[FastISel] Add basic infrastructure to support a target-independent call lowering hook in FastISel. WIP

The infrastructure mimics the call lowering we have already in place for
SelectionDAG, but with limitations. For example structure return demotion and
non-simple types are not supported (yet).

Currently every backend has its own implementation and duplicated code for call
lowering. There is also no specified interface that could be called from
target-independent code. The target-hook is opt-in and doesn't affect current
implementations.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@212848 91177308-0d34-0410-b5e6-96231b3b80d8

Author: ributzka

include/llvm/CodeGen/FastISel.h

@@ -16,7 +16,10 @@
 #define LLVM_CODEGEN_FASTISEL_H
 
 #include "llvm/ADT/DenseMap.h"
+#include "llvm/CodeGen/CallingConvLower.h"
 #include "llvm/CodeGen/MachineBasicBlock.h"
+#include "llvm/Target/TargetLowering.h"
+#include "llvm/IR/CallingConv.h"
 
 namespace llvm {
 
@@ -47,6 +50,144 @@ class Value;
 /// This is a fast-path instruction selection class that generates poor code and
 /// doesn't support illegal types or non-trivial lowering, but runs quickly.
 class FastISel {
+  public:
+  struct ArgListEntry {
+    Value *Val;
+    Type *Ty;
+    bool isSExt     : 1;
+    bool isZExt     : 1;
+    bool isInReg    : 1;
+    bool isSRet     : 1;
+    bool isNest     : 1;
+    bool isByVal    : 1;
+    bool isInAlloca : 1;
+    bool isReturned : 1;
+    uint16_t Alignment;
+
+    ArgListEntry()
+      : Val(nullptr), Ty(nullptr), isSExt(false), isZExt(false), isInReg(false),
+        isSRet(false), isNest(false), isByVal(false), isInAlloca(false),
+        isReturned(false), Alignment(0) { }
+
+    void setAttributes(ImmutableCallSite *CS, unsigned AttrIdx);
+  };
+  typedef std::vector<ArgListEntry> ArgListTy;
+
+  struct CallLoweringInfo {
+    Type *RetTy;
+    bool RetSExt           : 1;
+    bool RetZExt           : 1;
+    bool IsVarArg          : 1;
+    bool IsInReg           : 1;
+    bool DoesNotReturn     : 1;
+    bool IsReturnValueUsed : 1;
+
+    // IsTailCall should be modified by implementations of
+    // FastLowerCall that perform tail call conversions.
+    bool IsTailCall;
+
+    unsigned NumFixedArgs;
+    CallingConv::ID CallConv;
+    const Value *Callee;
+    const char *SymName;
+    ArgListTy Args;
+    ImmutableCallSite *CS;
+    MachineInstr *Call;
+    unsigned ResultReg;
+    unsigned NumResultRegs;
+
+    SmallVector<Value *, 16> OutVals;
+    SmallVector<ISD::ArgFlagsTy, 16> OutFlags;
+    SmallVector<unsigned, 16> OutRegs;
+    SmallVector<ISD::InputArg, 4> Ins;
+    SmallVector<unsigned, 4> InRegs;
+
+    CallLoweringInfo()
+      : RetTy(nullptr), RetSExt(false), RetZExt(false), IsVarArg(false),
+        IsInReg(false), DoesNotReturn(false), IsReturnValueUsed(true),
+        IsTailCall(false), NumFixedArgs(-1), CallConv(CallingConv::C),
+        Callee(nullptr), SymName(nullptr), CS(nullptr), Call(nullptr),
+        ResultReg(0), NumResultRegs(0)
+    {}
+
+    CallLoweringInfo &setCallee(Type *ResultTy, FunctionType *FuncTy,
+                                const Value *Target, ArgListTy &&ArgsList,
+                                ImmutableCallSite &Call) {
+      RetTy = ResultTy;
+      Callee = Target;
+
+      IsInReg = Call.paramHasAttr(0, Attribute::InReg);
+      DoesNotReturn = Call.doesNotReturn();
+      IsVarArg = FuncTy->isVarArg();
+      IsReturnValueUsed = !Call.getInstruction()->use_empty();
+      RetSExt = Call.paramHasAttr(0, Attribute::SExt);
+      RetZExt = Call.paramHasAttr(0, Attribute::ZExt);
+
+      CallConv = Call.getCallingConv();
+      NumFixedArgs = FuncTy->getNumParams();
+      Args = std::move(ArgsList);
+
+      CS = &Call;
+
+      return *this;
+    }
+
+    CallLoweringInfo &setCallee(Type *ResultTy, FunctionType *FuncTy,
+                                const char *Target, ArgListTy &&ArgsList,
+                                ImmutableCallSite &Call,
+                                unsigned FixedArgs = ~0U) {
+      RetTy = ResultTy;
+      Callee = Call.getCalledValue();
+      SymName = Target;
+
+      IsInReg = Call.paramHasAttr(0, Attribute::InReg);
+      DoesNotReturn = Call.doesNotReturn();
+      IsVarArg = FuncTy->isVarArg();
+      IsReturnValueUsed = !Call.getInstruction()->use_empty();
+      RetSExt = Call.paramHasAttr(0, Attribute::SExt);
+      RetZExt = Call.paramHasAttr(0, Attribute::ZExt);
+
+      CallConv = Call.getCallingConv();
+      NumFixedArgs = (FixedArgs == ~0U) ? FuncTy->getNumParams() : FixedArgs;
+      Args = std::move(ArgsList);
+
+      CS = &Call;
+
+      return *this;
+    }
+
+    CallLoweringInfo &setCallee(CallingConv::ID CC, Type *ResultTy,
+                                const Value *Target, ArgListTy &&ArgsList,
+                                unsigned FixedArgs = ~0U) {
+      RetTy = ResultTy;
+      Callee = Target;
+      CallConv = CC;
+      NumFixedArgs = (FixedArgs == ~0U) ? Args.size() : FixedArgs;
+      Args = std::move(ArgsList);
+      return *this;
+    }
+
+    CallLoweringInfo &setTailCall(bool Value = true) {
+      IsTailCall = Value;
+      return *this;
+    }
+
+    ArgListTy &getArgs() {
+      return Args;
+    }
+
+    void clearOuts() {
+      OutVals.clear();
+      OutFlags.clear();
+      OutRegs.clear();
+    }
+
+    void clearIns() {
+      Ins.clear();
+      InRegs.clear();
+    }
+  };
+
 protected:
   DenseMap<const Value *, unsigned> LocalValueMap;
   FunctionLoweringInfo &FuncInfo;
@@ -173,15 +314,18 @@ class FastISel {
   /// process fails to select an instruction.  This gives targets a chance to
   /// emit code for anything that doesn't fit into FastISel's framework. It
   /// returns true if it was successful.
-  virtual bool
-  TargetSelectInstruction(const Instruction *I) = 0;
+  virtual bool TargetSelectInstruction(const Instruction *I) = 0;
 
