index = LLVMConstInt(usize_type_ref, instruction->resume_block->resume_index, false);
LLVMBuildStore(g->builder, new_resume_index, g->cur_async_resume_index_ptr);
return nullptr;
}
@@ -5159,19 +5166,22 @@ static LLVMValueRef ir_render_suspend_br(CodeGen *g, IrExecutable *executable,
}
static LLVMValueRef ir_render_await(CodeGen *g, IrExecutable *executable, IrInstructionAwait *instruction) {
LLVMTypeRef usize_type_ref = g->builtin_types.entry_usize->llvm_type;
LLVMValueRef target_frame_ptr = ir_llvm_value(g, instruction->frame);
ZigType *result_type = instruction->base.value.type;
ZigType *ptr_result_type = get_pointer_to_type(g, result_type, true);
// Prepare to be suspended
LLVMValueRef split_llvm_fn = make_fn_llvm_value(g, g->cur_fn);
LLVMValueRef fn_ptr_ptr = LLVMBuildStructGEP(g->builder, g->cur_ret_ptr, coro_fn_ptr_index, "");
LLVMBuildStore(g->builder, split_llvm_fn, fn_ptr_ptr);
LLVMBasicBlockRef resume_bb = LLVMAppendBasicBlock(g->cur_fn_val, "AwaitResume");
size_t new_block_index = g->cur_fn->resume_blocks.length + coro_extra_resume_block_count;
g->cur_fn->resume_blocks.append(nullptr);
LLVMValueRef new_block_index_val = LLVMConstInt(usize_type_ref, new_block_index, false);
LLVMAddCase(g->cur_async_switch_instr, new_block_index_val, resume_bb);
LLVMBuildStore(g->builder, new_block_index_val, g->cur_async_resume_index_ptr);
// At this point resuming the function will do the correct thing.
// This code is as if it is running inside the suspend block.
LLVMTypeRef usize_type_ref = g->builtin_types.entry_usize->llvm_type;
// caller's own frame pointer
LLVMValueRef awaiter_init_val = LLVMBuildPtrToInt(g->builder, g->cur_ret_ptr, usize_type_ref, "");
LLVMValueRef awaiter_ptr = LLVMBuildStructGEP(g->builder, target_frame_ptr, coro_awaiter_index, "");
@@ -5184,18 +5194,20 @@ static LLVMValueRef ir_render_await(CodeGen *g, IrExecutable *executable, IrInst
result_ptr_as_usize = LLVMGetUndef(usize_type_ref);
}
LLVMValueRef prev_val = LLVMBuildAtomicRMW(g->builder, LLVMAtomicRMWBinOpXchg, awaiter_ptr, awaiter_init_val,
LLVMAtomicOrderingSequentiallyConsistent, g->is_single_threaded);
LLVMAtomicOrderingMonotonic, g->is_single_threaded);
LLVMBasicBlockRef bad_await_block = LLVMAppendBasicBlock(g->cur_fn_val, "BadAwait");
LLVMBasicBlockRef complete_suspend_block = LLVMAppendBasicBlock(g->cur_fn_val, "CompleteSuspend");
LLVMBasicBlockRef early_return_block = LLVMAppendBasicBlock(g->cur_fn_val, "EarlyReturn");
LLVMValueRef zero = LLVMConstNull(usize_type_ref);
LLVMValueRef all_ones = LLVMConstAllOnes(usize_type_ref);
LLVMValueRef switch_instr = LLVMBuildSwitch(g->builder, prev_val, bad_await_block, 2);
LLVMBasicBlockRef predecessor_bb = LLVMGetInsertBlock(g->builder);
LLVMAddCase(switch_instr, zero, complete_suspend_block);
LLVMAddCase(switch_instr, all_ones, early_return_block);
// Early return: The async function has already completed. No need to suspend.
LLVMAddCase(switch_instr, all_ones, resume_bb);
// We discovered that another awaiter was already here.
LLVMPositionBuilderAtEnd(g->builder, bad_await_block);
@@ -5205,25 +5217,18 @@ static LLVMValueRef ir_render_await(CodeGen *g, IrExecutable *executable, IrInst
LLVMPositionBuilderAtEnd(g->builder, complete_suspend_block);
LLVMBuildRetVoid(g->builder);
// The async function has already completed. So we use a tail call to resume ourselves.
