[CodeGen] Port WasmEHPrepare to new pass manager #74435

paperchalice · 2023-12-05T08:43:53Z

Port WasmEHPrepare to new pass manager, also rename wasmehprepare to wasm-eh-prepare.

llvmbot · 2023-12-05T08:44:22Z

@llvm/pr-subscribers-backend-webassembly

Author: None (paperchalice)

Changes

Port WasmEHPrepare to new pass manager, also rename wasmehprepare to wasm-eh-prepare.

Full diff: https://github.com/llvm/llvm-project/pull/74435.diff

7 Files Affected:

(modified) llvm/include/llvm/CodeGen/CodeGenPassBuilder.h (+2-1)
(modified) llvm/include/llvm/CodeGen/MachinePassRegistry.def (+1-1)
(added) llvm/include/llvm/CodeGen/WasmEHPrepare.h (+23)
(modified) llvm/lib/CodeGen/WasmEHPrepare.cpp (+36-11)
(modified) llvm/lib/Passes/PassBuilder.cpp (+1)
(modified) llvm/lib/Passes/PassRegistry.def (+1)
(renamed) llvm/test/CodeGen/WebAssembly/wasm-eh-prepare.ll (+4-2)

diff --git a/llvm/include/llvm/CodeGen/CodeGenPassBuilder.h b/llvm/include/llvm/CodeGen/CodeGenPassBuilder.h
index a8ab670ad77be..076719abd0356 100644
--- a/llvm/include/llvm/CodeGen/CodeGenPassBuilder.h
+++ b/llvm/include/llvm/CodeGen/CodeGenPassBuilder.h
@@ -29,6 +29,7 @@
 #include "llvm/CodeGen/ReplaceWithVeclib.h"
 #include "llvm/CodeGen/SafeStack.h"
 #include "llvm/CodeGen/UnreachableBlockElim.h"
+#include "llvm/CodeGen/WasmEHPrepare.h"
 #include "llvm/CodeGen/WinEHPrepare.h"
 #include "llvm/IR/PassManager.h"
 #include "llvm/IR/Verifier.h"
@@ -691,7 +692,7 @@ void CodeGenPassBuilder<Derived>::addPassesToHandleExceptions(
     // funclets. Catchswitch blocks are not lowered in SelectionDAG, so we
     // should remove PHIs there.
     addPass(WinEHPreparePass(/*DemoteCatchSwitchPHIOnly=*/false));
-    addPass(WasmEHPass());
+    addPass(WasmEHPreparePass());
     break;
   case ExceptionHandling::None:
     addPass(LowerInvokePass());
diff --git a/llvm/include/llvm/CodeGen/MachinePassRegistry.def b/llvm/include/llvm/CodeGen/MachinePassRegistry.def
index 4c6706cf42532..1e9e5838841b2 100644
--- a/llvm/include/llvm/CodeGen/MachinePassRegistry.def
+++ b/llvm/include/llvm/CodeGen/MachinePassRegistry.def
@@ -54,6 +54,7 @@ FUNCTION_PASS("scalarize-masked-mem-intrin", ScalarizeMaskedMemIntrinPass, ())
 FUNCTION_PASS("tlshoist", TLSVariableHoistPass, ())
 FUNCTION_PASS("unreachableblockelim", UnreachableBlockElimPass, ())
 FUNCTION_PASS("verify", VerifierPass, ())
+FUNCTION_PASS("wasm-eh-prepare", WasmEHPreparePass, ())
 FUNCTION_PASS("win-eh-prepare", WinEHPreparePass, ())
 #undef FUNCTION_PASS
 
@@ -131,7 +132,6 @@ DUMMY_FUNCTION_PASS("select-optimize", SelectOptimizePass, ())
 DUMMY_FUNCTION_PASS("shadow-stack-gc-lowering", ShadowStackGCLoweringPass, ())
 DUMMY_FUNCTION_PASS("sjljehprepare", SjLjEHPreparePass, ())
 DUMMY_FUNCTION_PASS("stack-protector", StackProtectorPass, ())
-DUMMY_FUNCTION_PASS("wasmehprepare", WasmEHPass, ())
 #undef DUMMY_FUNCTION_PASS
 
