[PATCH] [StaticAnalyzer] Add 'clang_analyzer_warnIfReached'
Jordan Rose
jordan_rose at apple.com
Tue Oct 1 09:13:50 PDT 2013
Should we change all the debug checkers to include an explanation? Right now they all just say "TRUE" or "FALSE" or "tainted". (The inlined checker saying "TRUE" is a bit funny, sure.)
Jordan
On Oct 1, 2013, at 9:10 , Anna Zaks <ganna at apple.com> wrote:
> I think the following would be the most consistent with the rest of the debug checkers:
> - BugReport *R = new BugReport(*BT, "REACHABLE", N);
> + BugReport *R = new BugReport(*BT, "Analyzer reached this line (WARN-REACHED)", N);
>
> Cheers,
> Anna.
>
> On Sep 30, 2013, at 8:40 PM, Jared Grubb <jared.grubb at gmail.com> wrote:
>
>> Sorry for the delay. My free time has been limited lately.
>>
>> From your comments, the only change you suggested was the capitalization:
>> - clang_analyzer_warnIfReached(); // expected-warning{{reached}}
>> + clang_analyzer_warnIfReached(); // expected-warning{{REACHED}}
>>
>> Attached are the minor changes required to make that work. Unit tests continue to all pass.
>>
>> <patch-warnIfReached.diff>
>>
>>
>> Jared
>>
>> On Sep 16, 2013, at 18:25, Jordan Rose <jordan_rose at apple.com> wrote:
>>
>>> [+Anna for opinions]
>>>
>>> Two comments:
>>>
>>> - I think we should keep the ExprInspection output in all caps, to make it clear that it's not a usual analyzer warning
>>> - The null-pointer deref tests also halt analysis along that path. I don't think that's something we usually need to do, but there might be a few cases where it's important. We could probably just add a return in most cases, though.
>>>
>>> I think you're right that it's better to be explicit, even though it's functionally equivalent to constructs we have already. Anna?
>>>
>>> Jordan
>>>
>>>
>>> On Sep 16, 2013, at 9:07 , Jared Grubb <jared.grubb at gmail.com> wrote:
>>>
>>>> While working on unit tests for a checker, I really wanted a facility to detect that the analyzer has (or has not) made certain branch choices.
>>>>
>>>> Looking through the unit test, this kind of check is done in various ways:
>>>> * Intentional deref of null pointer (the most popular, apparently)
>>>> * Intentional divide by zero (tests in "cast.c")
>>>> * "clang_analyzer_eval(true); // expected-warning{{TRUE}}"
>>>>
>>>> Adding a new directive to explicitly serve this purpose helps the readability of unit tests. As proof of concept, I've modified an existing test to remove the fake null-pointer derefs.
>>>>
>>>> Unit tests continue to pass. The direct patch to the analyzer is very minimal.
>>>>
>>>> Jared
>>>>
>>>>
>>>> diff --git a/docs/analyzer/DebugChecks.rst b/docs/analyzer/DebugChecks.rst
>>>> index a0f2a07..b0983e8 100644
>>>> --- a/docs/analyzer/DebugChecks.rst
>>>> +++ b/docs/analyzer/DebugChecks.rst
>>>> @@ -125,6 +125,19 @@ ExprInspection checks
>>>> clang_analyzer_eval(value == 42); // expected-warning{{TRUE}}
>>>> }
>>>>
>>>> +- void clang_analyzer_warnIfReached();
>>>> +
>>>> + Generate a warning if this line of code gets reached by the analyzer.
>>>> +
>>>> + Example usage::
>>>> +
>>>> + if (true) {
>>>> + clang_analyzer_warnIfReached(); // expected-warning{{reached}}
>>>> + }
>>>> + else {
>>>> + clang_analyzer_warnIfReached(); // no-warning
>>>> + }
>>>> +
>>>>
>>>> Statistics
>>>> ==========
>>>> diff --git a/lib/StaticAnalyzer/Checkers/ExprInspectionChecker.cpp b/lib/StaticAnalyzer/Checkers/ExprInspectionChecker.cpp
>>>> index 9522d1d..53f7c3d 100644
>>>> --- a/lib/StaticAnalyzer/Checkers/ExprInspectionChecker.cpp
>>>> +++ b/lib/StaticAnalyzer/Checkers/ExprInspectionChecker.cpp
>>>> @@ -22,6 +22,7 @@ class ExprInspectionChecker : public Checker< eval::Call > {
>>>>
>>>> void analyzerEval(const CallExpr *CE, CheckerContext &C) const;
>>>> void analyzerCheckInlined(const CallExpr *CE, CheckerContext &C) const;
>>>> + void analyzerWarnIfReached(const CallExpr *CE, CheckerContext &C) const;
