[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

104

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

#include "MipsGenAsmMatcher.inc"
   void clearFeatureBits(uint64_t Feature, StringRef FeatureString) {
     if (STI.getFeatureBits() & Feature) {
       setAvailableFeatures(
           ComputeAvailableFeatures(STI.ToggleFeature(FeatureString)));
     }
     AssemblerOptions.back()->setFeatures(getAvailableFeatures());
   }
 
+  void setModuleFeatureBits(uint64_t Feature, StringRef FeatureString) {
+    setFeatureBits(Feature, FeatureString);
+    AssemblerOptions.front()->setFeatures(getAvailableFeatures());
+  }
+
+  void clearModuleFeatureBits(uint64_t Feature, StringRef FeatureString) {
+    clearFeatureBits(Feature, FeatureString);
+    AssemblerOptions.front()->setFeatures(getAvailableFeatures());
+  }
+
 public:
   enum MipsMatchResultTy {
     Match_RequiresDifferentSrcAndDst = FIRST_TARGET_MATCH_RESULT_TY
 #define GET_OPERAND_DIAGNOSTIC_TYPES
 #include "MipsGenAsmMatcher.inc"
 #undef GET_OPERAND_DIAGNOSTIC_TYPES
 
   };
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") {
+    getTargetStreamer().emitDirectiveModuleSoftFloat();
+    setModuleFeatureBits(Mips::FeatureSoftFloat, "soft-float");
+    getTargetStreamer().updateABIInfo(*this);
+
+    // 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") {
+    getTargetStreamer().emitDirectiveModuleHardFloat();
+    clearModuleFeatureBits(Mips::FeatureSoftFloat, "soft-float");
+    getTargetStreamer().updateABIInfo(*this);
+
+    // 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 MipsTargetAsmStreamer::emitDirectiveSetFp(
     MipsABIFlagsSection::FpABIKind Value) {
   MipsTargetStreamer::emitDirectiveSetFp(Value);
 
   StringRef ModuleValue;
   OS << "\t.set\tfp=";
   OS << ABIFlagsSection.getFpABIString(Value) << "\n";
 }
 
+void MipsTargetAsmStreamer::emitDirectiveModuleSoftFloat() {
+  MipsTargetStreamer::emitDirectiveModuleSoftFloat();
+  OS << "\t.module\tsoftfloat\n";
+}
+
+void MipsTargetAsmStreamer::emitDirectiveModuleHardFloat() {
+  MipsTargetStreamer::emitDirectiveModuleHardFloat();
+  OS << "\t.module\thardfloat\n";
+}
+
 void MipsTargetAsmStreamer::emitDirectiveModuleOddSPReg(bool Enabled,
                                                         bool IsO32ABI) {
   MipsTargetStreamer::emitDirectiveModuleOddSPReg(Enabled, IsO32ABI);
 
   OS << "\t.module\t" << (Enabled ? "" : "no") << "oddspreg\n";
 }
 
 // This part is for ELF object output.

lib/Target/Mips/MipsTargetStreamer.h

public:
   /// .MIPS.abiflags section.
   void emitDirectiveModuleFP() {
     emitDirectiveModuleFP(ABIFlagsSection.getFpABI(),
                           ABIFlagsSection.Is32BitABI);
   }
 
   virtual void emitDirectiveModuleOddSPReg(bool Enabled, bool IsO32ABI);
   virtual void emitDirectiveSetFp(MipsABIFlagsSection::FpABIKind Value);
+
+  virtual void emitDirectiveModuleSoftFloat() {
+    ABIFlagsSection.setFpABI(MipsABIFlagsSection::FpABIKind::SOFT,
+                             ABIFlagsSection.Is32BitABI);
+  }
+
+  virtual void emitDirectiveModuleHardFloat() {
+    ABIFlagsSection.setFpABI(MipsABIFlagsSection::FpABIKind::ANY,
+                             ABIFlagsSection.Is32BitABI);
+  }
+
   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) {
public:
   void emitDirectiveCpsetup(unsigned RegNo, int RegOrOffset,
                             const MCSymbol &Sym, bool IsReg) override;
 
   // ABI Flags
   void emitDirectiveModuleFP(MipsABIFlagsSection::FpABIKind Value,
                              bool Is32BitABI) override;
   void emitDirectiveModuleOddSPReg(bool Enabled, bool IsO32ABI) override;
   void emitDirectiveSetFp(MipsABIFlagsSection::FpABIKind Value) override;
+  void emitDirectiveModuleSoftFloat() override;
+  void emitDirectiveModuleHardFloat() 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 -sections -section-data -section-relocations - | \
+# RUN:     FileCheck %s -check-prefix=CHECK-OBJ
+
+# CHECK-ASM: .module hardfloat
+
+# Check if the MIPS.abiflags section was correctly emitted:
+# CHECK-OBJ:       Section {
+# CHECK-OBJ-LABEL:   Name: .MIPS.abiflags
+# CHECK-OBJ:         SectionData (
+# CHECK-OBJ:              0000: 00002001 01010001 00000000 00000000  |.. .............|
+# CHECK-OBJ:              0010: 00000001 00000000                    |........|
+# CHECK-OBJ:            )
+# CHECK-OBJ:       }
+# The cpr1_size and fp_abi are in the second group of values:
+#   01 -> gpr_size  == AFL_REG_32
+#   01 -> cpr1_size == AFL_REG_32
+#   00 -> cpr2_size == AFL_REG_NONE
+#   01 -> fp_abi    == Val_GNU_MIPS_ABI_FP_DOUBLE
+
+  .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 -sections -section-data -section-relocations - | \
+# RUN:     FileCheck %s -check-prefix=CHECK-OBJ
+
+# CHECK-ASM: .module softfloat
+
+# Check if the MIPS.abiflags section was correctly emitted:
+# CHECK-OBJ:       Section {
+# CHECK-OBJ-LABEL:   Name: .MIPS.abiflags
+# CHECK-OBJ:         SectionData (
+# CHECK-OBJ:              0000: 00002001 01000003 00000000 00000000  |.. .............|
+# CHECK-OBJ:              0010: 00000001 00000000                    |........|
+# CHECK-OBJ:            )
+# CHECK-OBJ:       }
+# The cpr1_size and fp_abi are in the second group of values:
+#   01 -> gpr_size  == AFL_REG_32
+#   00 -> cpr1_size == AFL_REG_NONE
+#   00 -> cpr2_size == AFL_REG_NONE
+#   03 -> fp_abi    == Val_GNU_MIPS_ABI_FP_SOFT
+
+  .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.