[BPF] Permit all user instructed offset relocatiions

Currently, not all user specified relocations
(with clang intrinsic __builtin_preserve_access_index())
will turn into relocations.

In the current implementation, a __builtin_preserve_access_index()
chain is turned into relocation only if the result of the clang
intrinsic is used in a function call or a nonzero offset computation
of getelementptr. For all other cases, the relocatiion request
is ignored and the __builtin_preserve_access_index() is turned
into regular getelementptr instructions.
The main reason is to mimic bpf_probe_read() requirement.

But there are other use cases where relocatable offset is
generated but not used for bpf_probe_read(). This patch
relaxed previous constraints when to generate relocations.
Now, all user __builtin_preserve_access_index() will have
relocations generated.

Differential Revision: https://reviews.llvm.org/D67688

llvm-svn: 372198

1 files changed, 6 insertions, 0 deletions

diff --git a/llvm/lib/Target/BPF/BPFAbstractMemberAccess.cpp b/llvm/lib/Target/BPF/BPFAbstractMemberAccess.cpp
index e4f29fbb3db..c682c46fe31 100644
--- a/llvm/lib/Target/BPF/BPFAbstractMemberAccess.cpp
+++ b/llvm/lib/Target/BPF/BPFAbstractMemberAccess.cpp
@@ -375,6 +375,8 @@ void BPFAbstractMemberAccess::traceAICall(CallInst *Call, uint32_t Kind,
         traceGEP(GI, Call, Kind, ParentMeta, ParentAI);
       else
         BaseAICalls[Call] = Kind;
+    } else {
+      BaseAICalls[Call] = Kind;
     }
   }
 }
@@ -406,6 +408,8 @@ void BPFAbstractMemberAccess::traceBitCast(BitCastInst *BitCast,
         traceGEP(GI, Parent, Kind, ParentMeta, ParentAI);
       else
         BaseAICalls[Parent] = Kind;
+    } else {
+      BaseAICalls[Parent] = Kind;
     }
   }
 }
@@ -436,6 +440,8 @@ void BPFAbstractMemberAccess::traceGEP(GetElementPtrInst *GEP, CallInst *Parent,
         traceGEP(GI, Parent, Kind, ParentMeta, ParentAI);
       else
         BaseAICalls[Parent] = Kind;
+    } else {
+      BaseAICalls[Parent] = Kind;
     }
   }
 }