[mips] Add initial support for NaN2008 in the back-end.

This is so that EF_MIPS_NAN2008 is set if we are using IEEE 754-2008
NaN encoding (-mnan=2008). This patch also adds support for parsing
'.nan legacy' and '.nan 2008' assembly directives. The handling of
these directives should match GAS' behaviour i.e., the last directive
in use sets the ELF header bit (EF_MIPS_NAN2008).

Differential Revision: http://reviews.llvm.org/D3346


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206396 91177308-0d34-0410-b5e6-96231b3b80d8

12 files changed, 237 insertions, 12 deletions

diff --git a/include/llvm/Support/ELF.h b/include/llvm/Support/ELF.h
index 7b10ebd23f..9448a820bf 100644
--- a/include/llvm/Support/ELF.h
+++ b/include/llvm/Support/ELF.h
@@ -807,6 +807,7 @@ enum : unsigned {
   EF_MIPS_CPIC      = 0x00000004, // Call object with Position independent code
   EF_MIPS_ABI2      = 0x00000020,
   EF_MIPS_32BITMODE = 0x00000100,
+  EF_MIPS_NAN2008   = 0x00000400, // Uses IEE 754-2008 NaN encoding
   EF_MIPS_ABI_O32   = 0x00001000, // This file follows the first MIPS 32 bit ABI
 
   //ARCH_ASE
diff --git a/lib/Target/Mips/AsmParser/MipsAsmParser.cpp b/lib/Target/Mips/AsmParser/MipsAsmParser.cpp
index e1ebd7661c..41662d3f97 100644
--- a/lib/Target/Mips/AsmParser/MipsAsmParser.cpp
+++ b/lib/Target/Mips/AsmParser/MipsAsmParser.cpp
@@ -144,6 +144,7 @@ class MipsAsmParser : public MCTargetAsmParser {
   bool isEvaluated(const MCExpr *Expr);
   bool parseSetFeature(uint64_t Feature);
   bool parseDirectiveCPSetup();
+  bool parseDirectiveNaN();
   bool parseDirectiveSet();
   bool parseDirectiveOption();
 
@@ -2383,6 +2384,26 @@ bool MipsAsmParser::parseDirectiveCPSetup() {
   return false;
 }
 
+bool MipsAsmParser::parseDirectiveNaN() {
+  if (getLexer().isNot(AsmToken::EndOfStatement)) {
+    const AsmToken &Tok = Parser.getTok();
+
+    if (Tok.getString() == "2008") {
+      Parser.Lex();
+      getTargetStreamer().emitDirectiveNaN2008();
+      return false;
+    } else if (Tok.getString() == "legacy") {
+      Parser.Lex();
+      getTargetStreamer().emitDirectiveNaNLegacy();
+      return false;
+    }
+  }
+  // If we don't recognize the option passed to the .nan
+  // directive (e.g. no option or unknown option), emit an error.
+  reportParseError("invalid option in .nan directive");
+  return false;
+}
+
 bool MipsAsmParser::parseDirectiveSet() {
 
   // Get the next token.
@@ -2566,6 +2587,9 @@ bool MipsAsmParser::ParseDirective(AsmToken DirectiveID) {
     return false;
   }
 
+  if (IDVal == ".nan")
+    return parseDirectiveNaN();
+
   if (IDVal == ".gpword") {
     parseDirectiveGpWord();
     return false;
diff --git a/lib/Target/Mips/MCTargetDesc/MipsTargetStreamer.cpp b/lib/Target/Mips/MCTargetDesc/MipsTargetStreamer.cpp
index fb6aff2b0d..053e13e556 100644
--- a/lib/Target/Mips/MCTargetDesc/MipsTargetStreamer.cpp
+++ b/lib/Target/Mips/MCTargetDesc/MipsTargetStreamer.cpp
@@ -85,6 +85,13 @@ void MipsTargetAsmStreamer::emitDirectiveEnt(const MCSymbol &Symbol) {
 }
 
