[WebAssembly] Basic TargetTransformInfo support for SIMD128.

llvm-svn: 270508

Author: Dan Gohman

llvm/lib/Target/WebAssembly/WebAssemblyTargetTransformInfo.cpp

@@ -25,3 +25,59 @@ WebAssemblyTTIImpl::getPopcntSupport(unsigned TyWidth) const {
   assert(isPowerOf2_32(TyWidth) && "Ty width must be power of 2");
   return TargetTransformInfo::PSK_FastHardware;
 }
+
+unsigned WebAssemblyTTIImpl::getNumberOfRegisters(bool Vector) {
+  unsigned Result = BaseT::getNumberOfRegisters(Vector);
+
+  // For SIMD, use at least 16 registers, as a rough guess.
+  if (Vector)
+    Result = std::max(Result, 16u);
+
+  return Result;
+}
+
+unsigned WebAssemblyTTIImpl::getRegisterBitWidth(bool Vector) {
+  if (Vector && getST()->hasSIMD128())
+    return 128;
+
+  return 64;
+}
+
+unsigned WebAssemblyTTIImpl::getArithmeticInstrCost(
+    unsigned Opcode, Type *Ty, TTI::OperandValueKind Opd1Info,
+    TTI::OperandValueKind Opd2Info, TTI::OperandValueProperties Opd1PropInfo,
+    TTI::OperandValueProperties Opd2PropInfo) {
+
+  unsigned Cost = BasicTTIImplBase<WebAssemblyTTIImpl>::getArithmeticInstrCost(
+      Opcode, Ty, Opd1Info, Opd2Info, Opd1PropInfo, Opd2PropInfo);
+
+  if (VectorType *VTy = dyn_cast<VectorType>(Ty)) {
+    switch (Opcode) {
+    case Instruction::LShr:
+    case Instruction::AShr:
+    case Instruction::Shl:
+      // SIMD128's shifts currently only accept a scalar shift count. For each
+      // element, we'll need to extract, op, insert. The following is a rough
+      // approxmation.
+      if (Opd2Info != TTI::OK_UniformValue &&
+          Opd2Info != TTI::OK_UniformConstantValue)
+        Cost = VTy->getNumElements() *
+               (TargetTransformInfo::TCC_Basic +
+                getArithmeticInstrCost(Opcode, VTy->getElementType()) +
+                TargetTransformInfo::TCC_Basic);
+      break;
+    }
+  }
+  return Cost;
+}
+
+unsigned WebAssemblyTTIImpl::getVectorInstrCost(unsigned Opcode, Type *Val,
+                                                unsigned Index) {
+  unsigned Cost = BasicTTIImplBase::getVectorInstrCost(Opcode, Val, Index);
+
+  // SIMD128's insert/extract currently only take constant indices.
+  if (Index == -1u)
+    return Cost + 25 * TargetTransformInfo::TCC_Expensive;
+
+  return Cost;
+}

llvm/lib/Target/WebAssembly/WebAssemblyTargetTransformInfo.h

@@ -61,7 +61,15 @@ class WebAssemblyTTIImpl final : public BasicTTIImplBase<WebAssemblyTTIImpl> {
   /// \name Vector TTI Implementations
   /// @{
 
-  // TODO: Implement Vector TTI for WebAssembly
+  unsigned getNumberOfRegisters(bool Vector);
+  unsigned getRegisterBitWidth(bool Vector);
+  unsigned getArithmeticInstrCost(
+      unsigned Opcode, Type *Ty,
+      TTI::OperandValueKind Opd1Info = TTI::OK_AnyValue,
+      TTI::OperandValueKind Opd2Info = TTI::OK_AnyValue,
+      TTI::OperandValueProperties Opd1PropInfo = TTI::OP_None,
+      TTI::OperandValueProperties Opd2PropInfo = TTI::OP_None);
+  unsigned getVectorInstrCost(unsigned Opcode, Type *Val, unsigned Index);
 
   /// @}
 };