From c285a11efdb0821e6be9fcef695097890f44aa03 Mon Sep 17 00:00:00 2001 From: Heejin Ahn Date: Fri, 16 Jul 2021 23:37:09 -0700 Subject: [PATCH] [WebAssembly] Make Emscripten EH work with Emscripten SjLj When Emscripten EH mixes with Emscripten SjLj, we are not currently handling some of them correctly. There are three cases: 1. The current function calls `setjmp` and there is an `invoke` to a function that can either throw or longjmp. In this case, we have to check both for exception and longjmp. We are currently handling this case correctly: https://github.com/llvm/llvm-project/blob/0c0eb76782d5224b8d81a5afbb9a152bcf7c94c7/llvm/lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp#L1058-L1090 When inserting routines for functions that can longjmp, which we do only for setjmp-calling functions, we check if the function was previously an `invoke` and handle it correctly. 2. The current function does NOT call `setjmp` and there is an `invoke` to a function that can either throw or longjmp. Because there is no `setjmp` call, we haven't been doing any check for functions that can longjmp. But in that case, for `invoke`, we only check for an exception and if it is not an exception we reset `__THREW__` to 0, which can silently swallow the longjmp: https://github.com/llvm/llvm-project/blob/0c0eb76782d5224b8d81a5afbb9a152bcf7c94c7/llvm/lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp#L70-L80 This CL fixes this. 3. The current function calls `setjmp` and there is no `invoke`. Because it is not an `invoke`, we haven't been doing any check for functions that can throw, and only insert longjmp-checking routines for functions that can longjmp. But in that case, if a longjmpable function throws, we only check for a longjmp so if it is not a longjmp we reset `__THREW__` to 0, which can silently swallow the exception: https://github.com/llvm/llvm-project/blob/0c0eb76782d5224b8d81a5afbb9a152bcf7c94c7/llvm/lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp#L156-L169 This CL fixes this. To do that, this moves around some code, so we register necessary functions for both EH and SjLj and precompute some data (the set of functions that contains `setjmp`) before doing actual EH or SjLj transformation. This CL makes 2nd and 3rd tests in https://github.com/emscripten-core/emscripten/pull/14732 work. Reviewed By: dschuff Differential Revision: https://reviews.llvm.org/D106525 --- llvm/lib/Target/WebAssembly/WebAssembly.h | 3 +- .../WebAssemblyLowerEmscriptenEHSjLj.cpp | 134 +++++++++++++++--- .../CodeGen/WebAssembly/lower-em-ehsjlj.ll | 132 +++++++++++++++++ .../test/CodeGen/WebAssembly/lower-em-sjlj.ll | 43 +----- 4 files changed, 249 insertions(+), 63 deletions(-) create mode 100644 llvm/test/CodeGen/WebAssembly/lower-em-ehsjlj.ll diff --git a/llvm/lib/Target/WebAssembly/WebAssembly.h b/llvm/lib/Target/WebAssembly/WebAssembly.h index 3e9619fba3a3..9eb960d018d3 100644 --- a/llvm/lib/Target/WebAssembly/WebAssembly.h +++ b/llvm/lib/Target/WebAssembly/WebAssembly.h @@ -25,7 +25,8 @@ class ModulePass; class FunctionPass; // LLVM IR passes. -ModulePass *createWebAssemblyLowerEmscriptenEHSjLj(bool DoEH, bool DoSjLj); +ModulePass *createWebAssemblyLowerEmscriptenEHSjLj(bool EnableEH, + bool EnableSjLj); ModulePass *createWebAssemblyLowerGlobalDtors(); ModulePass *createWebAssemblyAddMissingPrototypes(); ModulePass *createWebAssemblyFixFunctionBitcasts(); diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp index fc2d93c3afab..599829a9e474 100644 --- a/llvm/lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp +++ b/llvm/lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp @@ -216,6 +216,7 @@ namespace { class WebAssemblyLowerEmscriptenEHSjLj final : public ModulePass { bool EnableEH; // Enable exception handling bool EnableSjLj; // Enable setjmp/longjmp handling + bool DoSjLj; // Whether we actually perform setjmp/longjmp handling GlobalVariable *ThrewGV = nullptr; GlobalVariable *ThrewValueGV = nullptr; @@ -234,6 +235,8 @@ class WebAssemblyLowerEmscriptenEHSjLj final : public ModulePass { StringMap InvokeWrappers; // Set of allowed function names for exception handling std::set EHAllowlistSet; + // Functions that contains calls to setjmp + SmallPtrSet SetjmpUsers; StringRef getPassName() const override { return "WebAssembly Lower Emscripten Exceptions"; @@ -252,6 +255,10 @@ class WebAssemblyLowerEmscriptenEHSjLj final : public ModulePass { bool areAllExceptionsAllowed() const { return EHAllowlistSet.empty(); } bool canLongjmp(Module &M, const Value *Callee) const; bool isEmAsmCall(Module &M, const Value *Callee) const; + bool supportsException(const Function *F) const { + return EnableEH && (areAllExceptionsAllowed() || + EHAllowlistSet.count(std::string(F->getName()))); + } void rebuildSSA(Function &F); @@ -287,7 +294,7 @@ static bool canThrow(const Value *V) { return false; StringRef Name = F->getName(); // leave setjmp and longjmp (mostly) alone, we process them properly later - if (Name == "setjmp" || Name == "longjmp") + if (Name == "setjmp" || Name == "longjmp" || Name == "emscripten_longjmp") return false; return !F->doesNotThrow(); } @@ -693,7 +700,7 @@ bool WebAssemblyLowerEmscriptenEHSjLj::runOnModule(Module &M) { Function *LongjmpF = M.getFunction("longjmp"); bool SetjmpUsed = SetjmpF && !SetjmpF->use_empty(); bool LongjmpUsed = LongjmpF && !LongjmpF->use_empty(); - bool DoSjLj = EnableSjLj && (SetjmpUsed || LongjmpUsed); + DoSjLj = EnableSjLj && (SetjmpUsed || LongjmpUsed); auto *TPC = getAnalysisIfAvailable(); assert(TPC && "Expected a TargetPassConfig"); @@ -718,7 +725,7 @@ bool WebAssemblyLowerEmscriptenEHSjLj::runOnModule(Module &M) { bool Changed = false; - // Exception handling + // Function registration for exception handling if (EnableEH) { // Register __resumeException function FunctionType *ResumeFTy = @@ -729,26 +736,15 @@ bool WebAssemblyLowerEmscriptenEHSjLj::runOnModule(Module &M) { FunctionType *EHTypeIDTy = FunctionType::get(IRB.getInt32Ty(), IRB.getInt8PtrTy(), false); EHTypeIDF = getEmscriptenFunction(EHTypeIDTy, "llvm_eh_typeid_for", &M); - - for (Function &F : M) { - if (F.isDeclaration()) - continue; - Changed |= runEHOnFunction(F); - } } - // Setjmp/longjmp handling + // Function registration and data pre-gathering for setjmp/longjmp handling if (DoSjLj) { - Changed = true; // We have setjmp or longjmp somewhere - // Register emscripten_longjmp function FunctionType *FTy = FunctionType::get( IRB.getVoidTy(), {getAddrIntType(&M), IRB.getInt32Ty()}, false); EmLongjmpF = getEmscriptenFunction(FTy, "emscripten_longjmp", &M); - if (LongjmpF) - replaceLongjmpWithEmscriptenLongjmp(LongjmpF, EmLongjmpF); - if (SetjmpF) { // Register saveSetjmp function FunctionType *SetjmpFTy = SetjmpF->getFunctionType(); @@ -765,16 +761,33 @@ bool WebAssemblyLowerEmscriptenEHSjLj::runOnModule(Module &M) { false); TestSetjmpF = getEmscriptenFunction(FTy, "testSetjmp", &M); - // Only traverse functions that uses setjmp in order not to insert - // unnecessary prep / cleanup code in every function - SmallPtrSet SetjmpUsers; + // Precompute setjmp users for (User *U : SetjmpF->users()) { auto *UI = cast(U); SetjmpUsers.insert(UI->getFunction()); } + } + } + + // Exception handling transformation + if (EnableEH) { + for (Function &F : M) { + if (F.isDeclaration()) + continue; + Changed |= runEHOnFunction(F); + } + } + + // Setjmp/longjmp handling transformation + if (DoSjLj) { + Changed = true; // We have setjmp or longjmp somewhere + if (LongjmpF) + replaceLongjmpWithEmscriptenLongjmp(LongjmpF, EmLongjmpF); + // Only traverse functions that uses setjmp in order not to insert + // unnecessary prep / cleanup code in every function + if (SetjmpF) for (Function *F : SetjmpUsers) runSjLjOnFunction(*F); - } } if (!Changed) { @@ -802,8 +815,6 @@ bool WebAssemblyLowerEmscriptenEHSjLj::runEHOnFunction(Function &F) { bool Changed = false; SmallVector ToErase; SmallPtrSet LandingPads; - bool AllowExceptions = areAllExceptionsAllowed() || - EHAllowlistSet.count(std::string(F.getName())); for (BasicBlock &BB : F) { auto *II = dyn_cast(BB.getTerminator()); @@ -813,12 +824,51 @@ bool WebAssemblyLowerEmscriptenEHSjLj::runEHOnFunction(Function &F) { LandingPads.insert(II->getLandingPadInst()); IRB.SetInsertPoint(II); - bool NeedInvoke = AllowExceptions && canThrow(II->getCalledOperand()); + const Value *Callee = II->getCalledOperand(); + bool NeedInvoke = supportsException(&F) && canThrow(Callee); if (NeedInvoke) { // Wrap invoke with invoke wrapper and generate preamble/postamble Value *Threw = wrapInvoke(II); ToErase.push_back(II); + // If setjmp/longjmp handling is enabled, the thrown value can be not an + // exception but a longjmp. If the current function contains calls to + // setjmp, it will be appropriately handled in runSjLjOnFunction. But even + // if the function does not contain setjmp calls, we shouldn't silently + // ignore longjmps; we should rethrow them so they can be correctly + // handled in somewhere up the call chain where setjmp is. + // __THREW__'s value is 0 when nothing happened, 1 when an exception is + // thrown, other values when longjmp is thrown. + // + // if (%__THREW__.val == 0 || %__THREW__.val == 1) + // goto %tail + // else + // goto %longjmp.rethrow + // + // longjmp.rethrow: ;; This is longjmp. Rethrow it + // %__threwValue.val = __threwValue + // emscripten_longjmp(%__THREW__.val, %__threwValue.val); + // + // tail: ;; Nothing happened or an exception is thrown + // ... Continue exception handling ... + if (DoSjLj && !SetjmpUsers.count(&F) && canLongjmp(M, Callee)) { + BasicBlock *Tail = BasicBlock::Create(C, "tail", &F); + BasicBlock *RethrowBB = BasicBlock::Create(C, "longjmp.rethrow", &F); + Value *CmpEqOne = + IRB.CreateICmpEQ(Threw, getAddrSizeInt(&M, 1), "cmp.eq.one"); + Value *CmpEqZero = + IRB.CreateICmpEQ(Threw, getAddrSizeInt(&M, 0), "cmp.eq.zero"); + Value *Or = IRB.CreateOr(CmpEqZero, CmpEqOne, "or"); + IRB.CreateCondBr(Or, Tail, RethrowBB); + IRB.SetInsertPoint(RethrowBB); + Value *ThrewValue = IRB.CreateLoad(IRB.getInt32Ty(), ThrewValueGV, + ThrewValueGV->getName() + ".val"); + IRB.CreateCall(EmLongjmpF, {Threw, ThrewValue}); + + IRB.CreateUnreachable(); + IRB.SetInsertPoint(Tail); + } + // Insert a branch based on __THREW__ variable Value *Cmp = IRB.CreateICmpEQ(Threw, getAddrSizeInt(&M, 1), "cmp"); IRB.CreateCondBr(Cmp, II->getUnwindDest(), II->getNormalDest()); @@ -1098,6 +1148,46 @@ bool WebAssemblyLowerEmscriptenEHSjLj::runSjLjOnFunction(Function &F) { Threw = wrapInvoke(CI); ToErase.push_back(CI); Tail = SplitBlock(BB, CI->getNextNode()); + + // If exception handling is enabled, the thrown value can be not a + // longjmp but an exception, in which case we shouldn't silently ignore + // exceptions; we should rethrow them. + // __THREW__'s value is 0 when nothing happened, 1 when an exception is + // thrown, other values when longjmp is thrown. + // + // if (%__THREW__.val == 1) + // goto %eh.rethrow + // else + // goto %normal + // + // eh.rethrow: ;; Rethrow exception + // %exn = call @__cxa_find_matching_catch_2() ;; Retrieve thrown ptr + // __resumeException(%exn) + // + // normal: + // <-- Insertion point. Will insert sjlj handling code from here + // goto %tail + // + // tail: + // ... + if (supportsException(&F) && canThrow(Callee)) { + IRB.SetInsertPoint(CI); + // We will add a new conditional branch. So remove the branch created + // when we split the BB + ToErase.push_back(BB->getTerminator()); + BasicBlock *NormalBB = BasicBlock::Create(C, "normal", &F); + BasicBlock *RethrowBB = BasicBlock::Create(C, "eh.rethrow", &F); + Value *CmpEqOne = + IRB.CreateICmpEQ(Threw, getAddrSizeInt(&M, 1), "cmp.eq.one"); + IRB.CreateCondBr(CmpEqOne, RethrowBB, NormalBB); + IRB.SetInsertPoint(RethrowBB); + CallInst *Exn = IRB.CreateCall(getFindMatchingCatch(M, 0), {}, "exn"); + IRB.CreateCall(ResumeF, {Exn}); + IRB.CreateUnreachable(); + IRB.SetInsertPoint(NormalBB); + IRB.CreateBr(Tail); + BB = NormalBB; // New insertion point to insert testSetjmp() + } } // We need to replace the terminator in Tail - SplitBlock makes BB go diff --git a/llvm/test/CodeGen/WebAssembly/lower-em-ehsjlj.ll b/llvm/test/CodeGen/WebAssembly/lower-em-ehsjlj.ll new file mode 100644 index 000000000000..7de4f2ccfd8e --- /dev/null +++ b/llvm/test/CodeGen/WebAssembly/lower-em-ehsjlj.ll @@ -0,0 +1,132 @@ +; RUN: opt < %s -wasm-lower-em-ehsjlj -S | FileCheck %s +; RUN: llc < %s + +; Tests for cases when exception handling and setjmp/longjmp handling are mixed. + +target datalayout = "e-m:e-p:32:32-i64:64-n32:64-S128" +target triple = "wasm32-unknown-unknown" + +%struct.__jmp_buf_tag = type { [6 x i32], i32, [32 x i32] } + +; There is a function call (@foo) that can either throw an exception or longjmp +; and there is also a setjmp call. When @foo throws, we have to check both for +; exception and longjmp and jump to exception or longjmp handling BB depending +; on the result. +define void @setjmp_longjmp_exception() personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*) { +; CHECK-LABEL: @setjmp_longjmp_exception +entry: + %buf = alloca [1 x %struct.__jmp_buf_tag], align 16 + %arraydecay = getelementptr inbounds [1 x %struct.__jmp_buf_tag], [1 x %struct.__jmp_buf_tag]* %buf, i32 0, i32 0 + %call = call i32 @setjmp(%struct.__jmp_buf_tag* %arraydecay) #0 + invoke void @foo() + to label %try.cont unwind label %lpad + +; CHECK: entry.split: +; CHECK: %[[CMP0:.