[mips] Add MipsOptionRecord abstraction and use it to implement .reginfo/.MIPS.options

This abstraction allows us to support the various records that can be placed in
the .MIPS.options section in the future. We currently use it to record register
usage information (the ODK_REGINFO record in our ELF64 spec).

Each .MIPS.options record should subclass MipsOptionRecord and provide an
implementation of EmitMipsOptionRecord.

Patch by Matheus Almeida and Toma Tabacu

llvm-svn: 213522

5 files changed, 144 insertions, 44 deletions

diff --git a/llvm/lib/Target/Mips/MCTargetDesc/CMakeLists.txt b/llvm/lib/Target/Mips/MCTargetDesc/CMakeLists.txt
index c14ee355f80..6b3788ca515 100644
--- a/llvm/lib/Target/Mips/MCTargetDesc/CMakeLists.txt
+++ b/llvm/lib/Target/Mips/MCTargetDesc/CMakeLists.txt
@@ -8,5 +8,6 @@ add_llvm_library(LLVMMipsDesc
   MipsMCExpr.cpp
   MipsMCTargetDesc.cpp
   MipsNaClELFStreamer.cpp
+  MipsOptionRecord.cpp
   MipsTargetStreamer.cpp
   )
diff --git a/llvm/lib/Target/Mips/MCTargetDesc/MipsELFStreamer.cpp b/llvm/lib/Target/Mips/MCTargetDesc/MipsELFStreamer.cpp
index fe378292bef..803ab85657d 100644
--- a/llvm/lib/Target/Mips/MCTargetDesc/MipsELFStreamer.cpp
+++ b/llvm/lib/Target/Mips/MCTargetDesc/MipsELFStreamer.cpp
@@ -8,6 +8,30 @@
 //===----------------------------------------------------------------------===//
 
 #include "MipsELFStreamer.h"
+#include "llvm/MC/MCInst.h"
+
+void MipsELFStreamer::EmitInstruction(const MCInst &Inst,
+                                      const MCSubtargetInfo &STI) {
+  MCELFStreamer::EmitInstruction(Inst, STI);
+
+  MCContext &Context = getContext();
+  const MCRegisterInfo *MCRegInfo = Context.getRegisterInfo();
+
+  for (unsigned OpIndex = 0; OpIndex < Inst.getNumOperands(); ++OpIndex) {
+    const MCOperand &Op = Inst.getOperand(OpIndex);
+
+    if (!Op.isReg())
+      continue;
+
+    unsigned Reg = Op.getReg();
+    RegInfoRecord->SetPhysRegUsed(Reg, MCRegInfo);
+  }
+}
+
+void MipsELFStreamer::EmitMipsOptionRecords() {
+  for (const auto &I : MipsOptionRecords)
+    I->EmitMipsOptionRecord();
+}
 
 namespace llvm {
 MCELFStreamer *createMipsELFStreamer(MCContext &Context, MCAsmBackend &MAB,
diff --git a/llvm/lib/Target/Mips/MCTargetDesc/MipsELFStreamer.h b/llvm/lib/Target/Mips/MCTargetDesc/MipsELFStreamer.h
index 641f8cf7af2..58863be9cc2 100644
--- a/llvm/lib/Target/Mips/MCTargetDesc/MipsELFStreamer.h
+++ b/llvm/lib/Target/Mips/MCTargetDesc/MipsELFStreamer.h
@@ -15,8 +15,10 @@
 #ifndef MIPSELFSTREAMER_H
 #define MIPSELFSTREAMER_H
 
+#include "MipsOptionRecord.h"
+#include "llvm/ADT/SmallVector.h"
 #include "llvm/MC/MCELFStreamer.h"
-#include "llvm/Support/raw_ostream.h"
+#include <memory>
 
 namespace llvm {
 class MCAsmBackend;
@@ -25,13 +27,27 @@ class MCContext;
 class MCSubtargetInfo;
 
 class MipsELFStreamer : public MCELFStreamer {
+  SmallVector<std::unique_ptr<MipsOptionRecord>, 8> MipsOptionRecords;
+  MipsRegInfoRecord *RegInfoRecord;
 
 public:
   MipsELFStreamer(MCContext &Context, MCAsmBackend &MAB, raw_ostream &OS,
                   MCCodeEmitter *Emitter, const MCSubtargetInfo &STI)
-      : MCELFStreamer(Context, MAB, OS, Emitter) {}
+      : MCELFStreamer(Context, MAB, OS, Emitter) {
 