 void MipsTargetAsmStreamer::emitDirectiveAbiCalls() { OS << "\t.abicalls\n"; }
+
+void MipsTargetAsmStreamer::emitDirectiveNaN2008() { OS << "\t.nan\t2008\n"; }
+
+void MipsTargetAsmStreamer::emitDirectiveNaNLegacy() {
+  OS << "\t.nan\tlegacy\n";
+}
+
 void MipsTargetAsmStreamer::emitDirectiveOptionPic0() {
   OS << "\t.option\tpic0\n";
 }
@@ -180,6 +187,10 @@ MipsTargetELFStreamer::MipsTargetELFStreamer(MCStreamer &S,
     EFlags |= ELF::EF_MIPS_ABI_O32;
   }
 
+  // Other options.
+  if (Features & Mips::FeatureNaN2008)
+    EFlags |= ELF::EF_MIPS_NAN2008;
+
   MCA.setELFHeaderEFlags(EFlags);
 }
 
@@ -325,6 +336,21 @@ void MipsTargetELFStreamer::emitDirectiveAbiCalls() {
   Flags |= ELF::EF_MIPS_CPIC | ELF::EF_MIPS_PIC;
   MCA.setELFHeaderEFlags(Flags);
 }
+
+void MipsTargetELFStreamer::emitDirectiveNaN2008() {
+  MCAssembler &MCA = getStreamer().getAssembler();
+  unsigned Flags = MCA.getELFHeaderEFlags();
+  Flags |= ELF::EF_MIPS_NAN2008;
+  MCA.setELFHeaderEFlags(Flags);
+}
+
+void MipsTargetELFStreamer::emitDirectiveNaNLegacy() {
+  MCAssembler &MCA = getStreamer().getAssembler();
+  unsigned Flags = MCA.getELFHeaderEFlags();
+  Flags &= ~ELF::EF_MIPS_NAN2008;
+  MCA.setELFHeaderEFlags(Flags);
+}
+
 void MipsTargetELFStreamer::emitDirectiveOptionPic0() {
   MCAssembler &MCA = getStreamer().getAssembler();
   unsigned Flags = MCA.getELFHeaderEFlags();
diff --git a/lib/Target/Mips/Mips.td b/lib/Target/Mips/Mips.td
index 7a8198c150..f0ada2b63f 100644
--- a/lib/Target/Mips/Mips.td
+++ b/lib/Target/Mips/Mips.td
@@ -34,6 +34,8 @@ def FeatureGP64Bit     : SubtargetFeature<"gp64", "IsGP64bit", "true",
                                 "General Purpose Registers are 64-bit wide.">;
 def FeatureFP64Bit     : SubtargetFeature<"fp64", "IsFP64bit", "true",
                                 "Support 64-bit FP registers.">;
+def FeatureNaN2008     : SubtargetFeature<"nan2008", "IsNaN2008bit", "true",
+                                "IEEE 754-2008 NaN encoding.">;
 def FeatureSingleFloat : SubtargetFeature<"single-float", "IsSingleFloat",
                                 "true", "Only supports single precision float">;
 def FeatureO32         : SubtargetFeature<"o32", "MipsABI", "O32",
diff --git a/lib/Target/Mips/MipsAsmPrinter.cpp b/lib/Target/Mips/MipsAsmPrinter.cpp
index c9b56aa635..1ad7e00fdc 100644
--- a/lib/Target/Mips/MipsAsmPrinter.cpp
+++ b/lib/Target/Mips/MipsAsmPrinter.cpp
@@ -637,6 +637,12 @@ void MipsAsmPrinter::EmitStartOfAsmFile(Module &M) {
   OutStreamer.SwitchSection(OutContext.getELFSection(
       SectionName, ELF::SHT_PROGBITS, 0, SectionKind::getDataRel()));
 
