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runtime safety check for casting null to pointer

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see #1059
This commit is contained in:
Andrew Kelley
2019-02-14 01:09:33 -05:00
parent d4d2718bca
commit 59de24817e
6 changed files with 67 additions and 27 deletions
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19
src/codegen.cpp
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@@ -950,6 +950,8 @@ static Buf *panic_msg_buf(PanicMsgId msg_id) {
return buf_create_from_str("invalid enum value");
case PanicMsgIdFloatToInt:
return buf_create_from_str("integer part of floating point value out of bounds");
case PanicMsgIdPtrCastNull:
return buf_create_from_str("cast causes pointer to be null");
}
zig_unreachable();
}
@@ -3028,7 +3030,22 @@ static LLVMValueRef ir_render_ptr_cast(CodeGen *g, IrExecutable *executable,
return nullptr;
}
LLVMValueRef ptr = ir_llvm_value(g, instruction->ptr);
return LLVMBuildBitCast(g->builder, ptr, wanted_type->type_ref, "");
LLVMValueRef result_ptr = LLVMBuildBitCast(g->builder, ptr, wanted_type->type_ref, "");
bool want_safety_check = instruction->safety_check_on && ir_want_runtime_safety(g, &instruction->base);
if (!want_safety_check || ptr_allows_addr_zero(wanted_type))
return result_ptr;
LLVMValueRef zero = LLVMConstNull(LLVMTypeOf(result_ptr));
LLVMValueRef ok_bit = LLVMBuildICmp(g->builder, LLVMIntNE, result_ptr, zero, "");
LLVMBasicBlockRef fail_block = LLVMAppendBasicBlock(g->cur_fn_val, "PtrCastFail");
LLVMBasicBlockRef ok_block = LLVMAppendBasicBlock(g->cur_fn_val, "PtrCastOk");
LLVMBuildCondBr(g->builder, ok_bit, ok_block, fail_block);
LLVMPositionBuilderAtEnd(g->builder, fail_block);
gen_safety_crash(g, PanicMsgIdPtrCastNull);
LLVMPositionBuilderAtEnd(g->builder, ok_block);
return result_ptr;
}
static LLVMValueRef ir_render_bit_cast(CodeGen *g, IrExecutable *executable,