Currently, if an array element type size is 0, the number of
array elements will be set to 0, regardless of what user
specified. This implementation is done in the beginning where
BTF is mostly used to calculate the member offset.
For example,
struct s {};
struct s1 {
int b;
struct s a[2];
};
struct s1 s1;
The BTF will have struct "s1" member "a" with element count 0.
Now BTF types are used for compile-once and run-everywhere
relocations and we need more precise type representation
for type comparison. Andrii reported the issue as there
are differences between original structure and BTF-generated
structure.
This patch made the change to correctly assign "2"
as the number elements of member "a".
Some dead codes related to ElemSize compuation are also removed.
Differential Revision: https://reviews.llvm.org/D67979
llvm-svn: 372785
For multi-dimensional array like below
int a[2][3];
the previous implementation generates BTF_KIND_ARRAY type
like below:
. element_type: int
. index_type: unsigned int
. number of elements: 6
This is not the best way to represent arrays, esp.,
when converting BTF back to headers and users will see
int a[6];
instead.
This patch generates proper support for multi-dimensional arrays.
For "int a[2][3]", the two BTF_KIND_ARRAY types will be
generated:
Type #n:
. element_type: int
. index_type: unsigned int
. number of elements: 3
Type #(n+1):
. element_type: #n
. index_type: unsigned int
. number of elements: 2
The linux kernel already supports such a multi-dimensional
array representation properly.
Signed-off-by: Yonghong Song <yhs@fb.com>
Differential Revision: https://reviews.llvm.org/D59943
llvm-svn: 357215
If There is no types/non-empty strings, do not generate
.BTF section. If there is no func_info/line_info, do
not generate .BTF.ext section.
Signed-off-by: Yonghong Song <yhs@fb.com>
Differential Revision: https://reviews.llvm.org/D58936
llvm-svn: 355360