   /// This method is called by target-independent code to do target specific
   /// argument lowering. It returns true if it was successful.
   virtual bool FastLowerArguments();
 
-  /// This method is called by target-independent code to do target specific
-  /// intrinsic lowering. It returns true if it was successful.
+  /// \brief This method is called by target-independent code to do target
+  /// specific call lowering. It returns true if it was successful.
+  virtual bool FastLowerCall(CallLoweringInfo &CLI);
+
+  /// \brief This method is called by target-independent code to do target
+  /// specific intrinsic lowering. It returns true if it was successful.
   virtual bool FastLowerIntrinsicCall(const IntrinsicInst *II);
 
   /// This method is called by target-independent code to request that an
@@ -386,6 +530,9 @@ class FastISel {
   /// \brief Create a machine mem operand from the given instruction.
   MachineMemOperand *createMachineMemOperandFor(const Instruction *I) const;
 
+  bool LowerCallTo(const CallInst *CI, const char *SymName, unsigned NumArgs);
+  bool LowerCallTo(CallLoweringInfo &CLI);
+
 private:
   bool SelectBinaryOp(const User *I, unsigned ISDOpcode);
 
@@ -394,7 +541,8 @@ class FastISel {
   bool SelectGetElementPtr(const User *I);
 
   bool SelectStackmap(const CallInst *I);
-  bool SelectCall(const User *I);
+  bool LowerCall(const CallInst *I);
+  bool SelectCall(const User *Call);
   bool SelectIntrinsicCall(const IntrinsicInst *II);
 
   bool SelectBitCast(const User *I);