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fix runtime branching tricking the comptime evaluation

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closes #167
This commit is contained in:
Andrew Kelley 2017-01-26 15:34:36 -05:00
parent 34a4d7a201
commit e0a422ae7e
3 changed files with 49 additions and 13 deletions
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4
src/all_types.hpp
View File

@ -1424,6 +1424,10 @@ struct IrBasicBlock {
size_t ref_count;
LLVMBasicBlockRef llvm_block;
LLVMBasicBlockRef llvm_exit_block;
// The instruction that referenced this basic block and caused us to
// analyze the basic block. If the same instruction wants us to emit
// the same basic block, then we re-generate it instead of saving it.
IrInstruction *ref_instruction;
};
enum IrInstructionId {

42
src/ir.cpp
View File

@ -5843,13 +5843,16 @@ static bool is_u8(TypeTableEntry *type) {
!type->data.integral.is_signed && type->data.integral.bit_count == 8;
}
static IrBasicBlock *ir_get_new_bb(IrAnalyze *ira, IrBasicBlock *old_bb) {
static IrBasicBlock *ir_get_new_bb(IrAnalyze *ira, IrBasicBlock *old_bb, IrInstruction *ref_old_instruction) {
assert(old_bb);
if (old_bb->other)
return old_bb->other;
if (old_bb->other) {
if (ref_old_instruction == nullptr || old_bb->other->ref_instruction != ref_old_instruction)
return old_bb->other;
}
IrBasicBlock *new_bb = ir_build_bb_from(&ira->new_irb, old_bb);
new_bb->ref_instruction = ref_old_instruction;
// We are about to enqueue old_bb for analysis. Before we do so, look over old_bb's
// instructions and make sure we have enqueued first the blocks which contain
@ -5865,7 +5868,7 @@ static IrBasicBlock *ir_get_new_bb(IrAnalyze *ira, IrBasicBlock *old_bb) {
continue;
if (dep_instruction->owner_bb == old_bb)
continue;
ir_get_new_bb(ira, dep_instruction->owner_bb);
ir_get_new_bb(ira, dep_instruction->owner_bb, nullptr);
}
}
ira->old_bb_queue.append(old_bb);
@ -5897,7 +5900,8 @@ static void ir_finish_bb(IrAnalyze *ira) {
if (ira->block_queue_index < ira->old_bb_queue.length) {
IrBasicBlock *old_bb = ira->old_bb_queue.at(ira->block_queue_index);
ira->new_irb.current_basic_block = ir_get_new_bb(ira, old_bb);
assert(old_bb->other);
ira->new_irb.current_basic_block = old_bb->other;
ir_start_bb(ira, old_bb, nullptr);
}
@ -8274,7 +8278,7 @@ static TypeTableEntry *ir_analyze_instruction_br(IrAnalyze *ira, IrInstructionBr
if (is_comptime || old_dest_block->ref_count == 1)
return ir_inline_bb(ira, &br_instruction->base, old_dest_block);
IrBasicBlock *new_bb = ir_get_new_bb(ira, old_dest_block);
IrBasicBlock *new_bb = ir_get_new_bb(ira, old_dest_block, &br_instruction->base);
ir_build_br_from(&ira->new_irb, &br_instruction->base, new_bb);
return ir_finish_anal(ira, ira->codegen->builtin_types.entry_unreachable);
}
@ -8307,7 +8311,7 @@ static TypeTableEntry *ir_analyze_instruction_cond_br(IrAnalyze *ira, IrInstruct
if (is_comptime || old_dest_block->ref_count == 1)
return ir_inline_bb(ira, &cond_br_instruction->base, old_dest_block);
IrBasicBlock *new_dest_block = ir_get_new_bb(ira, old_dest_block);
IrBasicBlock *new_dest_block = ir_get_new_bb(ira, old_dest_block, &cond_br_instruction->base);
ir_build_br_from(&ira->new_irb, &cond_br_instruction->base, new_dest_block);
return ir_finish_anal(ira, ira->codegen->builtin_types.entry_unreachable);
}
@ -8317,8 +8321,9 @@ static TypeTableEntry *ir_analyze_instruction_cond_br(IrAnalyze *ira, IrInstruct
if (casted_condition == ira->codegen->invalid_instruction)
return ir_unreach_error(ira);
IrBasicBlock *new_then_block = ir_get_new_bb(ira, cond_br_instruction->then_block);
