1 files changed, 110 insertions, 0 deletions
diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyRegNumbering.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyRegNumbering.cpp
new file mode 100644
index 000000000000..72e7a7cf5042
--- /dev/null
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyRegNumbering.cpp
@@ -0,0 +1,110 @@
+//===-- WebAssemblyRegNumbering.cpp - Register Numbering ------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// This file implements a pass which assigns WebAssembly register
+/// numbers for CodeGen virtual registers.
+///
+//===----------------------------------------------------------------------===//
+
+#include "MCTargetDesc/WebAssemblyMCTargetDesc.h"
+#include "WebAssembly.h"
+#include "WebAssemblyMachineFunctionInfo.h"
+#include "WebAssemblySubtarget.h"
+#include "WebAssemblyUtilities.h"
+#include "llvm/ADT/SCCIterator.h"
+#include "llvm/CodeGen/MachineFrameInfo.h"
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
+#include "llvm/CodeGen/MachineLoopInfo.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/CodeGen/Passes.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
+using namespace llvm;
+
+#define DEBUG_TYPE "wasm-reg-numbering"
+
+namespace {
+class WebAssemblyRegNumbering final : public MachineFunctionPass {
+  StringRef getPassName() const override {
+    return "WebAssembly Register Numbering";
+  }
+
+  void getAnalysisUsage(AnalysisUsage &AU) const override {
+    AU.setPreservesCFG();
+    MachineFunctionPass::getAnalysisUsage(AU);
+  }
+
+  bool runOnMachineFunction(MachineFunction &MF) override;
+
+public:
+  static char ID; // Pass identification, replacement for typeid
+  WebAssemblyRegNumbering() : MachineFunctionPass(ID) {}
+};
+} // end anonymous namespace
+
+char WebAssemblyRegNumbering::ID = 0;
+INITIALIZE_PASS(WebAssemblyRegNumbering, DEBUG_TYPE,
+                "Assigns WebAssembly register numbers for virtual registers",
+                false, false)
+
+FunctionPass *llvm::createWebAssemblyRegNumbering() {
+  return new WebAssemblyRegNumbering();
+}
+
+bool WebAssemblyRegNumbering::runOnMachineFunction(MachineFunction &MF) {
+  LLVM_DEBUG(dbgs() << "********** Register Numbering **********\n"
+                       "********** Function: "
+                    << MF.getName() << '\n');
+
+  WebAssemblyFunctionInfo &MFI = *MF.getInfo<WebAssemblyFunctionInfo>();
+  MachineRegisterInfo &MRI = MF.getRegInfo();
+
+  MFI.initWARegs();
+
+  // WebAssembly argument registers are in the same index space as local
+  // variables. Assign the numbers for them first.
+  MachineBasicBlock &EntryMBB = MF.front();
+  for (MachineInstr &MI : EntryMBB) {
+    if (!WebAssembly::isArgument(MI.getOpcode()))
+      break;
+
+    int64_t Imm = MI.getOperand(1).getImm();
+    LLVM_DEBUG(dbgs() << "Arg VReg " << MI.getOperand(0).getReg()
+                      << " -> WAReg " << Imm << "\n");
+    MFI.setWAReg(MI.getOperand(0).getReg(), Imm);
+  }
+
+  // Then assign regular WebAssembly registers for all remaining used
+  // virtual registers. TODO: Consider sorting the registers by frequency of
+  // use, to maximize usage of small immediate fields.
+  unsigned NumVRegs = MF.getRegInfo().getNumVirtRegs();
+  unsigned NumStackRegs = 0;
+  // Start the numbering for locals after the arg regs
+  unsigned CurReg = MFI.getParams().size();
+  for (unsigned VRegIdx = 0; VRegIdx < NumVRegs; ++VRegIdx) {
+    unsigned VReg = Register::index2VirtReg(VRegIdx);
+    // Skip unused registers.
+    if (MRI.use_empty(VReg))
+      continue;
+    // Handle stackified registers.
+    if (MFI.isVRegStackified(VReg)) {
+      LLVM_DEBUG(dbgs() << "VReg " << VReg << " -> WAReg "
+                        << (INT32_MIN | NumStackRegs) << "\n");
+      MFI.setWAReg(VReg, INT32_MIN | NumStackRegs++);
+      continue;
+    }
+    if (MFI.getWAReg(VReg) == WebAssemblyFunctionInfo::UnusedReg) {
+      LLVM_DEBUG(dbgs() << "VReg " << VReg << " -> WAReg " << CurReg << "\n");
+      MFI.setWAReg(VReg, CurReg++);
+    }
+  }
+
+  return true;
+}