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add debug safety checks for remainder division

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See #217
This commit is contained in:
Andrew Kelley
2017-03-26 15:06:43 -04:00
parent 6ee63c8f58
commit 8aeea72654
7 changed files with 76 additions and 29 deletions
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68
src/codegen.cpp
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@@ -512,6 +512,8 @@ static Buf *panic_msg_buf(PanicMsgId msg_id) {
return buf_create_from_str("left shift overflowed bits");
case PanicMsgIdDivisionByZero:
return buf_create_from_str("division by zero");
case PanicMsgIdRemainderDivisionByZero:
return buf_create_from_str("remainder division by zero");
case PanicMsgIdExactDivisionRemainder:
return buf_create_from_str("exact division produced remainder");
case PanicMsgIdSliceWidenRemainder:
@@ -956,6 +958,59 @@ static LLVMValueRef gen_div(CodeGen *g, bool want_debug_safety, LLVMValueRef val
}
}
static LLVMValueRef gen_rem(CodeGen *g, bool want_debug_safety, LLVMValueRef val1, LLVMValueRef val2,
TypeTableEntry *type_entry)
{
if (want_debug_safety) {
LLVMValueRef zero = LLVMConstNull(type_entry->type_ref);
LLVMValueRef is_zero_bit;
if (type_entry->id == TypeTableEntryIdInt) {
is_zero_bit = LLVMBuildICmp(g->builder, LLVMIntEQ, val2, zero, "");
} else if (type_entry->id == TypeTableEntryIdFloat) {
is_zero_bit = LLVMBuildFCmp(g->builder, LLVMRealOEQ, val2, zero, "");
} else {
zig_unreachable();
}
LLVMBasicBlockRef rem_zero_ok_block = LLVMAppendBasicBlock(g->cur_fn_val, "RemZeroOk");
LLVMBasicBlockRef rem_zero_fail_block = LLVMAppendBasicBlock(g->cur_fn_val, "RemZeroFail");
LLVMBuildCondBr(g->builder, is_zero_bit, rem_zero_fail_block, rem_zero_ok_block);
LLVMPositionBuilderAtEnd(g->builder, rem_zero_fail_block);
gen_debug_safety_crash(g, PanicMsgIdRemainderDivisionByZero);
LLVMPositionBuilderAtEnd(g->builder, rem_zero_ok_block);
if (type_entry->id == TypeTableEntryIdInt && type_entry->data.integral.is_signed) {
LLVMValueRef neg_1_value = LLVMConstInt(type_entry->type_ref, -1, true);
LLVMValueRef int_min_value = LLVMConstInt(type_entry->type_ref, min_signed_val(type_entry), true);
LLVMBasicBlockRef overflow_ok_block = LLVMAppendBasicBlock(g->cur_fn_val, "RemOverflowOk");
LLVMBasicBlockRef overflow_fail_block = LLVMAppendBasicBlock(g->cur_fn_val, "RemOverflowFail");
LLVMValueRef num_is_int_min = LLVMBuildICmp(g->builder, LLVMIntEQ, val1, int_min_value, "");
LLVMValueRef den_is_neg_1 = LLVMBuildICmp(g->builder, LLVMIntEQ, val2, neg_1_value, "");
LLVMValueRef overflow_fail_bit = LLVMBuildAnd(g->builder, num_is_int_min, den_is_neg_1, "");
LLVMBuildCondBr(g->builder, overflow_fail_bit, overflow_fail_block, overflow_ok_block);
LLVMPositionBuilderAtEnd(g->builder, overflow_fail_block);
gen_debug_safety_crash(g, PanicMsgIdIntegerOverflow);
LLVMPositionBuilderAtEnd(g->builder, overflow_ok_block);
}
}
if (type_entry->id == TypeTableEntryIdFloat) {
return LLVMBuildFRem(g->builder, val1, val2, "");
} else {
assert(type_entry->id == TypeTableEntryIdInt);
if (type_entry->data.integral.is_signed) {
return LLVMBuildSRem(g->builder, val1, val2, "");
} else {
return LLVMBuildURem(g->builder, val1, val2, "");
}
}
}
static LLVMValueRef ir_render_bin_op(CodeGen *g, IrExecutable *executable,
IrInstructionBinOp *bin_op_instruction)
{
@@ -1092,17 +1147,8 @@ static LLVMValueRef ir_render_bin_op(CodeGen *g, IrExecutable *executable,
}
case IrBinOpDiv:
return gen_div(g, want_debug_safety, op1_value, op2_value, canon_type, false);
case IrBinOpMod:
if (canon_type->id == TypeTableEntryIdFloat) {
return LLVMBuildFRem(g->builder, op1_value, op2_value, "");
} else {
assert(canon_type->id == TypeTableEntryIdInt);
if (canon_type->data.integral.is_signed) {
return LLVMBuildSRem(g->builder, op1_value, op2_value, "");
} else {
return LLVMBuildURem(g->builder, op1_value, op2_value, "");
}
}
case IrBinOpRem:
return gen_rem(g, want_debug_safety, op1_value, op2_value, canon_type);
}
zig_unreachable();
}