Copy ExpandInlineAsm to TargetLowering from TargetAsmInfo.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@76441 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Target/TargetLowering.h

@@ -1270,6 +1270,15 @@ public:
   // Inline Asm Support hooks
   //
   
+  /// ExpandInlineAsm - This hook allows the target to expand an inline asm
+  /// call to be explicit llvm code if it wants to.  This is useful for
+  /// turning simple inline asms into LLVM intrinsics, which gives the
+  /// compiler more information about the behavior of the code.
+  // FIXME: Move this to TargetLowering.
+  virtual bool ExpandInlineAsm(CallInst *CI) const {
+    return false;
+  }
+  
   enum ConstraintType {
     C_Register,            // Constraint represents specific register(s).
     C_RegisterClass,       // Constraint represents any of register(s) in class.

lib/Target/X86/X86ISelLowering.cpp

@@ -22,6 +22,7 @@
 #include "llvm/GlobalAlias.h"
 #include "llvm/GlobalVariable.h"
 #include "llvm/Function.h"
+#include "llvm/Instructions.h"
 #include "llvm/Intrinsics.h"
 #include "llvm/LLVMContext.h"
 #include "llvm/ADT/BitVector.h"
@@ -8658,6 +8659,100 @@ SDValue X86TargetLowering::PerformDAGCombine(SDNode *N,
 //                           X86 Inline Assembly Support
 //===----------------------------------------------------------------------===//
 
+static bool LowerToBSwap(CallInst *CI) {
+  // FIXME: this should verify that we are targetting a 486 or better.  If not,
+  // we will turn this bswap into something that will be lowered to logical ops
+  // instead of emitting the bswap asm.  For now, we don't support 486 or lower
+  // so don't worry about this.
+  
+  // Verify this is a simple bswap.
+  if (CI->getNumOperands() != 2 ||
+      CI->getType() != CI->getOperand(1)->getType() ||
+      !CI->getType()->isInteger())
+    return false;
+  
+  const IntegerType *Ty = dyn_cast<IntegerType>(CI->getType());
+  if (!Ty || Ty->getBitWidth() % 16 != 0)
+    return false;
+  
+  // Okay, we can do this xform, do so now.
+  const Type *Tys[] = { Ty };
+  Module *M = CI->getParent()->getParent()->getParent();
+  Constant *Int = Intrinsic::getDeclaration(M, Intrinsic::bswap, Tys, 1);
+  
+  Value *Op = CI->getOperand(1);
+  Op = CallInst::Create(Int, Op, CI->getName(), CI);
+  
+  CI->replaceAllUsesWith(Op);
+  CI->eraseFromParent();
+  return true;
+}
+
+bool X86TargetLowering::ExpandInlineAsm(CallInst *CI) const {
+  InlineAsm *IA = cast<InlineAsm>(CI->getCalledValue());
+  std::vector<InlineAsm::ConstraintInfo> Constraints = IA->ParseConstraints();
+
+  std::string AsmStr = IA->getAsmString();
+
+  // TODO: should remove alternatives from the asmstring: "foo {a|b}" -> "foo a"
+  std::vector<std::string> AsmPieces;
+  SplitString(AsmStr, AsmPieces, "\n");  // ; as separator?
+
+  switch (AsmPieces.size()) {
+  default: return false;
+  case 1:
+    AsmStr = AsmPieces[0];
+    AsmPieces.clear();
+    SplitString(AsmStr, AsmPieces, " \t");  // Split with whitespace.
+
+    // bswap $0
+    if (AsmPieces.size() == 2 &&
+        (AsmPieces[0] == "bswap" ||
+         AsmPieces[0] == "bswapq" ||
+         AsmPieces[0] == "bswapl") &&
+        (AsmPieces[1] == "$0" ||
+         AsmPieces[1] == "${0:q}")) {
+      // No need to check constraints, nothing other than the equivalent of
+      // "=r,0" would be valid here.
+      return LowerToBSwap(CI);
+    }
+    // rorw $$8, ${0:w}  -->  llvm.bswap.i16
+    if (CI->getType() == Type::Int16Ty &&
+        AsmPieces.size() == 3 &&
+        AsmPieces[0] == "rorw" &&
+        AsmPieces[1] == "$$8," &&
+        AsmPieces[2] == "${0:w}" &&
+        IA->getConstraintString() == "=r,0,~{dirflag},~{fpsr},~{flags},~{cc}") {
+      return LowerToBSwap(CI);
+    }
+    break;
+  case 3:
+    if (CI->getType() == Type::Int64Ty && Constraints.size() >= 2 &&
+        Constraints[0].Codes.size() == 1 && Constraints[0].Codes[0] == "A" &&
+        Constraints[1].Codes.size() == 1 && Constraints[1].Codes[0] == "0") {
+      // bswap %eax / bswap %edx / xchgl %eax, %edx  -> llvm.bswap.i64
+      std::vector<std::string> Words;
+      SplitString(AsmPieces[0], Words, " \t");
+      if (Words.size() == 2 && Words[0] == "bswap" && Words[1] == "%eax") {
+        Words.clear();
+        SplitString(AsmPieces[1], Words, " \t");
+        if (Words.size() == 2 && Words[0] == "bswap" && Words[1] == "%edx") {
+          Words.clear();
+          SplitString(AsmPieces[2], Words, " \t,");
+          if (Words.size() == 3 && Words[0] == "xchgl" && Words[1] == "%eax" &&
+              Words[2] == "%edx") {
+            return LowerToBSwap(CI);
+          }
+        }
+      }
+    }
+    break;
+  }
+  return false;
+}
+
+
+
 /// getConstraintType - Given a constraint letter, return the type of
 /// constraint it is for this target.
 X86TargetLowering::ConstraintType

lib/Target/X86/X86ISelLowering.h

@@ -420,6 +420,8 @@ namespace llvm {
     
     SDValue getReturnAddressFrameIndex(SelectionDAG &DAG);
 
+    virtual bool ExpandInlineAsm(CallInst *CI) const;
+    
     ConstraintType getConstraintType(const std::string &Constraint) const;
      
     std::vector<unsigned>