[llvm] r333696 - [WebAssembly] Add Wasm exception handling prepare pass
Heejin Ahn via llvm-commits
llvm-commits at lists.llvm.org
Thu May 31 15:02:34 PDT 2018
Author: aheejin
Date: Thu May 31 15:02:34 2018
New Revision: 333696
URL: http://llvm.org/viewvc/llvm-project?rev=333696&view=rev
Log:
[WebAssembly] Add Wasm exception handling prepare pass
Summary:
This adds a pass that transforms a program to be prepared for Wasm
exception handling. This is using Windows EH instructions and based on
the previous Wasm EH proposal.
(https://github.com/WebAssembly/exception-handling/blob/master/proposals/Exceptions.md)
Reviewers: dschuff, majnemer
Subscribers: jfb, mgorny, sbc100, jgravelle-google, JDevlieghere, sunfish, llvm-commits
Differential Revision: https://reviews.llvm.org/D43746
Added:
llvm/trunk/lib/CodeGen/WasmEHPrepare.cpp
llvm/trunk/test/CodeGen/WebAssembly/wasmehprepare.ll
Modified:
llvm/trunk/include/llvm/CodeGen/Passes.h
llvm/trunk/include/llvm/IR/IntrinsicsWebAssembly.td
llvm/trunk/include/llvm/InitializePasses.h
llvm/trunk/lib/CodeGen/CMakeLists.txt
llvm/trunk/lib/CodeGen/CodeGen.cpp
llvm/trunk/lib/CodeGen/TargetPassConfig.cpp
llvm/trunk/lib/CodeGen/WinEHPrepare.cpp
llvm/trunk/tools/opt/opt.cpp
Modified: llvm/trunk/include/llvm/CodeGen/Passes.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/CodeGen/Passes.h?rev=333696&r1=333695&r2=333696&view=diff
==============================================================================
--- llvm/trunk/include/llvm/CodeGen/Passes.h (original)
+++ llvm/trunk/include/llvm/CodeGen/Passes.h Thu May 31 15:02:34 2018
@@ -329,13 +329,17 @@ namespace llvm {
/// createWinEHPass - Prepares personality functions used by MSVC on Windows,
/// in addition to the Itanium LSDA based personalities.
- FunctionPass *createWinEHPass();
+ FunctionPass *createWinEHPass(bool DemoteCatchSwitchPHIOnly = false);
/// createSjLjEHPreparePass - This pass adapts exception handling code to use
/// the GCC-style builtin setjmp/longjmp (sjlj) to handling EH control flow.
///
FunctionPass *createSjLjEHPreparePass();
+ /// createWasmEHPass - This pass adapts exception handling code to use
+ /// WebAssembly's exception handling scheme.
+ FunctionPass *createWasmEHPass();
+
/// LocalStackSlotAllocation - This pass assigns local frame indices to stack
/// slots relative to one another and allocates base registers to access them
/// when it is estimated by the target to be out of range of normal frame
Modified: llvm/trunk/include/llvm/IR/IntrinsicsWebAssembly.td
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/IR/IntrinsicsWebAssembly.td?rev=333696&r1=333695&r2=333696&view=diff
==============================================================================
--- llvm/trunk/include/llvm/IR/IntrinsicsWebAssembly.td (original)
+++ llvm/trunk/include/llvm/IR/IntrinsicsWebAssembly.td Thu May 31 15:02:34 2018
@@ -42,7 +42,21 @@ def int_wasm_rethrow : Intrinsic<[], [],
// Since wasm does not use landingpad instructions, these instructions return
// exception pointer and selector values until we lower them in WasmEHPrepare.
-def int_wasm_get_exception : Intrinsic<[llvm_ptr_ty], [], [IntrHasSideEffects]>;
-def int_wasm_get_ehselector : Intrinsic<[llvm_i32_ty], [],
+def int_wasm_get_exception : Intrinsic<[llvm_ptr_ty], [llvm_token_ty],
+ [IntrHasSideEffects]>;
+def int_wasm_get_ehselector : Intrinsic<[llvm_i32_ty], [llvm_token_ty],
[IntrHasSideEffects]>;
+
+// wasm.catch returns the pointer to the exception object caught by wasm 'catch'
+// instruction.
+def int_wasm_catch : Intrinsic<[llvm_ptr_ty], [llvm_i32_ty],
+ [IntrHasSideEffects]>;
+
+// WebAssembly EH must maintain the landingpads in the order assigned to them
+// by WasmEHPrepare pass to generate landingpad table in EHStreamer. This is
+// used in order to give them the indices in WasmEHPrepare.
+def int_wasm_landingpad_index: Intrinsic<[], [llvm_i32_ty], [IntrNoMem]>;
+
+// Returns LSDA address of the current function.