 #ifndef DUMMY_MODULE_PASS
diff --git a/llvm/include/llvm/CodeGen/WasmEHPrepare.h b/llvm/include/llvm/CodeGen/WasmEHPrepare.h
new file mode 100644
index 0000000000000..8b3c07573a0d3
--- /dev/null
+++ b/llvm/include/llvm/CodeGen/WasmEHPrepare.h
@@ -0,0 +1,23 @@
+//===--- llvm/CodeGen/WasmEHPrepare.h ---------------------------*- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CODEGEN_WASMEHPREPARE_H
+#define LLVM_CODEGEN_WASMEHPREPARE_H
+
+#include "llvm/IR/PassManager.h"
+
+namespace llvm {
+
+class WasmEHPreparePass : public PassInfoMixin<WasmEHPreparePass> {
+public:
+  PreservedAnalyses run(Function &F, FunctionAnalysisManager &FAM);
+};
+
+} // namespace llvm
+
+#endif // LLVM_CODEGEN_WASMEHPREPARE_H
diff --git a/llvm/lib/CodeGen/WasmEHPrepare.cpp b/llvm/lib/CodeGen/WasmEHPrepare.cpp
index d99b10f4207f9..55d71128e7821 100644
--- a/llvm/lib/CodeGen/WasmEHPrepare.cpp
+++ b/llvm/lib/CodeGen/WasmEHPrepare.cpp
@@ -77,6 +77,7 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "llvm/CodeGen/WasmEHPrepare.h"
 #include "llvm/CodeGen/MachineBasicBlock.h"
 #include "llvm/CodeGen/Passes.h"
 #include "llvm/CodeGen/WasmEHFuncInfo.h"
@@ -88,10 +89,12 @@
 
 using namespace llvm;
 
-#define DEBUG_TYPE "wasmehprepare"
+#define DEBUG_TYPE "wasm-eh-prepare"
 
 namespace {
-class WasmEHPrepare : public FunctionPass {
+class WasmEHPrepareImpl {
+  friend class WasmEHPrepare;
+
   Type *LPadContextTy = nullptr; // type of 'struct _Unwind_LandingPadContext'
   GlobalVariable *LPadContextGV = nullptr; // __wasm_lpad_context
 
@@ -113,19 +116,41 @@ class WasmEHPrepare : public FunctionPass {
   bool prepareEHPads(Function &F);
   void prepareEHPad(BasicBlock *BB, bool NeedPersonality, unsigned Index = 0);
 
+public:
+  WasmEHPrepareImpl() = default;
+  WasmEHPrepareImpl(Type *LPadContextTy_) : LPadContextTy(LPadContextTy_) {}
+  bool runOnFunction(Function &F);
+};
+
+class WasmEHPrepare : public FunctionPass {
+  WasmEHPrepareImpl P;
+
 public:
   static char ID; // Pass identification, replacement for typeid
 
   WasmEHPrepare() : FunctionPass(ID) {}
   bool doInitialization(Module &M) override;
-  bool runOnFunction(Function &F) override;
+  bool runOnFunction(Function &F) override { return P.runOnFunction(F); }
 
   StringRef getPassName() const override {
     return "WebAssembly Exception handling preparation";
   }
 };
+
 } // end anonymous namespace
 
+PreservedAnalyses WasmEHPreparePass::run(Function &F,
+                                         FunctionAnalysisManager &) {
+  auto &Context = F.getContext();
+  auto *I32Ty = Type::getInt32Ty(Context);
+  auto *PtrTy = PointerType::get(Context, F.getAddressSpace());
+  auto *LPadContextTy =
+      StructType::get(I32Ty /*lpad_index*/, PtrTy /*lsda*/, I32Ty /*selector*/);
+  WasmEHPrepareImpl P(LPadContextTy);
+  bool Changed = P.runOnFunction(F);
+  return Changed ? PreservedAnalyses::none() : PreservedAnalyses ::all();
+}
+
 char WasmEHPrepare::ID = 0;
 INITIALIZE_PASS_BEGIN(WasmEHPrepare, DEBUG_TYPE,
                       "Prepare WebAssembly exceptions", false, false)
@@ -136,9 +161,9 @@ FunctionPass *llvm::createWasmEHPass() { return new WasmEHPrepare(); }
 
 bool WasmEHPrepare::doInitialization(Module &M) {
   IRBuilder<> IRB(M.getContext());
-  LPadContextTy = StructType::get(IRB.getInt32Ty(), // lpad_index
-                                  IRB.getPtrTy(),   // lsda
-                                  IRB.getInt32Ty()  // selector
+  P.LPadContextTy = StructType::get(IRB.getInt32Ty(), // lpad_index
+                                    IRB.getPtrTy(),   // lsda
+                                    IRB.getInt32Ty()  // selector
   );
   return false;
 }
@@ -157,14 +182,14 @@ static void eraseDeadBBsAndChildren(const Container &BBs) {
   }
 }
 
-bool WasmEHPrepare::runOnFunction(Function &F) {
+bool WasmEHPrepareImpl::runOnFunction(Function &F) {
   bool Changed = false;
   Changed |= prepareThrows(F);
   Changed |= prepareEHPads(F);
   return Changed;
 }
 
