Implement the ".rdata" MIPS assembly directive.

[bsdjhb]

Summary

Rather than creating a separate ".rdata" section distinct from the
customary ".rodata" in ELF, ".rdata" switches to the ".rodata"
section.

[bsdjhb]

I chose to just map .rdata to .rodata since that is what binutils appears to do for MIPS ELF. binutils doesn't appear to set SHF_MIPS_GPREL so I'm not sure if that should be set as it is for .sdata and .sbss. Having a separate .rdata from .rodata probably isn't the end of the world if that is more correct.

[sdardis]

LGTM. .rdata is the SGI pseudo op equivalent of the ELF .rodata.

Nit: The test should be in test/MC/Mips/mips-rdata.s

The SHF_MIPS_GPREL flag is set when a section is called "srdata" but there is no pseudo-op support for that. That's irrelevant to this patch though.

Do you need me to commit this for you?

test/CodeGen/Mips/mips-rdata.s

1–13

This file belongs in test/MC/Mips/mips-rdata.s

[davide]

Do you need somebody this to commit for you John, or you have commit access?

lib/Target/Mips/AsmParser/MipsAsmParser.cpp

#include "MipsGenAsmMatcher.inc"
   bool parseDirectiveCpLoad(SMLoc Loc);
   bool parseDirectiveCpRestore(SMLoc Loc);
   bool parseDirectiveCPSetup();
   bool parseDirectiveCPReturn();
   bool parseDirectiveNaN();
   bool parseDirectiveSet();
   bool parseDirectiveOption();
   bool parseInsnDirective();
+  bool parseRSectionDirective(StringRef Section);
   bool parseSSectionDirective(StringRef Section, unsigned Type);
 
   bool parseSetAtDirective();
   bool parseSetNoAtDirective();
   bool parseSetMacroDirective();
   bool parseSetNoMacroDirective();
   bool parseSetMsaDirective();
   bool parseSetNoMsaDirective();
bool MipsAsmParser::parseInsnDirective() {
   // The actual label marking happens in
   // MipsELFStreamer::createPendingLabelRelocs().
   getTargetStreamer().emitDirectiveInsn();
 
   getParser().Lex(); // Eat EndOfStatement token.
   return false;
 }
 
+/// parseRSectionDirective
+///  ::= .rdata
+bool MipsAsmParser::parseRSectionDirective(StringRef Section) {
+  // 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;
+  }
+
+  MCSection *ELFSection = getContext().getELFSection(
+      Section, ELF::SHT_PROGBITS, ELF::SHF_ALLOC);
+  getParser().getStreamer().SwitchSection(ELFSection);
+
+  getParser().Lex(); // Eat EndOfStatement token.
+  return false;
+}
+
 /// parseSSectionDirective
 ///  ::= .sbss
 ///  ::= .sdata
 bool MipsAsmParser::parseSSectionDirective(StringRef Section, unsigned Type) {
   // 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;
bool MipsAsmParser::ParseDirective(AsmToken DirectiveID) {
   if (IDVal == ".llvm_internal_mips_reallow_module_directive") {
     parseInternalDirectiveReallowModule();
     return false;
   }
   if (IDVal == ".insn") {
     parseInsnDirective();
     return false;
   }
+  if (IDVal == ".rdata") {
+    parseRSectionDirective(".rodata");
+    return false;
+  }
   if (IDVal == ".sbss") {
     parseSSectionDirective(IDVal, ELF::SHT_NOBITS);
     return false;
   }
   if (IDVal == ".sdata") {
     parseSSectionDirective(IDVal, ELF::SHT_PROGBITS);
     return false;
   }

test/CodeGen/Mips/mips-rdata.s

+# Check that .rdata sections have proper name, flags, and section types.
+
+# RUN: llvm-mc -filetype=obj -triple=mips-unknown-linux %s -o - \
+# RUN:   | llvm-readobj -s | FileCheck %s
+
+  .rdata
+  .word 0
+
+# CHECK:      Name: .rodata
+# CHECK-NEXT: Type: SHT_PROGBITS
+# CHECK-NEXT: Flags [ (0x2)
+# CHECK-NEXT:   SHF_ALLOC
+# CHECK-NEXT: ]