Implement Subtarget support

Implement the X86 Subtarget.

This consolidates the checks for target triple, and setting options based
on target triple into one place.  This allows us to convert the asm printer
and isel over from being littered with "forDarwin", "forCygwin", etc. into
just having the appropriate flags for each subtarget feature controlling
the code for that feature.

This patch also implements indirect external and weak references in the
X86 pattern isel, for darwin.  Next up is to convert over the asm printers
to use this new interface.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@22389 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Target/TargetMachine.h

@@ -19,6 +19,7 @@
 
 namespace llvm {
 
+class TargetSubtarget;
 class TargetInstrInfo;
 class TargetInstrDescriptor;
 class TargetJITInfo;
@@ -97,6 +98,13 @@ public:
   virtual const TargetFrameInfo        *getFrameInfo() const { return 0; }
   const TargetData &getTargetData() const { return DataLayout; }
 
+  virtual const TargetSubtarget *getSubtargetImpl() const { return 0; }
+  template<typename STC> STC *getSubtarget() const {
+    assert(getSubtargetImpl() && dynamic_cast<STC*>(getSubtargetImpl()) &&
+           "Not the right kind of subtarget!");
+    return (STC*)getSubtargetImpl();
+  }
+
   /// getRegisterInfo - If register information is available, return it.  If
   /// not, return null.  This is kept separate from RegInfo until RegInfo has
   /// details of graph coloring register allocation removed from it.

include/llvm/Target/TargetSubtarget.h

@@ -0,0 +1,41 @@
+//==-- llvm/Target/TargetSubtarget.h - Target Information --------*- C++ -*-==//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by Nate Begeman and is distributed under the
+// University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file describes the subtarget options of a Target machine.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TARGET_TARGETSUBTARGET_H
+#define LLVM_TARGET_TARGETSUBTARGET_H
+
+namespace llvm {
+
+class Module;
+
+//===----------------------------------------------------------------------===//
+///
+/// TargetSubtarget - Generic base class for all target subtargets.  All
+/// Target-specific options that control code generation and printing should
+/// be exposed through a TargetSubtarget-derived class.
+///
+class TargetSubtarget {
+  TargetSubtarget(const TargetSubtarget&);   // DO NOT IMPLEMENT
+  void operator=(const TargetSubtarget&);  // DO NOT IMPLEMENT
+protected: // Can only create subclasses...
+  /// This constructor initializes the data members to match that 
+  /// of the specified module.
+  ///
+  TargetSubtarget(const Module &M);
+public:
+  virtual ~TargetSubtarget();
+};
+
+} // End llvm namespace
+
+#endif

lib/Target/TargetSubtarget.cpp

@@ -0,0 +1,22 @@
+//===-- TargetSubtarget.cpp - General Target Information -------------------==//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by Nate Begeman and is distributed under the 
+// University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file describes the general parts of a Subtarget.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Target/TargetSubtarget.h"
+using namespace llvm;
+
+//---------------------------------------------------------------------------
+// TargetSubtarget Class
+//
+TargetSubtarget::TargetSubtarget(const Module &M) {}
+
+TargetSubtarget::~TargetSubtarget() {}

lib/Target/X86/X86ISelPattern.cpp

@@ -14,6 +14,7 @@
 #include "X86.h"
 #include "X86InstrBuilder.h"
 #include "X86RegisterInfo.h"
+#include "X86Subtarget.h"
 #include "llvm/CallingConv.h"
 #include "llvm/Constants.h"
 #include "llvm/Instructions.h"
@@ -26,6 +27,7 @@
 #include "llvm/CodeGen/SSARegMap.h"
 #include "llvm/Target/TargetData.h"
 #include "llvm/Target/TargetLowering.h"
+#include "llvm/Target/TargetMachine.h"
 #include "llvm/Target/TargetOptions.h"
 #include "llvm/Support/CFG.h"
 #include "llvm/Support/MathExtras.h"
@@ -996,8 +998,13 @@ namespace {
 
