From 79d84987ff2b54fb512c1b78bbed17f9b387cb62 Mon Sep 17 00:00:00 2001
From: Fangrui Song <maskray@google.com>
Date: Wed, 29 Apr 2020 23:17:14 -0700
Subject: [PATCH] [MC] Move MCInstrAnalysis::evaluateBranch to
 X86MCInstrAnalysis::evaluateBranch

The generic implementation is actually specific to x86. It assumes the
offset is relative to the end of the instruction and the immediate is
not scaled (which is false on most RISC).
---
 lib/MC/MCInstrAnalysis.cpp                      | 13 ++++---------
 lib/Target/X86/MCTargetDesc/X86MCTargetDesc.cpp | 12 ++++++++++++
 2 files changed, 16 insertions(+), 9 deletions(-)

diff --git a/lib/MC/MCInstrAnalysis.cpp b/lib/MC/MCInstrAnalysis.cpp
index 54741fdd686..a7dc0626d0a 100644
--- a/lib/MC/MCInstrAnalysis.cpp
+++ b/lib/MC/MCInstrAnalysis.cpp
@@ -23,15 +23,10 @@ bool MCInstrAnalysis::clearsSuperRegisters(const MCRegisterInfo &MRI,
   return false;
 }
 
-bool MCInstrAnalysis::evaluateBranch(const MCInst &Inst, uint64_t Addr,
-                                     uint64_t Size, uint64_t &Target) const {
-  if (Inst.getNumOperands() == 0 ||
-      Info->get(Inst.getOpcode()).OpInfo[0].OperandType != MCOI::OPERAND_PCREL)
-    return false;
-
-  int64_t Imm = Inst.getOperand(0).getImm();
-  Target = Addr+Size+Imm;
-  return true;
+bool MCInstrAnalysis::evaluateBranch(const MCInst & /*Inst*/, uint64_t /*Addr*/,
+                                     uint64_t /*Size*/,
+                                     uint64_t & /*Target*/) const {
+  return false;
 }
 
 Optional<uint64_t>
diff --git a/lib/Target/X86/MCTargetDesc/X86MCTargetDesc.cpp b/lib/Target/X86/MCTargetDesc/X86MCTargetDesc.cpp
index 20b8b855430..b056cab7fa7 100644
--- a/lib/Target/X86/MCTargetDesc/X86MCTargetDesc.cpp
+++ b/lib/Target/X86/MCTargetDesc/X86MCTargetDesc.cpp
@@ -400,6 +400,9 @@ public:
   findPltEntries(uint64_t PltSectionVA, ArrayRef<uint8_t> PltContents,
                  uint64_t GotSectionVA,
                  const Triple &TargetTriple) const override;
+
+  bool evaluateBranch(const MCInst &Inst, uint64_t Addr, uint64_t Size,
+                      uint64_t &Target) const override;
   Optional<uint64_t> evaluateMemoryOperandAddress(const MCInst &Inst,
                                                   uint64_t Addr,
                                                   uint64_t Size) const override;
@@ -518,6 +521,15 @@ std::vector<std::pair<uint64_t, uint64_t>> X86MCInstrAnalysis::findPltEntries(
     }
 }
 
+bool X86MCInstrAnalysis::evaluateBranch(const MCInst &Inst, uint64_t Addr,
+                                        uint64_t Size, uint64_t &Target) const {
+  if (Inst.getNumOperands() == 0 ||
+      Info->get(Inst.getOpcode()).OpInfo[0].OperandType != MCOI::OPERAND_PCREL)
+    return false;
+  Target = Addr + Size + Inst.getOperand(0).getImm();
+  return true;
+}
+
 Optional<uint64_t> X86MCInstrAnalysis::evaluateMemoryOperandAddress(
     const MCInst &Inst, uint64_t Addr, uint64_t Size) const {
   const MCInstrDesc &MCID = Info->get(Inst.getOpcode());