[mips][microMIPS] Mark symbols as microMIPS if necessary

[zoran.jovanovic]

Summary

Implements marking of all necessary symbols as microMIPS.

[zoran.jovanovic]

Provided context in patch.

[dsanders]

This needs to be reviewed on llvm-commits since it touches common code.

The obvious question is do we really need to change common code? We already subclass MCStreamer (see MipsELFStreamer), so could we override the things we need to there?

lib/Target/Mips/MCTargetDesc/MipsTargetStreamer.cpp

236 ↗

(On Diff #9437)

Use a range-based for loop.

[zoran.jovanovic]

New patch version that modifies MipsELFStreamer instead of using MCTargetStreamer methods.

[sstankovic]

lib/Target/Mips/MCTargetDesc/MipsELFStreamer.cpp

12

For one of my previous patches I received a comment that #includes should be sorted. So "llvm/MC/MCELF.h" should be placed before "llvm/MC/MCInst.h".

38

Type is unused.

lib/Target/Mips/MCTargetDesc/MipsELFStreamer.h

55

This line crosses the 80 columns limit. (There are other lines in the patch that also don't fit in 80 columns.)

[dsanders]

Resigning from review to remove it from my queue. It's an old patch and a similar change was committed.

[zoran.jovanovic]

Replaced by:

[zoran.jovanovic]

Replaced by:
http://reviews.llvm.org/D6039

include/llvm/MC/MCStreamer.h

bool SubSection(const MCExpr *Subsection) {
     SwitchSection(SectionStack.back().first.first, Subsection);
     return true;
   }
 
   /// SwitchSection - Set the current section where code is being emitted to
   /// @p Section.  This is required to update CurSection.
   ///
   /// This corresponds to assembler directives like .section, .text, etc.
-  void SwitchSection(const MCSection *Section,
+  virtual void SwitchSection(const MCSection *Section,
                              const MCExpr *Subsection = nullptr) {
     assert(Section && "Cannot switch to a null section!");
     MCSectionSubPair curSection = SectionStack.back().first;
     SectionStack.back().second = curSection;
     if (MCSectionSubPair(Section, Subsection) != curSection) {
       SectionStack.back().first = MCSectionSubPair(Section, Subsection);
       ChangeSection(Section, Subsection);
     }
   }

lib/Target/Mips/MCTargetDesc/MipsELFStreamer.h

 class MCAsmBackend;
 class MCCodeEmitter;
 class MCContext;
 class MCSubtargetInfo;
 
 class MipsELFStreamer : public MCELFStreamer {
   SmallVector<std::unique_ptr<MipsOptionRecord>, 8> MipsOptionRecords;
   MipsRegInfoRecord *RegInfoRecord;
+  SmallVector<MCSymbol*, 4> Labels;
+
 
 public:
   MipsELFStreamer(MCContext &Context, MCAsmBackend &MAB, raw_ostream &OS,
                   MCCodeEmitter *Emitter, const MCSubtargetInfo &STI)
       : MCELFStreamer(Context, MAB, OS, Emitter) {
 
     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;
 
+  /// Overriding this function allows us to record all labels that should be
+  /// marked as microMIPS. based on this data marking is done in
+  /// EmitInstruction.
+  void EmitLabel(MCSymbol *Symbol) override;
+
+  /// Overriding this function allows us to dismiss all labels that are candidates
+  /// for marking as microMIPS when .section directive is processed.
+  void SwitchSection(const MCSection *Section,
+                     const MCExpr *Subsection = nullptr) override;
+
+  /// Overriding this function allows us to dismiss all labels that are candidates
+  /// for marking as microMIPS when .word directive is emitted.
+  void EmitValueImpl(const MCExpr *Value, unsigned Size, const SMLoc &Loc) override;
+
   /// Emits all the option records stored up until the point it's called.
   void EmitMipsOptionRecords();
 };
 
 MCELFStreamer *createMipsELFStreamer(MCContext &Context, MCAsmBackend &MAB,
                                      raw_ostream &OS, MCCodeEmitter *Emitter,
                                      const MCSubtargetInfo &STI, bool RelaxAll,
                                      bool NoExecStack);
 } // namespace llvm.
 #endif

lib/Target/Mips/MCTargetDesc/MipsELFStreamer.cpp

 //===-------- MipsELFStreamer.cpp - ELF Object Output ---------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 
 #include "MipsELFStreamer.h"
+#include "MipsTargetStreamer.h"
 #include "llvm/MC/MCInst.h"
+#include "llvm/MC/MCELF.h"
+#include "llvm/Support/ELF.h"
+
 using namespace llvm;
 
 void MipsELFStreamer::EmitInstruction(const MCInst &Inst,
                                       const MCSubtargetInfo &STI) {
   MCELFStreamer::EmitInstruction(Inst, STI);
 
