This is a resubmittal. For some reason it broke the bots yesterday

but I cannot reproduce the problem and have scrubed my sources and
even tested with llvm-lit -v --vg.
Support for Mips register information sections.

Mips ELF object files have a section that is dedicated
to register use info. Some of this information such as
the assumed Global Pointer value is used by the linker
in relocation resolution.

The register info file is .reginfo in o32 and .MIPS.options
in 64 and n32 abi files.

This patch contains the changes needed to create the sections,
but leaves the actual register accounting for a future patch.


Contributer: Jack Carter
 
llvm-svn: 172847

llvm/include/llvm/Support/ELF.h

@@ -909,6 +909,9 @@ enum {
                                         // this section based on their sizes
   SHT_X86_64_UNWIND       = 0x70000001, // Unwind information
 
+  SHT_MIPS_REGINFO        = 0x70000006, // Register usage information
+  SHT_MIPS_OPTIONS        = 0x7000000d, // General options
+
   SHT_HIPROC        = 0x7fffffff, // Highest processor architecture-specific type.
   SHT_LOUSER        = 0x80000000, // Lowest type reserved for applications.
   SHT_HIUSER        = 0xffffffff  // Highest type reserved for applications.
@@ -975,8 +978,10 @@ enum {
 
   // All sections with the GPREL flag are grouped into a global data area 
   // for faster accesses
-  SHF_HEX_GPREL = 0x10000000
+  SHF_HEX_GPREL = 0x10000000,
 
+  // Do not strip this section. FIXME: We need target specific SHF_ enums.
+  SHF_MIPS_NOSTRIP = 0x8000000
 };
 
 // Section Group Flags

llvm/lib/MC/ELFObjectWriter.cpp

@@ -1319,6 +1319,8 @@ void ELFObjectWriter::WriteSection(MCAssembler &Asm,
   case ELF::SHT_FINI_ARRAY:
   case ELF::SHT_PREINIT_ARRAY:
   case ELF::SHT_X86_64_UNWIND:
+  case ELF::SHT_MIPS_REGINFO:
+  case ELF::SHT_MIPS_OPTIONS:
     // Nothing to do.
     break;
 

llvm/lib/Target/Mips/MCTargetDesc/CMakeLists.txt

@@ -5,6 +5,7 @@ add_llvm_library(LLVMMipsDesc
   MipsMCCodeEmitter.cpp
   MipsMCTargetDesc.cpp
   MipsELFObjectWriter.cpp
+  MipsReginfo.cpp
   )
 
 add_dependencies(LLVMMipsDesc MipsCommonTableGen)

