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ability to cast u8 slice to bigger slice

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This commit is contained in:
Andrew Kelley 2016-05-08 00:59:21 -07:00
parent aed96e3512
commit 18ed87c695
4 changed files with 57 additions and 14 deletions
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9
src/analyze.cpp
View File

@ -4240,17 +4240,16 @@ static TypeTableEntry *analyze_cast_expr(CodeGen *g, ImportTableEntry *import, B
return resolve_cast(g, context, node, expr_node, wanted_type, CastOpToUnknownSizeArray, true);
}
// explicit cast from []T to []u8
if (is_slice(wanted_type) &&
is_u8(wanted_type->data.structure.fields[0].type_entry->data.pointer.child_type) &&
is_slice(actual_type) &&
// explicit cast from []T to []u8 or []u8 to []T
if (is_slice(wanted_type) && is_slice(actual_type) &&
(is_u8(wanted_type->data.structure.fields[0].type_entry->data.pointer.child_type) ||
is_u8(actual_type->data.structure.fields[0].type_entry->data.pointer.child_type)) &&
(wanted_type->data.structure.fields[0].type_entry->data.pointer.is_const ||
!actual_type->data.structure.fields[0].type_entry->data.pointer.is_const))
{
return resolve_cast(g, context, node, expr_node, wanted_type, CastOpResizeSlice, true);
}
// explicit cast from pointer to another pointer
if ((actual_type->id == TypeTableEntryIdPointer || actual_type->id == TypeTableEntryIdFn) &&
(wanted_type->id == TypeTableEntryIdPointer || wanted_type->id == TypeTableEntryIdFn))

45
src/codegen.cpp
View File

@ -888,6 +888,8 @@ static LLVMValueRef gen_cast_expr(CodeGen *g, AstNode *node) {
TypeTableEntry *actual_pointer_type = actual_type->data.structure.fields[0].type_entry;
TypeTableEntry *actual_child_type = actual_pointer_type->data.pointer.child_type;
TypeTableEntry *wanted_pointer_type = wanted_type->data.structure.fields[0].type_entry;
TypeTableEntry *wanted_child_type = wanted_pointer_type->data.pointer.child_type;
set_debug_source_node(g, node);
@ -896,15 +898,6 @@ static LLVMValueRef gen_cast_expr(CodeGen *g, AstNode *node) {
int wanted_ptr_index = wanted_type->data.structure.fields[0].gen_index;
int wanted_len_index = wanted_type->data.structure.fields[1].gen_index;
LLVMValueRef src_len_ptr = LLVMBuildStructGEP(g->builder, expr_val, actual_len_index, "");
LLVMValueRef src_len = LLVMBuildLoad(g->builder, src_len_ptr, "");
LLVMValueRef src_size = LLVMConstInt(g->builtin_types.entry_isize->type_ref,
type_size(g, actual_child_type), false);
LLVMValueRef new_len = LLVMBuildMul(g->builder, src_len, src_size, "");
LLVMValueRef dest_len_ptr = LLVMBuildStructGEP(g->builder, cast_expr->tmp_ptr,
wanted_len_index, "");
LLVMBuildStore(g->builder, new_len, dest_len_ptr);
LLVMValueRef src_ptr_ptr = LLVMBuildStructGEP(g->builder, expr_val, actual_ptr_index, "");
LLVMValueRef src_ptr = LLVMBuildLoad(g->builder, src_ptr_ptr, "");
LLVMValueRef src_ptr_casted = LLVMBuildBitCast(g->builder, src_ptr,
@ -913,6 +906,40 @@ static LLVMValueRef gen_cast_expr(CodeGen *g, AstNode *node) {
wanted_ptr_index, "");
LLVMBuildStore(g->builder, src_ptr_casted, dest_ptr_ptr);
LLVMValueRef src_len_ptr = LLVMBuildStructGEP(g->builder, expr_val, actual_len_index, "");
LLVMValueRef src_len = LLVMBuildLoad(g->builder, src_len_ptr, "");
uint64_t src_size = type_size(g, actual_child_type);
uint64_t dest_size = type_size(g, wanted_child_type);
LLVMValueRef new_len;
if (dest_size == 1) {
LLVMValueRef src_size_val = LLVMConstInt(g->builtin_types.entry_isize->type_ref, src_size, false);
new_len = LLVMBuildMul(g->builder, src_len, src_size_val, "");
} else if (src_size == 1) {
LLVMValueRef dest_size_val = LLVMConstInt(g->builtin_types.entry_isize->type_ref, dest_size, false);
if (want_debug_safety(g, node)) {
LLVMValueRef remainder_val = LLVMBuildURem(g->builder, src_len, dest_size_val, "");
LLVMValueRef zero = LLVMConstNull(g->builtin_types.entry_isize->type_ref);
LLVMValueRef ok_bit = LLVMBuildICmp(g->builder, LLVMIntEQ, remainder_val, zero, "");
LLVMBasicBlockRef ok_block = LLVMAppendBasicBlock(g->cur_fn->fn_value, "SliceWidenOk");
LLVMBasicBlockRef fail_block = LLVMAppendBasicBlock(g->cur_fn->fn_value, "SliceWidenFail");
LLVMBuildCondBr(g->builder, ok_bit, ok_block, fail_block);
LLVMPositionBuilderAtEnd(g->builder, fail_block);
gen_debug_safety_crash(g);
LLVMPositionBuilderAtEnd(g->builder, ok_block);
}
new_len = ZigLLVMBuildExactUDiv(g->builder, src_len, dest_size_val, "");
} else {
zig_unreachable();
}
LLVMValueRef dest_len_ptr = LLVMBuildStructGEP(g->builder, cast_expr->tmp_ptr,
wanted_len_index, "");
LLVMBuildStore(g->builder, new_len, dest_len_ptr);
return cast_expr->tmp_ptr;
}
case CastOpIntToFloat:

10
test/run_tests.cpp
View File

@ -1466,6 +1466,16 @@ fn div_exact(a: i32, b: i32) -> i32 {
}
)SOURCE");
add_debug_safety_case("cast []u8 to bigger slice of wrong size", R"SOURCE(
pub fn main(args: [][]u8) -> %void {
widen_slice([]u8{1, 2, 3, 4, 5});
}
#static_eval_enable(false)
fn widen_slice(slice: []u8) -> []i32 {
([]i32)(slice)
}
)SOURCE");
}
//////////////////////////////////////////////////////////////////////////////

7
test/self_hosted.zig
View File

@ -1593,6 +1593,13 @@ fn cast_slice_to_u8_slice() {
bytes[6] = 0;
bytes[7] = 0;
assert(big_thing_slice[1] == 0);
const big_thing_again = ([]i32)(bytes);
assert(big_thing_again[2] == 3);
big_thing_again[2] = -1;
assert(bytes[8] == @max_value(u8));
assert(bytes[9] == @max_value(u8));
assert(bytes[10] == @max_value(u8));
assert(bytes[11] == @max_value(u8));
}
#attribute("test")