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error return traces for the early return case

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it would work but LLVM is not correctly spilling the addresses.

See #821
This commit is contained in:
Andrew Kelley
2018-03-29 00:24:04 -04:00
parent 7186e92c86
commit d26905c102
5 changed files with 391 additions and 92 deletions
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272
src/codegen.cpp
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@@ -1114,6 +1114,207 @@ static LLVMValueRef get_return_address_fn_val(CodeGen *g) {
return g->return_address_fn_val;
}
static LLVMValueRef get_add_error_return_trace_addr_fn(CodeGen *g) {
if (g->add_error_return_trace_addr_fn_val != nullptr)
return g->add_error_return_trace_addr_fn_val;
LLVMTypeRef arg_types[] = {
get_ptr_to_stack_trace_type(g)->type_ref,
g->builtin_types.entry_usize->type_ref,
};
LLVMTypeRef fn_type_ref = LLVMFunctionType(LLVMVoidType(), arg_types, 2, false);
Buf *fn_name = get_mangled_name(g, buf_create_from_str("__zig_add_err_ret_trace_addr"), false);
LLVMValueRef fn_val = LLVMAddFunction(g->module, buf_ptr(fn_name), fn_type_ref);
addLLVMFnAttr(fn_val, "alwaysinline");
LLVMSetLinkage(fn_val, LLVMInternalLinkage);
LLVMSetFunctionCallConv(fn_val, get_llvm_cc(g, CallingConventionUnspecified));
addLLVMFnAttr(fn_val, "nounwind");
add_uwtable_attr(g, fn_val);
addLLVMArgAttr(fn_val, (unsigned)0, "nonnull");
if (g->build_mode == BuildModeDebug) {
ZigLLVMAddFunctionAttr(fn_val, "no-frame-pointer-elim", "true");
ZigLLVMAddFunctionAttr(fn_val, "no-frame-pointer-elim-non-leaf", nullptr);
}
LLVMBasicBlockRef entry_block = LLVMAppendBasicBlock(fn_val, "Entry");
LLVMBasicBlockRef prev_block = LLVMGetInsertBlock(g->builder);
LLVMValueRef prev_debug_location = LLVMGetCurrentDebugLocation(g->builder);
LLVMPositionBuilderAtEnd(g->builder, entry_block);
ZigLLVMClearCurrentDebugLocation(g->builder);
LLVMTypeRef usize_type_ref = g->builtin_types.entry_usize->type_ref;
// stack_trace.instruction_addresses[stack_trace.index % stack_trace.instruction_addresses.len] = return_address;
LLVMValueRef err_ret_trace_ptr = LLVMGetParam(fn_val, 0);
LLVMValueRef address_value = LLVMGetParam(fn_val, 1);
size_t index_field_index = g->stack_trace_type->data.structure.fields[0].gen_index;
LLVMValueRef index_field_ptr = LLVMBuildStructGEP(g->builder, err_ret_trace_ptr, (unsigned)index_field_index, "");
size_t addresses_field_index = g->stack_trace_type->data.structure.fields[1].gen_index;
LLVMValueRef addresses_field_ptr = LLVMBuildStructGEP(g->builder, err_ret_trace_ptr, (unsigned)addresses_field_index, "");
TypeTableEntry *slice_type = g->stack_trace_type->data.structure.fields[1].type_entry;
size_t ptr_field_index = slice_type->data.structure.fields[slice_ptr_index].gen_index;
LLVMValueRef ptr_field_ptr = LLVMBuildStructGEP(g->builder, addresses_field_ptr, (unsigned)ptr_field_index, "");
size_t len_field_index = slice_type->data.structure.fields[slice_len_index].gen_index;