     /// TheDAG - The DAG being selected during Select* operations.
     SelectionDAG *TheDAG;
+    
+    /// Subtarget - Keep a pointer to the X86Subtarget around so that we can 
+    /// make the right decision when generating code for different targets.
+    const X86Subtarget *Subtarget;
   public:
     ISel(TargetMachine &TM) : SelectionDAGISel(X86Lowering), X86Lowering(TM) {
+      Subtarget = TM.getSubtarget<const X86Subtarget>();
     }
 
     virtual const char *getPassName() const {
@@ -1314,8 +1321,18 @@ bool ISel::MatchAddress(SDOperand N, X86ISelAddressMode &AM) {
     break;
   case ISD::GlobalAddress:
     if (AM.GV == 0) {
-      AM.GV = cast<GlobalAddressSDNode>(N)->getGlobal();
-      return false;
+      GlobalValue *GV = cast<GlobalAddressSDNode>(N)->getGlobal();
+      // For Darwin, external and weak symbols are indirect, so we want to load
+      // the value at address GV, not the value of GV itself.  This means that
+      // the GlobalAddress must be in the base or index register of the address,
+      // not the GV offset field.
+      if (Subtarget->getIndirectExternAndWeakGlobals() && 
+          (GV->hasWeakLinkage() || GV->isExternal())) {
+        break;
+      } else {
+        AM.GV = GV;
+        return false;
+      }
     }
     break;
   case ISD::Constant:
@@ -2236,7 +2253,15 @@ unsigned ISel::SelectExpr(SDOperand N) {
     return Result;
   case ISD::GlobalAddress: {
     GlobalValue *GV = cast<GlobalAddressSDNode>(N)->getGlobal();
-    BuildMI(BB, X86::MOV32ri, 1, Result).addGlobalAddress(GV);
+    // For Darwin, external and weak symbols are indirect, so we want to load
+    // the value at address GV, not the value of GV itself.
+    if (Subtarget->getIndirectExternAndWeakGlobals() && 
+        (GV->hasWeakLinkage() || GV->isExternal())) {
+      BuildMI(BB, X86::MOV32rm, 4, Result).addReg(0).addZImm(1).addReg(0)
+        .addGlobalAddress(GV, false, 0);
+    } else {
+      BuildMI(BB, X86::MOV32ri, 1, Result).addGlobalAddress(GV);
+    }
     return Result;
   }
   case ISD::ExternalSymbol: {

lib/Target/X86/X86Subtarget.cpp

@@ -0,0 +1,59 @@
+//===- X86Subtarget.cpp - X86 Instruction Information -----------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by Nate Begeman and is distributed under the
+// University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the X86 specific subclass of TargetSubtarget.
+//
+//===----------------------------------------------------------------------===//
+
+#include "X86Subtarget.h"
+#include "llvm/Module.h"
+using namespace llvm;
+
+X86Subtarget::X86Subtarget(const Module &M) 
+  : TargetSubtarget(M), stackAlignment(8), 
+    indirectExternAndWeakGlobals(false), asmDarwinLinkerStubs(false),
+    asmLeadingUnderscore(false), asmAlignmentIsInBytes(false),
+    asmPrintDotLocalConstants(false), asmPrintDotLCommConstants(false),
+    asmPrintConstantAlignment(false) {
+  // Declare a boolean for each platform
+  bool forCygwin = false;
+  bool forDarwin = false;
+  bool forWindows = false;
+  
+  // Set the boolean corresponding to the current target triple, or the default
+  // if one cannot be determined, to true.
+  const std::string& TT = M.getTargetTriple();
+  if (TT.length() > 5) {
+    forCygwin = TT.find("cygwin") != std::string::npos ||
+                TT.find("mingw")  != std::string::npos;
+    forDarwin = TT.find("darwin") != std::string::npos;
+    forWindows = TT.find("win32") != std::string::npos;
+  } else if (TT.empty()) {
+#if defined(__CYGWIN__) || defined(__MINGW32__)
+    forCygwin = true;
+#elif defined(__APPLE__)
+    forDarwin = true;
+#elif defined(_WIN32)
+    forWindws = true;
+#endif
+  }
+
+  if (forCygwin) {
+    asmLeadingUnderscore = true;
+  }
+  if (forDarwin) {
+    stackAlignment = 16;
+    indirectExternAndWeakGlobals = true;
+    asmDarwinLinkerStubs = true;
+    asmLeadingUnderscore = true;
+    asmPrintDotLCommConstants = true;
+  }
+  if (forWindows) {
+  }
+}