IrBasicBlock *new_else_block = ir_get_new_bb(ira, cond_br_instruction->else_block);
assert(cond_br_instruction->then_block != cond_br_instruction->else_block);
IrBasicBlock *new_then_block = ir_get_new_bb(ira, cond_br_instruction->then_block, &cond_br_instruction->base);
IrBasicBlock *new_else_block = ir_get_new_bb(ira, cond_br_instruction->else_block, &cond_br_instruction->base);
ir_build_cond_br_from(&ira->new_irb, &cond_br_instruction->base,
casted_condition, new_then_block, new_else_block, nullptr);
return ir_finish_anal(ira, ira->codegen->builtin_types.entry_unreachable);
@ -9683,7 +9688,7 @@ static TypeTableEntry *ir_analyze_instruction_switch_br(IrAnalyze *ira,
if (is_comptime || old_dest_block->ref_count == 1) {
return ir_inline_bb(ira, &switch_br_instruction->base, old_dest_block);
} else {
IrBasicBlock *new_dest_block = ir_get_new_bb(ira, old_dest_block);
IrBasicBlock *new_dest_block = ir_get_new_bb(ira, old_dest_block, &switch_br_instruction->base);
ir_build_br_from(&ira->new_irb, &switch_br_instruction->base, new_dest_block);
return ir_finish_anal(ira, ira->codegen->builtin_types.entry_unreachable);
}
@ -9693,9 +9698,15 @@ static TypeTableEntry *ir_analyze_instruction_switch_br(IrAnalyze *ira,
for (size_t i = 0; i < case_count; i += 1) {
IrInstructionSwitchBrCase *old_case = &switch_br_instruction->cases[i];
IrInstructionSwitchBrCase *new_case = &cases[i];
new_case->block = ir_get_new_bb(ira, old_case->block);
new_case->block = ir_get_new_bb(ira, old_case->block, &switch_br_instruction->base);
new_case->value = ira->codegen->invalid_instruction;
// Calling ir_get_new_bb set the ref_instruction on the new basic block.
// However a switch br may branch to the same basic block which would trigger an
// incorrect re-generation of the block. So we set it to null here and assign
// it back after the loop.
new_case->block->ref_instruction = nullptr;
IrInstruction *old_value = old_case->value;
IrInstruction *new_value = old_value->other;
if (new_value->value.type->id == TypeTableEntryIdInvalid)
@ -9717,7 +9728,12 @@ static TypeTableEntry *ir_analyze_instruction_switch_br(IrAnalyze *ira,
new_case->value = casted_new_value;
}
IrBasicBlock *new_else_block = ir_get_new_bb(ira, switch_br_instruction->else_block);
for (size_t i = 0; i < case_count; i += 1) {
IrInstructionSwitchBrCase *new_case = &cases[i];
new_case->block->ref_instruction = &switch_br_instruction->base;
}
IrBasicBlock *new_else_block = ir_get_new_bb(ira, switch_br_instruction->else_block, &switch_br_instruction->base);
ir_build_switch_br_from(&ira->new_irb, &switch_br_instruction->base,
target_value, new_else_block, case_count, cases, nullptr);
return ir_finish_anal(ira, ira->codegen->builtin_types.entry_unreachable);
@ -11751,7 +11767,7 @@ TypeTableEntry *ir_analyze(CodeGen *codegen, IrExecutable *old_exec, IrExecutabl
ira->exec_context.mem_slot_list = allocate<ConstExprValue>(ira->exec_context.mem_slot_count);
IrBasicBlock *old_entry_bb = ira->old_irb.exec->basic_block_list.at(0);
IrBasicBlock *new_entry_bb = ir_get_new_bb(ira, old_entry_bb);
IrBasicBlock *new_entry_bb = ir_get_new_bb(ira, old_entry_bb, nullptr);
ir_ref_bb(new_entry_bb);
ira->new_irb.current_basic_block = new_entry_bb;
ira->block_queue_index = 0;

16
test/cases/eval.zig
View File

@ -175,3 +175,19 @@ fn constSlice() {
assert(b[0] == '2');
}
}
fn tryToTrickEvalWithRuntimeIf() {
@setFnTest(this);
assert(testTryToTrickEvalWithRuntimeIf(true) == 10);
}
fn testTryToTrickEvalWithRuntimeIf(b: bool) -> usize {
comptime var i: usize = 0;
inline while (i < 10; i += 1) {
const result = if (b) false else true;
}
comptime {
return i;
}
}