-  virtual ~MipsELFStreamer() {}
+    RegInfoRecord = new MipsRegInfoRecord(this, Context, STI);
+    MipsOptionRecords.push_back(
+        std::unique_ptr<MipsRegInfoRecord>(RegInfoRecord));
+  }
+
+  /// Overriding this function allows us to add arbitrary behaviour before the
+  /// \p Inst is actually emitted. For example, we can inspect the operands and
+  /// gather sufficient information that allows us to reason about the register
+  /// usage for the translation unit.
+  void EmitInstruction(const MCInst &Inst, const MCSubtargetInfo &STI) override;
+
+  /// Emits all the option records stored up until the point it's called.
+  void EmitMipsOptionRecords();
 };
 
 MCELFStreamer *createMipsELFStreamer(MCContext &Context, MCAsmBackend &MAB,
diff --git a/llvm/lib/Target/Mips/MCTargetDesc/MipsOptionRecord.cpp b/llvm/lib/Target/Mips/MCTargetDesc/MipsOptionRecord.cpp
new file mode 100644
index 00000000000..0ef22082132
--- /dev/null
+++ b/llvm/lib/Target/Mips/MCTargetDesc/MipsOptionRecord.cpp
@@ -0,0 +1,92 @@
+//===-- MipsOptionRecord.cpp - Abstraction for storing information --------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "MipsOptionRecord.h"
+#include "MipsELFStreamer.h"
+#include "llvm/MC/MCSectionELF.h"
+
+using namespace llvm;
+
+void MipsRegInfoRecord::EmitMipsOptionRecord() {
+  MCAssembler &MCA = Streamer->getAssembler();
+  Triple T(STI.getTargetTriple());
+  uint64_t Features = STI.getFeatureBits();
+
+  Streamer->PushSection();
+
+  // We need to distinguish between N64 and the rest because at the moment
+  // we don't emit .Mips.options for other ELFs other than N64.
+  // Since .reginfo has the same information as .Mips.options (ODK_REGINFO),
+  // we can use the same abstraction (MipsRegInfoRecord class) to handle both.
+  if (Features & Mips::FeatureN64) {
+    // The EntrySize value of 1 seems strange since the records are neither
+    // 1-byte long nor fixed length but it matches the value GAS emits.
+    const MCSectionELF *Sec =
+        Context.getELFSection(".MIPS.options", ELF::SHT_MIPS_OPTIONS,
+                              ELF::SHF_ALLOC | ELF::SHF_MIPS_NOSTRIP,
+                              SectionKind::getMetadata(), 1, "");
+    MCA.getOrCreateSectionData(*Sec).setAlignment(8);
+    Streamer->SwitchSection(Sec);
+
+    Streamer->EmitIntValue(1, 1);  // kind
+    Streamer->EmitIntValue(40, 1); // size
+    Streamer->EmitIntValue(0, 2);  // section
+    Streamer->EmitIntValue(0, 4);  // info
+    Streamer->EmitIntValue(ri_gprmask, 4);
+    Streamer->EmitIntValue(0, 4); // pad
+    Streamer->EmitIntValue(ri_cprmask[0], 4);
+    Streamer->EmitIntValue(ri_cprmask[1], 4);
+    Streamer->EmitIntValue(ri_cprmask[2], 4);
+    Streamer->EmitIntValue(ri_cprmask[3], 4);
+    Streamer->EmitIntValue(ri_gp_value, 8);
+  } else {
+    const MCSectionELF *Sec =
+        Context.getELFSection(".reginfo", ELF::SHT_MIPS_REGINFO, ELF::SHF_ALLOC,
+                              SectionKind::getMetadata(), 24, "");
+    MCA.getOrCreateSectionData(*Sec)
+        .setAlignment(Features & Mips::FeatureN32 ? 8 : 4);
+    Streamer->SwitchSection(Sec);
+
+    Streamer->EmitIntValue(ri_gprmask, 4);
+    Streamer->EmitIntValue(ri_cprmask[0], 4);
+    Streamer->EmitIntValue(ri_cprmask[1], 4);
+    Streamer->EmitIntValue(ri_cprmask[2], 4);
+    Streamer->EmitIntValue(ri_cprmask[3], 4);
+    assert((ri_gp_value & 0xffffffff) == ri_gp_value);
+    Streamer->EmitIntValue(ri_gp_value, 4);
+  }
+
+  Streamer->PopSection();
+}
+
+void MipsRegInfoRecord::SetPhysRegUsed(unsigned Reg,
+                                       const MCRegisterInfo *MCRegInfo) {
+  unsigned Value = 0;
+
+  for (MCSubRegIterator SubRegIt(Reg, MCRegInfo, true); SubRegIt.isValid();
+       ++SubRegIt) {
+    unsigned CurrentSubReg = *SubRegIt;
+
+    unsigned EncVal = MCRegInfo->getEncodingValue(CurrentSubReg);
+    Value |= 1 << EncVal;
+
+    if (GPR32RegClass->contains(CurrentSubReg) ||
+        GPR64RegClass->contains(CurrentSubReg))
+      ri_gprmask |= Value;
+    else if (FGR32RegClass->contains(CurrentSubReg) ||
+             FGR64RegClass->contains(CurrentSubReg) ||
+             AFGR64RegClass->contains(CurrentSubReg) ||
+             MSA128BRegClass->contains(CurrentSubReg))
+      ri_cprmask[1] |= Value;
+    else if (COP2RegClass->contains(CurrentSubReg))
+      ri_cprmask[2] |= Value;
+    else if (COP3RegClass->contains(CurrentSubReg))
+      ri_cprmask[3] |= Value;
+  }
+}
diff --git a/llvm/lib/Target/Mips/MCTargetDesc/MipsTargetStreamer.cpp b/llvm/lib/Target/Mips/MCTargetDesc/MipsTargetStreamer.cpp
index 4e7216921b9..4a178e2df7a 100644
--- a/llvm/lib/Target/Mips/MCTargetDesc/MipsTargetStreamer.cpp
+++ b/llvm/lib/Target/Mips/MCTargetDesc/MipsTargetStreamer.cpp
@@ -12,6 +12,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "InstPrinter/MipsInstPrinter.h"
+#include "MipsELFStreamer.h"
 #include "MipsMCTargetDesc.h"
 #include "MipsTargetObjectFile.h"
 #include "MipsTargetStreamer.h"
@@ -323,11 +324,7 @@ void MipsTargetELFStreamer::emitLabel(MCSymbol *Symbol) {
 
