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EXP33-C-EX1: Reading uninitialized memory by an lvalue of type unsigned char that could not have been declared with the register storage class does not trigger undefined behavior. The unsigned char type is defined to not have a trap representation, which allows for moving bytes without knowing if they are initialized. (See the C Standard, 6.2.6.1, paragraph 3.) However, ) The requirement that register could not have been used (not merely that it was not used) is because on some architectures, such as the Intel Itanium, registers have a bit to indicate whether or not they have been initialized. The C Standard, 6.3.2.1, paragraph 2, allows such implementations to cause a trap for an object that never had its address taken and is stored in a register if such an object is referred to in any way.
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| Tool | Version | Checker | Description | ||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Astrée |
| uninitialized-local-read uninitialized-variable-use | Fully checked | ||||||||||||||||||||||
| Axivion Bauhaus Suite |
| CertC-EXP33 | |||||||||||||||||||||||
| CodeSonar |
| LANG.MEM.UVAR | Uninitialized variable | ||||||||||||||||||||||
| Compass/ROSE | Automatically detects simple violations of this rule, although it may return some false positives. It may not catch more complex violations, such as initialization within functions taking uninitialized variables as arguments. It does catch the second noncompliant code example, and can be extended to catch the first as well | ||||||||||||||||||||||||
| Coverity |
| UNINIT | Implemented | ||||||||||||||||||||||
| Cppcheck |
| uninitvar | Detects uninitialized variables, uninitialized pointers, uninitialized struct members, and uninitialized array elements (However, if one element is initialized, then cppcheck assumes the array is initialized.) | ||||||||||||||||||||||
| GCC | 4.3.5 | Can detect some violations of this rule when the | |||||||||||||||||||||||
| Helix QAC |
| Klocwork
| DF2726, DF2727, DF2728, DF2961, DF2962, DF2963, DF2966, DF2967, DF2968, DF2971, DF2972, DF2973, DF2976, DF2977, DF2978 | Fully implemented | |||||||||||||||||||||
| Klocwork |
| UNINIT.HEAP.MIGHT | Klocwork_V | Fully implemented | |||||||||||||||||||||
| LDRA tool suite |
| 53 D, 69 D, 631 S, 652 S | Fully implemented | ||||||||||||||||||||||
| Parasoft C/C++test |
| CERT_C-EXP33-a | Avoid use before initialization | ||||||||||||||||||||||
| Parasoft Insure++ |
| Runtime analysis | |||||||||||||||||||||||
| Polyspace Bug FinderPC-lint Plus |
| Polyspace Bug Finder
| Polyspace Bug Finder_V | Pointer not initialized before dereference Variable not initialized before use | PRQA QA-C | ||||||||||||||||||||
| Include Page | PRQA QA-C_v | PRQA QA-C_v | 2726, 2727, 2728, 2961, 2962, 2963, 2966, 2967, 2968, 2971, 2972, 2973, 2976, 2977, 2978 | Fully implemented | PRQA QA-C++ | ||||||||||||||||||||
| Include Page | cplusplus:PRQA QA-C++_V | cplusplus:PRQA QA-C++_V |
| 530, 603, 644, 901 | Fully supported | ||||||||||||||||||||
| Polyspace Bug Finder |
| Checks for:
Rule partially covered | |||||||||||||||||||||||
| PVS-Studio |
| V573, V614, V670, V679, V1050 | |||||||||||||||||||||||
| RuleChecker |
| uninitialized-local-read | Partially checked | ||||||||||||||||||||||
| Splint | 3.1.1 | ||||||||||||||||||||||||
| TrustInSoft Analyzer |
| initialisation | Exhaustively verified (see one compliant and one non-compliant example). |
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