LLVMValueRef len_field_ptr = LLVMBuildStructGEP(g->builder, addresses_field_ptr, (unsigned)len_field_index, "");
LLVMValueRef len_value = gen_load_untyped(g, len_field_ptr, 0, false, "");
LLVMValueRef index_val = gen_load_untyped(g, index_field_ptr, 0, false, "");
LLVMValueRef modded_val = LLVMBuildURem(g->builder, index_val, len_value, "");
LLVMValueRef address_indices[] = {
modded_val,
};
LLVMValueRef ptr_value = gen_load_untyped(g, ptr_field_ptr, 0, false, "");
LLVMValueRef address_slot = LLVMBuildInBoundsGEP(g->builder, ptr_value, address_indices, 1, "");
gen_store_untyped(g, address_value, address_slot, 0, false);
// stack_trace.index += 1;
LLVMValueRef index_plus_one_val = LLVMBuildNUWAdd(g->builder, index_val, LLVMConstInt(usize_type_ref, 1, false), "");
gen_store_untyped(g, index_plus_one_val, index_field_ptr, 0, false);
// return;
LLVMBuildRetVoid(g->builder);
LLVMPositionBuilderAtEnd(g->builder, prev_block);
LLVMSetCurrentDebugLocation(g->builder, prev_debug_location);
g->add_error_return_trace_addr_fn_val = fn_val;
return fn_val;
}
static LLVMValueRef get_merge_err_ret_traces_fn_val(CodeGen *g) {
if (g->merge_err_ret_traces_fn_val)
return g->merge_err_ret_traces_fn_val;
assert(g->stack_trace_type != nullptr);
LLVMTypeRef param_types[] = {
get_ptr_to_stack_trace_type(g)->type_ref,
get_ptr_to_stack_trace_type(g)->type_ref,
};
LLVMTypeRef fn_type_ref = LLVMFunctionType(LLVMVoidType(), param_types, 2, false);
Buf *fn_name = get_mangled_name(g, buf_create_from_str("__zig_merge_error_return_traces"), false);
LLVMValueRef fn_val = LLVMAddFunction(g->module, buf_ptr(fn_name), fn_type_ref);
LLVMSetLinkage(fn_val, LLVMInternalLinkage);
LLVMSetFunctionCallConv(fn_val, get_llvm_cc(g, CallingConventionUnspecified));
addLLVMFnAttr(fn_val, "nounwind");
add_uwtable_attr(g, fn_val);
addLLVMArgAttr(fn_val, (unsigned)0, "nonnull");
addLLVMArgAttr(fn_val, (unsigned)0, "noalias");
addLLVMArgAttr(fn_val, (unsigned)0, "writeonly");
addLLVMArgAttr(fn_val, (unsigned)1, "nonnull");
addLLVMArgAttr(fn_val, (unsigned)1, "noalias");
addLLVMArgAttr(fn_val, (unsigned)1, "readonly");
if (g->build_mode == BuildModeDebug) {
ZigLLVMAddFunctionAttr(fn_val, "no-frame-pointer-elim", "true");
ZigLLVMAddFunctionAttr(fn_val, "no-frame-pointer-elim-non-leaf", nullptr);
}
// this is above the ZigLLVMClearCurrentDebugLocation
LLVMValueRef add_error_return_trace_addr_fn_val = get_add_error_return_trace_addr_fn(g);
LLVMBasicBlockRef entry_block = LLVMAppendBasicBlock(fn_val, "Entry");
LLVMBasicBlockRef prev_block = LLVMGetInsertBlock(g->builder);
LLVMValueRef prev_debug_location = LLVMGetCurrentDebugLocation(g->builder);
LLVMPositionBuilderAtEnd(g->builder, entry_block);
ZigLLVMClearCurrentDebugLocation(g->builder);
// var frame_index: usize = undefined;
// var frames_left: usize = undefined;
// if (src_stack_trace.index < src_stack_trace.instruction_addresses.len) {
// frame_index = 0;
// frames_left = src_stack_trace.index;
// if (frames_left == 0) return;
// } else {
// frame_index = (src_stack_trace.index + 1) % src_stack_trace.instruction_addresses.len;
