[mips] Initial implementation of -mabicalls/-mno-abicalls.

This patch implements the main rules for -mno-abicalls such as reserving $gp,
and emitting the correct .option directive.

Patch by Matheus Almeida and Toma Tabacu

Differential Revision: http://reviews.llvm.org/D4231

llvm-svn: 215194

5 files changed, 20 insertions, 9 deletions

diff --git a/llvm/lib/Target/Mips/Mips.td b/llvm/lib/Target/Mips/Mips.td
index dd3bc9b08fc..8d90007ed72 100644
--- a/llvm/lib/Target/Mips/Mips.td
+++ b/llvm/lib/Target/Mips/Mips.td
@@ -57,6 +57,8 @@ def MipsInstrInfo : InstrInfo;
 // Mips Subtarget features                                                    //
 //===----------------------------------------------------------------------===//
 
+def FeatureABICalls    : SubtargetFeature<"abicalls", "IsABICalls", "true",
+                                "SVR4-style position-independent code.">;
 def FeatureGP64Bit     : SubtargetFeature<"gp64", "IsGP64bit", "true",
                                 "General Purpose Registers are 64-bit wide.">;
 def FeatureFP64Bit     : SubtargetFeature<"fp64", "IsFP64bit", "true",
diff --git a/llvm/lib/Target/Mips/MipsAsmPrinter.cpp b/llvm/lib/Target/Mips/MipsAsmPrinter.cpp
index dfc1b09738f..187252e9889 100644
--- a/llvm/lib/Target/Mips/MipsAsmPrinter.cpp
+++ b/llvm/lib/Target/Mips/MipsAsmPrinter.cpp
@@ -671,9 +671,7 @@ printFCCOperand(const MachineInstr *MI, int opNum, raw_ostream &O,
 }
 
 void MipsAsmPrinter::EmitStartOfAsmFile(Module &M) {
-  // TODO: Need to add -mabicalls and -mno-abicalls flags.
-  // Currently we assume that -mabicalls is the default.
-  bool IsABICalls = true;
+  bool IsABICalls = Subtarget->isABICalls();
   if (IsABICalls) {
     getTargetStreamer().emitDirectiveAbiCalls();
     Reloc::Model RM = TM.getRelocationModel();
diff --git a/llvm/lib/Target/Mips/MipsRegisterInfo.cpp b/llvm/lib/Target/Mips/MipsRegisterInfo.cpp
index ab371da72ca..20ef3f387dc 100644
--- a/llvm/lib/Target/Mips/MipsRegisterInfo.cpp
+++ b/llvm/lib/Target/Mips/MipsRegisterInfo.cpp
@@ -149,6 +149,12 @@ getReservedRegs(const MachineFunction &MF) const {
   for (unsigned I = 0; I < array_lengthof(ReservedGPR64); ++I)
     Reserved.set(ReservedGPR64[I]);
 
+  // For mno-abicalls, GP is a program invariant!
+  if (!Subtarget.isABICalls()) {
+    Reserved.set(Mips::GP);
+    Reserved.set(Mips::GP_64);
+  }
+
   if (Subtarget.isFP64bit()) {
     // Reserve all registers in AFGR64.
     for (RegIter Reg = Mips::AFGR64RegClass.begin(),
diff --git a/llvm/lib/Target/Mips/MipsSubtarget.cpp b/llvm/lib/Target/Mips/MipsSubtarget.cpp
index 5bf875daea9..2377f5c5d2b 100644
--- a/llvm/lib/Target/Mips/MipsSubtarget.cpp
+++ b/llvm/lib/Target/Mips/MipsSubtarget.cpp
@@ -107,12 +107,13 @@ MipsSubtarget::MipsSubtarget(const std::string &TT, const std::string &CPU,
                              MipsTargetMachine *_TM)
     : MipsGenSubtargetInfo(TT, CPU, FS), MipsArchVersion(Mips32),
       MipsABI(UnknownABI), IsLittle(little), IsSingleFloat(false),
-      IsFPXX(false), IsFP64bit(false), UseOddSPReg(true), IsNaN2008bit(false),
-      IsGP64bit(false), HasVFPU(false), HasCnMips(false), IsLinux(true),
-      HasMips3_32(false), HasMips3_32r2(false), HasMips4_32(false),
-      HasMips4_32r2(false), HasMips5_32r2(false), InMips16Mode(false),
-      InMips16HardFloat(Mips16HardFloat), InMicroMipsMode(false), HasDSP(false),
-      HasDSPR2(false), AllowMixed16_32(Mixed16_32 | Mips_Os16), Os16(Mips_Os16),
+      IsFPXX(false), IsABICalls(true), IsFP64bit(false), UseOddSPReg(true),
+      IsNaN2008bit(false), IsGP64bit(false), HasVFPU(false), HasCnMips(false),
+      IsLinux(true), HasMips3_32(false), HasMips3_32r2(false),
+      HasMips4_32(false), HasMips4_32r2(false), HasMips5_32r2(false),
+      InMips16Mode(false), InMips16HardFloat(Mips16HardFloat),
+      InMicroMipsMode(false), HasDSP(false), HasDSPR2(false),
+      AllowMixed16_32(Mixed16_32 | Mips_Os16), Os16(Mips_Os16),
       HasMSA(false), TM(_TM), TargetTriple(TT),
       DL(computeDataLayout(initializeSubtargetDependencies(CPU, FS, TM))),
       TSInfo(DL), JITInfo(), InstrInfo(MipsInstrInfo::create(*this)),
diff --git a/llvm/lib/Target/Mips/MipsSubtarget.h b/llvm/lib/Target/Mips/MipsSubtarget.h
index 3f7a6c3ed73..8415212a975 100644
--- a/llvm/lib/Target/Mips/MipsSubtarget.h
+++ b/llvm/lib/Target/Mips/MipsSubtarget.h
@@ -65,6 +65,9 @@ protected:
   // IsFPXX - MIPS O32 modeless ABI.
   bool IsFPXX;
 
+  // IsABICalls - SVR4-style position-independent code.
+  bool IsABICalls;
+
   // IsFP64bit - The target processor has 64-bit floating point registers.
   bool IsFP64bit;
 
@@ -200,6 +203,7 @@ public:
   bool hasCnMips() const { return HasCnMips; }
 
   bool isLittle() const { return IsLittle; }
+  bool isABICalls() const { return IsABICalls; }
   bool isFPXX() const { return IsFPXX; }
   bool isFP64bit() const { return IsFP64bit; }
   bool useOddSPReg() const { return UseOddSPReg; }