llvm/lib/Target/Mips/MCTargetDesc/MipsReginfo.cpp

@@ -0,0 +1,80 @@
+//===-- MipsReginfo.cpp - Registerinfo handling  --------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+// .reginfo
+//    Elf32_Word ri_gprmask
+//    Elf32_Word ri_cprmask[4]
+//    Elf32_Word ri_gp_value
+//
+// .MIPS.options - N64
+//    Elf64_Byte    kind (ODK_REGINFO)
+//    Elf64_Byte    size (40 bytes)
+//    Elf64_Section section (0)
+//    Elf64_Word    info (unused)
+//    Elf64_Word    ri_gprmask ()
+//    Elf64_Word    ri_pad ()
+//    Elf64_Word[4] ri_cprmask ()
+//    Elf64_Addr    ri_gp_value ()
+//
+// .MIPS.options - N32
+//    Elf32_Byte    kind (ODK_REGINFO)
+//    Elf32_Byte    size (36 bytes)
+//    Elf32_Section section (0)
+//    Elf32_Word    info (unused)
+//    Elf32_Word    ri_gprmask ()
+//    Elf32_Word    ri_pad ()
+//    Elf32_Word[4] ri_cprmask ()
+//    Elf32_Addr    ri_gp_value ()
+//
+//===----------------------------------------------------------------------===//
+#include "MCTargetDesc/MipsReginfo.h"
+#include "MipsSubtarget.h"
+#include "MipsTargetObjectFile.h"
+#include "llvm/MC/MCStreamer.h"
+
+using namespace llvm;
+
+// Integrated assembler version
+void
+MipsReginfo::emitMipsReginfoSectionCG(MCStreamer &OS,
+    const TargetLoweringObjectFile &TLOF,
+    const MipsSubtarget &MST) const
+{
+
+  if (OS.hasRawTextSupport())
+    return;
+
+  const MipsTargetObjectFile &TLOFELF =
+      static_cast<const MipsTargetObjectFile &>(TLOF);
+  OS.SwitchSection(TLOFELF.getReginfoSection());
+
+  // .reginfo
+  if (MST.isABI_O32()) {
+    OS.EmitIntValue(0, 4); // ri_gprmask
+    OS.EmitIntValue(0, 4); // ri_cpr[0]mask
+    OS.EmitIntValue(0, 4); // ri_cpr[1]mask
+    OS.EmitIntValue(0, 4); // ri_cpr[2]mask
+    OS.EmitIntValue(0, 4); // ri_cpr[3]mask
+    OS.EmitIntValue(0, 4); // ri_gp_value
+  }
+  // .MIPS.options
+  else if (MST.isABI_N64()) {
+    OS.EmitIntValue(1, 1); // kind
+    OS.EmitIntValue(40, 1); // size
+    OS.EmitIntValue(0, 2); // section
+    OS.EmitIntValue(0, 4); // info
+    OS.EmitIntValue(0, 4); // ri_gprmask
+    OS.EmitIntValue(0, 4); // pad
+    OS.EmitIntValue(0, 4); // ri_cpr[0]mask
+    OS.EmitIntValue(0, 4); // ri_cpr[1]mask
+    OS.EmitIntValue(0, 4); // ri_cpr[2]mask
+    OS.EmitIntValue(0, 4); // ri_cpr[3]mask
+    OS.EmitIntValue(0, 8); // ri_gp_value
+  }
+  else llvm_unreachable("Unsupported abi for reginfo");
+}
+

llvm/lib/Target/Mips/MCTargetDesc/MipsReginfo.h

@@ -0,0 +1,31 @@
+//=== MipsReginfo.h - MipsReginfo -----------------------------------------===//
+//
+//                    The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENCE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef MIPSREGINFO_H
+#define MIPSREGINFO_H
+
+namespace llvm {
+  class MCStreamer;
+  class TargetLoweringObjectFile;
+  class MipsSubtarget;
+
+  class MipsReginfo {
+    void anchor();
+  public:
+    MipsReginfo() {}
+
+    void emitMipsReginfoSectionCG(MCStreamer &OS,
+        const TargetLoweringObjectFile &TLOF,
+        const MipsSubtarget &MST) const;
+  };
+
+} // namespace llvm
+
+#endif
+

llvm/lib/Target/Mips/MipsAsmPrinter.cpp

@@ -13,10 +13,10 @@
 //===----------------------------------------------------------------------===//
 
 #define DEBUG_TYPE "mips-asm-printer"
-#include "MipsAsmPrinter.h"
 #include "InstPrinter/MipsInstPrinter.h"
 #include "MCTargetDesc/MipsBaseInfo.h"
 #include "Mips.h"
+#include "MipsAsmPrinter.h"
 #include "MipsInstrInfo.h"
 #include "MipsMCInstLower.h"
 #include "llvm/ADT/SmallString.h"
@@ -540,6 +540,14 @@ void MipsAsmPrinter::EmitStartOfAsmFile(Module &M) {
   // return to previous section
   if (OutStreamer.hasRawTextSupport())
     OutStreamer.EmitRawText(StringRef("\t.previous"));
+
+}
+
+void MipsAsmPrinter::EmitEndOfAsmFile(Module &M) {
+
+  // Emit Mips ELF register info
+  Subtarget->getMReginfo().emitMipsReginfoSectionCG(
+             OutStreamer, getObjFileLowering(), *Subtarget);
 }
 
 MachineLocation

llvm/lib/Target/Mips/MipsAsmPrinter.h

@@ -80,6 +80,7 @@ public:
   void printFCCOperand(const MachineInstr *MI, int opNum, raw_ostream &O,
                        const char *Modifier = 0);
   void EmitStartOfAsmFile(Module &M);
+  void EmitEndOfAsmFile(Module &M);
   virtual MachineLocation getDebugValueLocation(const MachineInstr *MI) const;
   void PrintDebugValueComment(const MachineInstr *MI, raw_ostream &OS);
 };

llvm/lib/Target/Mips/MipsSubtarget.h

@@ -14,6 +14,7 @@
 #ifndef MIPSSUBTARGET_H
 #define MIPSSUBTARGET_H
 
+#include "MCTargetDesc/MipsReginfo.h"
 #include "llvm/MC/MCInstrItineraries.h"
 #include "llvm/Target/TargetSubtargetInfo.h"
 #include <string>
@@ -96,6 +97,9 @@ protected:
 