+def int_wasm_lsda : Intrinsic<[llvm_ptr_ty], [], [IntrNoMem]>;
}
Modified: llvm/trunk/include/llvm/InitializePasses.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/InitializePasses.h?rev=333696&r1=333695&r2=333696&view=diff
==============================================================================
--- llvm/trunk/include/llvm/InitializePasses.h (original)
+++ llvm/trunk/include/llvm/InitializePasses.h Thu May 31 15:02:34 2018
@@ -389,6 +389,7 @@ void initializeUnreachableMachineBlockEl
void initializeVerifierLegacyPassPass(PassRegistry&);
void initializeVirtRegMapPass(PassRegistry&);
void initializeVirtRegRewriterPass(PassRegistry&);
+void initializeWasmEHPreparePass(PassRegistry&);
void initializeWholeProgramDevirtPass(PassRegistry&);
void initializeWinEHPreparePass(PassRegistry&);
void initializeWriteBitcodePassPass(PassRegistry&);
Modified: llvm/trunk/lib/CodeGen/CMakeLists.txt
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/CMakeLists.txt?rev=333696&r1=333695&r2=333696&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/CMakeLists.txt (original)
+++ llvm/trunk/lib/CodeGen/CMakeLists.txt Thu May 31 15:02:34 2018
@@ -158,6 +158,7 @@ add_llvm_library(LLVMCodeGen
UnreachableBlockElim.cpp
ValueTypes.cpp
VirtRegMap.cpp
+ WasmEHPrepare.cpp
WinEHPrepare.cpp
XRayInstrumentation.cpp
Modified: llvm/trunk/lib/CodeGen/CodeGen.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/CodeGen.cpp?rev=333696&r1=333695&r2=333696&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/CodeGen.cpp (original)
+++ llvm/trunk/lib/CodeGen/CodeGen.cpp Thu May 31 15:02:34 2018
@@ -102,6 +102,7 @@ void llvm::initializeCodeGen(PassRegistr
initializeUnreachableMachineBlockElimPass(Registry);
initializeVirtRegMapPass(Registry);
initializeVirtRegRewriterPass(Registry);
+ initializeWasmEHPreparePass(Registry);
initializeWinEHPreparePass(Registry);
initializeXRayInstrumentationPass(Registry);
initializeMIRCanonicalizerPass(Registry);
Modified: llvm/trunk/lib/CodeGen/TargetPassConfig.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/TargetPassConfig.cpp?rev=333696&r1=333695&r2=333696&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/TargetPassConfig.cpp (original)
+++ llvm/trunk/lib/CodeGen/TargetPassConfig.cpp Thu May 31 15:02:34 2018
@@ -656,7 +656,12 @@ void TargetPassConfig::addPassesToHandle
addPass(createDwarfEHPass());
break;
case ExceptionHandling::Wasm:
- // TODO to prevent warning
+ // Wasm EH uses Windows EH instructions, but it does not need to demote PHIs
+ // on catchpads and cleanuppads because it does not outline them into
+ // funclets. Catchswitch blocks are not lowered in SelectionDAG, so we
+ // should remove PHIs there.
+ addPass(createWinEHPass(/*DemoteCatchSwitchPHIOnly=*/false));
+ addPass(createWasmEHPass());
break;
case ExceptionHandling::None:
addPass(createLowerInvokePass());
Added: llvm/trunk/lib/CodeGen/WasmEHPrepare.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/WasmEHPrepare.cpp?rev=333696&view=auto
==============================================================================
--- llvm/trunk/lib/CodeGen/WasmEHPrepare.cpp (added)
+++ llvm/trunk/lib/CodeGen/WasmEHPrepare.cpp Thu May 31 15:02:34 2018
@@ -0,0 +1,331 @@
+//===-- WasmEHPrepare - Prepare excepton handling for WebAssembly --------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This transformation is designed for use by code generators which use
+// WebAssembly exception handling scheme.
+//
+// WebAssembly exception handling uses Windows exception IR for the middle level
+// representation. This pass does the following transformation for every
+// catchpad block:
+// (In C-style pseudocode)
+//
+// - Before:
+// catchpad ...
+// exn = wasm.get.exception();
+// selector = wasm.get.selector();
+// ...
+//
+// - After:
+// catchpad ...
+// exn = wasm.catch(0); // 0 is a tag for C++
+// wasm.landingpad.index(index);
+// // Only add below in case it's not a single catch (...)
+// __wasm_lpad_context.lpad_index = index;
+// __wasm_lpad_context.lsda = wasm.lsda();
+// _Unwind_CallPersonality(exn);
+// int selector = __wasm.landingpad_context.selector;
+// ...
+//
+// Also, does the following for a cleanuppad block with a call to
+// __clang_call_terminate():
+// - Before:
+// cleanuppad ...
+// exn = wasm.get.exception();
+// __clang_call_terminate(exn);
+//
+// - After:
+// cleanuppad ...
+// exn = wasm.catch(0); // 0 is a tag for C++
+// __clang_call_terminate(exn);
+//
+//
+// * Background: WebAssembly EH instructions
+// WebAssembly's try and catch instructions are structured as follows:
+// try
+// instruction*
+// catch (C++ tag)
+// instruction*
+// ...
+// catch_all
+// instruction*
+// try_end
+//
+// A catch instruction in WebAssembly does not correspond to a C++ catch clause.
+// In WebAssembly, there is a single catch instruction for all C++ exceptions.
+// There can be more catch instructions for exceptions in other languages, but
+// they are not generated for now. catch_all catches all exceptions including
+// foreign exceptions (e.g. JavaScript). We turn catchpads into catch (C++ tag)
+// and cleanuppads into catch_all, with one exception: cleanuppad with a call to
+// __clang_call_terminate should be both in catch (C++ tag) and catch_all.
+//
+//
+// * Background: Direct personality function call
+// In WebAssembly EH, the VM is responsible for unwinding the stack once an
+// exception is thrown. After the stack is unwound, the control flow is
+// transfered to WebAssembly 'catch' instruction, which returns a caught
+// exception object.
+//
+// Unwinding the stack is not done by libunwind but the VM, so the personality
+// function in libcxxabi cannot be called from libunwind during the unwinding
+// process. So after a catch instruction, we insert a call to a wrapper function
+// in libunwind that in turn calls the real personality function.
+//
+// In Itanium EH, if the personality function decides there is no matching catch
+// clause in a call frame and no cleanup action to perform, the unwinder doesn't
+// stop there and continues unwinding. But in Wasm EH, the unwinder stops at
+// every call frame with a catch intruction, after which the personality
+// function is called from the compiler-generated user code here.
