[mips] Improve support for the .set mips16/nomips16 assembler directives.

Summary:
Appropriately set/clear the FeatureBit for Mips16 when these assembler directives are used and also emit ".set nomips16" (previously, only ".set mips16" was being emitted).

These improvements allow for better testing of the .cpload/.cprestore assembler directives (which are not supposed to work when Mips16 is enabled).

Test Plan: The test is bare-bones because there are no MC tests for Mips16 instructions (there's only one, which checks that the Mips16 ELF header flag gets set), and that suggests to me that it has not been implemented yet in the IAS.

Reviewers: dsanders

Reviewed By: dsanders

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D5462

llvm-svn: 221277

llvm/lib/Target/Mips/AsmParser/MipsAsmParser.cpp

@@ -200,6 +200,7 @@ class MipsAsmParser : public MCTargetAsmParser {
   bool parseSetNoDspDirective();
   bool parseSetReorderDirective();
   bool parseSetNoReorderDirective();
+  bool parseSetMips16Directive();
   bool parseSetNoMips16Directive();
   bool parseSetFpDirective();
   bool parseSetPopDirective();
@@ -2783,14 +2784,32 @@ bool MipsAsmParser::parseSetNoDspDirective() {
   return false;
 }
 
-bool MipsAsmParser::parseSetNoMips16Directive() {
+bool MipsAsmParser::parseSetMips16Directive() {
-  Parser.Lex();
+  Parser.Lex(); // Eat "mips16".
+
   // 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;
   }
-  // For now do nothing.
+
+  setFeatureBits(Mips::FeatureMips16, "mips16");
+  getTargetStreamer().emitDirectiveSetMips16();
+  Parser.Lex(); // Consume the EndOfStatement.
+  return false;
+}
+
+bool MipsAsmParser::parseSetNoMips16Directive() {
+  Parser.Lex(); // Eat "nomips16".
+
+  // 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;
+  }
+
+  clearFeatureBits(Mips::FeatureMips16, "mips16");
+  getTargetStreamer().emitDirectiveSetNoMips16();
   Parser.Lex(); // Consume the EndOfStatement.
   return false;
 }
@@ -2940,9 +2959,6 @@ bool MipsAsmParser::parseSetFeature(uint64_t Feature) {
   case Mips::FeatureMicroMips:
     getTargetStreamer().emitDirectiveSetMicroMips();
     break;
-  case Mips::FeatureMips16:
-    getTargetStreamer().emitDirectiveSetMips16();
-    break;
   case Mips::FeatureMips1:
     selectArch("mips1");
     getTargetStreamer().emitDirectiveSetMips1();
@@ -3131,7 +3147,7 @@ bool MipsAsmParser::parseDirectiveSet() {
   } else if (Tok.getString() == "nomacro") {
     return parseSetNoMacroDirective();
   } else if (Tok.getString() == "mips16") {
-    return parseSetFeature(Mips::FeatureMips16);
+    return parseSetMips16Directive();
   } else if (Tok.getString() == "nomips16") {
     return parseSetNoMips16Directive();
   } else if (Tok.getString() == "nomicromips") {

llvm/test/MC/Mips/set-mips16-directive.s

@@ -0,0 +1,10 @@
+# RUN: llvm-mc %s -arch=mips | FileCheck %s
+# FIXME: Update this test when we have a more mature implementation of Mips16 in the IAS.
+
+.text
+.set mips16
+.set nomips16
+
+# CHECK: .text
+# CHECK: .set mips16
+# CHECK: .set nomips16