   InstrItineraryData InstrItins;
 
+  // The instance to the register info section object
+  MipsReginfo MRI;
+
 public:
   virtual bool enablePostRAScheduler(CodeGenOpt::Level OptLevel,
                                      AntiDepBreakMode& Mode,
@@ -145,6 +149,9 @@ public:
   bool hasSwap()      const { return HasSwap; }
   bool hasBitCount()  const { return HasBitCount; }
   bool hasFPIdx()     const { return HasFPIdx; }
+
+  // Grab MipsRegInfo object
+  const MipsReginfo &getMReginfo() const { return MRI; }
 };
 } // End llvm namespace
 

llvm/lib/Target/Mips/MipsTargetObjectFile.cpp

@@ -38,6 +38,20 @@ void MipsTargetObjectFile::Initialize(MCContext &Ctx, const TargetMachine &TM){
                                ELF::SHF_WRITE |ELF::SHF_ALLOC,
                                SectionKind::getBSS());
 
+  // Register info information
+  const MipsSubtarget &Subtarget = TM.getSubtarget<MipsSubtarget>();
+  if (Subtarget.isABI_N64() || Subtarget.isABI_N32())
+    ReginfoSection =
+      getContext().getELFSection(".MIPS.options",
+                                 ELF::SHT_MIPS_OPTIONS,
+                                 ELF::SHF_ALLOC |ELF::SHF_MIPS_NOSTRIP,
+                                 SectionKind::getMetadata());
+  else
+    ReginfoSection =
+      getContext().getELFSection(".reginfo",
+                                 ELF::SHT_MIPS_REGINFO,
+                                 ELF::SHF_ALLOC,
+                                 SectionKind::getMetadata());
 }
 
 // A address must be loaded from a small section if its size is less than the

llvm/lib/Target/Mips/MipsTargetObjectFile.h

@@ -17,6 +17,7 @@ namespace llvm {
   class MipsTargetObjectFile : public TargetLoweringObjectFileELF {
     const MCSection *SmallDataSection;
     const MCSection *SmallBSSSection;
+    const MCSection *ReginfoSection;
   public:
 
     void Initialize(MCContext &Ctx, const TargetMachine &TM);
@@ -35,6 +36,7 @@ namespace llvm {
                                             const TargetMachine &TM) const;
 
     // TODO: Classify globals as mips wishes.
+    const MCSection *getReginfoSection() const { return ReginfoSection; }
   };
 } // end namespace llvm
 

llvm/test/MC/Mips/elf-reginfo.ll

@@ -0,0 +1,31 @@
+ ; RUN: llc -filetype=obj -march=mips64el -mcpu=mips64 %s -o - \
+ ; RUN: | elf-dump --dump-section-data  | FileCheck --check-prefix=CHECK_64 %s
+ ; RUN: llc -filetype=obj -march=mipsel -mcpu=mips32 %s -o - \
+ ; RUN: | elf-dump --dump-section-data  | FileCheck --check-prefix=CHECK_32 %s
+
+; Check for register information sections.
+;
+
+@str = private unnamed_addr constant [12 x i8] c"hello world\00"
+
+define i32 @main() nounwind {
+entry:
+; Check that the appropriate relocations were created.
+
+; check for .MIPS.options
+; CHECK_64:      (('sh_name', 0x{{[0-9|a-f]+}}) # '.MIPS.options'
+; CHECK_64-NEXT: ('sh_type', 0x7000000d)
+; CHECK_64-NEXT: ('sh_flags', 0x0000000008000002)
+
+; check for .reginfo
+; CHECK_32:      (('sh_name', 0x{{[0-9|a-f]+}}) # '.reginfo'
+; CHECK_32-NEXT: ('sh_type', 0x70000006)
+; CHECK_32-NEXT: ('sh_flags', 0x00000002)
+
+
+  %puts = tail call i32 @puts(i8* getelementptr inbounds ([12 x i8]* @str, i64 0, i64 0))
+  ret i32 0
+
+}
+declare i32 @puts(i8* nocapture) nounwind
+