Imported Upstream version 6.0.0.172

Former-commit-id: f3cc9b82f3e5bd8f0fd3ebc098f789556b44e9cd

external/llvm/lib/Target/WebAssembly/WebAssemblyISelDAGToDAG.cpp

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+//- WebAssemblyISelDAGToDAG.cpp - A dag to dag inst selector for WebAssembly -//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// \brief This file defines an instruction selector for the WebAssembly target.
+///
+//===----------------------------------------------------------------------===//
+
+#include "MCTargetDesc/WebAssemblyMCTargetDesc.h"
+#include "WebAssembly.h"
+#include "WebAssemblyTargetMachine.h"
+#include "llvm/CodeGen/SelectionDAGISel.h"
+#include "llvm/IR/Function.h" // To access function attributes.
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/KnownBits.h"
+#include "llvm/Support/MathExtras.h"
+#include "llvm/Support/raw_ostream.h"
+using namespace llvm;
+
+#define DEBUG_TYPE "wasm-isel"
+
+//===--------------------------------------------------------------------===//
+/// WebAssembly-specific code to select WebAssembly machine instructions for
+/// SelectionDAG operations.
+///
+namespace {
+class WebAssemblyDAGToDAGISel final : public SelectionDAGISel {
+  /// Keep a pointer to the WebAssemblySubtarget around so that we can make the
+  /// right decision when generating code for different targets.
+  const WebAssemblySubtarget *Subtarget;
+
+  bool ForCodeSize;
+
+public:
+  WebAssemblyDAGToDAGISel(WebAssemblyTargetMachine &tm,
+                          CodeGenOpt::Level OptLevel)
+      : SelectionDAGISel(tm, OptLevel), Subtarget(nullptr), ForCodeSize(false) {
+  }
+
+  StringRef getPassName() const override {
+    return "WebAssembly Instruction Selection";
+  }
+
+  bool runOnMachineFunction(MachineFunction &MF) override {
+    ForCodeSize = MF.getFunction().hasFnAttribute(Attribute::OptimizeForSize) ||
+                  MF.getFunction().hasFnAttribute(Attribute::MinSize);
+    Subtarget = &MF.getSubtarget<WebAssemblySubtarget>();
+    return SelectionDAGISel::runOnMachineFunction(MF);
+  }
+
+  void Select(SDNode *Node) override;
+
+  bool SelectInlineAsmMemoryOperand(const SDValue &Op, unsigned ConstraintID,
+                                    std::vector<SDValue> &OutOps) override;
+
+// Include the pieces autogenerated from the target description.
+#include "WebAssemblyGenDAGISel.inc"
+
+private:
+  // add select functions here...
+};
+} // end anonymous namespace
+
+void WebAssemblyDAGToDAGISel::Select(SDNode *Node) {
+  // Dump information about the Node being selected.
+  DEBUG(errs() << "Selecting: ");
+  DEBUG(Node->dump(CurDAG));
+  DEBUG(errs() << "\n");
+
+  // If we have a custom node, we already have selected!
+  if (Node->isMachineOpcode()) {
+    DEBUG(errs() << "== "; Node->dump(CurDAG); errs() << "\n");
+    Node->setNodeId(-1);
+    return;
+  }
+
+  // Few custom selection stuff.
+  EVT VT = Node->getValueType(0);
+
+  switch (Node->getOpcode()) {
+  default:
+    break;
+    // If we need WebAssembly-specific selection, it would go here.
+    (void)VT;
+  }
+
+  // Select the default instruction.
+  SelectCode(Node);
+}
+
+bool WebAssemblyDAGToDAGISel::SelectInlineAsmMemoryOperand(
+    const SDValue &Op, unsigned ConstraintID, std::vector<SDValue> &OutOps) {
+  switch (ConstraintID) {
+  case InlineAsm::Constraint_i:
+  case InlineAsm::Constraint_m:
+    // We just support simple memory operands that just have a single address
+    // operand and need no special handling.
+    OutOps.push_back(Op);
+    return false;
+  default:
+    break;
+  }
+
+  return true;
+}
+
+/// This pass converts a legalized DAG into a WebAssembly-specific DAG, ready
+/// for instruction scheduling.
+FunctionPass *llvm::createWebAssemblyISelDag(WebAssemblyTargetMachine &TM,
+                                             CodeGenOpt::Level OptLevel) {
+  return new WebAssemblyDAGToDAGISel(TM, OptLevel);
+}