[mips] [IAS] Add support for the .module softfloat/hardfloat directives.

[tomatabacu]

Summary

These directives are used to set the default value of the SoftFloat feature.
They have the same effect as setting -m{soft, hard}-float from the command line.

[mpf]

lib/Target/Mips/MipsTargetStreamer.h

96

This looks fishy, the FPABI should return to whatever hard-float ABI is in force due to other options. I.e. you need to know which fp=32|xx|64 was set and/or if oddspreg is in force and/or if single float is in force.

'Any' is generally used to describe a no-float ABI which is very different from hard-float.

[tomatabacu]

Fixed restoration of previous hardfloat settings:

• The settings aren't actually changed, it's just that when in soft-float they are ignored.
• emitDirectiveModule{SoftFloat,HardFloat}() doesn't change the MipsABIFlagsSection data anymore, it only prints it.
• That data is changed by setting/clearing the soft-float bit in STI.FeatureBits and then calling updateABIInfo().
• updateABIInfo() uses the update mechanism from MipsABIFlagsSection to properly update.

Changed test to use -mips-abi-flags feature of llvm-readobj.
Made the module-hardfloat.s test more thorough.
Rebased on top of D10641, D10642, and D10643, which fix the other .module directives.

[dsanders]

@mpf: Should the ODDSPREG flag be clear for softfloat?
@tomatabacu: If Matthew says 'yes', then please add an appropriate CHECK-NOT to module-softfloat.s then it will LGTM. If he says 'no' or "doesn't matter", then LGTM.

[mpf]

@mpf: Should the ODDSPREG flag be clear for softfloat?
@tomatabacu: If Matthew says 'yes', then please add an appropriate
CHECK-NOT to module-softfloat.s then it will LGTM. If he says 'no' or
"doesn't matter", then LGTM.

Hoping I can just email a reply...

The flag is undefined for soft-float and since it has 'or' semantics
for merging then it doesn't matter what it is set to for soft-float.
I don't actually know how it will be set for GNU tools and I mask
it out for most assembler tests that are not checking for the flag
specifically.

Matthew

[dsanders]

Thanks. In that case LGTM as-is.

lib/Target/Mips/AsmParser/MipsAsmParser.cpp

bool MipsAsmParser::parseInsnDirective() {
   getParser().Lex(); // Eat EndOfStatement token.
   return false;
 }
 
 /// parseDirectiveModule
 ///  ::= .module oddspreg
 ///  ::= .module nooddspreg
 ///  ::= .module fp=value
+///  ::= .module softfloat
+///  ::= .module hardfloat
 bool MipsAsmParser::parseDirectiveModule() {
   MCAsmParser &Parser = getParser();
   MCAsmLexer &Lexer = getLexer();
   SMLoc L = Lexer.getLoc();
 
   if (!getTargetStreamer().isModuleDirectiveAllowed()) {
     // TODO : get a better message.
     reportParseError(".module directive must appear before any code");
if (Option == "oddspreg") {
     if (getLexer().isNot(AsmToken::EndOfStatement)) {
       reportParseError("unexpected token, expected end of statement");
       return false;
     }
 