+  // NaN: At the moment we only support:
+  // 1. .nan legacy (default)
+  // 2. .nan 2008
+  Subtarget->isNaN2008() ? getTargetStreamer().emitDirectiveNaN2008()
+    : getTargetStreamer().emitDirectiveNaNLegacy();
+
   // TODO: handle O64 ABI
 
   if (Subtarget->isABI_EABI()) {
diff --git a/lib/Target/Mips/MipsSubtarget.cpp b/lib/Target/Mips/MipsSubtarget.cpp
index ffc3d2f46d..601467b72e 100644
--- a/lib/Target/Mips/MipsSubtarget.cpp
+++ b/lib/Target/Mips/MipsSubtarget.cpp
@@ -77,17 +77,16 @@ void MipsSubtarget::anchor() { }
 
 MipsSubtarget::MipsSubtarget(const std::string &TT, const std::string &CPU,
                              const std::string &FS, bool little,
-                             Reloc::Model _RM, MipsTargetMachine *_TM) :
-  MipsGenSubtargetInfo(TT, CPU, FS),
-  MipsArchVersion(Mips32), MipsABI(UnknownABI), IsLittle(little),
-  IsSingleFloat(false), IsFP64bit(false), IsGP64bit(false), HasVFPU(false),
-  HasCnMips(false), IsLinux(true), HasSEInReg(false), HasCondMov(false),
-  HasSwap(false), HasBitCount(false), HasFPIdx(false),
-  InMips16Mode(false), InMips16HardFloat(Mips16HardFloat),
-  InMicroMipsMode(false), HasDSP(false), HasDSPR2(false),
-  AllowMixed16_32(Mixed16_32 | Mips_Os16), Os16(Mips_Os16), HasMSA(false),
-  RM(_RM), OverrideMode(NoOverride), TM(_TM), TargetTriple(TT)
-{
+                             Reloc::Model _RM, MipsTargetMachine *_TM)
+    : MipsGenSubtargetInfo(TT, CPU, FS), MipsArchVersion(Mips32),
+      MipsABI(UnknownABI), IsLittle(little), IsSingleFloat(false),
+      IsFP64bit(false), IsNaN2008bit(false), IsGP64bit(false), HasVFPU(false),
+      HasCnMips(false), IsLinux(true), HasSEInReg(false), HasCondMov(false),
+      HasSwap(false), HasBitCount(false), HasFPIdx(false), InMips16Mode(false),
+      InMips16HardFloat(Mips16HardFloat), InMicroMipsMode(false), HasDSP(false),
+      HasDSPR2(false), AllowMixed16_32(Mixed16_32 | Mips_Os16), Os16(Mips_Os16),
+      HasMSA(false), RM(_RM), OverrideMode(NoOverride), TM(_TM),
+      TargetTriple(TT) {
   std::string CPUName = CPU;
   CPUName = selectMipsCPU(TT, CPUName);
 
diff --git a/lib/Target/Mips/MipsSubtarget.h b/lib/Target/Mips/MipsSubtarget.h
index a4246e980b..c739f91817 100644
--- a/lib/Target/Mips/MipsSubtarget.h
+++ b/lib/Target/Mips/MipsSubtarget.h
@@ -56,6 +56,9 @@ protected:
   // IsFP64bit - The target processor has 64-bit floating point registers.
   bool IsFP64bit;
 
+  // IsNan2008 - IEEE 754-2008 NaN encoding.
+  bool IsNaN2008bit;
+
   // IsFP64bit - General-purpose registers are 64 bits wide
   bool IsGP64bit;
 