*]] = icmp ne i32 %__THREW__.val, 0 +; CHECK-NEXT: %__threwValue.val = load i32, i32* @__threwValue +; CHECK-NEXT: %[[CMP1:.*]] = icmp ne i32 %__threwValue.val, 0 +; CHECK-NEXT: %[[CMP:.*]] = and i1 %[[CMP0]], %[[CMP1]] +; CHECK-NEXT: br i1 %[[CMP]], label %if.then1, label %if.else1 + +; This is exception checking part. %if.else1 leads here +; CHECK: entry.split.split: +; CHECK-NEXT: %[[CMP:.*]] = icmp eq i32 %__THREW__.val, 1 +; CHECK-NEXT: br i1 %[[CMP]], label %lpad, label %try.cont + +; longjmp checking part +; CHECK: if.then1: +; CHECK: call i32 @testSetjmp + +lpad: ; preds = %entry + %0 = landingpad { i8*, i32 } + catch i8* null + %1 = extractvalue { i8*, i32 } %0, 0 + %2 = extractvalue { i8*, i32 } %0, 1 + %3 = call i8* @__cxa_begin_catch(i8* %1) #2 + call void @__cxa_end_catch() + br label %try.cont + +try.cont: ; preds = %entry, %lpad + ret void +} + +; @foo can either throw an exception or longjmp. Because this function doesn't +; have any setjmp calls, we only handle exceptions in this function. But because +; sjlj is enabled, we check if the thrown value is longjmp and if so rethrow it +; by calling @emscripten_longjmp. +define void @rethrow_longjmp() personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*) { +; CHECK-LABEL: @rethrow_longjmp +entry: + invoke void @foo() + to label %try.cont unwind label %lpad +; CHECK: entry: +; CHECK: %cmp.eq.one = icmp eq i32 %__THREW__.val, 1 +; CHECK-NEXT: %cmp.eq.zero = icmp eq i32 %__THREW__.val, 0 +; CHECK-NEXT: %or = or i1 %cmp.eq.zero, %cmp.eq.one +; CHECK-NEXT: br i1 %or, label %tail, label %longjmp.rethrow + +; CHECK: tail: +; CHECK-NEXT: %cmp = icmp eq i32 %__THREW__.val, 1 +; CHECK-NEXT: br i1 %cmp, label %lpad, label %try.cont + +; CHECK: longjmp.rethrow: +; CHECK-NEXT: %__threwValue.val = load i32, i32* @__threwValue, align 4 +; CHECK-NEXT: call void @emscripten_longjmp(i32 %__THREW__.val, i32 %__threwValue.val) +; CHECK-NEXT: unreachable + +lpad: ; preds = %entry + %0 = landingpad { i8*, i32 } + catch i8* null + %1 = extractvalue { i8*, i32 } %0, 0 + %2 = extractvalue { i8*, i32 } %0, 1 + %3 = call i8* @__cxa_begin_catch(i8* %1) #5 + call void @__cxa_end_catch() + br label %try.cont + +try.cont: ; preds = %entry, %lpad + ret void +} + +; This function contains a setjmp call and no invoke, so we only handle longjmp +; here. But @foo can also throw an exception, so we check if an exception is +; thrown and if so rethrow it by calling @__resumeException. +define void @rethrow_exception() { +; CHECK-LABEL: @rethrow_exception +entry: + %buf = alloca [1 x %struct.__jmp_buf_tag], align 16 + %arraydecay = getelementptr inbounds [1 x %struct.__jmp_buf_tag], [1 x %struct.__jmp_buf_tag]* %buf, i32 0, i32 0 + %call = call i32 @setjmp(%struct.__jmp_buf_tag* %arraydecay) #0 + %cmp = icmp ne i32 %call, 0 + br i1 %cmp, label %return, label %if.end + +if.end: ; preds = %entry + call void @foo() + br label %return + +; CHECK: if.end: +; CHECK: %cmp.eq.one = icmp eq i32 %__THREW__.val, 1 +; CHECK-NEXT: br i1 %cmp.eq.one, label %eh.rethrow, label %normal + +; CHECK: normal: +; CHECK-NEXT: icmp ne i32 %__THREW__.val, 0 + +; CHECK: eh.rethrow: +; CHECK-NEXT: %exn = call i8* @__cxa_find_matching_catch_2() +; CHECK-NEXT: call void @__resumeException(i8* %exn) +; CHECK-NEXT: unreachable + +return: ; preds = %entry, %if.end + ret void +} + +declare void @foo() +; Function Attrs: returns_twice +declare i32 @setjmp(%struct.