motiejus/zig
1
Fork 0
Code Releases Activity

bit shifting safety

Browse Source 
* add u3, u4, u5, u6, u7 and i3, i4, i5, i6, i7
 * shift operations shift amount parameter type is
   integer with log2 bit width of other param
   - This enforces not violating undefined behavior on
     shift amount >= bit width with the type system
 * clean up math.log, math.ln, math.log2, math.log10

closes #403
This commit is contained in:
Andrew Kelley
2017-08-19 01:32:15 -04:00
parent 558ece8f6f
commit 987768778a
25 changed files with 359 additions and 164 deletions
Download Patch File Download Diff File Expand all files Collapse all files

40
src/codegen.cpp
View File

@@ -1451,7 +1451,9 @@ static LLVMValueRef ir_render_bin_op(CodeGen *g, IrExecutable *executable,
IrInstruction *op1 = bin_op_instruction->op1;
IrInstruction *op2 = bin_op_instruction->op2;
assert(op1->value.type == op2->value.type);
assert(op1->value.type == op2->value.type || op_id == IrBinOpBitShiftLeftLossy ||
op_id == IrBinOpBitShiftLeftExact || op_id == IrBinOpBitShiftRightLossy ||
op_id == IrBinOpBitShiftRightExact);
TypeTableEntry *type_entry = op1->value.type;
bool want_debug_safety = bin_op_instruction->safety_check_on &&
@@ -1527,34 +1529,38 @@ static LLVMValueRef ir_render_bin_op(CodeGen *g, IrExecutable *executable,
case IrBinOpBitShiftLeftExact:
{
assert(type_entry->id == TypeTableEntryIdInt);
LLVMValueRef op2_casted = gen_widen_or_shorten(g, false, op2->value.type,
type_entry, op2_value);
bool is_sloppy = (op_id == IrBinOpBitShiftLeftLossy);
if (is_sloppy) {
return LLVMBuildShl(g->builder, op1_value, op2_value, "");
return LLVMBuildShl(g->builder, op1_value, op2_casted, "");
} else if (want_debug_safety) {
return gen_overflow_shl_op(g, type_entry, op1_value, op2_value);
return gen_overflow_shl_op(g, type_entry, op1_value, op2_casted);
} else if (type_entry->data.integral.is_signed) {
return ZigLLVMBuildNSWShl(g->builder, op1_value, op2_value, "");
return ZigLLVMBuildNSWShl(g->builder, op1_value, op2_casted, "");
} else {
return ZigLLVMBuildNUWShl(g->builder, op1_value, op2_value, "");
return ZigLLVMBuildNUWShl(g->builder, op1_value, op2_casted, "");
}
}
case IrBinOpBitShiftRightLossy:
case IrBinOpBitShiftRightExact:
{
assert(type_entry->id == TypeTableEntryIdInt);
LLVMValueRef op2_casted = gen_widen_or_shorten(g, false, op2->value.type,
type_entry, op2_value);
bool is_sloppy = (op_id == IrBinOpBitShiftRightLossy);
if (is_sloppy) {
if (type_entry->data.integral.is_signed) {
return LLVMBuildAShr(g->builder, op1_value, op2_value, "");
return LLVMBuildAShr(g->builder, op1_value, op2_casted, "");
} else {
return LLVMBuildLShr(g->builder, op1_value, op2_value, "");
return LLVMBuildLShr(g->builder, op1_value, op2_casted, "");
}
} else if (want_debug_safety) {
return gen_overflow_shr_op(g, type_entry, op1_value, op2_value);
return gen_overflow_shr_op(g, type_entry, op1_value, op2_casted);
} else if (type_entry->data.integral.is_signed) {
return ZigLLVMBuildAShrExact(g->builder, op1_value, op2_value, "");
return ZigLLVMBuildAShrExact(g->builder, op1_value, op2_casted, "");
} else {
return ZigLLVMBuildLShrExact(g->builder, op1_value, op2_value, "");
return ZigLLVMBuildLShrExact(g->builder, op1_value, op2_casted, "");
}
}
case IrBinOpSub:
@@ -2824,12 +2830,15 @@ static LLVMValueRef render_shl_with_overflow(CodeGen *g, IrInstructionOverflowOp
LLVMValueRef op2 = ir_llvm_value(g, instruction->op2);
LLVMValueRef ptr_result = ir_llvm_value(g, instruction->result_ptr);
LLVMValueRef result = LLVMBuildShl(g->builder, op1, op2, "");
LLVMValueRef op2_casted = gen_widen_or_shorten(g, false, instruction->op2->value.type,
instruction->op1->value.type, op2);
LLVMValueRef result = LLVMBuildShl(g->builder, op1, op2_casted, "");
LLVMValueRef orig_val;
if (int_type->data.integral.is_signed) {
orig_val = LLVMBuildAShr(g->builder, result, op2, "");
orig_val = LLVMBuildAShr(g->builder, result, op2_casted, "");
} else {
orig_val = LLVMBuildLShr(g->builder, result, op2, "");
orig_val = LLVMBuildLShr(g->builder, result, op2_casted, "");
}
LLVMValueRef overflow_bit = LLVMBuildICmp(g->builder, LLVMIntNE, op1, orig_val, "");
@@ -4212,6 +4221,11 @@ static void do_code_gen(CodeGen *g) {
}
static const uint8_t int_sizes_in_bits[] = {
3,
4,
5,
6,
7,
8,
16,
32,