@@ -158,6 +161,7 @@ public:
 
   bool isLittle() const { return IsLittle; }
   bool isFP64bit() const { return IsFP64bit; }
+  bool isNaN2008() const { return IsNaN2008bit; }
   bool isNotFP64bit() const { return !IsFP64bit; }
   bool isGP64bit() const { return IsGP64bit; }
   bool isGP32bit() const { return !IsGP64bit; }
diff --git a/lib/Target/Mips/MipsTargetStreamer.h b/lib/Target/Mips/MipsTargetStreamer.h
index 5f4b74b3ba..198888cf52 100644
--- a/lib/Target/Mips/MipsTargetStreamer.h
+++ b/lib/Target/Mips/MipsTargetStreamer.h
@@ -34,6 +34,8 @@ public:
 
   virtual void emitDirectiveEnt(const MCSymbol &Symbol) = 0;
   virtual void emitDirectiveAbiCalls() = 0;
+  virtual void emitDirectiveNaN2008() = 0;
+  virtual void emitDirectiveNaNLegacy() = 0;
   virtual void emitDirectiveOptionPic0() = 0;
   virtual void emitDirectiveOptionPic2() = 0;
   virtual void emitFrame(unsigned StackReg, unsigned StackSize,
@@ -68,6 +70,8 @@ public:
 
   virtual void emitDirectiveEnt(const MCSymbol &Symbol);
   virtual void emitDirectiveAbiCalls();
+  virtual void emitDirectiveNaN2008();
+  virtual void emitDirectiveNaNLegacy();
   virtual void emitDirectiveOptionPic0();
   virtual void emitDirectiveOptionPic2();
   virtual void emitFrame(unsigned StackReg, unsigned StackSize,
@@ -111,6 +115,8 @@ public:
 
