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add runtime debug safety for dividing integer min value by -1

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closes #260
This commit is contained in:
Andrew Kelley
2017-02-14 01:08:30 -05:00
parent 0931b85bd0
commit 63d37b7cff
4 changed files with 39 additions and 7 deletions
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26
src/codegen.cpp
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@@ -846,14 +846,30 @@ static LLVMValueRef gen_div(CodeGen *g, bool want_debug_safety, LLVMValueRef val
} else {
zig_unreachable();
}
LLVMBasicBlockRef ok_block = LLVMAppendBasicBlock(g->cur_fn_val, "DivZeroOk");
LLVMBasicBlockRef fail_block = LLVMAppendBasicBlock(g->cur_fn_val, "DivZeroFail");
LLVMBuildCondBr(g->builder, is_zero_bit, fail_block, ok_block);
LLVMBasicBlockRef div_zero_ok_block = LLVMAppendBasicBlock(g->cur_fn_val, "DivZeroOk");
LLVMBasicBlockRef div_zero_fail_block = LLVMAppendBasicBlock(g->cur_fn_val, "DivZeroFail");
LLVMBuildCondBr(g->builder, is_zero_bit, div_zero_fail_block, div_zero_ok_block);
LLVMPositionBuilderAtEnd(g->builder, fail_block);
LLVMPositionBuilderAtEnd(g->builder, div_zero_fail_block);
gen_debug_safety_crash(g, PanicMsgIdDivisionByZero);
LLVMPositionBuilderAtEnd(g->builder, ok_block);
LLVMPositionBuilderAtEnd(g->builder, div_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, "DivOverflowOk");
LLVMBasicBlockRef overflow_fail_block = LLVMAppendBasicBlock(g->cur_fn_val, "DivOverflowFail");
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) {