LLVMPositionBuilderAtEnd(g->builder, early_return_block);
LLVMValueRef args[] = {g->cur_ret_ptr, result_ptr_as_usize};
LLVMValueRef call_inst = ZigLLVMBuildCall(g->builder, split_llvm_fn, args, 2, LLVMFastCallConv,
ZigLLVM_FnInlineAuto, "");
ZigLLVMSetTailCall(call_inst);
LLVMBuildRetVoid(g->builder);
g->cur_fn_val = split_llvm_fn;
g->cur_ret_ptr = LLVMGetParam(split_llvm_fn, 0);
LLVMBasicBlockRef call_bb = LLVMAppendBasicBlock(split_llvm_fn, "AwaitResume");
LLVMPositionBuilderAtEnd(g->builder, call_bb);
LLVMPositionBuilderAtEnd(g->builder, resume_bb);
// We either got here from Entry (function call) or from the switch above
LLVMValueRef spilled_result_ptr = LLVMBuildPhi(g->builder, usize_type_ref, "");
LLVMValueRef incoming_values[] = { LLVMGetParam(g->cur_fn_val, 1), result_ptr_as_usize };
LLVMBasicBlockRef incoming_blocks[] = { g->cur_fn->preamble_llvm_block, predecessor_bb };
LLVMAddIncoming(spilled_result_ptr, incoming_values, incoming_blocks, 2);
if (ir_want_runtime_safety(g, &instruction->base)) {
LLVMBasicBlockRef bad_resume_block = LLVMAppendBasicBlock(split_llvm_fn, "BadResume");
LLVMBasicBlockRef ok_resume_block = LLVMAppendBasicBlock(split_llvm_fn, "OkResume");
LLVMValueRef arg_val = LLVMGetParam(split_llvm_fn, 1);
LLVMBasicBlockRef bad_resume_block = LLVMAppendBasicBlock(g->cur_fn_val, "BadResume");
LLVMBasicBlockRef ok_resume_block = LLVMAppendBasicBlock(g->cur_fn_val, "OkResume");
LLVMValueRef all_ones = LLVMConstAllOnes(usize_type_ref);
LLVMValueRef ok_bit = LLVMBuildICmp(g->builder, LLVMIntNE, arg_val, all_ones, "");
LLVMValueRef ok_bit = LLVMBuildICmp(g->builder, LLVMIntNE, spilled_result_ptr, all_ones, "");
LLVMBuildCondBr(g->builder, ok_bit, ok_resume_block, bad_resume_block);
LLVMPositionBuilderAtEnd(g->builder, bad_resume_block);
@@ -5235,7 +5240,6 @@ static LLVMValueRef ir_render_await(CodeGen *g, IrExecutable *executable, IrInst
render_async_var_decls(g, instruction->base.scope);
if (type_has_bits(result_type)) {
LLVMValueRef spilled_result_ptr = LLVMGetParam(g->cur_fn_val, 1);
LLVMValueRef casted_spilled_result_ptr = LLVMBuildIntToPtr(g->builder, spilled_result_ptr,
get_llvm_type(g, ptr_result_type), "");
return get_handle_value(g, casted_spilled_result_ptr, result_type, ptr_result_type);
@@ -5547,13 +5551,18 @@ static void ir_render(CodeGen *g, ZigFn *fn_entry) {
IrExecutable *executable = &fn_entry->analyzed_executable;
assert(executable->basic_block_list.length > 0);
if (fn_is_async(fn_entry)) {
IrBasicBlock *entry_block = executable->basic_block_list.at(0);
LLVMPositionBuilderAtEnd(g->builder, entry_block->llvm_block);
render_async_var_decls(g, entry_block->instruction_list.at(0)->scope);
}
for (size_t block_i = 0; block_i < executable->basic_block_list.length; block_i += 1) {
IrBasicBlock *current_block = executable->basic_block_list.at(block_i);
assert(current_block->llvm_block);
LLVMPositionBuilderAtEnd(g->builder, current_block->llvm_block);
if (current_block->split_llvm_fn != nullptr) {
g->cur_fn_val = current_block->split_llvm_fn;
g->cur_ret_ptr = LLVMGetParam(g->cur_fn_val, 0);
if (current_block->resume_index != 0) {
render_async_var_decls(g, current_block->instruction_list.at(0)->scope);
}
for (size_t instr_i = 0; instr_i < current_block->instruction_list.length; instr_i += 1) {
@@ -6416,17 +6425,19 @@ static void build_all_basic_blocks(CodeGen *g, ZigFn *fn) {
IrExecutable *executable = &fn->analyzed_executable;
assert(executable->basic_block_list.length > 0);
LLVMValueRef fn_val = fn_llvm_value(g, fn);
LLVMBasicBlockRef first_bb = nullptr;
if (fn_is_async(fn)) {
first_bb = LLVMAppendBasicBlock(fn_val, "AsyncSwitch");
