[PATCH] D63847: [MC] Add MCInstrAnalysis::evaluateMemoryOperandAddress

[Seiya Nuta via Phabricator via llvm-commits]

seiya created this revision.
Herald added subscribers: llvm-commits, hiraditya.
Herald added a project: LLVM.

Add a new method which tries to compute the target address referenced by an operand.

This patch supports x86_64 RIP-relative addressing for now.

It is necessary to print referenced symbol names in llvm-objdump.


https://reviews.llvm.org/D63847

Files:
  llvm/include/llvm/MC/MCInstrAnalysis.h
  llvm/lib/MC/MCInstrAnalysis.cpp
  llvm/lib/Target/X86/MCTargetDesc/X86MCTargetDesc.cpp


Index: llvm/lib/Target/X86/MCTargetDesc/X86MCTargetDesc.cpp
===================================================================
--- llvm/lib/Target/X86/MCTargetDesc/X86MCTargetDesc.cpp
+++ llvm/lib/Target/X86/MCTargetDesc/X86MCTargetDesc.cpp
@@ -399,6 +399,8 @@
   findPltEntries(uint64_t PltSectionVA, ArrayRef<uint8_t> PltContents,
                  uint64_t GotSectionVA,
                  const Triple &TargetTriple) const override;
+  bool evaluateMemoryOperandAddress(const MCInst &Inst, uint64_t Addr,
+                                                 uint64_t Size, uint64_t &Target) const override;
 };
 
 #define GET_STIPREDICATE_DEFS_FOR_MC_ANALYSIS
@@ -514,6 +516,30 @@
   }
 }
 
+bool X86MCInstrAnalysis::evaluateMemoryOperandAddress(const MCInst &Inst, uint64_t Addr,
+                                            uint64_t Size, uint64_t &Target) const {
+  MCInstrDesc Opcode = Info->get(Inst.getOpcode());
+  int MemOpStart = X86II::getMemoryOperandNo(Opcode.TSFlags);
+  if (MemOpStart == -1)
+    return false;
+  MemOpStart += X86II::getOperandBias(Opcode);
+
+  const MCOperand &BaseReg = Inst.getOperand(MemOpStart + X86::AddrBaseReg);
+  const MCOperand &IndexReg = Inst.getOperand(MemOpStart + X86::AddrIndexReg);
+  const MCOperand &ScaleAmt = Inst.getOperand(MemOpStart + X86::AddrScaleAmt);
+  const MCOperand &Disp = Inst.getOperand(MemOpStart + X86::AddrDisp);
+  if (IndexReg.getReg() != 0 || ScaleAmt.getImm() != 1 || !Disp.isImm())
+    return false;
+
+  // RIP-relative addressing
+  if (BaseReg.getReg() == X86::RIP) {
+    Target = Addr + Size + Disp.getImm();
+    return true;
+  }
+
+  return false;
+}
+
 } // end of namespace X86_MC
 
 } // end of namespace llvm
Index: llvm/lib/MC/MCInstrAnalysis.cpp
===================================================================
--- llvm/lib/MC/MCInstrAnalysis.cpp
+++ llvm/lib/MC/MCInstrAnalysis.cpp
@@ -33,3 +33,8 @@
   Target = Addr+Size+Imm;
   return true;
 }
+
+bool MCInstrAnalysis::evaluateMemoryOperandAddress(const MCInst &Inst, uint64_t Addr,
+                                                   uint64_t Size, uint64_t &Target) const {
+  return false;
+}
Index: llvm/include/llvm/MC/MCInstrAnalysis.h
===================================================================
--- llvm/include/llvm/MC/MCInstrAnalysis.h
+++ llvm/include/llvm/MC/MCInstrAnalysis.h
@@ -152,6 +152,12 @@
   evaluateBranch(const MCInst &Inst, uint64_t Addr, uint64_t Size,
                  uint64_t &Target) const;
 
+  /// Given an instruction tries to get the address of a memory operand. Returns
+  /// true on success, and the address in Target.
+  virtual bool
+  evaluateMemoryOperandAddress(const MCInst &Inst, uint64_t Addr, uint64_t Size,
+                               uint64_t &Target) const;
+
   /// Returns (PLT virtual address, GOT virtual address) pairs for PLT entries.
   virtual std::vector<std::pair<uint64_t, uint64_t>>
   findPltEntries(uint64_t PltSectionVA, ArrayRef<uint8_t> PltContents,


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