>>>> void analyzerCrash(const CallExpr *CE, CheckerContext &C) const;
>>>>
>>>> typedef void (ExprInspectionChecker::*FnCheck)(const CallExpr *,
>>>> @@ -41,6 +42,7 @@ bool ExprInspectionChecker::evalCall(const CallExpr *CE,
>>>> .Case("clang_analyzer_checkInlined",
>>>> &ExprInspectionChecker::analyzerCheckInlined)
>>>> .Case("clang_analyzer_crash", &ExprInspectionChecker::analyzerCrash)
>>>> + .Case("clang_analyzer_warnIfReached", &ExprInspectionChecker::analyzerWarnIfReached)
>>>> .Default(0);
>>>>
>>>> if (!Handler)
>>>> @@ -99,6 +101,17 @@ void ExprInspectionChecker::analyzerEval(const CallExpr *CE,
>>>> C.emitReport(R);
>>>> }
>>>>
>>>> +void ExprInspectionChecker::analyzerWarnIfReached(const CallExpr *CE,
>>>> + CheckerContext &C) const {
>>>> + ExplodedNode *N = C.getPredecessor();
>>>> +
>>>> + if (!BT)
>>>> + BT.reset(new BugType("Checking analyzer assumptions", "debug"));
>>>> +
>>>> + BugReport *R = new BugReport(*BT, "Analyzer reached this line", N);
>>>> + C.emitReport(R);
>>>> +}
>>>> +
>>>> void ExprInspectionChecker::analyzerCheckInlined(const CallExpr *CE,
>>>> CheckerContext &C) const {
>>>> ExplodedNode *N = C.getPredecessor();
>>>> diff --git a/test/Analysis/misc-ps-region-store.cpp b/test/Analysis/misc-ps-region-store.cpp
>>>> index 902a5e5..c00d357 100644
>>>> --- a/test/Analysis/misc-ps-region-store.cpp
>>>> +++ b/test/Analysis/misc-ps-region-store.cpp
>>>> @@ -1,5 +1,7 @@
>>>> -// RUN: %clang_cc1 -triple i386-apple-darwin9 -analyze -analyzer-checker=core,alpha.core -analyzer-store=region -verify -fblocks -analyzer-opt-analyze-nested-blocks %s -fexceptions -fcxx-exceptions
>>>> -// RUN: %clang_cc1 -triple x86_64-apple-darwin9 -analyze -analyzer-checker=core,alpha.core -analyzer-store=region -verify -fblocks -analyzer-opt-analyze-nested-blocks %s -fexceptions -fcxx-exceptions
>>>> +// RUN: %clang_cc1 -triple i386-apple-darwin9 -analyze -analyzer-checker=core,alpha.core,debug.ExprInspection -analyzer-store=region -verify -fblocks -analyzer-opt-analyze-nested-blocks %s -fexceptions -fcxx-exceptions
>>>> +// RUN: %clang_cc1 -triple x86_64-apple-darwin9 -analyze -analyzer-checker=core,alpha.core,debug.ExprInspection -analyzer-store=region -verify -fblocks -analyzer-opt-analyze-nested-blocks %s -fexceptions -fcxx-exceptions
>>>> +
>>>> +void clang_analyzer_warnIfReached();
>>>>
>>>> // Test basic handling of references.
>>>> char &test1_aux();
>>>> @@ -54,9 +56,7 @@ int test_init_in_condition_switch() {
>>>> if (x == 2)
>>>> return 0;
>>>> else {
>>>> - // Unreachable.
>>>> - int *p = 0;
>>>> - *p = 0xDEADBEEF; // no-warning
>>>> + clang_analyzer_warnIfReached(); // unreachable
>>>> }
>>>> default:
>>>> break;
>>>> @@ -74,8 +74,7 @@ int test_init_in_condition_while() {
>>>> if (z == 2)
>>>> return 0;
>>>>
>>>> - int *p = 0;
>>>> - *p = 0xDEADBEEF; // no-warning
>>>> + clang_analyzer_warnIfReached(); // unreachable
>>>> return 0;
>>>> }
>>>>
>>>> @@ -89,8 +88,7 @@ int test_init_in_condition_for() {
>>>> if (z == 1)
>>>> return 0;
>>>>
>>>> - int *p = 0;
>>>> - *p = 0xDEADBEEF; // no-warning
>>>> + clang_analyzer_warnIfReached(); // unreachable
>>>> return 0;
>>>> }
>>>>
>>>> @@ -117,8 +115,7 @@ int TestHandleThis::null_deref_negative() {
>>>> if (x == 10) {
>>>> return 1;
>>>> }
>>>> - int *p = 0;
>>>> - *p = 0xDEADBEEF; // no-warning
>>>> + clang_analyzer_warnIfReached(); // unreachable
>>>> return 0;
>>>> }
>>>>
>>>> @@ -127,8 +124,7 @@ int TestHandleThis::null_deref_positive() {
>>>> if (x == 9) {
>>>> return 1;
>>>> }
>>>> - int *p = 0;
>>>> - *p = 0xDEADBEEF; // expected-warning{{null pointer}}
>>>> + clang_analyzer_warnIfReached(); // expected-warning{{reached}}
>>>> return 0;
>>>> }
>>>>
>>>> @@ -143,9 +139,9 @@ void pr7675_test() {
>>>> pr7675(10);
>>>> pr7675('c');
>>>> pr7675_i(4.0i);
>>>> - // Add null deref to ensure we are analyzing the code up to this point.