// frames_left = src_stack_trace.instruction_addresses.len;
// }
// while (true) {
// __zig_add_err_ret_trace_addr(dest_stack_trace, src_stack_trace.instruction_addresses[frame_index]);
// frames_left -= 1;
// if (frames_left == 0) return;
// frame_index = (frame_index + 1) % src_stack_trace.instruction_addresses.len;
// }
LLVMBasicBlockRef return_block = LLVMAppendBasicBlock(fn_val, "Return");
LLVMValueRef frame_index_ptr = LLVMBuildAlloca(g->builder, g->builtin_types.entry_usize->type_ref, "frame_index");
LLVMValueRef frames_left_ptr = LLVMBuildAlloca(g->builder, g->builtin_types.entry_usize->type_ref, "frames_left");
LLVMValueRef dest_stack_trace_ptr = LLVMGetParam(fn_val, 0);
LLVMValueRef src_stack_trace_ptr = LLVMGetParam(fn_val, 1);
size_t src_index_field_index = g->stack_trace_type->data.structure.fields[0].gen_index;
size_t src_addresses_field_index = g->stack_trace_type->data.structure.fields[1].gen_index;
LLVMValueRef src_index_field_ptr = LLVMBuildStructGEP(g->builder, src_stack_trace_ptr,
(unsigned)src_index_field_index, "");
LLVMValueRef src_addresses_field_ptr = LLVMBuildStructGEP(g->builder, src_stack_trace_ptr,
(unsigned)src_addresses_field_index, "");
TypeTableEntry *slice_type = g->stack_trace_type->data.structure.fields[1].type_entry;
size_t ptr_field_index = slice_type->data.structure.fields[slice_ptr_index].gen_index;
LLVMValueRef src_ptr_field_ptr = LLVMBuildStructGEP(g->builder, src_addresses_field_ptr, (unsigned)ptr_field_index, "");
size_t len_field_index = slice_type->data.structure.fields[slice_len_index].gen_index;
LLVMValueRef src_len_field_ptr = LLVMBuildStructGEP(g->builder, src_addresses_field_ptr, (unsigned)len_field_index, "");
LLVMValueRef src_index_val = LLVMBuildLoad(g->builder, src_index_field_ptr, "");
LLVMValueRef src_ptr_val = LLVMBuildLoad(g->builder, src_ptr_field_ptr, "");
LLVMValueRef src_len_val = LLVMBuildLoad(g->builder, src_len_field_ptr, "");
LLVMValueRef no_wrap_bit = LLVMBuildICmp(g->builder, LLVMIntULT, src_index_val, src_len_val, "");
LLVMBasicBlockRef no_wrap_block = LLVMAppendBasicBlock(fn_val, "NoWrap");
LLVMBasicBlockRef yes_wrap_block = LLVMAppendBasicBlock(fn_val, "YesWrap");
LLVMBasicBlockRef loop_block = LLVMAppendBasicBlock(fn_val, "Loop");
LLVMBuildCondBr(g->builder, no_wrap_bit, no_wrap_block, yes_wrap_block);
LLVMPositionBuilderAtEnd(g->builder, no_wrap_block);
LLVMValueRef usize_zero = LLVMConstNull(g->builtin_types.entry_usize->type_ref);
LLVMBuildStore(g->builder, usize_zero, frame_index_ptr);
LLVMBuildStore(g->builder, src_index_val, frames_left_ptr);
LLVMValueRef frames_left_eq_zero_bit = LLVMBuildICmp(g->builder, LLVMIntEQ, src_index_val, usize_zero, "");
LLVMBuildCondBr(g->builder, frames_left_eq_zero_bit, return_block, loop_block);
LLVMPositionBuilderAtEnd(g->builder, yes_wrap_block);
LLVMValueRef usize_one = LLVMConstInt(g->builtin_types.entry_usize->type_ref, 1, false);
LLVMValueRef plus_one = LLVMBuildNUWAdd(g->builder, src_index_val, usize_one, "");
LLVMValueRef mod_len = LLVMBuildURem(g->builder, plus_one, src_len_val, "");
