[cfe-commits] r146430 - in /cfe/trunk: lib/Sema/SemaChecking.cpp test/SemaCXX/Inputs/array-bounds-system-header.h test/SemaCXX/array-bounds-system-header.cpp

[Matt Beaumont-Gay]

Thanks for the heads up. I'm working on optimizing that codepath some more.

On Tue, Dec 13, 2011 at 11:10, Peter Cooper <peter_cooper at apple.com> wrote:
> Hi Matt
>
> Unfortunately we're getting a ~10% drop in compile-time on a test case with this revision.
>
> The problematic test is MultiSource/Benchmarks/MiBench/security-rijndael
>
> Can you please take a look?
>
> Thanks,
> Pete
>
> On Dec 12, 2011, at 2:35 PM, Matt Beaumont-Gay wrote:
>
>> Author: matthewbg
>> Date: Mon Dec 12 16:35:02 2011
>> New Revision: 146430
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=146430&view=rev
>> Log:
>> Suppress -Warray-bounds in certain cases involving macros from system headers.
>>
>> The motivation here is a "clever" implementation of strncmp(), which peels the first few comparisons via chained conditional expressions which ensure that the input arrays are known at compile time to be sufficiently large.
>>
>> Added:
>>    cfe/trunk/test/SemaCXX/Inputs/array-bounds-system-header.h
>>    cfe/trunk/test/SemaCXX/array-bounds-system-header.cpp
>> Modified:
>>    cfe/trunk/lib/Sema/SemaChecking.cpp
>>
>> Modified: cfe/trunk/lib/Sema/SemaChecking.cpp
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaChecking.cpp?rev=146430&r1=146429&r2=146430&view=diff
>> ==============================================================================
>> --- cfe/trunk/lib/Sema/SemaChecking.cpp (original)
>> +++ cfe/trunk/lib/Sema/SemaChecking.cpp Mon Dec 12 16:35:02 2011
>> @@ -4275,7 +4275,7 @@
>>
>> void Sema::CheckArrayAccess(const Expr *BaseExpr, const Expr *IndexExpr,
>>                             bool isSubscript, bool AllowOnePastEnd) {
>> -  const Type* EffectiveType = getElementType(BaseExpr);
>> +  const Type *EffectiveType = getElementType(BaseExpr);
>>   BaseExpr = BaseExpr->IgnoreParenCasts();
>>   IndexExpr = IndexExpr->IgnoreParenCasts();
>>
>> @@ -4381,6 +4381,16 @@
>>     switch (expr->getStmtClass()) {
>>       case Stmt::ArraySubscriptExprClass: {
>>         const ArraySubscriptExpr *ASE = cast<ArraySubscriptExpr>(expr);
>> +        // Suppress the warning if the subscript expression (as identified by
>> +        // the ']' location) and the index expression are both from macro
>> +        // expansions within a system header.
>> +        SourceLocation RBracketLoc = SourceMgr.getSpellingLoc(
>> +            ASE->getRBracketLoc());
>> +        SourceLocation IndexLoc = SourceMgr.getSpellingLoc(
>> +            ASE->getIdx()->IgnoreParens()->getLocStart());
>> +        if (SourceMgr.isFromSameFile(RBracketLoc, IndexLoc) &&
>> +            SourceMgr.isInSystemHeader(RBracketLoc))
>> +          return;
>>         CheckArrayAccess(ASE->getBase(), ASE->getIdx(), true,
>>                          AllowOnePastEnd > 0);
>>         return;
>>
>> Added: cfe/trunk/test/SemaCXX/Inputs/array-bounds-system-header.h
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/Inputs/array-bounds-system-header.h?rev=146430&view=auto
>> ==============================================================================
>> --- cfe/trunk/test/SemaCXX/Inputs/array-bounds-system-header.h (added)
>> +++ cfe/trunk/test/SemaCXX/Inputs/array-bounds-system-header.h Mon Dec 12 16:35:02 2011
>> @@ -0,0 +1,11 @@
>> +// "System header" for testing that -Warray-bounds is properly suppressed in
>> +// certain cases.
>> +
>> +#define BAD_MACRO_1 \
>> +    int i[3]; \
>> +    i[3] = 5
>> +#define BAD_MACRO_2(_b, _i) \
>> +    (_b)[(_i)] = 5
>> +#define QUESTIONABLE_MACRO(_a) \
>> +    sizeof(_a) > 3 ? (_a)[3] = 5 : 5
>> +#define NOP(x) (x)
>>
>> Added: cfe/trunk/test/SemaCXX/array-bounds-system-header.cpp
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/array-bounds-system-header.cpp?rev=146430&view=auto
>> ==============================================================================
>> --- cfe/trunk/test/SemaCXX/array-bounds-system-header.cpp (added)
>> +++ cfe/trunk/test/SemaCXX/array-bounds-system-header.cpp Mon Dec 12 16:35:02 2011
>> @@ -0,0 +1,9 @@
>> +// RUN: %clang_cc1 -isystem %S/Inputs -verify %s
>> +#include <array-bounds-system-header.h>
>> +void test_system_header_macro() {
>> +  BAD_MACRO_1; // no-warning
>> +  char a[3]; // expected-note 2 {{declared here}}
>> +  BAD_MACRO_2(a, 3); // expected-warning {{array index 3}}
>> +  QUESTIONABLE_MACRO(a);
>> +  NOP(a[3] = 5); // expected-warning {{array index 3}}
>> +}
>>
>>
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