[mips] Make the MipsAsmParser capable of knowing whether PIC mode is enabled or not.

Summary:
This information is needed to decide whether we do the PIC-only JAL expansions or not. It's also needed for an upcoming patch which implements the .cprestore assembler directive (which can only be used effectively in PIC mode).

By making this information available to the MipsAsmParser, we will know when to insert the instructions mandated by the .cprestore assembler directive and we will be able to give some useful warnings when we encounter a potential misuse of this directive.

Patch by Toma Tabacu

Reviewers: dsanders, seanbruno

Subscribers: brooks, seanbruno, rafael, llvm-commits

Differential Revision: http://reviews.llvm.org/D5626

llvm-svn: 245291

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

@@ -11,6 +11,7 @@
 #include "MCTargetDesc/MipsMCExpr.h"
 #include "MCTargetDesc/MipsMCTargetDesc.h"
 #include "MipsRegisterInfo.h"
+#include "MipsTargetObjectFile.h"
 #include "MipsTargetStreamer.h"
 #include "llvm/ADT/APInt.h"
 #include "llvm/ADT/SmallVector.h"
@@ -114,6 +115,7 @@ class MipsAsmParser : public MCTargetAsmParser {
                        // selected. This usually happens after an '.end func'
                        // directive.
   bool IsLittleEndian;
+  bool IsPicEnabled;
 
   // Print a warning along with its fix-it message at the given range.
   void printWarningWithFixIt(const Twine &Msg, const Twine &FixMsg,
@@ -406,6 +408,9 @@ public:
 
     CurrentFn = nullptr;
 
+    IsPicEnabled =
+        (getContext().getObjectFileInfo()->getRelocM() == Reloc::PIC_);
+
     Triple TheTriple(sti.getTargetTriple());
     if ((TheTriple.getArch() == Triple::mips) ||
         (TheTriple.getArch() == Triple::mips64))
@@ -475,6 +480,10 @@ public:
     return (STI.getFeatureBits()[Mips::FeatureCnMips]);
   }
 
+  bool inPicMode() {
+    return IsPicEnabled;
+  }
+
   bool inMips16Mode() const {
     return STI.getFeatureBits()[Mips::FeatureMips16];
   }
@@ -4714,6 +4723,9 @@ bool MipsAsmParser::parseDirectiveOption() {
   StringRef Option = Tok.getIdentifier();
 
   if (Option == "pic0") {
+    // MipsAsmParser needs to know if the current PIC mode changes.
+    IsPicEnabled = false;
+
     getTargetStreamer().emitDirectiveOptionPic0();
     Parser.Lex();
     if (Parser.getTok().isNot(AsmToken::EndOfStatement)) {
@@ -4725,6 +4737,9 @@ bool MipsAsmParser::parseDirectiveOption() {
   }
 
   if (Option == "pic2") {
+    // MipsAsmParser needs to know if the current PIC mode changes.
+    IsPicEnabled = true;
+
     getTargetStreamer().emitDirectiveOptionPic2();
     Parser.Lex();
     if (Parser.getTok().isNot(AsmToken::EndOfStatement)) {