     return false; // parseDirectiveModule has finished successfully.
   } else if (Option == "fp") {
     return parseDirectiveModuleFP();
+  } else if (Option == "softfloat") {
+    setModuleFeatureBits(Mips::FeatureSoftFloat, "soft-float");
+
+    // Synchronize the ABI Flags information with the FeatureBits information we
+    // updated above.
+    getTargetStreamer().updateABIInfo(*this);
+
+    // If printing assembly, use the recently updated ABI Flags information.
+    // If generating ELF, don't do anything (the .MIPS.abiflags section gets
+    // emitted later).
+    getTargetStreamer().emitDirectiveModuleSoftFloat();
+
+    // If this is not the end of the statement, report an error.
+    if (getLexer().isNot(AsmToken::EndOfStatement)) {
+      reportParseError("unexpected token, expected end of statement");
+      return false;
+    }
+
+    return false; // parseDirectiveModule has finished successfully.
+  } else if (Option == "hardfloat") {
+    clearModuleFeatureBits(Mips::FeatureSoftFloat, "soft-float");
+
+    // Synchronize the ABI Flags information with the FeatureBits information we
+    // updated above.
+    getTargetStreamer().updateABIInfo(*this);
+
+    // If printing assembly, use the recently updated ABI Flags information.
+    // If generating ELF, don't do anything (the .MIPS.abiflags section gets
+    // emitted later).
+    getTargetStreamer().emitDirectiveModuleHardFloat();
+
+    // If this is not the end of the statement, report an error.
+    if (getLexer().isNot(AsmToken::EndOfStatement)) {
+      reportParseError("unexpected token, expected end of statement");
+      return false;
+    }
+
+    return false; // parseDirectiveModule has finished successfully.
   } else {
     return Error(L, "'" + Twine(Option) + "' is not a valid .module option.");
   }
 }
 
 /// parseDirectiveModuleFP
 ///  ::= =32
 ///  ::= =xx

lib/Target/Mips/MCTargetDesc/MipsTargetStreamer.cpp

 }
 
 void MipsTargetStreamer::emitDirectiveModuleFP() {}
 
 void MipsTargetStreamer::emitDirectiveModuleOddSPReg() {
   if (!ABIFlagsSection.OddSPReg && !ABIFlagsSection.Is32BitABI)
     report_fatal_error("+nooddspreg is only valid for O32");
 }
+void MipsTargetStreamer::emitDirectiveModuleSoftFloat() {}
+void MipsTargetStreamer::emitDirectiveModuleHardFloat() {}
 void MipsTargetStreamer::emitDirectiveSetFp(
     MipsABIFlagsSection::FpABIKind Value) {
   forbidModuleDirective();
 }
 
 MipsTargetAsmStreamer::MipsTargetAsmStreamer(MCStreamer &S,
                                              formatted_raw_ostream &OS)
     : MipsTargetStreamer(S), OS(OS) {}

 }
 
 void MipsTargetAsmStreamer::emitDirectiveModuleOddSPReg() {
   MipsTargetStreamer::emitDirectiveModuleOddSPReg();
 
   OS << "\t.module\t" << (ABIFlagsSection.OddSPReg ? "" : "no") << "oddspreg\n";
 }
 
+void MipsTargetAsmStreamer::emitDirectiveModuleSoftFloat() {
+  OS << "\t.module\tsoftfloat\n";
+}
+
+void MipsTargetAsmStreamer::emitDirectiveModuleHardFloat() {
+  OS << "\t.module\thardfloat\n";
+}
+
 // This part is for ELF object output.
 MipsTargetELFStreamer::MipsTargetELFStreamer(MCStreamer &S,
                                              const MCSubtargetInfo &STI)
     : MipsTargetStreamer(S), MicroMipsEnabled(false), STI(STI) {
   MCAssembler &MCA = getStreamer().getAssembler();
   Pic = MCA.getContext().getObjectFileInfo()->getRelocM() == Reloc::PIC_;
 
   const FeatureBitset &Features = STI.getFeatureBits();

lib/Target/Mips/MipsTargetStreamer.h

public:
   // PIC support
   virtual void emitDirectiveCpLoad(unsigned RegNo);
   virtual void emitDirectiveCpsetup(unsigned RegNo, int RegOrOffset,
                                     const MCSymbol &Sym, bool IsReg);
 
   // FP abiflags directives
   virtual void emitDirectiveModuleFP();
   virtual void emitDirectiveModuleOddSPReg();
+  virtual void emitDirectiveModuleSoftFloat();
+  virtual void emitDirectiveModuleHardFloat();
   virtual void emitDirectiveSetFp(MipsABIFlagsSection::FpABIKind Value);
 
   void forbidModuleDirective() { ModuleDirectiveAllowed = false; }
   void reallowModuleDirective() { ModuleDirectiveAllowed = true; }
   bool isModuleDirectiveAllowed() { return ModuleDirectiveAllowed; }
 