-bool WasmEHPrepare::prepareThrows(Function &F) {
+bool WasmEHPrepareImpl::prepareThrows(Function &F) {
   Module &M = *F.getParent();
   IRBuilder<> IRB(F.getContext());
   bool Changed = false;
@@ -192,7 +217,7 @@ bool WasmEHPrepare::prepareThrows(Function &F) {
   return Changed;
 }
 
-bool WasmEHPrepare::prepareEHPads(Function &F) {
+bool WasmEHPrepareImpl::prepareEHPads(Function &F) {
   Module &M = *F.getParent();
   IRBuilder<> IRB(F.getContext());
 
@@ -275,8 +300,8 @@ bool WasmEHPrepare::prepareEHPads(Function &F) {
 
 // Prepare an EH pad for Wasm EH handling. If NeedPersonality is false, Index is
 // ignored.
-void WasmEHPrepare::prepareEHPad(BasicBlock *BB, bool NeedPersonality,
-                                 unsigned Index) {
+void WasmEHPrepareImpl::prepareEHPad(BasicBlock *BB, bool NeedPersonality,
+                                     unsigned Index) {
   assert(BB->isEHPad() && "BB is not an EHPad!");
   IRBuilder<> IRB(BB->getContext());
   IRB.SetInsertPoint(BB, BB->getFirstInsertionPt());
diff --git a/llvm/lib/Passes/PassBuilder.cpp b/llvm/lib/Passes/PassBuilder.cpp
index 729b050c5d1d3..a5f9b5424358e 100644
--- a/llvm/lib/Passes/PassBuilder.cpp
+++ b/llvm/lib/Passes/PassBuilder.cpp
@@ -79,6 +79,7 @@
 #include "llvm/CodeGen/HardwareLoops.h"
 #include "llvm/CodeGen/SafeStack.h"
 #include "llvm/CodeGen/TypePromotion.h"
+#include "llvm/CodeGen/WasmEHPrepare.h"
 #include "llvm/CodeGen/WinEHPrepare.h"
 #include "llvm/IR/DebugInfo.h"
 #include "llvm/IR/Dominators.h"
diff --git a/llvm/lib/Passes/PassRegistry.def b/llvm/lib/Passes/PassRegistry.def
index 37c0d6c29b429..7462704ec2df8 100644
--- a/llvm/lib/Passes/PassRegistry.def
+++ b/llvm/lib/Passes/PassRegistry.def
@@ -423,6 +423,7 @@ FUNCTION_PASS("view-dom", DomViewer())
 FUNCTION_PASS("view-dom-only", DomOnlyViewer())
 FUNCTION_PASS("view-post-dom", PostDomViewer())
 FUNCTION_PASS("view-post-dom-only", PostDomOnlyViewer())
+FUNCTION_PASS("wasm-eh-prepare", WasmEHPreparePass())
 #undef FUNCTION_PASS
 
 #ifndef FUNCTION_PASS_WITH_PARAMS
diff --git a/llvm/test/CodeGen/WebAssembly/wasmehprepare.ll b/llvm/test/CodeGen/WebAssembly/wasm-eh-prepare.ll
similarity index 95%
rename from llvm/test/CodeGen/WebAssembly/wasmehprepare.ll
rename to llvm/test/CodeGen/WebAssembly/wasm-eh-prepare.ll
index a418eb4ec890e..e3de251017384 100644
--- a/llvm/test/CodeGen/WebAssembly/wasmehprepare.ll
+++ b/llvm/test/CodeGen/WebAssembly/wasm-eh-prepare.ll
@@ -1,5 +1,7 @@
-; RUN: opt < %s -winehprepare -demote-catchswitch-only -wasmehprepare -S | FileCheck %s
-; RUN: opt < %s -winehprepare -demote-catchswitch-only -wasmehprepare -S --mattr=+atomics,+bulk-memory | FileCheck %s
+; RUN: opt < %s -winehprepare -demote-catchswitch-only -wasm-eh-prepare -S | FileCheck %s
+; RUN: opt < %s -winehprepare -demote-catchswitch-only -wasm-eh-prepare -S --mattr=+atomics,+bulk-memory | FileCheck %s
+; RUN: opt < %s -passes='win-eh-prepare<demote-catchswitch-only>,wasm-eh-prepare' -S | FileCheck %s
+; RUN: opt < %s -passes='win-eh-prepare<demote-catchswitch-only>,wasm-eh-prepare' -S --mattr=+atomics,+bulk-memory | FileCheck %s
 
 target datalayout = "e-m:e-p:32:32-i64:64-n32:64-S128"
 target triple = "wasm32-unknown-unknown"

dschuff

/cc @aheejin

dschuff · 2023-12-05T20:56:47Z

llvm/lib/CodeGen/WasmEHPrepare.cpp

 } // end anonymous namespace

+PreservedAnalyses WasmEHPreparePass::run(Function &F,
+                                         FunctionAnalysisManager &) {
+  auto &Context = F.getContext();


I'm not super familiar with the new pass manager, but this new code seems to be the same as what's in WasmEHPrepare::doInitialization() below. Are they both necessary?