   MCContext &Context = getContext();
   const MCRegisterInfo *MCRegInfo = Context.getRegisterInfo();
+  MipsTargetELFStreamer *ELFTargetStreamer = static_cast<MipsTargetELFStreamer *>(getTargetStreamer());
 
   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);
   }
+
+  if (ELFTargetStreamer->isMicroMipsEnabled()) {
+    for (auto Label : Labels) {
+      MCSymbolData &Data = getOrCreateSymbolData(Label);
+      uint8_t Type = MCELF::GetType(Data);
+      // The "other" values are stored in the last 6 bits of the second byte
+      // The traditional defines for STO values assume the full byte and thus
+      // the shift to pack it.
+      MCELF::setOther(Data, ELF::STO_MIPS_MICROMIPS >> 2);
+    }
+  }
+
+  Labels.clear();
+}
+
+void MipsELFStreamer::EmitLabel(MCSymbol *Symbol) {
+  MCELFStreamer::EmitLabel(Symbol);
+  Labels.push_back(Symbol);
+}
+
+void MipsELFStreamer::SwitchSection(const MCSection * Section, const MCExpr *Subsection) {
+  MCELFStreamer::SwitchSection(Section, Subsection);
+  Labels.clear();
+}
+
+void MipsELFStreamer::EmitValueImpl(const MCExpr *Value, unsigned Size, const SMLoc &Loc) {
+  MCELFStreamer::EmitValueImpl(Value, Size, Loc);
+  Labels.clear();
 }
 
 void MipsELFStreamer::EmitMipsOptionRecords() {
   for (const auto &I : MipsOptionRecords)
     I->EmitMipsOptionRecord();
 }
 
 namespace llvm {
 MCELFStreamer *createMipsELFStreamer(MCContext &Context, MCAsmBackend &MAB,
                                      raw_ostream &OS, MCCodeEmitter *Emitter,
                                      const MCSubtargetInfo &STI, bool RelaxAll,
                                      bool NoExecStack) {
   return new MipsELFStreamer(Context, MAB, OS, Emitter, STI);
 }
 }

test/MC/Mips/micromips-label-test-sections.s

+# RUN: llvm-mc %s -triple=mipsel-unknown-linux -mcpu=mips32r2 \
+# RUN:   -mattr=+micromips -filetype=obj -o - | llvm-readobj -t | FileCheck %s
+  .text
+  .set micromips
+f:
+  nop
+g:
+  .section .text
+h:
+  nop
+
+# CHECK: Symbols [
+# CHECK:   Symbol {
+# CHECK:     Name: f
+# CHECK:     Binding: Local
+# CHECK:     Type: None
+# CHECK:     Other: 128
+# CHECK:     Section: .text
+# CHECK:   }
+# CHECK:   Symbol {
+# CHECK:     Name: g
+# CHECK:     Binding: Local
+# CHECK:     Type: None
+# CHECK:     Other: 0
+# CHECK:     Section: .text
+# CHECK:   }
+# CHECK:   Symbol {
+# CHECK:     Name: h
+# CHECK:     Binding: Local
+# CHECK:     Type: None
+# CHECK:     Other: 128
+# CHECK:     Section: .text
+# CHECK:   }
+# CHECK: ]
+

test/MC/Mips/micromips-label-test.s

+# RUN: llvm-mc %s -triple=mipsel-unknown-linux -mcpu=mips32r2 \
+# RUN:   -mattr=+micromips -filetype=obj -o - | llvm-readobj -t | FileCheck %s
+  .text
+  .set nomicromips
+f:
+  nop
+g:
+  .set micromips
+  nop
+h:
+  .word 0
+i:
+  nop
+j:
+  .set nomicromips
+  nop
+# CHECK: Symbols [
+# CHECK:   Symbol {
+# CHECK:     Name: f
+# CHECK:     Binding: Local
+# CHECK:     Type: None
+# CHECK:     Other: 0
+# CHECK:     Section: .text
+# CHECK:   }
+# CHECK:   Symbol {
+# CHECK:     Name: g
+# CHECK:     Binding: Local
+# CHECK:     Type: None
+# CHECK:     Other: 128
+# CHECK:     Section: .text
+# CHECK:   }
+# CHECK:   Symbol {
+# CHECK:     Name: h
+# CHECK:     Binding: Local
+# CHECK:     Type: None
+# CHECK:     Other: 0
+# CHECK:     Section: .text
+# CHECK:   }
+# CHECK:   Symbol {
+# CHECK:     Name: i
+# CHECK:     Binding: Local
+# CHECK:     Type: None
+# CHECK:     Other: 128
+# CHECK:     Section: .text
+# CHECK:   }
+# CHECK:   Symbol {
+# CHECK:     Name: j
+# CHECK:     Binding: Local
+# CHECK:     Type: None
+# CHECK:     Other: 0
+# CHECK:     Section: .text
+# CHECK:   }
+# CHECK: ]
+