   virtual void emitDirectiveEnt(const MCSymbol &Symbol);
   virtual void emitDirectiveAbiCalls();
+  virtual void emitDirectiveNaN2008();
+  virtual void emitDirectiveNaNLegacy();
   virtual void emitDirectiveOptionPic0();
   virtual void emitDirectiveOptionPic2();
   virtual void emitFrame(unsigned StackReg, unsigned StackSize,
diff --git a/test/CodeGen/Mips/start-asm-file.ll b/test/CodeGen/Mips/start-asm-file.ll
new file mode 100644
index 0000000000..8872464316
--- /dev/null
+++ b/test/CodeGen/Mips/start-asm-file.ll
@@ -0,0 +1,91 @@
+; Check the emission of directives at the start of an asm file.
+; This test is XFAILED until we fix the emission of '.option pic0' on
+; N32. At the moment we check if subtarget is Mips64 when we should be
+; checking the Subtarget's ABI.
+
+; ### O32 ABI ###
+; RUN: llc -filetype=asm -mtriple mips-unknown-linux -mcpu=mips32 \
+; RUN: -relocation-model=static %s -o - | \
+; RUN:   FileCheck -check-prefix=CHECK-STATIC-O32 -check-prefix=CHECK-STATIC-O32-NLEGACY %s
+
+; RUN: llc -filetype=asm -mtriple mips-unknown-linux -mcpu=mips32 \
+; RUN: -relocation-model=pic %s -o - | \
+; RUN:   FileCheck -check-prefix=CHECK-PIC-O32 -check-prefix=CHECK-PIC-O32-NLEGACY %s
+
+; RUN: llc -filetype=asm -mtriple mips-unknown-linux -mcpu=mips32 \
+; RUN: -relocation-model=static -mattr=+nan2008 %s -o - | \
+; RUN:   FileCheck -check-prefix=CHECK-STATIC-O32 -check-prefix=CHECK-STATIC-O32-N2008 %s
+
+; RUN: llc -filetype=asm -mtriple mips-unknown-linux -mcpu=mips32 \
+; RUN: -relocation-model=pic -mattr=+nan2008 %s -o - | \
+; RUN:   FileCheck -check-prefix=CHECK-PIC-O32 -check-prefix=CHECK-PIC-O32-N2008 %s
+
+; ### N32 ABI ###
+; RUN: llc -filetype=asm -mtriple mips64-unknown-linux -mcpu=mips64 \
+; RUN: -relocation-model=static -mattr=-n64,+n32 %s -o - | \
+; RUN:   FileCheck -check-prefix=CHECK-STATIC-N32 -check-prefix=CHECK-STATIC-N32-NLEGACY %s
+
+; RUN: llc -filetype=asm -mtriple mips64-unknown-linux -mcpu=mips64 \
+; RUN: -relocation-model=pic -mattr=-n64,+n32 %s -o - | \
+; RUN:   FileCheck -check-prefix=CHECK-PIC-N32 -check-prefix=CHECK-PIC-N32-NLEGACY %s
+
+; RUN: llc -filetype=asm -mtriple mips64-unknown-linux -mcpu=mips64 \
+; RUN: -relocation-model=static -mattr=-n64,+n32,+nan2008 %s -o - | \
+; RUN:   FileCheck -check-prefix=CHECK-STATIC-N32 -check-prefix=CHECK-STATIC-N32-N2008 %s
+
+; RUN: llc -filetype=asm -mtriple mips64-unknown-linux -mcpu=mips64 \
+; RUN: -relocation-model=pic -mattr=-n64,+n32,+nan2008 %s -o - | \
+; RUN:   FileCheck -check-prefix=CHECK-PIC-N32 -check-prefix=CHECK-PIC-N32-N2008 %s
+
+; ### N64 ABI ###
+; RUN: llc -filetype=asm -mtriple mips64-unknown-linux -mcpu=mips64 \
+; RUN: -relocation-model=static -mattr=+n64 %s -o - | \
+; RUN:   FileCheck -check-prefix=CHECK-STATIC-N64 -check-prefix=CHECK-STATIC-N64-NLEGACY %s
+
+; RUN: llc -filetype=asm -mtriple mips64-unknown-linux -mcpu=mips64 \
+; RUN: -relocation-model=pic -mattr=+n64 %s -o - | \
+; RUN:   FileCheck -check-prefix=CHECK-PIC-N64 -check-prefix=CHECK-PIC-N64-NLEGACY %s
+
+; RUN: llc -filetype=asm -mtriple mips64-unknown-linux -mcpu=mips64 \
+; RUN: -relocation-model=static -mattr=+n64,+nan2008 %s -o - | \
+; RUN:   FileCheck -check-prefix=CHECK-STATIC-N64 -check-prefix=CHECK-STATIC-N64-N2008 %s
+
+; RUN: llc -filetype=asm -mtriple mips64-unknown-linux -mcpu=mips64 \
+; RUN: -relocation-model=pic -mattr=+n64,+nan2008 %s -o - | \
+; RUN:   FileCheck -check-prefix=CHECK-PIC-N64 -check-prefix=CHECK-PIC-N64-N2008 %s
+
+; CHECK-STATIC-O32: .abicalls
+; CHECK-STATIC-O32: .option pic0
+; CHECK-STATIC-O32: .section .mdebug.abi32
+; CHECK-STATIC-O32-NLEGACY: .nan legacy
+; CHECK-STATIC-O32-N2008: .nan 2008
+
+; CHECK-PIC-O32: .abicalls
+; CHECK-PIC-O32-NOT: .option pic0
+; CHECK-PIC-O32: .section .mdebug.abi32
+; CHECK-PIC-O32-NLEGACY: .nan legacy
+; CHECK-PIC-O32-N2008: .nan 2008
+
+; CHECK-STATIC-N32: .abicalls
+; CHECK-STATIC-N32: .option pic0
+; CHECK-STATIC-N32: .section .mdebug.abiN32
+; CHECK-STATIC-N32-NLEGACY: .nan legacy
+; CHECK-STATIC-N32-N2008: .nan 2008
+
+; CHECK-PIC-N32: .abicalls
+; CHECK-PIC-N32-NOT: .option pic0
+; CHECK-PIC-N32: .section .mdebug.abiN32
+; CHECK-PIC-N32-NLEGACY: .nan legacy
+; CHECK-PIC-N32-N2008: .nan 2008
+
+; CHECK-STATIC-N64: .abicalls
+; CHECK-STATIC-N64-NOT: .option pic0
+; CHECK-STATIC-N64: .section .mdebug.abi64
+; CHECK-STATIC-N64-NLEGACY: .nan legacy
+; CHECK-STATIC-N64-N2008: .nan 2008
+
+; CHECK-PIC-N64: .abicalls
+; CHECK-PIC-N64-NOT: .option pic0
+; CHECK-PIC-N64: .section .mdebug.abi64
+; CHECK-PIC-N64-NLEGACY: .nan legacy
+; CHECK-PIC-N64-N2008: .nan 2008
diff --git a/test/MC/Mips/elf_eflags.s b/test/MC/Mips/elf_eflags.s
index c789428b42..8cf4960e17 100644
--- a/test/MC/Mips/elf_eflags.s
+++ b/test/MC/Mips/elf_eflags.s
@@ -4,40 +4,79 @@
 # RUN: llvm-mc -filetype=obj -triple mipsel-unknown-linux -mcpu=mips64r2 %s -o -| llvm-readobj -h | FileCheck --check-prefix=MIPSEL-MIPS64R2 %s
 # MIPSEL-MIPS64R2: Flags [ (0x80001100)
 