+//
+// In libunwind, we have this struct that serves as a communincation channel
+// between the compiler-generated user code and the personality function in
+// libcxxabi.
+//
+// struct _Unwind_LandingPadContext {
+// uintptr_t lpad_index;
+// uintptr_t lsda;
+// uintptr_t selector;
+// };
+// struct _Unwind_LandingPadContext __wasm_lpad_context = ...;
+//
+// And this wrapper in libunwind calls the personality function.
+//
+// _Unwind_Reason_Code _Unwind_CallPersonality(void *exception_ptr) {
+// struct _Unwind_Exception *exception_obj =
+// (struct _Unwind_Exception *)exception_ptr;
+// _Unwind_Reason_Code ret = __gxx_personality_v0(
+// 1, _UA_CLEANUP_PHASE, exception_obj->exception_class, exception_obj,
+// (struct _Unwind_Context *)__wasm_lpad_context);
+// return ret;
+// }
+//
+// We pass a landing pad index, and the address of LSDA for the current function
+// to the wrapper function _Unwind_CallPersonality in libunwind, and we retrieve
+// the selector after it returns.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ADT/SetVector.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/ADT/Triple.h"
+#include "llvm/CodeGen/Passes.h"
+#include "llvm/CodeGen/TargetLowering.h"
+#include "llvm/CodeGen/TargetSubtargetInfo.h"
+#include "llvm/IR/Dominators.h"
+#include "llvm/IR/IRBuilder.h"
+#include "llvm/IR/Intrinsics.h"
+#include "llvm/Pass.h"
+#include "llvm/Transforms/Utils/BasicBlockUtils.h"
+
+using namespace llvm;
+
+#define DEBUG_TYPE "wasmehprepare"
+
+namespace {
+class WasmEHPrepare : public FunctionPass {
+ Type *LPadContextTy = nullptr; // type of 'struct _Unwind_LandingPadContext'
+ GlobalVariable *LPadContextGV = nullptr; // __wasm_lpad_context
+
+ // Field addresses of struct _Unwind_LandingPadContext
+ Value *LPadIndexField = nullptr; // lpad_index field
+ Value *LSDAField = nullptr; // lsda field
+ Value *SelectorField = nullptr; // selector
+
+ Function *CatchF = nullptr; // wasm.catch.extract() intrinsic
+ Function *LPadIndexF = nullptr; // wasm.landingpad.index() intrinsic
+ Function *LSDAF = nullptr; // wasm.lsda() intrinsic
+ Function *GetExnF = nullptr; // wasm.get.exception() intrinsic
+ Function *GetSelectorF = nullptr; // wasm.get.ehselector() intrinsic
+ Function *CallPersonalityF = nullptr; // _Unwind_CallPersonality() wrapper
+ Function *ClangCallTermF = nullptr; // __clang_call_terminate() function
+
+ void prepareEHPad(BasicBlock *BB, unsigned Index);
+ void prepareTerminateCleanupPad(BasicBlock *BB);
+
+public:
+ static char ID; // Pass identification, replacement for typeid
+
+ WasmEHPrepare() : FunctionPass(ID) {}
+
+ bool doInitialization(Module &M) override;
+ bool runOnFunction(Function &F) override;
+
+ StringRef getPassName() const override {
+ return "WebAssembly Exception handling preparation";
+ }
+};
+} // end anonymous namespace
+
+char WasmEHPrepare::ID = 0;
+INITIALIZE_PASS(WasmEHPrepare, DEBUG_TYPE, "Prepare WebAssembly exceptions",
+ false, false);
+
+FunctionPass *llvm::createWasmEHPass() { return new WasmEHPrepare(); }
+
+bool WasmEHPrepare::doInitialization(Module &M) {
+ IRBuilder<> IRB(M.getContext());
+ LPadContextTy = StructType::get(IRB.getInt32Ty(), // lpad_index
+ IRB.getInt8PtrTy(), // lsda
+ IRB.getInt32Ty() // selector
+ );
+ return false;
+}
+
+bool WasmEHPrepare::runOnFunction(Function &F) {
+ SmallVector<BasicBlock *, 16> CatchPads;
+ SmallVector<BasicBlock *, 16> CleanupPads;
+ for (BasicBlock &BB : F) {
+ if (!BB.isEHPad())
+ continue;
+ auto *Pad = BB.getFirstNonPHI();
+ if (isa<CatchPadInst>(Pad))
+ CatchPads.push_back(&BB);
+ else if (isa<CleanupPadInst>(Pad))
+ CleanupPads.push_back(&BB);
+ }
+
+ if (CatchPads.empty() && CleanupPads.empty())
+ return false;
+ assert(F.hasPersonalityFn() && "Personality function not found");
+
+ Module &M = *F.getParent();
+ IRBuilder<> IRB(F.getContext());
+
+ // __wasm_lpad_context global variable
+ LPadContextGV = cast<GlobalVariable>(
+ M.getOrInsertGlobal("__wasm_lpad_context", LPadContextTy));
+ LPadIndexField = IRB.CreateConstGEP2_32(LPadContextTy, LPadContextGV, 0, 0,
+ "lpad_index_gep");
+ LSDAField =
+ IRB.CreateConstGEP2_32(LPadContextTy, LPadContextGV, 0, 1, "lsda_gep");
+ SelectorField = IRB.CreateConstGEP2_32(LPadContextTy, LPadContextGV, 0, 2,
+ "selector_gep");
+
+ // wasm.catch() intinsic, which will be lowered to wasm 'catch' instruction.
