[RISCV][MC] Implement evaluateBranch for auipc+jalr pairs (#65480)

This patch implements `MCInstrAnalysis` state in order to be able
analyze auipc+jalr pairs inside `evaluateBranch`.

This is implemented as follows:
- State: array of currently known GPR values;
- Whenever an auipc is detected in `updateState`, update the state value
of RD with the immediate;
- Whenever a jalr is detected in `evaluateBranch`, check if the state
holds a value for RS1 and use that to compute its target.

Note that this is similar to how binutils implements it and the output
of llvm-objdump should now mostly match the one of GNU objdump.

This patch also updates the relevant llvm-objdump patches and adds a new
one testing the output for interleaved auipc+jalr pairs.

1 files changed, 4 insertions, 0 deletions

diff --git a/llvm/tools/llvm-objdump/llvm-objdump.cpp b/llvm/tools/llvm-objdump/llvm-objdump.cpp
index f02bd6a..a112c50 100644
--- a/llvm/tools/llvm-objdump/llvm-objdump.cpp
+++ b/llvm/tools/llvm-objdump/llvm-objdump.cpp
@@ -1322,6 +1322,8 @@ collectLocalBranchTargets(ArrayRef<uint8_t> Bytes, MCInstrAnalysis *MIA,
           !(STI->getTargetTriple().isPPC() && Target == Index))
         Labels[Target] = ("L" + Twine(LabelCount++)).str();
       MIA->updateState(Inst, Index);
+    } else if (!Disassembled && MIA) {
+      MIA->resetState();
     }
     Index += Size;
   }
@@ -2194,6 +2196,8 @@ disassembleObject(ObjectFile &Obj, const ObjectFile &DbgObj,
             }
 
             DT->InstrAnalysis->updateState(Inst, SectionAddr + Index);
+          } else if (!Disassembled && DT->InstrAnalysis) {
+            DT->InstrAnalysis->resetState();
           }
         }