[WebAssembly] Add WebAssemblyLateEHPrepare pass

Summary:
Add WebAssemblyLateEHPrepare pass that does several small jobs for
exception handling. This runs before CFGSort, and is different from
WasmEHPrepare pass that runs before ISel, even though the names are
similar.

Reviewers: dschuff, majnemer

Subscribers: sbc100, jgravelle-google, sunfish, mgorny, llvm-commits

Differential Revision: https://reviews.llvm.org/D46803

llvm-svn: 335438

1 files changed, 0 insertions, 88 deletions

diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyExceptionPrepare.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyExceptionPrepare.cpp
deleted file mode 100644
index 837e9576c85..00000000000
--- a/llvm/lib/Target/WebAssembly/WebAssemblyExceptionPrepare.cpp
+++ /dev/null
@@ -1,88 +0,0 @@
-//=== WebAssemblyExceptionPrepare.cpp - WebAssembly Exception Preparation -===//
-//
-//                     The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-///
-/// \file
-/// \brief Does various transformations for exception handling.
-///
-//===----------------------------------------------------------------------===//
-
-#include "MCTargetDesc/WebAssemblyMCTargetDesc.h"
-#include "WebAssembly.h"
-#include "WebAssemblySubtarget.h"
-#include "llvm/CodeGen/MachineInstrBuilder.h"
-using namespace llvm;
-
-#define DEBUG_TYPE "wasm-exception-prepare"
-
-namespace {
-class WebAssemblyExceptionPrepare final : public MachineFunctionPass {
-  StringRef getPassName() const override {
-    return "WebAssembly Prepare Exception";
-  }
-
-  bool runOnMachineFunction(MachineFunction &MF) override;
-
-  bool replaceFuncletReturns(MachineFunction &MF);
-
-public:
-  static char ID; // Pass identification, replacement for typeid
-  WebAssemblyExceptionPrepare() : MachineFunctionPass(ID) {}
-};
-} // end anonymous namespace
-
-char WebAssemblyExceptionPrepare::ID = 0;
-INITIALIZE_PASS(WebAssemblyExceptionPrepare, DEBUG_TYPE,
-                "WebAssembly Exception Preparation", false, false)
-
-FunctionPass *llvm::createWebAssemblyExceptionPrepare() {
-  return new WebAssemblyExceptionPrepare();
-}
-
-bool WebAssemblyExceptionPrepare::runOnMachineFunction(MachineFunction &MF) {
-  bool Changed = false;
-  if (!MF.getFunction().hasPersonalityFn())
-    return false;
-  Changed |= replaceFuncletReturns(MF);
-  // TODO More transformations will be added
-  return Changed;
-}
-
-bool WebAssemblyExceptionPrepare::replaceFuncletReturns(MachineFunction &MF) {
-  bool Changed = false;
-  const auto &TII = *MF.getSubtarget<WebAssemblySubtarget>().getInstrInfo();
-
-  for (auto &MBB : MF) {
-    auto Pos = MBB.getFirstTerminator();
-    if (Pos == MBB.end())
-      continue;
-    MachineInstr *TI = &*Pos;
-
-    switch (TI->getOpcode()) {
-    case WebAssembly::CATCHRET: {
-      // Replace a catchret with a branch
-      MachineBasicBlock *TBB = TI->getOperand(0).getMBB();
-      if (!MBB.isLayoutSuccessor(TBB))
-        BuildMI(MBB, TI, TI->getDebugLoc(), TII.get(WebAssembly::BR))
-            .addMBB(TBB);
-      TI->eraseFromParent();
-      Changed = true;
-      break;
-    }
-    case WebAssembly::CLEANUPRET: {
-      // Replace a cleanupret with a rethrow
-      BuildMI(MBB, TI, TI->getDebugLoc(), TII.get(WebAssembly::RETHROW))
-          .addImm(0);
-      TI->eraseFromParent();
-      Changed = true;
-      break;
-    }
-    }
-  }
-  return Changed;
-}