+ CatchF = Intrinsic::getDeclaration(&M, Intrinsic::wasm_catch);
+ // wasm.landingpad.index() intrinsic, which is to specify landingpad index
+ LPadIndexF = Intrinsic::getDeclaration(&M, Intrinsic::wasm_landingpad_index);
+ // wasm.lsda() intrinsic. Returns the address of LSDA table for the current
+ // function.
+ LSDAF = Intrinsic::getDeclaration(&M, Intrinsic::wasm_lsda);
+ // wasm.get.exception() and wasm.get.ehselector() intrinsics. Calls to these
+ // are generated in clang.
+ GetExnF = Intrinsic::getDeclaration(&M, Intrinsic::wasm_get_exception);
+ GetSelectorF = Intrinsic::getDeclaration(&M, Intrinsic::wasm_get_ehselector);
+
+ // _Unwind_CallPersonality() wrapper function, which calls the personality
+ CallPersonalityF = cast<Function>(M.getOrInsertFunction(
+ "_Unwind_CallPersonality", IRB.getInt32Ty(), IRB.getInt8PtrTy()));
+ CallPersonalityF->setDoesNotThrow();
+
+ // __clang_call_terminate() function, which is inserted by clang in case a
+ // cleanup throws
+ ClangCallTermF = M.getFunction("__clang_call_terminate");
+
+ unsigned Index = 0;
+ for (auto *BB : CatchPads) {
+ auto *CPI = cast<CatchPadInst>(BB->getFirstNonPHI());
+ // In case of a single catch (...), we don't need to emit LSDA
+ if (CPI->getNumArgOperands() == 1 &&
+ cast<Constant>(CPI->getArgOperand(0))->isNullValue())
+ prepareEHPad(BB, -1);
+ else
+ prepareEHPad(BB, Index++);
+ }
+
+ if (!ClangCallTermF)
+ return !CatchPads.empty();
+
+ // Cleanuppads will turn into catch_all later, but cleanuppads with a call to
+ // __clang_call_terminate() is a special case. __clang_call_terminate() takes
+ // an exception object, so we have to duplicate call in both 'catch <C++ tag>'
+ // and 'catch_all' clauses. Here we only insert a call to catch; the
+ // duplication will be done later. In catch_all, the exception object will be
+ // set to null.
+ for (auto *BB : CleanupPads)
+ for (auto &I : *BB)
+ if (auto *CI = dyn_cast<CallInst>(&I))
+ if (CI->getCalledValue() == ClangCallTermF)
+ prepareEHPad(BB, -1);
+
+ return true;
+}
+
+void WasmEHPrepare::prepareEHPad(BasicBlock *BB, unsigned Index) {
+ assert(BB->isEHPad() && "BB is not an EHPad!");
+ IRBuilder<> IRB(BB->getContext());
+
+ IRB.SetInsertPoint(&*BB->getFirstInsertionPt());
+ // The argument to wasm.catch() is the tag for C++ exceptions, which we set to
+ // 0 for this module.
+ // Pseudocode: void *exn = wasm.catch(0);
+ Instruction *Exn = IRB.CreateCall(CatchF, IRB.getInt32(0), "exn");
+ // Replace the return value of wasm.get.exception() with the return value from
+ // wasm.catch().
+ auto *FPI = cast<FuncletPadInst>(BB->getFirstNonPHI());
+ Instruction *GetExnCI = nullptr, *GetSelectorCI = nullptr;
+ for (auto &U : FPI->uses()) {
+ if (auto *CI = dyn_cast<CallInst>(U.getUser())) {
+ if (CI->getCalledValue() == GetExnF)
+ GetExnCI = CI;
+ else if (CI->getCalledValue() == GetSelectorF)
+ GetSelectorCI = CI;
+ }
+ }
+
+ assert(GetExnCI && "wasm.get.exception() call does not exist");
+ GetExnCI->replaceAllUsesWith(Exn);
+ GetExnCI->eraseFromParent();
+
+ // In case it is a catchpad with single catch (...) or a cleanuppad, we don't
+ // need to call personality function because we don't need a selector.
+ if (FPI->getNumArgOperands() == 0 ||
+ (FPI->getNumArgOperands() == 1 &&
+ cast<Constant>(FPI->getArgOperand(0))->isNullValue())) {
+ if (GetSelectorCI) {
+ assert(GetSelectorCI->use_empty() &&
+ "wasm.get.ehselector() still has uses!");
+ GetSelectorCI->eraseFromParent();
+ }
+ return;
+ }
+ IRB.SetInsertPoint(Exn->getNextNode());
+
+ // This is to create a map of <landingpad EH label, landingpad index> in
+ // SelectionDAGISel, which is to be used in EHStreamer to emit LSDA tables.
+ // Pseudocode: wasm.landingpad.index(Index);
+ IRB.CreateCall(LPadIndexF, IRB.getInt32(Index));
+
+ // Pseudocode: __wasm_lpad_context.lpad_index = index;
+ IRB.CreateStore(IRB.getInt32(Index), LPadIndexField);
+
+ // Store LSDA address only if this catchpad belongs to a top-level
+ // catchswitch. If there is another catchpad that dominates this pad, we don't
+ // need to store LSDA address again, because they are the same throughout the
+ // function and have been already stored before.
+ // TODO Can we not store LSDA address in user function but make libcxxabi
+ // compute it?