+# RUN: llvm-mc -filetype=obj -triple mipsel-unknown-linux -mcpu=mips64r2 -mattr=+nan2008 %s -o -| llvm-readobj -h | FileCheck --check-prefix=MIPSEL-MIPS64R2-NAN2008 %s
+# MIPSEL-MIPS64R2-NAN2008: Flags [ (0x80001500)
+
 # RUN: llvm-mc -filetype=obj -triple mipsel-unknown-linux -mcpu=mips64 %s -o -| llvm-readobj -h | FileCheck --check-prefix=MIPSEL-MIPS64 %s
 # MIPSEL-MIPS64: Flags [ (0x60001100)
 
+# RUN: llvm-mc -filetype=obj -triple mipsel-unknown-linux -mcpu=mips64 -mattr=+nan2008 %s -o -| llvm-readobj -h | FileCheck --check-prefix=MIPSEL-MIPS64-NAN2008 %s
+# MIPSEL-MIPS64-NAN2008: Flags [ (0x60001500)
+
 # RUN: llvm-mc -filetype=obj -triple mipsel-unknown-linux -mcpu=mips32r2 %s -o -| llvm-readobj -h | FileCheck --check-prefix=MIPSEL-MIPS32R2 %s
 # MIPSEL-MIPS32R2: Flags [ (0x70001000)
 
+# RUN: llvm-mc -filetype=obj -triple mipsel-unknown-linux -mcpu=mips32r2 -mattr=+nan2008 %s -o -| llvm-readobj -h | FileCheck --check-prefix=MIPSEL-MIPS32R2-NAN2008 %s
+# MIPSEL-MIPS32R2-NAN2008: Flags [ (0x70001400)
+
 # RUN: llvm-mc -filetype=obj -triple mipsel-unknown-linux -mcpu=mips32 %s -o -| llvm-readobj -h | FileCheck --check-prefix=MIPSEL-MIPS32 %s
 # MIPSEL-MIPS32: Flags [ (0x50001000)
 
+# RUN: llvm-mc -filetype=obj -triple mipsel-unknown-linux -mcpu=mips32 -mattr=+nan2008 %s -o -| llvm-readobj -h | FileCheck --check-prefix=MIPSEL-MIPS32-NAN2008 %s
+# MIPSEL-MIPS32-NAN2008: Flags [ (0x50001400)
+
 # RUN: llvm-mc -filetype=obj -triple mips64el-unknown-linux -mcpu=mips64r2 -mattr=-n64,n32 %s -o -| llvm-readobj -h | FileCheck --check-prefix=MIPS64EL-MIPS64R2-N32 %s
 # MIPS64EL-MIPS64R2-N32: Flags [ (0x80000020)
 