LLVMBuildStore(g->builder, mod_len, frame_index_ptr);
LLVMBuildStore(g->builder, src_len_val, frames_left_ptr);
LLVMBuildBr(g->builder, loop_block);
LLVMPositionBuilderAtEnd(g->builder, loop_block);
LLVMValueRef ptr_index = LLVMBuildLoad(g->builder, frame_index_ptr, "");
LLVMValueRef addr_ptr = LLVMBuildInBoundsGEP(g->builder, src_ptr_val, &ptr_index, 1, "");
LLVMValueRef this_addr_val = LLVMBuildLoad(g->builder, addr_ptr, "");
LLVMValueRef args[] = {dest_stack_trace_ptr, this_addr_val};
LLVMBuildCall(g->builder, add_error_return_trace_addr_fn_val, args, 2, "");
LLVMValueRef prev_frames_left = LLVMBuildLoad(g->builder, frames_left_ptr, "");
LLVMValueRef new_frames_left = LLVMBuildNUWSub(g->builder, prev_frames_left, usize_one, "");
LLVMValueRef done_bit = LLVMBuildICmp(g->builder, LLVMIntEQ, new_frames_left, usize_zero, "");
LLVMBasicBlockRef continue_block = LLVMAppendBasicBlock(fn_val, "Continue");
LLVMBuildCondBr(g->builder, done_bit, return_block, continue_block);
LLVMPositionBuilderAtEnd(g->builder, return_block);
LLVMBuildRetVoid(g->builder);
LLVMPositionBuilderAtEnd(g->builder, continue_block);
LLVMBuildStore(g->builder, new_frames_left, frames_left_ptr);
LLVMValueRef prev_index = LLVMBuildLoad(g->builder, frame_index_ptr, "");
LLVMValueRef index_plus_one = LLVMBuildNUWAdd(g->builder, prev_index, usize_one, "");
LLVMValueRef index_mod_len = LLVMBuildURem(g->builder, index_plus_one, src_len_val, "");
LLVMBuildStore(g->builder, index_mod_len, frame_index_ptr);
LLVMBuildBr(g->builder, loop_block);
LLVMPositionBuilderAtEnd(g->builder, prev_block);
LLVMSetCurrentDebugLocation(g->builder, prev_debug_location);
g->merge_err_ret_traces_fn_val = fn_val;
return fn_val;
}
static LLVMValueRef get_return_err_fn(CodeGen *g) {
if (g->return_err_fn != nullptr)
return g->return_err_fn;
@@ -1140,50 +1341,24 @@ static LLVMValueRef get_return_err_fn(CodeGen *g) {
ZigLLVMAddFunctionAttr(fn_val, "no-frame-pointer-elim-non-leaf", nullptr);
}
// this is above the ZigLLVMClearCurrentDebugLocation
LLVMValueRef add_error_return_trace_addr_fn_val = get_add_error_return_trace_addr_fn(g);
LLVMBasicBlockRef entry_block = LLVMAppendBasicBlock(fn_val, "Entry");
LLVMBasicBlockRef prev_block = LLVMGetInsertBlock(g->builder);
LLVMValueRef prev_debug_location = LLVMGetCurrentDebugLocation(g->builder);
LLVMPositionBuilderAtEnd(g->builder, entry_block);
ZigLLVMClearCurrentDebugLocation(g->builder);
LLVMTypeRef usize_type_ref = g->builtin_types.entry_usize->type_ref;
// stack_trace.instruction_addresses[stack_trace.index % stack_trace.instruction_addresses.len] = return_address;
LLVMValueRef err_ret_trace_ptr = LLVMGetParam(fn_val, 0);
size_t index_field_index = g->stack_trace_type->data.structure.fields[0].gen_index;
LLVMValueRef index_field_ptr = LLVMBuildStructGEP(g->builder, err_ret_trace_ptr, (unsigned)index_field_index, "");
size_t addresses_field_index = g->stack_trace_type->data.structure.fields[1].gen_index;
LLVMValueRef addresses_field_ptr = LLVMBuildStructGEP(g->builder, err_ret_trace_ptr, (unsigned)addresses_field_index, "");
