Author: jrtc27 Date: Tue Oct 8 04:34:02 2019 New Revision: 374035 URL: http://llvm.org/viewvc/llvm-project?rev=374035&view=rev Log: [Diagnostics] Silence -Wsizeof-array-div for character buffers
Summary: Character buffers are sometimes used to represent a pool of memory that contains non-character objects, due to them being synonymous with a stream of bytes on almost all modern architectures. Often, when interacting with hardware devices, byte buffers are therefore used as an intermediary and so we can end Character buffers are sometimes used to represent a pool of memory that contains non-character objects, due to them being synonymous with a stream of bytes on almost all modern architectures. Often, when interacting with hardware devices, byte buffers are therefore used as an intermediary and so we can end up generating lots of false-positives. Moreover, due to the ability of character pointers to alias non-character pointers, the strict aliasing violations that would generally be implied by the calculations caught by the warning (if the calculation itself is in fact correct) do not apply here, and so although the length calculation may be wrong, that is the only possible issue. Reviewers: rsmith, xbolva00, thakis Reviewed By: xbolva00, thakis Subscribers: thakis, lebedev.ri, cfe-commits Tags: #clang Differential Revision: https://reviews.llvm.org/D68526 Modified: cfe/trunk/lib/Sema/SemaExpr.cpp cfe/trunk/test/Sema/div-sizeof-array.cpp Modified: cfe/trunk/lib/Sema/SemaExpr.cpp URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaExpr.cpp?rev=374035&r1=374034&r2=374035&view=diff ============================================================================== --- cfe/trunk/lib/Sema/SemaExpr.cpp (original) +++ cfe/trunk/lib/Sema/SemaExpr.cpp Tue Oct 8 04:34:02 2019 @@ -9197,6 +9197,7 @@ static void DiagnoseDivisionSizeofPointe QualType ArrayElemTy = ArrayTy->getElementType(); if (ArrayElemTy != S.Context.getBaseElementType(ArrayTy) || ArrayElemTy->isDependentType() || RHSTy->isDependentType() || + ArrayElemTy->isCharType() || S.Context.getTypeSize(ArrayElemTy) == S.Context.getTypeSize(RHSTy)) return; S.Diag(Loc, diag::warn_division_sizeof_array) Modified: cfe/trunk/test/Sema/div-sizeof-array.cpp URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/div-sizeof-array.cpp?rev=374035&r1=374034&r2=374035&view=diff ============================================================================== --- cfe/trunk/test/Sema/div-sizeof-array.cpp (original) +++ cfe/trunk/test/Sema/div-sizeof-array.cpp Tue Oct 8 04:34:02 2019 @@ -25,6 +25,8 @@ void test(void) { int a10 = sizeof(arr3) / sizeof(char); int a11 = sizeof(arr2) / (sizeof(unsigned)); int a12 = sizeof(arr) / (sizeof(short)); + int a13 = sizeof(arr3) / sizeof(p); + int a14 = sizeof(arr3) / sizeof(int); int arr4[10][12]; int b1 = sizeof(arr4) / sizeof(arr2[12]); _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