>>>> - int *p = 0;
>>>> - *p = 0xDEADBEEF; // expected-warning{{null pointer}}
>>>> +
>>>> + // Add check to ensure we are analyzing the code up to this point.
>>>> + clang_analyzer_warnIfReached(); // expected-warning{{reached}}
>>>> }
>>>>
>>>> // <rdar://problem/8375510> - CFGBuilder should handle temporaries.
>>>> @@ -328,26 +324,23 @@ class RDar9267815 {
>>>> };
>>>>
>>>> void RDar9267815::test_pos() {
>>>> - int *p = 0;
>>>> if (x == 42)
>>>> return;
>>>> - *p = 0xDEADBEEF; // expected-warning {{null}}
>>>> + clang_analyzer_warnIfReached(); // expected-warning{{reached}}
>>>> }
>>>> void RDar9267815::test() {
>>>> - int *p = 0;
>>>> if (x == 42)
>>>> return;
>>>> if (x == 42)
>>>> - *p = 0xDEADBEEF; // no-warning
>>>> + clang_analyzer_warnIfReached(); // no-warning
>>>> }
>>>>
>>>> void RDar9267815::test2() {
>>>> - int *p = 0;
>>>> if (x == 42)
>>>> return;
>>>> invalidate();
>>>> if (x == 42)
>>>> - *p = 0xDEADBEEF; // expected-warning {{null}}
>>>> + clang_analyzer_warnIfReached(); // expected-warning{{reached}}
>>>> }
>>>>
>>>> // Test reference parameters.
>>>> @@ -440,8 +433,7 @@ int rdar9948787_negative() {
>>>> unsigned value = classWithStatic.value;
>>>> if (value == 1)
>>>> return 1;
>>>> - int *p = 0;
>>>> - *p = 0xDEADBEEF; // no-warning
>>>> + clang_analyzer_warnIfReached(); // no-warning
>>>> return 0;
>>>> }
>>>>
>>>> @@ -450,8 +442,7 @@ int rdar9948787_positive() {
>>>> unsigned value = classWithStatic.value;
>>>> if (value == 0)
>>>> return 1;
>>>> - int *p = 0;
>>>> - *p = 0xDEADBEEF; // expected-warning {{null}}
>>>> + clang_analyzer_warnIfReached(); // expected-warning{{reached}}
>>>> return 0;
>>>> }
>>>>
>>>> @@ -467,8 +458,7 @@ void rdar10202899_test1() {
>>>> void rdar10202899_test2() {
>>>> if (val == rdar10202899_ValTA)
>>>> return;
>>>> - int *p = 0;
>>>> - *p = 0xDEADBEEF;
>>>> + clang_analyzer_warnIfReached(); // no-warning
>>>> }
>>>>
>>>> void rdar10202899_test3() {
>>>> @@ -476,8 +466,7 @@ void rdar10202899_test3() {
>>>> case rdar10202899_ValTA: return;
>>>> default: ;
>>>> };
>>>> - int *p = 0;
>>>> - *p = 0xDEADBEEF;
>>>> + clang_analyzer_warnIfReached(); // no-warning
>>>> }
>>>>
>>>> // This used to crash the analyzer because of the unnamed bitfield.
>>>> @@ -489,13 +478,12 @@ void PR11249()
>>>> char f2[1];
>>>> char f3;
>>>> } V = { 1, {2}, 3 };
>>>> - int *p = 0;
>>>> if (V.f1 != 1)
>>>> - *p = 0xDEADBEEF; // no-warning
>>>> + clang_analyzer_warnIfReached(); // no-warning
>>>> if (V.f2[0] != 2)
>>>> - *p = 0xDEADBEEF; // no-warning
>>>> + clang_analyzer_warnIfReached(); // no-warning
>>>> if (V.f3 != 3)
>>>> - *p = 0xDEADBEEF; // no-warning
>>>> + clang_analyzer_warnIfReached(); // no-warning
>>>> }
>>>>
>>>> // Handle doing a load from the memory associated with the code for
>>>> @@ -599,12 +587,10 @@ void rdar10924675(unsigned short x[], int index, int index2) {
>>>> void rdar11401827() {
>>>> int x = int();
>>>> if (!x) {
>>>> - int *p = 0;
>>>> - *p = 0xDEADBEEF; // expected-warning {{null pointer}}
>>>> + clang_analyzer_warnIfReached(); // expected-warning{{reached}}
>>>> }
>>>> else {
>>>> - int *p = 0;
>>>> - *p = 0xDEADBEEF;
>>>> + clang_analyzer_warnIfReached(); // no-warning
>>>> }
>>>> }
>>>>
>>>> @@ -701,8 +687,7 @@ const Rdar12755044_foo *radar12755044() {
>>>> void rdar12759044() {
>>>> int flag = 512;
>>>> if (!(flag & 512)) {
>>>> - int *p = 0;
>>>> - *p = 0xDEADBEEF; // no-warning
>>>> + clang_analyzer_warnIfReached(); // no-warning
>>>> }
>>>> }
>>>>
>>>>
>>>> _______________________________________________
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>>>
>>
>
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