__jmp_buf_tag*) +; Function Attrs: noreturn +declare void @longjmp(%struct.__jmp_buf_tag*, i32) +declare i32 @__gxx_personality_v0(...) +declare i8* @__cxa_begin_catch(i8*) +declare void @__cxa_end_catch() + +attributes #0 = { returns_twice } +attributes #1 = { noreturn } diff --git a/llvm/test/CodeGen/WebAssembly/lower-em-sjlj.ll b/llvm/test/CodeGen/WebAssembly/lower-em-sjlj.ll index e918ac6b8031..afac9422fbc9 100644 --- a/llvm/test/CodeGen/WebAssembly/lower-em-sjlj.ll +++ b/llvm/test/CodeGen/WebAssembly/lower-em-sjlj.ll @@ -100,44 +100,6 @@ entry: ; CHECK-NEXT: ret void } -; Test a case when a function call is within try-catch, after a setjmp -define void @exception_and_longjmp() personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*) { -; CHECK-LABEL: @exception_and_longjmp -entry: - %buf = alloca [1 x %struct.__jmp_buf_tag], align 16 - %arraydecay = getelementptr inbounds [1 x %struct.__jmp_buf_tag], [1 x %struct.__jmp_buf_tag]* %buf, i32 0, i32 0 - %call = call i32 @setjmp(%struct.__jmp_buf_tag* %arraydecay) #0 - invoke void @foo() - to label %try.cont unwind label %lpad - -; CHECK: entry.split: -; CHECK: store [[PTR]] 0, [[PTR]]* @__THREW__ -; CHECK-NEXT: call cc{{.*}} void @__invoke_void(void ()* @foo) -; CHECK-NEXT: %[[__THREW__VAL:.*]] = load [[PTR]], [[PTR]]* @__THREW__ -; CHECK-NEXT: store [[PTR]] 0, [[PTR]]* @__THREW__ -; CHECK-NEXT: %[[CMP0:.*]] = icmp ne [[PTR]] %[[__THREW__VAL]], 0 -; CHECK-NEXT: %[[THREWVALUE_VAL:.*]] = load i32, i32* @__threwValue -; CHECK-NEXT: %[[CMP1:.*]] = icmp ne i32 %[[THREWVALUE_VAL]], 0 -; CHECK-NEXT: %[[CMP:.*]] = and i1 %[[CMP0]], %[[CMP1]] -; CHECK-NEXT: br i1 %[[CMP]], label %if.then1, label %if.else1 - -; CHECK: entry.split.split: -; CHECK-NEXT: %[[CMP:.*]] = icmp eq [[PTR]] %[[__THREW__VAL]], 1 -; CHECK-NEXT: br i1 %[[CMP]], label %lpad, label %try.cont - -lpad: ; preds = %entry - %0 = landingpad { i8*, i32 } - catch i8* null - %1 = extractvalue { i8*, i32 } %0, 0 - %2 = extractvalue { i8*, i32 } %0, 1 - %3 = call i8* @__cxa_begin_catch(i8* %1) #2 - call void @__cxa_end_catch() - br label %try.cont - -try.cont: ; preds = %entry, %lpad - ret void -} - ; Test SSA validity define void @ssa(i32 %n) { ; CHECK-LABEL: @ssa @@ -283,7 +245,8 @@ entry: ret void } -declare void @foo() +; Function Attrs: nounwind +declare void @foo() #2 ; Function Attrs: returns_twice declare i32 @setjmp(%struct.__jmp_buf_tag*) #0 ; Function Attrs: noreturn @@ -311,7 +274,7 @@ attributes #3 = { allocsize(0) } ; CHECK-DAG: attributes #{{[0-9]+}} = { "wasm-import-module"="env" "wasm-import-name"="__resumeException" } ; CHECK-DAG: attributes #{{[0-9]+}} = { "wasm-import-module"="env" "wasm-import-name"="llvm_eh_typeid_for" } ; CHECK-DAG: attributes #{{[0-9]+}} = { "wasm-import-module"="env" "wasm-import-name"="__invoke_void" } -; CHECK-DAG: attributes #{{[0-9]+}} = { "wasm-import-module"="env" "wasm-import-name"="__cxa_find_matching_catch_3" } +; CHECK-DAG: attributes #{{[0-9]+}} = { "wasm-import-module"="env" "wasm-import-name"="__cxa_find_matching_catch_2" } ; CHECK-DAG: attributes #{{[0-9]+}} = { "wasm-import-module"="env" "wasm-import-name"="saveSetjmp" } ; CHECK-DAG: attributes #{{[0-9]+}} = { "wasm-import-module"="env" "wasm-import-name"="testSetjmp" } ; CHECK-DAG: attributes #{{[0-9]+}} = { "wasm-import-module"="env" "wasm-import-name"="emscripten_longjmp" }