   // This method enables template classes to set internal abi flags
   // structure values.
   template <class PredicateLibrary>
   void updateABIInfo(const PredicateLibrary &P) {
     ABI = &P.getABI();
     ABIFlagsSection.setAllFromPredicates(P);
   }
 
   MipsABIFlagsSection &getABIFlagsSection() { return ABIFlagsSection; }
   const MipsABIInfo &getABI() const {
     assert(ABI && "ABI hasn't been set!");
public:
   // PIC support
   void emitDirectiveCpLoad(unsigned RegNo) override;
   void emitDirectiveCpsetup(unsigned RegNo, int RegOrOffset,
                             const MCSymbol &Sym, bool IsReg) override;
 
   // FP abiflags directives
   void emitDirectiveModuleFP() override;
   void emitDirectiveModuleOddSPReg() override;
+  void emitDirectiveModuleSoftFloat() override;
+  void emitDirectiveModuleHardFloat() override;
   void emitDirectiveSetFp(MipsABIFlagsSection::FpABIKind Value) override;
 };
 
 // This part is for ELF object output
 class MipsTargetELFStreamer : public MipsTargetStreamer {
   bool MicroMipsEnabled;
   const MCSubtargetInfo &STI;
   bool Pic;

test/MC/Mips/module-hardfloat.s

+# RUN: llvm-mc %s -arch=mips -mcpu=mips32 | \
+# RUN:   FileCheck %s -check-prefix=CHECK-ASM
+#
+# RUN: llvm-mc %s -arch=mips -mcpu=mips32 -filetype=obj -o - | \
+# RUN:   llvm-readobj -mips-abi-flags - | \
+# RUN:     FileCheck %s -check-prefix=CHECK-OBJ
+
+# CHECK-ASM: .module hardfloat
+
+# Check if the MIPS.abiflags section was correctly emitted:
+# CHECK-OBJ: MIPS ABI Flags {
+# CHECK-OBJ:   FP ABI: Hard float (32-bit CPU, Any FPU) (0x5)
+# CHECK-OBJ:   CPR1 size: 32
+# CHECK-OBJ:   Flags 1 [ (0x1)
+# CHECK-OBJ:     ODDSPREG (0x1)
+# CHECK-OBJ:   ]
+# CHECK-OBJ: }
+
+  .module fp=xx
+  .module oddspreg
+  .module softfloat
+  .module hardfloat
+
+# FIXME: Test should include gnu_attributes directive when implemented.
+#        An explicit .gnu_attribute must be checked against the effective
+#        command line options and any inconsistencies reported via a warning.

test/MC/Mips/module-softfloat.s

+# RUN: llvm-mc %s -arch=mips -mcpu=mips32 | \
+# RUN:   FileCheck %s -check-prefix=CHECK-ASM
+#
+# RUN: llvm-mc %s -arch=mips -mcpu=mips32 -filetype=obj -o - | \
+# RUN:   llvm-readobj -mips-abi-flags - | \
+# RUN:     FileCheck %s -check-prefix=CHECK-OBJ
+
+# CHECK-ASM: .module softfloat
+
+# Check if the MIPS.abiflags section was correctly emitted:
+# CHECK-OBJ: MIPS ABI Flags {
+# CHECK-OBJ:   FP ABI: Soft float (0x3)
+# CHECK-OBJ:   CPR1 size: 0
+# CHECK-OBJ: }
+
+  .module softfloat
+
+# FIXME: Test should include gnu_attributes directive when implemented.
+#        An explicit .gnu_attribute must be checked against the effective
+#        command line options and any inconsistencies reported via a warning.