[MC][mips] Add MipsMCInstrAnalysis class and register it as MC instruction analyzer

[atanasyan]

Summary

The MipsMCInstrAnalysis class overrides the evaluateBranch method and calculates target addresses for branch and calls instructions. That allows llvm-objdump to print functions' names in branch instructions in the disassemble mode.

[• rafael]

LGTM

llvm/trunk/lib/Target/Mips/MCTargetDesc/MipsMCTargetDesc.cpp

 #include "MipsELFStreamer.h"
 #include "MipsMCAsmInfo.h"
 #include "MipsMCNaCl.h"
 #include "MipsMCTargetDesc.h"
 #include "MipsTargetStreamer.h"
 #include "llvm/ADT/Triple.h"
 #include "llvm/MC/MCCodeGenInfo.h"
 #include "llvm/MC/MCELFStreamer.h"
+#include "llvm/MC/MCInstrAnalysis.h"
 #include "llvm/MC/MCInstrInfo.h"
 #include "llvm/MC/MCRegisterInfo.h"
 #include "llvm/MC/MCSubtargetInfo.h"
 #include "llvm/MC/MCSymbol.h"
 #include "llvm/MC/MachineLocation.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/FormattedStream.h"
static MCTargetStreamer *createMipsNullTargetStreamer(MCStreamer &S) {
   return new MipsTargetStreamer(S);
 }
 
 static MCTargetStreamer *
 createMipsObjectTargetStreamer(MCStreamer &S, const MCSubtargetInfo &STI) {
   return new MipsTargetELFStreamer(S, STI);
 }
 
+namespace {
+
+class MipsMCInstrAnalysis : public MCInstrAnalysis {
+public:
+  MipsMCInstrAnalysis(const MCInstrInfo *Info) : MCInstrAnalysis(Info) {}
+
+  bool evaluateBranch(const MCInst &Inst, uint64_t Addr, uint64_t Size,
+                      uint64_t &Target) const override {
+    unsigned NumOps = Inst.getNumOperands();
+    if (NumOps == 0)
+      return false;
+    switch (Info->get(Inst.getOpcode()).OpInfo[NumOps - 1].OperandType) {
+    case MCOI::OPERAND_UNKNOWN:
+    case MCOI::OPERAND_IMMEDIATE:
+      // jal, bal ...
+      Target = Inst.getOperand(NumOps - 1).getImm();
+      return true;
+    case MCOI::OPERAND_PCREL:
+      // b, j, beq ...
+      Target = Addr + Inst.getOperand(NumOps - 1).getImm();
+      return true;
+    default:
+      return false;
+    }
+  }
+};
+}
+
+static MCInstrAnalysis *createMipsMCInstrAnalysis(const MCInstrInfo *Info) {
+  return new MipsMCInstrAnalysis(Info);
+}
+
 extern "C" void LLVMInitializeMipsTargetMC() {
   for (Target *T : {&TheMipsTarget, &TheMipselTarget, &TheMips64Target,
                     &TheMips64elTarget}) {
     // Register the MC asm info.
     RegisterMCAsmInfoFn X(*T, createMipsMCAsmInfo);
 
     // Register the MC codegen info.
     TargetRegistry::RegisterMCCodeGenInfo(*T, createMipsMCCodeGenInfo);
for (Target *T : {&TheMipsTarget, &TheMipselTarget, &TheMips64Target,
     TargetRegistry::RegisterAsmTargetStreamer(*T, createMipsAsmTargetStreamer);
 
     TargetRegistry::RegisterNullTargetStreamer(*T,
                                                createMipsNullTargetStreamer);
 
     // Register the MC subtarget info.
     TargetRegistry::RegisterMCSubtargetInfo(*T, createMipsMCSubtargetInfo);
 
+    // Register the MC instruction analyzer.
+    TargetRegistry::RegisterMCInstrAnalysis(*T, createMipsMCInstrAnalysis);
+
     // Register the MCInstPrinter.
     TargetRegistry::RegisterMCInstPrinter(*T, createMipsMCInstPrinter);
 
     TargetRegistry::RegisterObjectTargetStreamer(
         *T, createMipsObjectTargetStreamer);
   }
 
   // Register the MC Code Emitter

llvm/trunk/test/MC/Mips/instr-analysis.s

+# RUN: llvm-mc -filetype=obj -triple=mips-unknown-linux %s -o - \
+# RUN:   | llvm-objdump -d - | FileCheck %s
+
+# CHECK:      foo:
+# CHECK-NEXT:        0:       0c 00 00 02     jal     8 <loc1>
+# CHECK-NEXT:        4:       00 00 00 00     nop
+#
+# CHECK:      loc1:
+# CHECK-NEXT:        8:       0c 00 00 06     jal     24 <loc3>
+# CHECK-NEXT:        c:       00 00 00 00     nop
+#
+# CHECK:      loc2:
+# CHECK-NEXT:       10:       10 00 ff fd     b       -8 <loc1>
+# CHECK-NEXT:       14:       00 00 00 00     nop
+#
+# CHECK:      loc3:
+# CHECK-NEXT:       18:       10 43 ff fd     beq     $2, $3, -8 <loc2>
+# CHECK-NEXT:       1c:       00 00 00 00     nop
+# CHECK-NEXT:       20:       04 11 ff f9     bal     -24 <loc1>
+# CHECK-NEXT:       24:       00 00 00 00     nop
+# CHECK-NEXT:       28:       08 00 00 04     j       16 <loc2>
+
+  .text
+  .globl foo
+  .ent foo
+foo:
+  jal loc1
+loc1:
+  jal loc3
+loc2:
+  b   loc1
+loc3:
+  beq $2, $3, loc2
+  bal loc1
+  j   loc2
+  .end foo