[mips][ias] Fix N32 and N64 .cprestore directive when inside .set noat region.

[dsanders]

Summary

r268058 unintentionally made the retrieval of the current assembler temporary
unconditional. This was fine for the existing tests but it broke the cases
where the assembler temporary is not needed (N32/N64 or not PIC) and is
unavailable due to a '.set noat' directive.

This should fix FreeBSD's libc.

[dsanders]

Include the test case.

[sdardis]

LGTM with missing include addressed.

lib/Target/Mips/MipsTargetStreamer.h

84–86

Missing "#include <functional>" for use of std::function.

[seanbruno]

This does fix the errors I reported. Thanks!

lib/Target/Mips/AsmParser/MipsAsmParser.cpp

bool MipsAsmParser::parseDirectiveCpRestore(SMLoc Loc) {
   }
 
   // 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;
   }
 
-  unsigned ATReg = getATReg(Loc);
-  if (!ATReg)
+  if (!getTargetStreamer().emitDirectiveCpRestore(
+          CpRestoreOffset, [&]() { return getATReg(Loc); }, Loc, STI))
     return true;
-
-  getTargetStreamer().emitDirectiveCpRestore(CpRestoreOffset, ATReg, Loc, STI);
   Parser.Lex(); // Consume the EndOfStatement.
   return false;
 }
 
 bool MipsAsmParser::parseDirectiveCPSetup() {
   MCAsmParser &Parser = getParser();
   unsigned FuncReg;
   unsigned Save;

lib/Target/Mips/MCTargetDesc/MipsTargetStreamer.cpp

void MipsTargetStreamer::emitDirectiveSetSoftFloat() {
   forbidModuleDirective();
 }
 void MipsTargetStreamer::emitDirectiveSetHardFloat() {
   forbidModuleDirective();
 }
 void MipsTargetStreamer::emitDirectiveSetDsp() { forbidModuleDirective(); }
 void MipsTargetStreamer::emitDirectiveSetNoDsp() { forbidModuleDirective(); }
 void MipsTargetStreamer::emitDirectiveCpLoad(unsigned RegNo) {}
-void MipsTargetStreamer::emitDirectiveCpRestore(int Offset, unsigned ATReg,
-                                                SMLoc IDLoc,
-                                                const MCSubtargetInfo *STI) {
+bool MipsTargetStreamer::emitDirectiveCpRestore(
+    int Offset, std::function<unsigned()> GetATReg, SMLoc IDLoc,
   forbidModuleDirective();
+  return true;
 }
 void MipsTargetStreamer::emitDirectiveCpsetup(unsigned RegNo, int RegOrOffset,
                                               const MCSymbol &Sym, bool IsReg) {
 }
 void MipsTargetStreamer::emitDirectiveCpreturn(unsigned SaveLocation,
                                                bool SaveLocationIsRegister) {}
 
 void MipsTargetStreamer::emitDirectiveModuleFP() {}

 }
 
 void MipsTargetAsmStreamer::emitDirectiveCpLoad(unsigned RegNo) {
   OS << "\t.cpload\t$"
      << StringRef(MipsInstPrinter::getRegisterName(RegNo)).lower() << "\n";
   forbidModuleDirective();
 }
 
-void MipsTargetAsmStreamer::emitDirectiveCpRestore(int Offset, unsigned ATReg,
-                                                   SMLoc IDLoc,
-                                                   const MCSubtargetInfo *STI) {
-  MipsTargetStreamer::emitDirectiveCpRestore(Offset, ATReg, IDLoc, STI);
+bool MipsTargetAsmStreamer::emitDirectiveCpRestore(
+    int Offset, std::function<unsigned()> GetATReg, SMLoc IDLoc,
+  MipsTargetStreamer::emitDirectiveCpRestore(Offset, GetATReg, IDLoc, STI);
   OS << "\t.cprestore\t" << Offset << "\n";
+  return true;
 }
 