TypeTableEntry *slice_type = g->stack_trace_type->data.structure.fields[1].type_entry;
size_t ptr_field_index = slice_type->data.structure.fields[slice_ptr_index].gen_index;
LLVMValueRef ptr_field_ptr = LLVMBuildStructGEP(g->builder, addresses_field_ptr, (unsigned)ptr_field_index, "");
size_t len_field_index = slice_type->data.structure.fields[slice_len_index].gen_index;
LLVMValueRef len_field_ptr = LLVMBuildStructGEP(g->builder, addresses_field_ptr, (unsigned)len_field_index, "");
LLVMValueRef len_value = gen_load_untyped(g, len_field_ptr, 0, false, "");
LLVMValueRef index_val = gen_load_untyped(g, index_field_ptr, 0, false, "");
LLVMValueRef modded_val = LLVMBuildURem(g->builder, index_val, len_value, "");
LLVMValueRef address_indices[] = {
modded_val,
};
LLVMValueRef ptr_value = gen_load_untyped(g, ptr_field_ptr, 0, false, "");
LLVMValueRef address_slot = LLVMBuildInBoundsGEP(g->builder, ptr_value, address_indices, 1, "");
LLVMTypeRef usize_type_ref = g->builtin_types.entry_usize->type_ref;
LLVMValueRef zero = LLVMConstNull(g->builtin_types.entry_i32->type_ref);
LLVMValueRef return_address_ptr = LLVMBuildCall(g->builder, get_return_address_fn_val(g), &zero, 1, "");
LLVMValueRef return_address = LLVMBuildPtrToInt(g->builder, return_address_ptr, usize_type_ref, "");
LLVMValueRef address_value = LLVMBuildPtrToInt(g->builder, return_address, usize_type_ref, "");
gen_store_untyped(g, address_value, address_slot, 0, false);
// stack_trace.index += 1;
LLVMValueRef index_plus_one_val = LLVMBuildAdd(g->builder, index_val, LLVMConstInt(usize_type_ref, 1, false), "");
gen_store_untyped(g, index_plus_one_val, index_field_ptr, 0, false);
// return;
LLVMValueRef args[] = { err_ret_trace_ptr, return_address };
LLVMBuildCall(g->builder, add_error_return_trace_addr_fn_val, args, 2, "");
LLVMBuildRetVoid(g->builder);
LLVMPositionBuilderAtEnd(g->builder, prev_block);
@@ -1641,7 +1816,6 @@ static LLVMValueRef ir_render_save_err_ret_addr(CodeGen *g, IrExecutable *execut
};
LLVMValueRef call_instruction = ZigLLVMBuildCall(g->builder, return_err_fn, args, 1,
get_llvm_cc(g, CallingConventionUnspecified), ZigLLVM_FnInlineAuto, "");
LLVMSetTailCall(call_instruction, true);
return call_instruction;
}
@@ -4204,6 +4378,22 @@ static LLVMValueRef ir_render_atomic_rmw(CodeGen *g, IrExecutable *executable,
return LLVMBuildIntToPtr(g->builder, uncasted_result, operand_type->type_ref, "");
}
static LLVMValueRef ir_render_merge_err_ret_traces(CodeGen *g, IrExecutable *executable,
IrInstructionMergeErrRetTraces *instruction)
{
assert(g->have_err_ret_tracing);
LLVMValueRef coro_promise_ptr = ir_llvm_value(g, instruction->coro_promise_ptr);
TypeStructField *field = instruction->resolved_field;
LLVMValueRef ptr_field_ptr = LLVMBuildStructGEP(g->builder, coro_promise_ptr, field->gen_index, "");
LLVMValueRef src_trace_ptr = LLVMBuildLoad(g->builder, ptr_field_ptr, "");
LLVMValueRef dest_trace_ptr = get_cur_err_ret_trace_val(g, instruction->base.scope);