+ auto *CPI = cast<CatchPadInst>(FPI);
+ if (isa<ConstantTokenNone>(CPI->getCatchSwitch()->getParentPad()))
+ // Pseudocode: __wasm_lpad_context.lsda = wasm.lsda();
+ IRB.CreateStore(IRB.CreateCall(LSDAF), LSDAField);
+
+ // Pseudocode: _Unwind_CallPersonality(exn);
+ CallInst *PersCI =
+ IRB.CreateCall(CallPersonalityF, Exn, OperandBundleDef("funclet", CPI));
+ PersCI->setDoesNotThrow();
+
+ // Pseudocode: int selector = __wasm.landingpad_context.selector;
+ Instruction *Selector = IRB.CreateLoad(SelectorField, "selector");
+
+ // Replace the return value from wasm.get.ehselector() with the selector value
+ // loaded from __wasm_lpad_context.selector.
+ assert(GetSelectorCI && "wasm.get.ehselector() call does not exist");
+ GetSelectorCI->replaceAllUsesWith(Selector);
+ GetSelectorCI->eraseFromParent();
+}
Modified: llvm/trunk/lib/CodeGen/WinEHPrepare.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/WinEHPrepare.cpp?rev=333696&r1=333695&r2=333696&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/WinEHPrepare.cpp (original)
+++ llvm/trunk/lib/CodeGen/WinEHPrepare.cpp Thu May 31 15:02:34 2018
@@ -49,12 +49,17 @@ static cl::opt<bool> DisableCleanups(
cl::desc("Do not remove implausible terminators or other similar cleanups"),
cl::init(false));
+static cl::opt<bool> DemoteCatchSwitchPHIOnlyOpt(
+ "demote-catchswitch-only", cl::Hidden,
+ cl::desc("Demote catchswitch BBs only (for wasm EH)"), cl::init(false));
+
namespace {
class WinEHPrepare : public FunctionPass {
public:
static char ID; // Pass identification, replacement for typeid.
- WinEHPrepare() : FunctionPass(ID) {}
+ WinEHPrepare(bool DemoteCatchSwitchPHIOnly = false)
+ : FunctionPass(ID), DemoteCatchSwitchPHIOnly(DemoteCatchSwitchPHIOnly) {}
bool runOnFunction(Function &Fn) override;
@@ -77,12 +82,14 @@ private:
bool prepareExplicitEH(Function &F);
void colorFunclets(Function &F);
- void demotePHIsOnFunclets(Function &F);
+ void demotePHIsOnFunclets(Function &F, bool DemoteCatchSwitchPHIOnly);
void cloneCommonBlocks(Function &F);
void removeImplausibleInstructions(Function &F);
void cleanupPreparedFunclets(Function &F);
void verifyPreparedFunclets(Function &F);
+ bool DemoteCatchSwitchPHIOnly;
+
// All fields are reset by runOnFunction.
EHPersonality Personality = EHPersonality::Unknown;
@@ -97,7 +104,9 @@ char WinEHPrepare::ID = 0;
INITIALIZE_PASS(WinEHPrepare, DEBUG_TYPE, "Prepare Windows exceptions",
false, false)
-FunctionPass *llvm::createWinEHPass() { return new WinEHPrepare(); }
+FunctionPass *llvm::createWinEHPass(bool DemoteCatchSwitchPHIOnly) {
+ return new WinEHPrepare(DemoteCatchSwitchPHIOnly);
+}
bool WinEHPrepare::runOnFunction(Function &Fn) {
if (!Fn.hasPersonalityFn())
@@ -678,13 +687,17 @@ void WinEHPrepare::colorFunclets(Functio
}
}
-void WinEHPrepare::demotePHIsOnFunclets(Function &F) {
+void WinEHPrepare::demotePHIsOnFunclets(Function &F,
+ bool DemoteCatchSwitchPHIOnly) {
// Strip PHI nodes off of EH pads.
SmallVector<PHINode *, 16> PHINodes;
for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE;) {
BasicBlock *BB = &*FI++;
if (!BB->isEHPad())
continue;
+ if (DemoteCatchSwitchPHIOnly && !isa<CatchSwitchInst>(BB->getFirstNonPHI()))
+ continue;
+
for (BasicBlock::iterator BI = BB->begin(), BE = BB->end(); BI != BE;) {
Instruction *I = &*BI++;
auto *PN = dyn_cast<PHINode>(I);
@@ -1032,7 +1045,8 @@ bool WinEHPrepare::prepareExplicitEH(Fun
cloneCommonBlocks(F);
if (!DisableDemotion)
- demotePHIsOnFunclets(F);
+ demotePHIsOnFunclets(F, DemoteCatchSwitchPHIOnly ||
+ DemoteCatchSwitchPHIOnlyOpt);
if (!DisableCleanups) {
LLVM_DEBUG(verifyFunction(F));
Added: llvm/trunk/test/CodeGen/WebAssembly/wasmehprepare.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/WebAssembly/wasmehprepare.ll?rev=333696&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/WebAssembly/wasmehprepare.ll (added)
+++ llvm/trunk/test/CodeGen/WebAssembly/wasmehprepare.ll Thu May 31 15:02:34 2018
@@ -0,0 +1,317 @@
+; RUN: opt < %s -winehprepare -demote-catchswitch-only -wasmehprepare -S | FileCheck %s
+
+target datalayout = "e-m:e-p:32:32-i64:64-n32:64-S128"
+target triple = "wasm32-unknown-unknown"
+
+; CHECK: @__wasm_lpad_context = external global { i32, i8*, i32 }
+
+ at _ZTIi = external constant i8*
+%struct.Cleanup = type { i8 }
+
+; A single 'catch (int)' clause.
+; A wasm.catch() call, wasm.lsda() call, and personality call to generate a
+; selector should all be genereated after the catchpad.