 void MipsTargetAsmStreamer::emitDirectiveCpsetup(unsigned RegNo,
                                                  int RegOrOffset,
                                                  const MCSymbol &Sym,
                                                  bool IsReg) {
   OS << "\t.cpsetup\t$"
      << StringRef(MipsInstPrinter::getRegisterName(RegNo)).lower() << ", ";
void MipsTargetELFStreamer::emitDirectiveCpLoad(unsigned RegNo) {
   TmpInst.addOperand(MCOperand::createReg(Mips::GP));
   TmpInst.addOperand(MCOperand::createReg(Mips::GP));
   TmpInst.addOperand(MCOperand::createReg(RegNo));
   getStreamer().EmitInstruction(TmpInst, STI);
 
   forbidModuleDirective();
 }
 
-void MipsTargetELFStreamer::emitDirectiveCpRestore(int Offset, unsigned ATReg,
-                                                   SMLoc IDLoc,
-                                                   const MCSubtargetInfo *STI) {
-  MipsTargetStreamer::emitDirectiveCpRestore(Offset, ATReg, IDLoc, STI);
+bool MipsTargetELFStreamer::emitDirectiveCpRestore(
+    int Offset, std::function<unsigned()> GetATReg, SMLoc IDLoc,
+  MipsTargetStreamer::emitDirectiveCpRestore(Offset, GetATReg, IDLoc, STI);
   // .cprestore offset
   // When PIC mode is enabled and the O32 ABI is used, this directive expands
   // to:
   //    sw $gp, offset($sp)
   // and adds a corresponding LW after every JAL.
 
   // Note that .cprestore is ignored if used with the N32 and N64 ABIs or if it
   // is used in non-PIC mode.
   if (!Pic || (getABI().IsN32() || getABI().IsN64()))
-    return;
+    return true;
+
+  unsigned ATReg = GetATReg();
+  if (!ATReg)
+    return false;
 
   // Store the $gp on the stack.
   emitStoreWithImmOffset(Mips::SW, Mips::GP, Mips::SP, Offset, ATReg, IDLoc,
                          STI);
+  return true;
 }
 
 void MipsTargetELFStreamer::emitDirectiveCpsetup(unsigned RegNo,
                                                  int RegOrOffset,
                                                  const MCSymbol &Sym,
                                                  bool IsReg) {
   // Only N32 and N64 emit anything for .cpsetup iff PIC is set.
   if (!Pic || !(getABI().IsN32() || getABI().IsN64()))

lib/Target/Mips/MipsTargetStreamer.h

public:
   virtual void emitDirectiveSetNoDsp();
   virtual void emitDirectiveSetPop();
   virtual void emitDirectiveSetPush();
   virtual void emitDirectiveSetSoftFloat();
   virtual void emitDirectiveSetHardFloat();
 
   // PIC support
   virtual void emitDirectiveCpLoad(unsigned RegNo);
-  virtual void emitDirectiveCpRestore(int Offset, unsigned ATReg, SMLoc IDLoc,
-                                      const MCSubtargetInfo *STI);
+  virtual bool emitDirectiveCpRestore(int Offset,
+                                      std::function<unsigned()> GetATReg,
+                                      SMLoc IDLoc, const MCSubtargetInfo *STI);
   virtual void emitDirectiveCpsetup(unsigned RegNo, int RegOrOffset,
                                     const MCSymbol &Sym, bool IsReg);
   virtual void emitDirectiveCpreturn(unsigned SaveLocation,
                                      bool SaveLocationIsRegister);
 
   // FP abiflags directives
   virtual void emitDirectiveModuleFP();
   virtual void emitDirectiveModuleOddSPReg();
public:
   void emitDirectiveSetNoDsp() override;
   void emitDirectiveSetPop() override;
   void emitDirectiveSetPush() override;
   void emitDirectiveSetSoftFloat() override;
   void emitDirectiveSetHardFloat() override;
 