 void MipsTargetELFStreamer::finish() {
   MCAssembler &MCA = getStreamer().getAssembler();
-  MCContext &Context = MCA.getContext();
-  MCStreamer &OS = getStreamer();
-  const MCObjectFileInfo &OFI = *Context.getObjectFileInfo();
-  Triple T(STI.getTargetTriple());
-  uint64_t Features = STI.getFeatureBits();
+  const MCObjectFileInfo &OFI = *MCA.getContext().getObjectFileInfo();
 
   // .bss, .text and .data are always at least 16-byte aligned.
   MCSectionData &TextSectionData =
@@ -341,42 +338,12 @@ void MipsTargetELFStreamer::finish() {
   DataSectionData.setAlignment(std::max(16u, DataSectionData.getAlignment()));
   BSSSectionData.setAlignment(std::max(16u, BSSSectionData.getAlignment()));
 
-  if (T.isArch64Bit() && (Features & Mips::FeatureN64)) {
-    // The EntrySize value of 1 seems strange since the records are neither
-    // 1-byte long nor fixed length but it matches the value GAS emits.
-    const MCSectionELF *Sec =
-        Context.getELFSection(".MIPS.options", ELF::SHT_MIPS_OPTIONS,
-                              ELF::SHF_ALLOC | ELF::SHF_MIPS_NOSTRIP,
-                              SectionKind::getMetadata(), 1, "");
-    MCA.getOrCreateSectionData(*Sec).setAlignment(8);
-    OS.SwitchSection(Sec);
-
-    OS.EmitIntValue(1, 1);  // kind
-    OS.EmitIntValue(40, 1); // size
-    OS.EmitIntValue(0, 2);  // section
-    OS.EmitIntValue(0, 4);  // info
-    OS.EmitIntValue(0, 4);  // ri_gprmask
-    OS.EmitIntValue(0, 4);  // pad
-    OS.EmitIntValue(0, 4);  // ri_cpr[0]mask
-    OS.EmitIntValue(0, 4);  // ri_cpr[1]mask
-    OS.EmitIntValue(0, 4);  // ri_cpr[2]mask
-    OS.EmitIntValue(0, 4);  // ri_cpr[3]mask
-    OS.EmitIntValue(0, 8);  // ri_gp_value
-  } else {
-    const MCSectionELF *Sec =
-        Context.getELFSection(".reginfo", ELF::SHT_MIPS_REGINFO, ELF::SHF_ALLOC,
-                              SectionKind::getMetadata(), 24, "");
-    MCA.getOrCreateSectionData(*Sec)
-        .setAlignment(Features & Mips::FeatureN32 ? 8 : 4);
-    OS.SwitchSection(Sec);
-
-    OS.EmitIntValue(0, 4); // ri_gprmask
-    OS.EmitIntValue(0, 4); // ri_cpr[0]mask
-    OS.EmitIntValue(0, 4); // ri_cpr[1]mask
-    OS.EmitIntValue(0, 4); // ri_cpr[2]mask
-    OS.EmitIntValue(0, 4); // ri_cpr[3]mask
-    OS.EmitIntValue(0, 4); // ri_gp_value
-  }
+  // Emit all the option records.
+  // At the moment we are only emitting .Mips.options (ODK_REGINFO) and
+  // .reginfo.
+  MipsELFStreamer &MEF = static_cast<MipsELFStreamer &>(Streamer);
+  MEF.EmitMipsOptionRecords();
+
   emitMipsAbiFlags();
 }