Author: Bill Wendling Date: 2022-10-14T14:46:19-07:00 New Revision: 91b3823bd000b1a6ffde96a6363098f59307317a
URL: https://github.com/llvm/llvm-project/commit/91b3823bd000b1a6ffde96a6363098f59307317a DIFF: https://github.com/llvm/llvm-project/commit/91b3823bd000b1a6ffde96a6363098f59307317a.diff LOG: [clang][Sema] Use size of char in bits for void types The extension that allows for pointer arithmetic on 'void' types treats the 'void' as a 'char'. We should use the 'char' size in bits instead of 1 (the number of bytes) to allow warning when pointer arithmetic would go out of bounds. Differential Revision: https://reviews.llvm.org/D135989 Added: Modified: clang/lib/Sema/SemaChecking.cpp clang/test/Sema/array-bounds-ptr-arith.c Removed: ################################################################################ diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp index a1e3db1b57af2..c0ecd7b091000 100644 --- a/clang/lib/Sema/SemaChecking.cpp +++ b/clang/lib/Sema/SemaChecking.cpp @@ -16020,16 +16020,22 @@ void Sema::CheckArrayAccess(const Expr *BaseExpr, const Expr *IndexExpr, llvm::APInt size = ArrayTy->getSize(); if (BaseType != EffectiveType) { - // Make sure we're comparing apples to apples when comparing index to size + // Make sure we're comparing apples to apples when comparing index to + // size. uint64_t ptrarith_typesize = Context.getTypeSize(EffectiveType); uint64_t array_typesize = Context.getTypeSize(BaseType); - // Handle ptrarith_typesize being zero, such as when casting to void* - if (!ptrarith_typesize) ptrarith_typesize = 1; + + // Handle ptrarith_typesize being zero, such as when casting to void*. + // Use the size in bits (what "getTypeSize()" returns) rather than bytes. + if (!ptrarith_typesize) + ptrarith_typesize = Context.getCharWidth(); + if (ptrarith_typesize != array_typesize) { - // There's a cast to a diff erent size type involved + // There's a cast to a diff erent size type involved. uint64_t ratio = array_typesize / ptrarith_typesize; + // TODO: Be smarter about handling cases where array_typesize is not a - // multiple of ptrarith_typesize + // multiple of ptrarith_typesize. if (ptrarith_typesize * ratio == array_typesize) size *= llvm::APInt(size.getBitWidth(), ratio); } diff --git a/clang/test/Sema/array-bounds-ptr-arith.c b/clang/test/Sema/array-bounds-ptr-arith.c index a447f19dfe830..57baf9241cf0e 100644 --- a/clang/test/Sema/array-bounds-ptr-arith.c +++ b/clang/test/Sema/array-bounds-ptr-arith.c @@ -6,13 +6,12 @@ struct ext2_super_block{ unsigned char s_uuid[8]; // expected-note {{declared here}} }; -void* ext2_statfs (struct ext2_super_block *es,int a) -{ - return (void *)es->s_uuid + sizeof(int); // no-warning + +void* ext2_statfs (struct ext2_super_block *es,int a) { + return (void *)es->s_uuid + sizeof(int); // no-warning } -void* broken (struct ext2_super_block *es,int a) -{ - return (void *)es->s_uuid + 80; // expected-warning {{refers past the end of the array}} +void* broken (struct ext2_super_block *es,int a) { + return (void *)es->s_uuid + 9; // expected-warning {{the pointer incremented by 9 refers past the end of the array}} } // Test case reduced from PR11594 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits