1 files changed, 97 insertions, 0 deletions
diff --git a/llvm/lib/Target/WebAssembly/WebAssemblySetP2AlignOperands.cpp b/llvm/lib/Target/WebAssembly/WebAssemblySetP2AlignOperands.cpp
new file mode 100644
index 000000000000..a249ccf17638
--- /dev/null
+++ b/llvm/lib/Target/WebAssembly/WebAssemblySetP2AlignOperands.cpp
@@ -0,0 +1,97 @@
+//=- WebAssemblySetP2AlignOperands.cpp - Set alignments on loads and stores -=//
+//
+// 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 sets the p2align operands on load and store instructions.
+///
+//===----------------------------------------------------------------------===//
+
+#include "MCTargetDesc/WebAssemblyMCTargetDesc.h"
+#include "WebAssembly.h"
+#include "WebAssemblyInstrInfo.h"
+#include "WebAssemblyMachineFunctionInfo.h"
+#include "llvm/CodeGen/MachineBlockFrequencyInfo.h"
+#include "llvm/CodeGen/MachineMemOperand.h"
+#include "llvm/CodeGen/Passes.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
+using namespace llvm;
+
+#define DEBUG_TYPE "wasm-set-p2align-operands"
+
+namespace {
+class WebAssemblySetP2AlignOperands final : public MachineFunctionPass {
+public:
+  static char ID; // Pass identification, replacement for typeid
+  WebAssemblySetP2AlignOperands() : MachineFunctionPass(ID) {}
+
+  StringRef getPassName() const override {
+    return "WebAssembly Set p2align Operands";
+  }
+
+  void getAnalysisUsage(AnalysisUsage &AU) const override {
+    AU.setPreservesCFG();
+    AU.addPreserved<MachineBlockFrequencyInfo>();
+    AU.addPreservedID(MachineDominatorsID);
+    MachineFunctionPass::getAnalysisUsage(AU);
+  }
+
+  bool runOnMachineFunction(MachineFunction &MF) override;
+};
+} // end anonymous namespace
+
+char WebAssemblySetP2AlignOperands::ID = 0;
+INITIALIZE_PASS(WebAssemblySetP2AlignOperands, DEBUG_TYPE,
+                "Set the p2align operands for WebAssembly loads and stores",
+                false, false)
+
+FunctionPass *llvm::createWebAssemblySetP2AlignOperands() {
+  return new WebAssemblySetP2AlignOperands();
+}
+
+static void rewriteP2Align(MachineInstr &MI, unsigned OperandNo) {
+  assert(MI.getOperand(OperandNo).getImm() == 0 &&
+         "ISel should set p2align operands to 0");
+  assert(MI.hasOneMemOperand() &&
+         "Load and store instructions have exactly one mem operand");
+  assert((*MI.memoperands_begin())->getSize() ==
+             (UINT64_C(1) << WebAssembly::GetDefaultP2Align(MI.getOpcode())) &&
+         "Default p2align value should be natural");
+  assert(MI.getDesc().OpInfo[OperandNo].OperandType ==
+             WebAssembly::OPERAND_P2ALIGN &&
+         "Load and store instructions should have a p2align operand");
+  uint64_t P2Align = Log2_64((*MI.memoperands_begin())->getAlignment());
+
+  // WebAssembly does not currently support supernatural alignment.
+  P2Align = std::min(P2Align,
+                     uint64_t(WebAssembly::GetDefaultP2Align(MI.getOpcode())));
+
+  MI.getOperand(OperandNo).setImm(P2Align);
+}
+
+bool WebAssemblySetP2AlignOperands::runOnMachineFunction(MachineFunction &MF) {
+  LLVM_DEBUG({
+    dbgs() << "********** Set p2align Operands **********\n"
+           << "********** Function: " << MF.getName() << '\n';
+  });
+
+  bool Changed = false;
+
+  for (auto &MBB : MF) {
+    for (auto &MI : MBB) {
+      int16_t P2AlignOpNum = WebAssembly::getNamedOperandIdx(
+          MI.getOpcode(), WebAssembly::OpName::p2align);
+      if (P2AlignOpNum != -1) {
+        rewriteP2Align(MI, P2AlignOpNum);
+        Changed = true;
+      }
+    }
+  }
+
+  return Changed;
+}