   // PIC support
   void emitDirectiveCpLoad(unsigned RegNo) override;
-  void emitDirectiveCpRestore(int Offset, unsigned ATReg, SMLoc IDLoc,
-                              const MCSubtargetInfo *STI) override;
+  bool emitDirectiveCpRestore(int Offset, std::function<unsigned()> GetATReg,
+                              SMLoc IDLoc, const MCSubtargetInfo *STI) override;
   void emitDirectiveCpsetup(unsigned RegNo, int RegOrOffset,
                             const MCSymbol &Sym, bool IsReg) override;
   void emitDirectiveCpreturn(unsigned SaveLocation,
                              bool SaveLocationIsRegister) override;
 
   // FP abiflags directives
   void emitDirectiveModuleFP() override;
   void emitDirectiveModuleOddSPReg() override;
public:
   void emitDirectiveInsn() override;
   void emitFrame(unsigned StackReg, unsigned StackSize,
                  unsigned ReturnReg) override;
   void emitMask(unsigned CPUBitmask, int CPUTopSavedRegOff) override;
   void emitFMask(unsigned FPUBitmask, int FPUTopSavedRegOff) override;
 
   // PIC support
   void emitDirectiveCpLoad(unsigned RegNo) override;
-  void emitDirectiveCpRestore(int Offset, unsigned ATReg, SMLoc IDLoc,
-                              const MCSubtargetInfo *STI) override;
+  bool emitDirectiveCpRestore(int Offset, std::function<unsigned()> GetATReg,
+                              SMLoc IDLoc, const MCSubtargetInfo *STI) override;
   void emitDirectiveCpsetup(unsigned RegNo, int RegOrOffset,
                             const MCSymbol &Sym, bool IsReg) override;
   void emitDirectiveCpreturn(unsigned SaveLocation,
                              bool SaveLocationIsRegister) override;
 
   void emitMipsAbiFlags();
 };
 }
 #endif

test/MC/Mips/cprestore-noreorder-noat.s

+# RUN: not llvm-mc %s -arch=mips -mcpu=mips32 -relocation-model=pic -filetype=obj \
+# RUN:   -o /dev/null 2>&1 | FileCheck %s -check-prefix=O32
+
+# RUN: llvm-mc %s -arch=mips64 -mcpu=mips64 -relocation-model=pic \
+# RUN:   -filetype=obj -o /dev/null 2>&1 | FileCheck %s -allow-empty -check-prefix=N32
+
+# RUN: llvm-mc %s -arch=mips64 -mcpu=mips64 -relocation-model=pic -target-abi=n32 \
+# RUN:   -filetype=obj -o /dev/null 2>&1 | FileCheck %s -allow-empty -check-prefix=N64
+
+# RUN: llvm-mc %s -arch=mips64 -mcpu=mips64 -relocation-model=pic -target-abi=n32 \
+# RUN:   -filetype=obj -o - | llvm-objdump -d -r - | \
+# RUN:   FileCheck %s -check-prefix=NO-STORE
+
+# RUN: llvm-mc %s -arch=mips64 -mcpu=mips64 -relocation-model=pic -filetype=obj -o - | \
+# RUN:   llvm-objdump -d -r - | \
+# RUN:   FileCheck %s -check-prefix=NO-STORE
+
+  .text
+  .ent foo
+foo:
+  .frame  $sp, 0, $ra
+  .set noreorder
+  .set noat
+
+  .cpload $25
+  .cprestore 8
+# O32: :[[@LINE-1]]:3: error: pseudo-instruction requires $at, which is not available
+# N32-NOT: error: pseudo-instruction requires $at, which is not available
+# N64-NOT: error: pseudo-instruction requires $at, which is not available
+# NO-STORE-NOT: sw  $gp, 8($sp)
+
+  jal $25
+  jal $4, $25
+  jal foo
+
+  .end foo