lib/Target/X86/X86Subtarget.h

@@ -0,0 +1,55 @@
+//=====-- X86Subtarget.h - Define TargetMachine for the X86 ---*- C++ -*--====//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by Nate Begeman and is distributed under the
+// University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file declares the X86 specific subclass of TargetSubtarget.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef X86SUBTARGET_H
+#define X86SUBTARGET_H
+
+#include "llvm/Target/TargetSubtarget.h"
+
+namespace llvm {
+class Module;
+
+class X86Subtarget : public TargetSubtarget {
+protected:
+  /// Used by the target machine to set up the target frame info
+  unsigned stackAlignment;
+  
+  /// Used by instruction selector
+  bool indirectExternAndWeakGlobals;
+  
+  /// Used by the asm printer
+  bool asmDarwinLinkerStubs;
+  bool asmLeadingUnderscore;
+  bool asmAlignmentIsInBytes;
+  bool asmPrintDotLocalConstants;
+  bool asmPrintDotLCommConstants;
+  bool asmPrintConstantAlignment;
+public:
+  /// This constructor initializes the data members to match that 
+  /// of the specified module.
+  ///
+  X86Subtarget(const Module &M);
+  
+  /// Returns the preferred stack alignment for the current target triple, or
+  /// the default if no target triple is set.
+  unsigned getStackAlignment() const { return stackAlignment; }
+  
+  /// Returns true if the instruction selector should treat global values
+  /// referencing external or weak symbols as indirect rather than direct 
+  /// references.
+  bool getIndirectExternAndWeakGlobals() const { 
+    return indirectExternAndWeakGlobals; }
+};
+} // End llvm namespace
+
+#endif

lib/Target/X86/X86TargetMachine.cpp

@@ -92,7 +92,9 @@ unsigned X86TargetMachine::getModuleMatchQuality(const Module &M) {
 ///
 X86TargetMachine::X86TargetMachine(const Module &M, IntrinsicLowering *IL)
   : TargetMachine("X86", IL, true, 4, 4, 4, 4, 4),
-    FrameInfo(TargetFrameInfo::StackGrowsDown, 8, -4),
+    Subtarget(M),
+    FrameInfo(TargetFrameInfo::StackGrowsDown,
+              Subtarget.getStackAlignment(), -4),
     JITInfo(*this) {
   // Scalar SSE FP requires at least SSE2
   X86ScalarSSE &= X86Vector >= SSE2;

lib/Target/X86/X86TargetMachine.h

@@ -19,12 +19,14 @@
 #include "llvm/PassManager.h"
 #include "X86InstrInfo.h"
 #include "X86JITInfo.h"
+#include "X86Subtarget.h"
 
 namespace llvm {
 class IntrinsicLowering;
 
 class X86TargetMachine : public TargetMachine {
   X86InstrInfo    InstrInfo;
+  X86Subtarget    Subtarget;
   TargetFrameInfo FrameInfo;
   X86JITInfo      JITInfo;
 public:
@@ -33,6 +35,7 @@ public:
   virtual const X86InstrInfo     *getInstrInfo() const { return &InstrInfo; }
   virtual const TargetFrameInfo  *getFrameInfo() const { return &FrameInfo; }
   virtual       TargetJITInfo    *getJITInfo()         { return &JITInfo; }
+  virtual const TargetSubtarget  *getSubtargetImpl() const{ return &Subtarget; }
   virtual const MRegisterInfo    *getRegisterInfo() const {
     return &InstrInfo.getRegisterInfo();
   }