1 files changed, 117 insertions, 0 deletions
diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp
index 4184eb6dc5a..b1bb4deb626 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp
@@ -21,6 +21,8 @@
 #include "llvm/CodeGen/Analysis.h"
 #include "llvm/CodeGen/MachineRegisterInfo.h"
 #include "llvm/CodeGen/SelectionDAG.h"
+#include "llvm/IR/DiagnosticInfo.h"
+#include "llvm/IR/DiagnosticPrinter.h"
 #include "llvm/IR/Function.h"
 #include "llvm/IR/Intrinsics.h"
 #include "llvm/Support/CommandLine.h"
@@ -28,10 +30,65 @@
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Target/TargetOptions.h"
+
 using namespace llvm;
 
 #define DEBUG_TYPE "wasm-lower"
 
+namespace {
+// Diagnostic information for unimplemented or unsupported feature reporting.
+// FIXME copied from BPF and AMDGPU.
+class DiagnosticInfoUnsupported : public DiagnosticInfo {
+private:
+  // Debug location where this diagnostic is triggered.
+  DebugLoc DLoc;
+  const Twine &Description;
+  const Function &Fn;
+  SDValue Value;
+
+  static int KindID;
+
+  static int getKindID() {
+    if (KindID == 0)
+      KindID = llvm::getNextAvailablePluginDiagnosticKind();
+    return KindID;
+  }
+
+public:
+  DiagnosticInfoUnsupported(SDLoc DLoc, const Function &Fn, const Twine &Desc,
+                            SDValue Value)
+      : DiagnosticInfo(getKindID(), DS_Error), DLoc(DLoc.getDebugLoc()),
+        Description(Desc), Fn(Fn), Value(Value) {}
+
+  void print(DiagnosticPrinter &DP) const override {
+    std::string Str;
+    raw_string_ostream OS(Str);
+
+    if (DLoc) {
+      auto DIL = DLoc.get();
+      StringRef Filename = DIL->getFilename();
+      unsigned Line = DIL->getLine();
+      unsigned Column = DIL->getColumn();
+      OS << Filename << ':' << Line << ':' << Column << ' ';
+    }
+
+    OS << "in function " << Fn.getName() << ' ' << *Fn.getFunctionType() << '\n'
+       << Description;
+    if (Value)
+      Value->print(OS);
+    OS << '\n';
+    OS.flush();
+    DP << Str;
+  }
+
+  static bool classof(const DiagnosticInfo *DI) {
+    return DI->getKind() == getKindID();
+  }
+};
+
+int DiagnosticInfoUnsupported::KindID = 0;
+} // end anonymous namespace
+
 WebAssemblyTargetLowering::WebAssemblyTargetLowering(
     const TargetMachine &TM, const WebAssemblySubtarget &STI)
     : TargetLowering(TM), Subtarget(&STI) {
@@ -40,6 +97,18 @@ WebAssemblyTargetLowering::WebAssemblyTargetLowering(
   setHasFloatingPointExceptions(false);
   // We don't know the microarchitecture here, so just reduce register pressure.
   setSchedulingPreference(Sched::RegPressure);
+  // Tell ISel that we have a stack pointer.
+  setStackPointerRegisterToSaveRestore(
+      Subtarget->hasAddr64() ? WebAssembly::SP64 : WebAssembly::SP32);
+  // Set up the register classes.
+  addRegisterClass(MVT::i32, &WebAssembly::Int32RegClass);
+  addRegisterClass(MVT::i64, &WebAssembly::Int64RegClass);
+  addRegisterClass(MVT::f32, &WebAssembly::Float32RegClass);
+  addRegisterClass(MVT::f64, &WebAssembly::Float64RegClass);
+  // Compute derived properties from the register classes.
+  computeRegisterProperties(Subtarget->getRegisterInfo());
+
+  // FIXME: setOperationAction...
 }
 
 //===----------------------------------------------------------------------===//
@@ -50,6 +119,54 @@ WebAssemblyTargetLowering::WebAssemblyTargetLowering(
 // Lowering Code
 //===----------------------------------------------------------------------===//
 
+static void fail(SDLoc DL, SelectionDAG &DAG, const char *msg) {
+  MachineFunction &MF = DAG.getMachineFunction();
+  DAG.getContext()->diagnose(
+      DiagnosticInfoUnsupported(DL, *MF.getFunction(), msg, SDValue()));
+}
+
+bool WebAssemblyTargetLowering::CanLowerReturn(
+    CallingConv::ID CallConv, MachineFunction &MF, bool IsVarArg,
+    const SmallVectorImpl<ISD::OutputArg> &Outs, LLVMContext &Context) const {
+  // WebAssembly can't currently handle returning tuples.
+  return Outs.size() <= 1;
+}
+
+SDValue WebAssemblyTargetLowering::LowerReturn(
+    SDValue Chain, CallingConv::ID CallConv, bool IsVarArg,
+    const SmallVectorImpl<ISD::OutputArg> &Outs,
+    const SmallVectorImpl<SDValue> &OutVals, SDLoc DL,
+    SelectionDAG &DAG) const {
+
+  assert(Outs.size() <= 1 && "WebAssembly can only return up to one value");
+  if (CallConv != CallingConv::C)
+    fail(DL, DAG, "WebAssembly doesn't support non-C calling conventions");
+
+  // FIXME: Implement LowerReturn.
+
+  return Chain;
+}
+
+SDValue WebAssemblyTargetLowering::LowerFormalArguments(
+    SDValue Chain, CallingConv::ID CallConv, bool IsVarArg,
+    const SmallVectorImpl<ISD::InputArg> &Ins, SDLoc DL, SelectionDAG &DAG,
+    SmallVectorImpl<SDValue> &InVals) const {
+  MachineFunction &MF = DAG.getMachineFunction();
+
+  if (CallConv != CallingConv::C)
+    fail(DL, DAG, "WebAssembly doesn't support non-C calling conventions");
+  if (IsVarArg)
+    fail(DL, DAG, "WebAssembly doesn't support varargs yet");
+  if (MF.getFunction()->hasStructRetAttr())
+    fail(DL, DAG, "WebAssembly doesn't support struct return yet");
+
+  // FIXME: Implement LowerFormalArguments.
+  for (const ISD::InputArg &In : Ins)
+    InVals.push_back(DAG.getNode(ISD::UNDEF, DL, In.VT));
+
+  return Chain;
+}
+
 //===----------------------------------------------------------------------===//
 //  Other Lowering Code
 //===----------------------------------------------------------------------===//