+# RUN: llvm-mc -filetype=obj -triple mips64el-unknown-linux -mcpu=mips64r2 -mattr=-n64,n32,+nan2008 %s -o -| llvm-readobj -h | FileCheck --check-prefix=MIPS64EL-MIPS64R2-N32-NAN2008 %s
+# MIPS64EL-MIPS64R2-N32-NAN2008: Flags [ (0x80000420)
+
 # RUN: llvm-mc -filetype=obj -triple mips64el-unknown-linux -mcpu=mips64 -mattr=-n64,n32 %s -o -| llvm-readobj -h | FileCheck --check-prefix=MIPS64EL-MIPS64-N32 %s
 # MIPS64EL-MIPS64-N32: Flags [ (0x60000020)
 
+# RUN: llvm-mc -filetype=obj -triple mips64el-unknown-linux -mcpu=mips64 -mattr=-n64,n32,+nan2008 %s -o -| llvm-readobj -h | FileCheck --check-prefix=MIPS64EL-MIPS64-N32-NAN2008 %s
+# MIPS64EL-MIPS64-N32-NAN2008: Flags [ (0x60000420)
+
 # RUN: llvm-mc -filetype=obj -triple mips64el-unknown-linux -mcpu=mips64r2 -mattr=n64 %s -o -| llvm-readobj -h | FileCheck --check-prefix=MIPS64EL-MIPS64R2-N64 %s
 # MIPS64EL-MIPS64R2-N64: Flags [ (0x80000000)
 
+# RUN: llvm-mc -filetype=obj -triple mips64el-unknown-linux -mcpu=mips64r2 -mattr=n64,+nan2008 %s -o -| llvm-readobj -h | FileCheck --check-prefix=MIPS64EL-MIPS64R2-N64-NAN2008 %s
+# MIPS64EL-MIPS64R2-N64-NAN2008: Flags [ (0x80000400)
+
 # RUN: llvm-mc -filetype=obj -triple mips64el-unknown-linux -mcpu=mips64 %s -mattr=n64 -o -| llvm-readobj -h | FileCheck --check-prefix=MIPS64EL-MIPS64-N64 %s
 # MIPS64EL-MIPS64-N64: Flags [ (0x60000000)
 
+# RUN: llvm-mc -filetype=obj -triple mips64el-unknown-linux -mcpu=mips64 %s -mattr=n64,+nan2008 -o -| llvm-readobj -h | FileCheck --check-prefix=MIPS64EL-MIPS64-N64-NAN2008 %s
+# MIPS64EL-MIPS64-N64-NAN2008: Flags [ (0x60000400)
+
 # RUN: llvm-mc -filetype=obj -triple mips64el-unknown-linux -mcpu=mips64r2 -mattr=-n64,o32 %s -o -| llvm-readobj -h | FileCheck --check-prefix=MIPS64EL-MIPS64R2-O32 %s
 # MIPS64EL-MIPS64R2-O32: Flags [ (0x80001100)
 
+# RUN: llvm-mc -filetype=obj -triple mips64el-unknown-linux -mcpu=mips64r2 -mattr=-n64,o32,+nan2008 %s -o -| llvm-readobj -h | FileCheck --check-prefix=MIPS64EL-MIPS64R2-O32-NAN2008 %s
+# MIPS64EL-MIPS64R2-O32-NAN2008: Flags [ (0x80001500)
+
 # RUN: llvm-mc -filetype=obj -triple mips64-unknown-linux -mcpu=mips4 %s -o -| llvm-readobj -h | FileCheck --check-prefix=MIPS4 %s
 # MIPS4: Flags [ (0x30000000)
 
