[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

[Chris Lattner]

On Dec 13, 2011, at 3:08 PM, Matt Beaumont-Gay wrote:

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

In the meantime, would it be best to temporarily revert the patch so that other performance regressions aren't lost in this noise?

-Chris

> 
> 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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>> 
> 
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