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

[zoran.jovanovic]

Summary

Implements marking of all necessary symbols as microMIPS.

[• rafael]

include/llvm/MC/MCStreamer.h

349 ↗

(On Diff #15579)

can't you use the already virtual ChangeSection?

[zoran.jovanovic]

include/llvm/MC/MCStreamer.h

349 ↗

(On Diff #15579)

ChangeSection is called only if section is actually changed.
If section in .section directive is the same as current section then ChangeSection is not called (unlike SwitchSection).
As consequence, test micromips-label-test-sections.s would fail.

[• rafael]

---

rafael wrote:

can't you use the already virtual ChangeSection?

ChangeSection is called only if section is actually changed.
If section in .section directive is the same as current section then ChangeSection is not called (unlike SwitchSection).
As consequence, test micromips-label-test-sections.s would fail.

I see.

Eventually we should move all of these to be part of the target
streamer, but for now this is probably fine for now.

I know nothing about micromips, so please wait for a review about the
mips specific bits from someone that does :-)

Cheers,
Rafael

[sstankovic]

LGTM, with two changes.

lib/Target/Mips/MCTargetDesc/MipsELFStreamer.cpp

39 ↗

(On Diff #15579)

Add '.' at the end of sentence.

lib/Target/Mips/MCTargetDesc/MipsELFStreamer.h

51 ↗

(On Diff #15579)

"based" should start with uppercase.

Closed by commit rL221355 (authored by zjovanovic).

llvm/trunk/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);
     }
   }

llvm/trunk/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);
 } // namespace llvm.
 #endif

llvm/trunk/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/MCELF.h"
 #include "llvm/MC/MCInst.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);
+      // 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) {
   return new MipsELFStreamer(Context, MAB, OS, Emitter, STI);
 }
 }

llvm/trunk/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: ]
+

llvm/trunk/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: ]
+