[BPF] add proper multi-dimensional array support

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

1 files changed, 1 insertions, 2 deletions

diff --git a/llvm/lib/Target/BPF/BTFDebug.h b/llvm/lib/Target/BPF/BTFDebug.h
index 58fba7f5a9c..7d7a1d9b707 100644
--- a/llvm/lib/Target/BPF/BTFDebug.h
+++ b/llvm/lib/Target/BPF/BTFDebug.h
@@ -100,11 +100,10 @@ public:
 
 /// Handle array type.
 class BTFTypeArray : public BTFTypeBase {
-  const DICompositeType *ATy;
   struct BTF::BTFArray ArrayInfo;
 
 public:
-  BTFTypeArray(const DICompositeType *ATy);
+  BTFTypeArray(uint32_t ElemTypeId, uint32_t NumElems);
   uint32_t getSize() { return BTFTypeBase::getSize() + BTF::BTFArraySize; }
   void completeType(BTFDebug &BDebug);
   void emitType(MCStreamer &OS);