There is no doInitialization/doFinalization concept in new pass manager. I add the same code here to ensure the same behavior for new and legacy pass.

Then we should delete the current doInitialization. But then where do we do stuff that was only possible in doInitialization before, like things listed here? https://llvm.org/docs/WritingAnLLVMPass.html#the-doinitialization-module-method

Using an analysis pass to fetch information about module may be an option, or convert it to module pass. If it is a machine function pass, the machine function pass manager provides ability to run doInitialization/doFinalization.

aheejin · 2023-12-05T22:56:12Z

llvm/lib/CodeGen/WasmEHPrepare.cpp


 namespace {
-class WasmEHPrepare : public FunctionPass {
+class WasmEHPrepareImpl {


I'm not familiar with the new pass manager. Does this additional Impl class necessary for the new pass manager? If there is a guide to port passes to the new pass manager, can you point it out? (I searched a little but didn't find much other than https://llvm.org/docs/NewPassManager.html)

Sadly, there is no particular porting guide, but discourse has some topics about it. If we can remove the legacy pass entirely in future, we can merge WasmEHPrepareImpl and WasmEHPreparePass.

What makes the current WasmEHPrepare class not sharable between the legacy and the new PM and why do we need the additional Impl class? Isn't the Impl class an implementation detail within WasmEHPrepare? It looks the interface of WasmEHPrepare hasn't changed.

Also I'd appreciate if you can point to some related discussions in discourse!

Legacy WasmEHPrepare need to inherit FunctionPass, new WasmEHPreparePass need to inherit PassInfoMixin and register the pass info in PassRegistry.def so PassBuilder can reference them.

Some useful links:
https://llvm.org/devmtg/2014-10/Slides/Carruth-TheLLVMPassManagerPart2.pdf
https://discourse.llvm.org/t/solved-migrating-legacypm-passes-to-newpm/63073
https://discourse.llvm.org/t/porting-pass-to-new-passmanager/49866/7
https://discourse.llvm.org/t/doinitialization-finalization-equivalent-for-new-pass-manager/49888

Ah OK, I think I now get it. This PR makes WasmEHPrepare supported in both the old and new PM. I thought we are removing the old PM support, which was the source of the confusion.. Thanks for the info.

paperchalice · 2023-12-06T00:54:26Z

CC @arsenm @aeubanks @boomanaiden154.

arsenm · 2023-12-06T03:37:23Z

llvm/lib/CodeGen/WasmEHPrepare.cpp

+                                         FunctionAnalysisManager &) {
+  auto &Context = F.getContext();
+  auto *I32Ty = Type::getInt32Ty(Context);
+  auto *PtrTy = PointerType::get(Context, F.getAddressSpace());


If you're being precise about the address space, it should probably come from LSDA instead of the calling function

Checked existing code, the address space is 0 here, will update later.

aheejin

Thanks!

llvmbot added the backend:WebAssembly label Dec 5, 2023

paperchalice force-pushed the NPM/CodeGen/wasmehprepare branch 2 times, most recently from 8020c0e to 5f5bc99 Compare December 5, 2023 11:48

dschuff reviewed Dec 5, 2023

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aheejin reviewed Dec 5, 2023

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arsenm reviewed Dec 6, 2023

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[CodeGen] Port WasmEHPrepare to new pass manager

eabb088

paperchalice force-pushed the NPM/CodeGen/wasmehprepare branch from 5f5bc99 to eabb088 Compare December 6, 2023 04:57

arsenm approved these changes Dec 6, 2023

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aheejin approved these changes Dec 6, 2023

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aheejin merged commit 5baf66f into llvm:main Dec 6, 2023
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paperchalice deleted the NPM/CodeGen/wasmehprepare branch December 7, 2023 00:23

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[CodeGen] Port WasmEHPrepare to new pass manager #74435

[CodeGen] Port WasmEHPrepare to new pass manager #74435

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[CodeGen] Port WasmEHPrepare to new pass manager #74435

[CodeGen] Port WasmEHPrepare to new pass manager #74435

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