+ # RUN: llvm-mc -filetype=obj -triple mips64-unknown-linux -mcpu=mips4 -mattr=+nan2008 %s -o -| llvm-readobj -h | FileCheck --check-prefix=MIPS4-NAN2008 %s
+# MIPS4-NAN2008: Flags [ (0x30000400)
+
 # RUN: llvm-mc -filetype=obj -triple mips64el-unknown-linux -mcpu=mips64 %s -mattr=-n64,o32 -o -| llvm-readobj -h | FileCheck --check-prefix=MIPS64EL-MIPS64-O32 %s
 # MIPS64EL-MIPS64-O32: Flags [ (0x60001100)
-	
+
+# RUN: llvm-mc -filetype=obj -triple mips64el-unknown-linux -mcpu=mips64 %s -mattr=-n64,o32,+nan2008 -o -| llvm-readobj -h | FileCheck --check-prefix=MIPS64EL-MIPS64-O32-NAN2008 %s
+# MIPS64EL-MIPS64-O32-NAN2008: Flags [ (0x60001500)
+
 # Default ABI for MIPS64 is N64 as opposed to GCC/GAS (N32)
 # RUN: llvm-mc -filetype=obj -triple mips64el-unknown-linux -mcpu=mips64r2 %s -o -| llvm-readobj -h | FileCheck --check-prefix=MIPS64EL-MIPS64R2 %s
 # MIPS64EL-MIPS64R2: Flags [ (0x80000000)
 
+# RUN: llvm-mc -filetype=obj -triple mips64el-unknown-linux -mcpu=mips64r2 -mattr=+nan2008 %s -o -| llvm-readobj -h | FileCheck --check-prefix=MIPS64EL-MIPS64R2-NAN2008 %s
+# MIPS64EL-MIPS64R2-NAN2008: Flags [ (0x80000400)
+
 # Default ABI for MIPS64 is N64 as opposed to GCC/GAS (N32)
 # RUN: llvm-mc -filetype=obj -triple mips64el-unknown-linux -mcpu=mips64 %s -o -| llvm-readobj -h | FileCheck --check-prefix=MIPS64EL-MIPS64 %s
 # MIPS64EL-MIPS64: Flags [ (0x60000000)
+
+# RUN: llvm-mc -filetype=obj -triple mips64el-unknown-linux -mcpu=mips64 -mattr=+nan2008 %s -o -| llvm-readobj -h | FileCheck --check-prefix=MIPS64EL-MIPS64-NAN2008 %s
+# MIPS64EL-MIPS64-NAN2008: Flags [ (0x60000400)
diff --git a/test/MC/Mips/elf_eflags_nan2008.s b/test/MC/Mips/elf_eflags_nan2008.s
new file mode 100644
index 0000000000..71a22be2b4
--- /dev/null
+++ b/test/MC/Mips/elf_eflags_nan2008.s
@@ -0,0 +1,12 @@
+# RUN: llvm-mc -filetype=obj -triple mipsel-unknown-linux -mcpu=mips32 %s -o - | \
+# RUN:   llvm-readobj -h | \
+# RUN:     FileCheck %s -check-prefix=CHECK-OBJ
+# RUN: llvm-mc -triple mipsel-unknown-linux -mcpu=mips32 %s -o -| \
+# RUN:   FileCheck %s -check-prefix=CHECK-ASM
+
+# This *MUST* match the output of gas compiled with the same triple.
+# CHECK-OBJ: Flags [ (0x50001400)
+
+# CHECK-ASM: .nan 2008
+
+.nan 2008
diff --git a/test/MC/Mips/elf_eflags_nanlegacy.s b/test/MC/Mips/elf_eflags_nanlegacy.s
new file mode 100644
index 0000000000..6897ad2bda
--- /dev/null
+++ b/test/MC/Mips/elf_eflags_nanlegacy.s
@@ -0,0 +1,15 @@
+# RUN: llvm-mc -filetype=obj -triple mipsel-unknown-linux -mcpu=mips32 %s -o - | \
+# RUN:   llvm-readobj -h | \
+# RUN:     FileCheck %s -check-prefix=CHECK-OBJ
+# RUN: llvm-mc -triple mipsel-unknown-linux -mcpu=mips32 %s -o -| \
+# RUN:   FileCheck %s -check-prefix=CHECK-ASM
+
+# This *MUST* match the output of gas compiled with the same triple.
+# CHECK-OBJ: Flags [ (0x50001000)
+
+# CHECK-ASM: .nan 2008
+# CHECK-ASM: .nan legacy
+
+.nan 2008
+// Let's override the previous directive!
+.nan legacy