+define void @test0() personality i8* bitcast (i32 (...)* @__gxx_wasm_personality_v0 to i8*) {
+; CHECK-LABEL: @test0()
+entry:
+ invoke void @foo()
+ to label %try.cont unwind label %catch.dispatch
+
+catch.dispatch: ; preds = %entry
+ %0 = catchswitch within none [label %catch.start] unwind to caller
+
+catch.start: ; preds = %catch.dispatch
+ %1 = catchpad within %0 [i8* bitcast (i8** @_ZTIi to i8*)]
+ %2 = call i8* @llvm.wasm.get.exception(token %1)
+ %3 = call i32 @llvm.wasm.get.ehselector(token %1)
+ %4 = call i32 @llvm.eh.typeid.for(i8* bitcast (i8** @_ZTIi to i8*))
+ %matches = icmp eq i32 %3, %4
+ br i1 %matches, label %catch, label %rethrow
+; CHECK: catch.start:
+; CHECK-NEXT: %[[CATCHPAD:.*]] = catchpad
+; CHECK-NEXT: %[[EXN:.*]] = call i8* @llvm.wasm.catch(i32 0)
+; CHECK-NEXT: call void @llvm.wasm.landingpad.index(i32 0)
+; CHECK-NEXT: store i32 0, i32* getelementptr inbounds ({ i32, i8*, i32 }, { i32, i8*, i32 }* @__wasm_lpad_context, i32 0, i32 0)
+; CHECK-NEXT: %[[LSDA:.*]] = call i8* @llvm.wasm.lsda()
+; CHECK-NEXT: store i8* %[[LSDA]], i8** getelementptr inbounds ({ i32, i8*, i32 }, { i32, i8*, i32 }* @__wasm_lpad_context, i32 0, i32 1)
+; CHECK-NEXT: call i32 @_Unwind_CallPersonality(i8* %[[EXN]]) {{.*}} [ "funclet"(token %[[CATCHPAD]]) ]
+; CHECK-NEXT: %[[SELECTOR:.*]] = load i32, i32* getelementptr inbounds ({ i32, i8*, i32 }, { i32, i8*, i32 }* @__wasm_lpad_context, i32 0, i32 2)
+; CHECK: icmp eq i32 %[[SELECTOR]]
+
+catch: ; preds = %catch.start
+ %5 = call i8* @__cxa_begin_catch(i8* %2) [ "funclet"(token %1) ]
+ call void @__cxa_end_catch() [ "funclet"(token %1) ]
+ catchret from %1 to label %try.cont
+; CHECK: catch:
+; CHECK-NEXT: call i8* @__cxa_begin_catch(i8* %[[EXN]])
+
+rethrow: ; preds = %catch.start
+ call void @__cxa_rethrow() [ "funclet"(token %1) ]
+ unreachable
+
+try.cont: ; preds = %entry, %catch
+ ret void
+}
+
+; Two try-catches, one of them is with a single 'catch (...)' clause.
+; For the catchpad with a single 'catch (...)', only a wasm.catch() call should
+; be generated after the catchpad; wasm.landingpad.index() and personality call
+; should NOT be generated. For the other catchpad, the argument of
+; wasm.landingpad.index() should be not 1 but 0.
+define void @test1() personality i8* bitcast (i32 (...)* @__gxx_wasm_personality_v0 to i8*) {
+; CHECK-LABEL: @test1()
+entry:
+ invoke void @foo()
+ to label %try.cont unwind label %catch.dispatch
+
+catch.dispatch: ; preds = %entry
+ %0 = catchswitch within none [label %catch.start] unwind to caller
+
+catch.start: ; preds = %catch.dispatch
+ %1 = catchpad within %0 [i8* null]
+ %2 = call i8* @llvm.wasm.get.exception(token %1)
+ %3 = call i32 @llvm.wasm.get.ehselector(token %1)
+ %4 = call i8* @__cxa_begin_catch(i8* %2) [ "funclet"(token %1) ]
+ call void @__cxa_end_catch() [ "funclet"(token %1) ]
+ catchret from %1 to label %try.cont
+; CHECK: catch.start:
+; CHECK-NEXT: catchpad within %0 [i8* null]
+; CHECK-NEXT: call i8* @llvm.wasm.catch(i32 0)
+; CHECK-NOT: call void @llvm.wasm.landingpad.index
+; CHECK-NOT: store {{.*}} @__wasm_lpad_context
+; CHECK-NOT: call i8* @llvm.wasm.lsda()
+; CHECK-NOT: call i32 @_Unwind_CallPersonality
+; CHECK-NOT: load {{.*}} @__wasm_lpad_context
+
+try.cont: ; preds = %entry, %catch.start
+ invoke void @foo()
+ to label %try.cont7 unwind label %catch.dispatch2
+
+catch.dispatch2: ; preds = %try.cont
+ %5 = catchswitch within none [label %catch.start3] unwind to caller
+
+catch.start3: ; preds = %catch.dispatch2
+ %6 = catchpad within %5 [i8* bitcast (i8** @_ZTIi to i8*)]
+ %7 = call i8* @llvm.wasm.get.exception(token %6)
+ %8 = call i32 @llvm.wasm.get.ehselector(token %6)
+ %9 = call i32 @llvm.eh.typeid.for(i8* bitcast (i8** @_ZTIi to i8*))
+ %matches = icmp eq i32 %8, %9
+ br i1 %matches, label %catch4, label %rethrow
+; CHECK: catch.start3:
+; CHECK: call void @llvm.wasm.landingpad.index(i32 0)
+
+catch4: ; preds = %catch.start3
+ %10 = call i8* @__cxa_begin_catch(i8* %7) [ "funclet"(token %6) ]
+ call void @__cxa_end_catch() [ "funclet"(token %6) ]
+ catchret from %6 to label %try.cont7
+
+rethrow: ; preds = %catch.start3
+ call void @__cxa_rethrow() [ "funclet"(token %6) ]
+ unreachable
+
+try.cont7: ; preds = %try.cont, %catch4
+ ret void
+}
+
+; A nested try-catch within a catch. Within the nested catchpad, wasm.lsda()
+; call should NOT be generated.