fn->preamble_llvm_block = first_bb;
}
for (size_t block_i = 0; block_i < executable->basic_block_list.length; block_i += 1) {
IrBasicBlock *bb = executable->basic_block_list.at(block_i);
if (bb->split_llvm_fn != nullptr) {
assert(bb->split_llvm_fn == reinterpret_cast<LLVMValueRef>(0x1));
fn_val = make_fn_llvm_value(g, fn);
bb->split_llvm_fn = fn_val;
}
bb->llvm_block = LLVMAppendBasicBlock(fn_val, bb->name_hint);
}
IrBasicBlock *entry_bb = executable->basic_block_list.at(0);
LLVMPositionBuilderAtEnd(g->builder, entry_bb->llvm_block);
if (first_bb == nullptr) {
first_bb = executable->basic_block_list.at(0)->llvm_block;
}
LLVMPositionBuilderAtEnd(g->builder, first_bb);
}
static void gen_global_var(CodeGen *g, ZigVar *var, LLVMValueRef init_val,
@@ -6636,9 +6647,7 @@ static void do_code_gen(CodeGen *g) {
g->cur_err_ret_trace_val_stack = nullptr;
}
if (is_async) {
render_async_spills(g);
} else {
if (!is_async) {
// allocate temporary stack data
for (size_t alloca_i = 0; alloca_i < fn_table_entry->alloca_gen_list.length; alloca_i += 1) {
IrInstructionAllocaGen *instruction = fn_table_entry->alloca_gen_list.at(alloca_i);
@@ -6752,17 +6761,35 @@ static void do_code_gen(CodeGen *g) {
LLVMValueRef size_val = LLVMConstInt(usize_type_ref, fn_table_entry->frame_type->abi_size, false);
ZigLLVMFunctionSetPrefixData(fn_table_entry->llvm_value, size_val);
if (ir_want_runtime_safety_scope(g, fn_table_entry->child_scope)) {
IrBasicBlock *bad_resume_block = allocate<IrBasicBlock>(1);
bad_resume_block->name_hint = "BadResume";
bad_resume_block->split_llvm_fn = make_fn_llvm_value(g, fn_table_entry);
LLVMBasicBlockRef llvm_block = LLVMAppendBasicBlock(bad_resume_block->split_llvm_fn, "BadResume");
LLVMPositionBuilderAtEnd(g->builder, llvm_block);
gen_safety_crash(g, PanicMsgIdBadResume);
fn_table_entry->resume_blocks.append(bad_resume_block);
if (!g->strip_debug_symbols) {
AstNode *source_node = fn_table_entry->proto_node;
ZigLLVMSetCurrentDebugLocation(g->builder, (int)source_node->line + 1,
(int)source_node->column + 1, get_di_scope(g, fn_table_entry->child_scope));
}
IrExecutable *executable = &fn_table_entry->analyzed_executable;
LLVMBasicBlockRef bad_resume_block = LLVMAppendBasicBlock(g->cur_fn_val, "BadResume");
LLVMPositionBuilderAtEnd(g->builder, bad_resume_block);
gen_assertion_scope(g, PanicMsgIdBadResume, fn_table_entry->child_scope);
LLVMPositionBuilderAtEnd(g->builder, fn_table_entry->preamble_llvm_block);
render_async_spills(g);
g->cur_async_awaiter_ptr = LLVMBuildStructGEP(g->builder, g->cur_ret_ptr, coro_awaiter_index, "");
LLVMValueRef resume_index_ptr = LLVMBuildStructGEP(g->builder, g->cur_ret_ptr, coro_resume_index, "");
g->cur_async_resume_index_ptr = resume_index_ptr;
LLVMValueRef resume_index = LLVMBuildLoad(g->builder, resume_index_ptr, "");
LLVMValueRef switch_instr = LLVMBuildSwitch(g->builder, resume_index, bad_resume_block,
fn_table_entry->resume_blocks.length + coro_extra_resume_block_count);
g->cur_async_switch_instr = switch_instr;
LLVMValueRef zero = LLVMConstNull(usize_type_ref);
LLVMAddCase(switch_instr, zero, executable->basic_block_list.at(0)->llvm_block);
for (size_t resume_i = 0; resume_i < fn_table_entry->resume_blocks.length; resume_i += 1) {
IrBasicBlock *resume_block = fn_table_entry->resume_blocks.at(resume_i);
LLVMValueRef case_value = LLVMConstInt(usize_type_ref, resume_block->resume_index, false);
LLVMAddCase(switch_instr, case_value, resume_block->llvm_block);
}
} else {
// create debug variable declarations for parameters
// rely on the first variables in the variable_list being parameters.