LLVMValueRef args[] = { dest_trace_ptr, src_trace_ptr };
LLVMBuildCall(g->builder, get_merge_err_ret_traces_fn_val(g), args, 2, "");
return nullptr;
}
static void set_debug_location(CodeGen *g, IrInstruction *instruction) {
AstNode *source_node = instruction->source_node;
Scope *scope = instruction->scope;
@@ -4421,6 +4611,8 @@ static LLVMValueRef ir_render_instruction(CodeGen *g, IrExecutable *executable,
return ir_render_atomic_rmw(g, executable, (IrInstructionAtomicRmw *)instruction);
case IrInstructionIdSaveErrRetAddr:
return ir_render_save_err_ret_addr(g, executable, (IrInstructionSaveErrRetAddr *)instruction);
case IrInstructionIdMergeErrRetTraces:
return ir_render_merge_err_ret_traces(g, executable, (IrInstructionMergeErrRetTraces *)instruction);
}
zig_unreachable();
}
@@ -5313,12 +5505,12 @@ static void do_code_gen(CodeGen *g) {
bool is_async = fn_table_entry->type_entry->data.fn.fn_type_id.cc == CallingConventionAsync;
bool have_err_ret_trace_stack = g->have_err_ret_tracing && fn_table_entry->calls_or_awaits_errorable_fn &&
(is_async || !have_err_ret_trace_arg);
if (have_err_ret_trace_stack) {
// TODO call graph analysis to find out what this number needs to be for every function
static const size_t stack_trace_ptr_count = 30;
bool have_exactly_one_err_ret_value = !have_err_ret_trace_stack && g->have_err_ret_tracing && is_async &&
type_can_fail(fn_table_entry->type_entry->data.fn.fn_type_id.return_type);
if (have_err_ret_trace_stack || have_exactly_one_err_ret_value) {
TypeTableEntry *usize = g->builtin_types.entry_usize;
TypeTableEntry *array_type = get_array_type(g, usize, stack_trace_ptr_count);
uint32_t ret_addr_count = have_exactly_one_err_ret_value ? 1 : stack_trace_ptr_count;
TypeTableEntry *array_type = get_array_type(g, usize, ret_addr_count);
LLVMValueRef err_ret_array_val = build_alloca(g, array_type, "error_return_trace_addresses",
get_abi_alignment(g, array_type));
g->cur_err_ret_trace_val_stack = build_alloca(g, g->stack_trace_type, "error_return_trace", get_abi_alignment(g, g->stack_trace_type));
@@ -5341,7 +5533,7 @@ static void do_code_gen(CodeGen *g) {
size_t len_field_index = slice_type->data.structure.fields[slice_len_index].gen_index;
LLVMValueRef len_field_ptr = LLVMBuildStructGEP(g->builder, addresses_field_ptr, (unsigned)len_field_index, "");
gen_store(g, LLVMConstInt(usize->type_ref, stack_trace_ptr_count, false), len_field_ptr, get_pointer_to_type(g, usize, false));
gen_store(g, LLVMConstInt(usize->type_ref, ret_addr_count, false), len_field_ptr, get_pointer_to_type(g, usize, false));
} else {
g->cur_err_ret_trace_val_stack = nullptr;
}
@@ -5943,6 +6135,8 @@ static void define_builtin_compile_vars(CodeGen *g) {
os_path_join(g->cache_dir, buf_create_from_str(builtin_zig_basename), builtin_zig_path);
Buf *contents = buf_alloc();
// Modifications to this struct must be coordinated with code that does anything with
// g->stack_trace_type. There are hard-coded references to the field indexes.
buf_append_str(contents,
"pub const StackTrace = struct {\n"
" index: usize,\n"