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| Differential D105340
[analyzer] Produce SymbolCast symbols for integral types in SValBuilder::evalCast ClosedPublic Authored by ASDenysPetrov on Jul 2 2021, 2:47 AM.
Details Summary Produce SymbolCast for integral types in evalCast function. Apply several simplification techniques while producing the symbols. Added a boolean option support-symbolic-integer-casts under -analyzer-config flag. Disabled the feature by default. Due to suggestions for splitting D103096 this patch has appeared. It's the first part of the D103096 revision.
Diff Detail
Event TimelineHerald added subscribers: manas, dkrupp, donat.nagy and 7 others. · View Herald TranscriptJul 2 2021, 2:47 AM Comment Actions Hey, thanks for starting on splitting into more pieces!
Comment Actions I will update the patch soon according to your suggestions.
Comment Actions Retruned back SValBuilder::evalIntegralCast to eliminated regression. Fixed tests when long == 4bytes. Added doc-comment to simplifySymbolCast. Comment Actions Also, although the test is very extensive, it is pretty lopsided at the same time. C-style cast is only one case out of the myriad of all explicit and, more importantly, implicit casts.
Comment Actions
I agree in a part of size, but these C-style casts generates the same AST tree as all other ex/implicit forms of casts . Though, casts can look completely differently but at a low level they are very similar. void test(long x) {
(llong)(short)(char)x;
}
FunctionDecl 0xbc306b8 <test.cpp:1:1, line:3:1> line:1:6 test 'void (long)'
|-ParmVarDecl 0xbc305f0 <col:11, col:16> col:16 used x 'long'
`-CompoundStmt 0xbc9f4b0 <col:19, line:3:1>
`-CStyleCastExpr 0xbc9f488 <line:2:3, col:27> 'long long' <NoOp>
`-ImplicitCastExpr 0xbc9f470 <col:14, col:27> 'long long' <IntegralCast> part_of_explicit_cast
`-CStyleCastExpr 0xbc9f430 <col:14, col:27> 'short' <NoOp>
`-ImplicitCastExpr 0xbc9f418 <col:21, col:27> 'short' <IntegralCast> part_of_explicit_cast
`-CStyleCastExpr 0xbc9f3d8 <col:21, col:27> 'char' <NoOp>
`-ImplicitCastExpr 0xbc9f3c0 <col:27> 'char' <IntegralCast> part_of_explicit_cast
`-ImplicitCastExpr 0xbc9f3a8 <col:27> 'long' <LValueToRValue> part_of_explicit_cast
`-DeclRefExpr 0xbc9f378 <col:27> 'long' lvalue ParmVar 0xbc305f0 'x' 'long'and void test(long x) {
char c = x;
if(static_cast<short>(c) == -1ll);
}
`-FunctionDecl 0xbc606b8 <test.cpp:1:1, line:4:1> line:1:6 test 'void (long)'
|-ParmVarDecl 0xbc605f0 <col:11, col:16> col:16 used x 'long'
`-CompoundStmt 0xbcd0598 <col:19, line:4:1>
|-DeclStmt 0xbcd0450 <line:2:3, col:13>
| `-VarDecl 0xbcd0398 <col:3, col:12> col:8 used c 'char' cinit
| `-ImplicitCastExpr 0xbcd0438 <col:12> 'char' <IntegralCast>
| `-ImplicitCastExpr 0xbcd0420 <col:12> 'long' <LValueToRValue>
| `-DeclRefExpr 0xbcd0400 <col:12> 'long' lvalue ParmVar 0xbc605f0 'x' 'long'
`-IfStmt 0xbcd0578 <line:3:3, col:36>
|-BinaryOperator 0xbcd0550 <col:6, col:32> 'bool' '=='
| |-ImplicitCastExpr 0xbcd0538 <col:6, col:26> 'long long' <IntegralCast>
| | `-CXXStaticCastExpr 0xbcd04d0 <col:6, col:26> 'short' static_cast<short> <NoOp>
| | `-ImplicitCastExpr 0xbcd04b8 <col:25> 'short' <IntegralCast> part_of_explicit_cast
| | `-ImplicitCastExpr 0xbcd04a0 <col:25> 'char' <LValueToRValue> part_of_explicit_cast
| | `-DeclRefExpr 0xbcd0468 <col:25> 'char' lvalue Var 0xbcd0398 'c' 'char'
| `-UnaryOperator 0xbcd0520 <col:31, col:32> 'long long' prefix '-'
| `-IntegerLiteral 0xbcd0500 <col:32> 'long long' 1
`-NullStmt 0xbcd0570 <col:36>We can see similar IntegralCast for both variants. I was aiming to generate all the cases of IntegralCast and C-style cast is enough for me.
Comment Actions Changed option name to support-symbolic-integer-casts. Added signed char to tests. Splitted tests into x86 and x64 versions, where sizeof(long) is 4 and 8 correspondingly. ASDenysPetrov mentioned this in D103096: [analyzer] Implement cast for ranges of symbolic integers.Jul 6 2021, 3:46 AM ASDenysPetrov added a child revision: D103096: [analyzer] Implement cast for ranges of symbolic integers. Comment Actions This looks great with the option flag. Landing this patch will enable more people to test the new mode and produce feedback on whether the constraint solver keeps working well enough in presence of the new symbols.
This revision is now accepted and ready to land.Jan 10 2022, 1:50 PM Comment Actions
Many thanks for your approval, @NoQ! The upset thing is that to get this loaded we also should close this parent revision D103094 :-( Comment Actions
Actually, this patch does not depend on castTo and thus it is independent from the rest of the patch stack. So we could just land it as it is. (In this patch, you just create the SymbolCasts but there is no handling of that in the constraint manager which needs the castTo.) Comment Actions Thank you @martong. Shame on me :) I'm mixed up in my own patches. I forgot that I separated them consciously for this purpose. martong added a child revision: D117229: [Analyzer] Produce SymbolCast for pointer to integer cast.Jan 13 2022, 8:19 AM Closed by commit rGd835dd4cf5cc: [analyzer] Produce SymbolCast symbols for integral types in SValBuilder… (authored by ASDenysPetrov). · Explain WhyJan 18 2022, 6:08 AM This revision was automatically updated to reflect the committed changes. martong added a child revision: D126779: [analyzer] Fix assertion in simplifySymbolCast.Jun 10 2022, 6:44 AM ASDenysPetrov removed a child revision: D103096: [analyzer] Implement cast for ranges of symbolic integers.Nov 22 2022, 9:33 AM
Revision Contents
Diff 400823 clang/include/clang/StaticAnalyzer/Core/AnalyzerOptions.def
clang/include/clang/StaticAnalyzer/Core/PathSensitive/SValBuilder.h
clang/lib/StaticAnalyzer/Core/ExprEngineC.cpp
clang/lib/StaticAnalyzer/Core/SValBuilder.cpp
clang/test/Analysis/analyzer-config.c
clang/test/Analysis/produce-symbolcast_x64.cpp
clang/test/Analysis/produce-symbolcast_x86.cpp
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BTW, mb it should be less specific? Something like ShouldSupportSymbolicIntegerCasts?
BTW 2, do you even plan on supporting symbolic casts in other cases?