[mips] Add support for '.option pic2'.

The directive '.option pic2' enables PIC from assembly source.
At the moment none of the macros/directives check the PIC bit
but that's going to be fixed relatively soon. For example, the
expansion of macros like 'la' depend on the relocation model.

llvm-svn: 204803

3 files changed, 36 insertions, 0 deletions

diff --git a/llvm/lib/Target/Mips/AsmParser/MipsAsmParser.cpp b/llvm/lib/Target/Mips/AsmParser/MipsAsmParser.cpp
index d733caae500..394703595fa 100644
--- a/llvm/lib/Target/Mips/AsmParser/MipsAsmParser.cpp
+++ b/llvm/lib/Target/Mips/AsmParser/MipsAsmParser.cpp
@@ -2596,6 +2596,17 @@ bool MipsAsmParser::parseDirectiveOption() {
     return false;
   }
 
+  if (Option == "pic2") {
+    getTargetStreamer().emitDirectiveOptionPic2();
+    Parser.Lex();
+    if (Parser.getTok().isNot(AsmToken::EndOfStatement)) {
+      Error(Parser.getTok().getLoc(),
+            "unexpected token in .option pic2 directive");
+      Parser.eatToEndOfStatement();
+    }
+    return false;
+  }
+
   // Unknown option.
   Warning(Parser.getTok().getLoc(), "unknown option in .option directive");
   Parser.eatToEndOfStatement();
diff --git a/llvm/lib/Target/Mips/MCTargetDesc/MipsTargetStreamer.cpp b/llvm/lib/Target/Mips/MCTargetDesc/MipsTargetStreamer.cpp
index f31743a2eae..afe501b2ea5 100644
--- a/llvm/lib/Target/Mips/MCTargetDesc/MipsTargetStreamer.cpp
+++ b/llvm/lib/Target/Mips/MCTargetDesc/MipsTargetStreamer.cpp
@@ -89,6 +89,10 @@ void MipsTargetAsmStreamer::emitDirectiveOptionPic0() {
   OS << "\t.option\tpic0\n";
 }
 
+void MipsTargetAsmStreamer::emitDirectiveOptionPic2() {
+  OS << "\t.option\tpic2\n";
+}
+
 void MipsTargetAsmStreamer::emitFrame(unsigned StackReg, unsigned StackSize,
                                       unsigned ReturnReg) {
   OS << "\t.frame\t$"
@@ -132,6 +136,9 @@ MipsTargetELFStreamer::MipsTargetELFStreamer(MCStreamer &S,
   MCAssembler &MCA = getStreamer().getAssembler();
   uint64_t Features = STI.getFeatureBits();
   Triple T(STI.getTargetTriple());
+  Pic = (MCA.getContext().getObjectFileInfo()->getRelocM() ==  Reloc::PIC_)
+            ? true
+            : false;
 
   // Update e_header flags
   unsigned EFlags = 0;
@@ -311,10 +318,24 @@ void MipsTargetELFStreamer::emitDirectiveAbiCalls() {
 void MipsTargetELFStreamer::emitDirectiveOptionPic0() {
   MCAssembler &MCA = getStreamer().getAssembler();
   unsigned Flags = MCA.getELFHeaderEFlags();
+  // This option overrides other PIC options like -KPIC.
+  Pic = false;
   Flags &= ~ELF::EF_MIPS_PIC;
   MCA.setELFHeaderEFlags(Flags);
 }
 
+void MipsTargetELFStreamer::emitDirectiveOptionPic2() {
+  MCAssembler &MCA = getStreamer().getAssembler();
+  unsigned Flags = MCA.getELFHeaderEFlags();
+  Pic = true;
+  // NOTE: We are following the GAS behaviour here which means the directive
+  // 'pic2' also sets the CPIC bit in the ELF header. This is different from
+  // what is stated in the SYSV ABI which consider the bits EF_MIPS_PIC and
+  // EF_MIPS_CPIC to be mutually exclusive.
+  Flags |= ELF::EF_MIPS_PIC | ELF::EF_MIPS_CPIC;
+  MCA.setELFHeaderEFlags(Flags);
+}
+
 void MipsTargetELFStreamer::emitFrame(unsigned StackReg, unsigned StackSize,
                                       unsigned ReturnReg) {
   // FIXME: implement.
diff --git a/llvm/lib/Target/Mips/MipsTargetStreamer.h b/llvm/lib/Target/Mips/MipsTargetStreamer.h
index 5550e7d5602..72d6891e427 100644
--- a/llvm/lib/Target/Mips/MipsTargetStreamer.h
+++ b/llvm/lib/Target/Mips/MipsTargetStreamer.h
@@ -35,6 +35,7 @@ public:
   virtual void emitDirectiveEnt(const MCSymbol &Symbol) = 0;
   virtual void emitDirectiveAbiCalls() = 0;
   virtual void emitDirectiveOptionPic0() = 0;
+  virtual void emitDirectiveOptionPic2() = 0;
   virtual void emitFrame(unsigned StackReg, unsigned StackSize,
                          unsigned ReturnReg) = 0;
   virtual void emitMask(unsigned CPUBitmask, int CPUTopSavedRegOff) = 0;
@@ -66,6 +67,7 @@ public:
   virtual void emitDirectiveEnt(const MCSymbol &Symbol);
   virtual void emitDirectiveAbiCalls();
   virtual void emitDirectiveOptionPic0();
+  virtual void emitDirectiveOptionPic2();
   virtual void emitFrame(unsigned StackReg, unsigned StackSize,
                          unsigned ReturnReg);
   virtual void emitMask(unsigned CPUBitmask, int CPUTopSavedRegOff);
@@ -79,6 +81,7 @@ public:
 class MipsTargetELFStreamer : public MipsTargetStreamer {
   bool MicroMipsEnabled;
   const MCSubtargetInfo &STI;
+  bool Pic;
 
 public:
   bool isMicroMipsEnabled() const { return MicroMipsEnabled; }
@@ -105,6 +108,7 @@ public:
   virtual void emitDirectiveEnt(const MCSymbol &Symbol);
   virtual void emitDirectiveAbiCalls();
   virtual void emitDirectiveOptionPic0();
+  virtual void emitDirectiveOptionPic2();
   virtual void emitFrame(unsigned StackReg, unsigned StackSize,
                          unsigned ReturnReg);
   virtual void emitMask(unsigned CPUBitmask, int CPUTopSavedRegOff);