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The extension that allows for pointer arithmetic on 'void' types treats
the 'void' as a 'char'. We should use the 'char' size instead of one in
this case to allow warning when pointer arithmetic would go out of
bounds.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D135989
Files:
clang/lib/Sema/SemaChecking.cpp
clang/test/Sema/array-bounds-ptr-arith.c
Index: clang/test/Sema/array-bounds-ptr-arith.c
===================================================================
--- clang/test/Sema/array-bounds-ptr-arith.c
+++ 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 (that contains 8 elements)}}
+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 (that contains 8 elements)}}
}
// Test case reduced from PR11594
Index: clang/lib/Sema/SemaChecking.cpp
===================================================================
--- clang/lib/Sema/SemaChecking.cpp
+++ clang/lib/Sema/SemaChecking.cpp
@@ -16020,16 +16020,21 @@
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*.
+ if (!ptrarith_typesize)
+ ptrarith_typesize = Context.getCharWidth();
+
if (ptrarith_typesize != array_typesize) {
- // There's a cast to a different size type involved
+ // There's a cast to a different 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);
}
Index: clang/test/Sema/array-bounds-ptr-arith.c
===================================================================
--- clang/test/Sema/array-bounds-ptr-arith.c
+++ 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 (that contains 8 elements)}}
+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 (that contains 8 elements)}}
}
// Test case reduced from PR11594
Index: clang/lib/Sema/SemaChecking.cpp
===================================================================
--- clang/lib/Sema/SemaChecking.cpp
+++ clang/lib/Sema/SemaChecking.cpp
@@ -16020,16 +16020,21 @@
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*.
+ if (!ptrarith_typesize)
+ ptrarith_typesize = Context.getCharWidth();
+
if (ptrarith_typesize != array_typesize) {
- // There's a cast to a different size type involved
+ // There's a cast to a different 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);
}
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