+define void @test2() personality i8* bitcast (i32 (...)* @__gxx_wasm_personality_v0 to i8*) {
+; CHECK-LABEL: @test2()
+entry:
+ invoke void @foo()
+ to label %try.cont9 unwind label %catch.dispatch
+
+catch.dispatch: ; preds = %entry
+ %0 = catchswitch within none [label %catch.start] unwind to caller
+
+catch.start: ; preds = %catch.dispatch
+ %1 = catchpad within %0 [i8* bitcast (i8** @_ZTIi to i8*)]
+ %2 = call i8* @llvm.wasm.get.exception(token %1)
+ %3 = call i32 @llvm.wasm.get.ehselector(token %1)
+ %4 = call i32 @llvm.eh.typeid.for(i8* bitcast (i8** @_ZTIi to i8*))
+ %matches = icmp eq i32 %3, %4
+ br i1 %matches, label %catch, label %rethrow
+; CHECK: catch.start:
+; CHECK: call i8* @llvm.wasm.lsda()
+
+catch: ; preds = %catch.start
+ %5 = call i8* @__cxa_begin_catch(i8* %2) [ "funclet"(token %1) ]
+ invoke void @foo() [ "funclet"(token %1) ]
+ to label %try.cont unwind label %catch.dispatch2
+
+catch.dispatch2: ; preds = %catch
+ %6 = catchswitch within %1 [label %catch.start3] unwind label %ehcleanup
+
+catch.start3: ; preds = %catch.dispatch2
+ %7 = catchpad within %6 [i8* bitcast (i8** @_ZTIi to i8*)]
+ %8 = call i8* @llvm.wasm.get.exception(token %7)
+ %9 = call i32 @llvm.wasm.get.ehselector(token %7)
+ %10 = call i32 @llvm.eh.typeid.for(i8* bitcast (i8** @_ZTIi to i8*))
+ %matches4 = icmp eq i32 %9, %10
+ br i1 %matches4, label %catch6, label %rethrow5
+; CHECK: catch.start3:
+; CHECK-NOT: call i8* @llvm.wasm.lsda()
+
+catch6: ; preds = %catch.start3
+ %11 = call i8* @__cxa_begin_catch(i8* %8) [ "funclet"(token %7) ]
+ call void @__cxa_end_catch() [ "funclet"(token %7) ]
+ catchret from %7 to label %try.cont
+
+rethrow5: ; preds = %catch.start3
+ invoke void @__cxa_rethrow() [ "funclet"(token %7) ]
+ to label %unreachable unwind label %ehcleanup
+
+try.cont: ; preds = %catch, %catch6
+ call void @__cxa_end_catch() [ "funclet"(token %1) ]
+ catchret from %1 to label %try.cont9
+
+rethrow: ; preds = %catch.start
+ call void @__cxa_rethrow() [ "funclet"(token %1) ]
+ unreachable
+
+try.cont9: ; preds = %entry, %try.cont
+ ret void
+
+ehcleanup: ; preds = %rethrow5, %catch.dispatch2
+ %12 = cleanuppad within %1 []
+ call void @__cxa_end_catch() [ "funclet"(token %12) ]
+ cleanupret from %12 unwind to caller
+; CHECK: ehcleanup:
+; CHECK-NEXT: cleanuppad
+; CHECK-NOT: call i8* @llvm.wasm.catch(i32 0)
+; CHECK-NOT: call void @llvm.wasm.landingpad.index
+; CHECK-NOT: store {{.*}} @__wasm_lpad_context
+; CHECK-NOT: call i8* @llvm.wasm.lsda()
+; CHECK-NOT: call i32 @_Unwind_CallPersonality
+; CHECK-NOT: load {{.*}} @__wasm_lpad_context
+
+unreachable: ; preds = %rethrow5
+ unreachable
+}
+
+; A cleanuppad with a call to __clang_call_terminate().
+; A call to wasm.catch() should be generated after the cleanuppad.
+define hidden void @test3() personality i8* bitcast (i32 (...)* @__gxx_wasm_personality_v0 to i8*) {
+; CHECK-LABEL: @test3
+entry:
+ invoke void @foo()
+ to label %try.cont unwind label %catch.dispatch
+
+catch.dispatch: ; preds = %entry
+ %0 = catchswitch within none [label %catch.start] unwind to caller
+
+catch.start: ; preds = %catch.dispatch
+ %1 = catchpad within %0 [i8* null]
+ %2 = call i8* @llvm.wasm.get.exception(token %1)
+ %3 = call i32 @llvm.wasm.get.ehselector(token %1)
+ %4 = call i8* @__cxa_begin_catch(i8* %2) [ "funclet"(token %1) ]
+ invoke void @foo() [ "funclet"(token %1) ]
+ to label %invoke.cont1 unwind label %ehcleanup
+
+invoke.cont1: ; preds = %catch.start
+ call void @__cxa_end_catch() [ "funclet"(token %1) ]
+ catchret from %1 to label %try.cont
+
+try.cont: ; preds = %entry, %invoke.cont1
+ ret void
+
+ehcleanup: ; preds = %catch.start
+ %5 = cleanuppad within %1 []
+ invoke void @__cxa_end_catch() [ "funclet"(token %5) ]
+ to label %invoke.cont2 unwind label %terminate
+
+invoke.cont2: ; preds = %ehcleanup
+ cleanupret from %5 unwind to caller
+
+terminate: ; preds = %ehcleanup
+ %6 = cleanuppad within %5 []
+ %7 = call i8* @llvm.wasm.get.exception(token %6)
+ call void @__clang_call_terminate(i8* %7) [ "funclet"(token %6) ]
+ unreachable
+; CHECK: terminate:
+; CHECK-NEXT: cleanuppad
+; CHECK-NEXT: %[[EXN:.*]] = call i8* @llvm.wasm.catch(i32 0)
+; CHECK-NEXT: call void @__clang_call_terminate(i8* %[[EXN]])
+}
+
+; PHI demotion test. Only the phi before catchswitch should be demoted; the phi
+; before cleanuppad should NOT.
