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sentinel slicing improvements

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* add runtime safety for slicing pointers, arrays, and slices.
 * slicing without a sentinel value results in non-sentineled slice
 * improved `std.debug.panic` handling of panic-during-panic
This commit is contained in:
Andrew Kelley
2019-12-20 17:48:45 -05:00
parent 26f3c2d061
commit 8918cb06fc
6 changed files with 118 additions and 26 deletions
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46
src/codegen.cpp
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@@ -941,6 +941,8 @@ static Buf *panic_msg_buf(PanicMsgId msg_id) {
return buf_create_from_str("async function called with noasync suspended");
case PanicMsgIdResumeNotSuspendedFn:
return buf_create_from_str("resumed a non-suspended function");
case PanicMsgIdBadSentinel:
return buf_create_from_str("sentinel mismatch");
}
zig_unreachable();
}
@@ -1419,6 +1421,22 @@ static void add_bounds_check(CodeGen *g, LLVMValueRef target_val,
LLVMPositionBuilderAtEnd(g->builder, ok_block);
}
static void add_sentinel_check(CodeGen *g, LLVMValueRef sentinel_elem_ptr, ZigValue *sentinel) {
LLVMValueRef expected_sentinel = gen_const_val(g, sentinel, "");
LLVMValueRef actual_sentinel = gen_load_untyped(g, sentinel_elem_ptr, 0, false, "");
LLVMValueRef ok_bit = LLVMBuildICmp(g->builder, LLVMIntEQ, actual_sentinel, expected_sentinel, "");
LLVMBasicBlockRef fail_block = LLVMAppendBasicBlock(g->cur_fn_val, "SentinelFail");
LLVMBasicBlockRef ok_block = LLVMAppendBasicBlock(g->cur_fn_val, "SentinelOk");
LLVMBuildCondBr(g->builder, ok_bit, ok_block, fail_block);
LLVMPositionBuilderAtEnd(g->builder, fail_block);
gen_safety_crash(g, PanicMsgIdBadSentinel);
LLVMPositionBuilderAtEnd(g->builder, ok_block);
}
static LLVMValueRef gen_assert_zero(CodeGen *g, LLVMValueRef expr_val, ZigType *int_type) {
LLVMValueRef zero = LLVMConstNull(get_llvm_type(g, int_type));
LLVMValueRef ok_bit = LLVMBuildICmp(g->builder, LLVMIntEQ, expr_val, zero, "");
@@ -5244,6 +5262,9 @@ static LLVMValueRef ir_render_slice(CodeGen *g, IrExecutable *executable, IrInst
bool want_runtime_safety = instruction->safety_check_on && ir_want_runtime_safety(g, &instruction->base);
ZigType *res_slice_ptr_type = instruction->base.value->type->data.structure.fields[slice_ptr_index]->type_entry;
ZigValue *sentinel = res_slice_ptr_type->data.pointer.sentinel;
if (array_type->id == ZigTypeIdArray ||
(array_type->id == ZigTypeIdPointer && array_type->data.pointer.ptr_len == PtrLenSingle))
{
@@ -5265,6 +5286,15 @@ static LLVMValueRef ir_render_slice(CodeGen *g, IrExecutable *executable, IrInst
LLVMValueRef array_end = LLVMConstInt(g->builtin_types.entry_usize->llvm_type,
array_type->data.array.len, false);
add_bounds_check(g, end_val, LLVMIntEQ, nullptr, LLVMIntULE, array_end);
if (sentinel != nullptr) {
LLVMValueRef indices[] = {
LLVMConstNull(g->builtin_types.entry_usize->llvm_type),
end_val,
};
LLVMValueRef sentinel_elem_ptr = LLVMBuildInBoundsGEP(g->builder, array_ptr, indices, 2, "");
add_sentinel_check(g, sentinel_elem_ptr, sentinel);
}
}
}
if (!type_has_bits(array_type)) {
@@ -5297,6 +5327,10 @@ static LLVMValueRef ir_render_slice(CodeGen *g, IrExecutable *executable, IrInst
if (want_runtime_safety) {
add_bounds_check(g, start_val, LLVMIntEQ, nullptr, LLVMIntULE, end_val);
if (sentinel != nullptr) {
LLVMValueRef sentinel_elem_ptr = LLVMBuildInBoundsGEP(g->builder, array_ptr, &end_val, 1, "");
add_sentinel_check(g, sentinel_elem_ptr, sentinel);
}
}
if (type_has_bits(array_type)) {
@@ -5337,18 +5371,24 @@ static LLVMValueRef ir_render_slice(CodeGen *g, IrExecutable *executable, IrInst
end_val = prev_end;
}
LLVMValueRef src_ptr_ptr = LLVMBuildStructGEP(g->builder, array_ptr, (unsigned)ptr_index, "");
LLVMValueRef src_ptr = gen_load_untyped(g, src_ptr_ptr, 0, false, "");
if (want_runtime_safety) {
assert(prev_end);
add_bounds_check(g, start_val, LLVMIntEQ, nullptr, LLVMIntULE, end_val);
if (instruction->end) {
add_bounds_check(g, end_val, LLVMIntEQ, nullptr, LLVMIntULE, prev_end);
if (sentinel != nullptr) {
LLVMValueRef sentinel_elem_ptr = LLVMBuildInBoundsGEP(g->builder, src_ptr, &end_val, 1, "");
add_sentinel_check(g, sentinel_elem_ptr, sentinel);
}
}
}
LLVMValueRef src_ptr_ptr = LLVMBuildStructGEP(g->builder, array_ptr, (unsigned)ptr_index, "");
LLVMValueRef src_ptr = gen_load_untyped(g, src_ptr_ptr, 0, false, "");
LLVMValueRef ptr_field_ptr = LLVMBuildStructGEP(g->builder, tmp_struct_ptr, (unsigned)ptr_index, "");
LLVMValueRef slice_start_ptr = LLVMBuildInBoundsGEP(g->builder, src_ptr, &start_val, (unsigned)len_index, "");
LLVMValueRef slice_start_ptr = LLVMBuildInBoundsGEP(g->builder, src_ptr, &start_val, 1, "");
gen_store_untyped(g, slice_start_ptr, ptr_field_ptr, 0, false);
LLVMValueRef len_field_ptr = LLVMBuildStructGEP(g->builder, tmp_struct_ptr, (unsigned)len_index, "");