[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

[Peter Cooper]

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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