+define void @test5() personality i8* bitcast (i32 (...)* @__gxx_wasm_personality_v0 to i8*) {
+; CHECK-LABEL: @test5
+entry:
+ %c = alloca %struct.Cleanup, align 1
+ invoke void @foo()
+ to label %invoke.cont unwind label %ehcleanup
+
+invoke.cont: ; preds = %entry
+ invoke void @foo()
+ to label %invoke.cont1 unwind label %ehcleanup
+
+invoke.cont1: ; preds = %invoke.cont
+ %call = call %struct.Cleanup* @_ZN7CleanupD1Ev(%struct.Cleanup* %c)
+ br label %try.cont
+
+ehcleanup: ; preds = %invoke.cont, %entry
+ %num.0 = phi i32 [ 2, %invoke.cont ], [ 1, %entry ]
+ %0 = cleanuppad within none []
+ %call2 = call %struct.Cleanup* @_ZN7CleanupD1Ev(%struct.Cleanup* %c) [ "funclet"(token %0) ]
+ cleanupret from %0 unwind label %catch.dispatch
+; CHECK: ehcleanup:
+; CHECK-NEXT: = phi
+
+catch.dispatch: ; preds = %ehcleanup
+ %1 = catchswitch within none [label %catch.start] unwind to caller
+
+catch.start: ; preds = %catch.dispatch
+ %2 = catchpad within %1 [i8* null]
+ %3 = call i8* @llvm.wasm.get.exception(token %2)
+ %4 = call i32 @llvm.wasm.get.ehselector(token %2)
+ %5 = call i8* @__cxa_begin_catch(i8* %3) [ "funclet"(token %2) ]
+ call void @func(i32 %num.0) [ "funclet"(token %2) ]
+ call void @__cxa_end_catch() [ "funclet"(token %2) ]
+ catchret from %2 to label %try.cont
+
+try.cont: ; preds = %catch.start, %invoke.cont1
+ invoke void @foo()
+ to label %invoke.cont3 unwind label %catch.dispatch5
+
+invoke.cont3: ; preds = %try.cont
+ invoke void @foo()
+ to label %try.cont10 unwind label %catch.dispatch5
+
+catch.dispatch5: ; preds = %invoke.cont3, %try.cont
+ %num.1 = phi i32 [ 2, %invoke.cont3 ], [ 1, %try.cont ]
+ %6 = catchswitch within none [label %catch.start6] unwind to caller
+; CHECK: catch.dispatch5:
+; CHECK-NOT: = phi
+
+catch.start6: ; preds = %catch.dispatch5
+ %7 = catchpad within %6 [i8* null]
+ %8 = call i8* @llvm.wasm.get.exception(token %7)
+ %9 = call i32 @llvm.wasm.get.ehselector(token %7)
+ %10 = call i8* @__cxa_begin_catch(i8* %8) [ "funclet"(token %7) ]
+ call void @func(i32 %num.1) [ "funclet"(token %7) ]
+ call void @__cxa_end_catch() [ "funclet"(token %7) ]
+ catchret from %7 to label %try.cont10
+
+try.cont10: ; preds = %invoke.cont3, %catch.start6
+ ret void
+}
+
+declare void @foo()
+declare void @func(i32)
+declare %struct.Cleanup* @_ZN7CleanupD1Ev(%struct.Cleanup* returned)
+declare i32 @__gxx_wasm_personality_v0(...)
+declare i8* @llvm.wasm.get.exception(token)
+declare i32 @llvm.wasm.get.ehselector(token)
+declare i32 @llvm.eh.typeid.for(i8*)
+declare i8* @__cxa_begin_catch(i8*)
+declare void @__cxa_end_catch()
+declare void @__cxa_rethrow()
+declare void @__clang_call_terminate(i8*)
+
+; CHECK-DAG: declare i8* @llvm.wasm.catch(i32)
+; CHECK-DAG: declare void @llvm.wasm.landingpad.index(i32)
+; CHECK-DAG: declare i8* @llvm.wasm.lsda()
+; CHECK-DAG: declare i32 @_Unwind_CallPersonality(i8*)
+
Modified: llvm/trunk/tools/opt/opt.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/opt/opt.cpp?rev=333696&r1=333695&r2=333696&view=diff
==============================================================================
--- llvm/trunk/tools/opt/opt.cpp (original)
+++ llvm/trunk/tools/opt/opt.cpp Thu May 31 15:02:34 2018
@@ -447,6 +447,7 @@ int main(int argc, char **argv) {
initializePostInlineEntryExitInstrumenterPass(Registry);
initializeUnreachableBlockElimLegacyPassPass(Registry);
initializeExpandReductionsPass(Registry);
+ initializeWasmEHPreparePass(Registry);
initializeWriteBitcodePassPass(Registry);
#ifdef LINK_POLLY_INTO_TOOLS
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