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[WebAssembly] Stop generating helper functions in WebAssemblyLowerEmscriptenEHSjLj 

Previously we were creating weakly defined helper function in
each translation unit:

-  setThrew
-  setTempRet0

Instead we now assume these will be provided at link time.  In
emscripten they are provided in compiler-rt:
 https://github.com/kripken/emscripten/pull/7203

Additionally we previously created three global variable which are
also now required to exist at link time instead.

- __THREW__
- _threwValue
- __tempRet0

Differential Revision: https://reviews.llvm.org/D49208

llvm-svn: 343640
This commit is contained in:
Sam Clegg 2018-10-02 22:12:15 +00:00
parent e5652fc682
commit b2486f118d
3 changed files with 23 additions and 112 deletions
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102
llvm/lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp
View File

@ -50,7 +50,8 @@
///
/// In detail, this pass does following things:
///
/// 1) Create three global variables: __THREW__, __threwValue, and __tempRet0.
/// 1) Assumes the existence of global variables: __THREW__, __threwValue, and
/// __tempRet0.
/// __tempRet0 will be set within __cxa_find_matching_catch() function in
/// JS library, and __THREW__ and __threwValue will be set in invoke wrappers
/// in JS glue code. For what invoke wrappers are, refer to 3). These
@ -65,9 +66,10 @@
///
/// * Exception handling
///
/// 2) Create setThrew and setTempRet0 functions.
/// The global variables created in 1) will exist in wasm address space,
/// but their values should be set in JS code, so we provide these functions
/// 2) We assume the existence of setThrew and setTempRet0 functions at link
/// time.
/// The global variables in 1) will exist in wasm address space,
/// but their values should be set in JS code, so these functions
/// as interfaces to JS glue code. These functions are equivalent to the
/// following JS functions, which actually exist in asm.js version of JS
/// library.
@ -272,9 +274,6 @@ class WebAssemblyLowerEmscriptenEHSjLj final : public ModulePass {
bool areAllExceptionsAllowed() const { return EHWhitelistSet.empty(); }
bool canLongjmp(Module &M, const Value *Callee) const;
void createSetThrewFunction(Module &M);
void createSetTempRet0Function(Module &M);
void rebuildSSA(Function &F);
public:
@ -333,13 +332,15 @@ static bool canThrow(const Value *V) {
return true;
}
static GlobalVariable *createGlobalVariableI32(Module &M, IRBuilder<> &IRB,
const char *Name) {
// Get a global variable with the given name. If it doesn't exist declare it,
// which will generate an import and asssumes that it will exist at link time.
static GlobalVariable *getGlobalVariableI32(Module &M, IRBuilder<> &IRB,
const char *Name) {
if (M.getNamedGlobal(Name))
report_fatal_error(Twine("variable name is reserved: ") + Name);
return new GlobalVariable(M, IRB.getInt32Ty(), false,
GlobalValue::WeakODRLinkage, IRB.getInt32(0), Name);
GlobalValue::ExternalLinkage, nullptr, Name);
}
// Simple function name mangler.
@ -590,67 +591,6 @@ void WebAssemblyLowerEmscriptenEHSjLj::wrapTestSetjmp(
LongjmpResult = IRB.CreateLoad(TempRet0GV, "longjmp_result");
}
// Create setThrew function
// function setThrew(threw, value) {
// if (__THREW__ == 0) {
// __THREW__ = threw;
// __threwValue = value;
// }
// }
void WebAssemblyLowerEmscriptenEHSjLj::createSetThrewFunction(Module &M) {
LLVMContext &C = M.getContext();
IRBuilder<> IRB(C);
if (M.getNamedGlobal("setThrew"))
report_fatal_error("setThrew already exists");
Type *Params[] = {IRB.getInt32Ty(), IRB.getInt32Ty()};
FunctionType *FTy = FunctionType::get(IRB.getVoidTy(), Params, false);
Function *F =
Function::Create(FTy, GlobalValue::WeakODRLinkage, "setThrew", &M);
Argument *Arg1 = &*(F->arg_begin());
Argument *Arg2 = &*std::next(F->arg_begin());
Arg1->setName("threw");
Arg2->setName("value");
BasicBlock *EntryBB = BasicBlock::Create(C, "entry", F);
BasicBlock *ThenBB = BasicBlock::Create(C, "if.then", F);
BasicBlock *EndBB = BasicBlock::Create(C, "if.end", F);
IRB.SetInsertPoint(EntryBB);
Value *Threw = IRB.CreateLoad(ThrewGV, ThrewGV->getName() + ".val");
Value *Cmp = IRB.CreateICmpEQ(Threw, IRB.getInt32(0), "cmp");
IRB.CreateCondBr(Cmp, ThenBB, EndBB);
IRB.SetInsertPoint(ThenBB);
IRB.CreateStore(Arg1, ThrewGV);
IRB.CreateStore(Arg2, ThrewValueGV);
IRB.CreateBr(EndBB);
IRB.SetInsertPoint(EndBB);
IRB.CreateRetVoid();
}
// Create setTempRet0 function
// function setTempRet0(value) {
// __tempRet0 = value;
// }
void WebAssemblyLowerEmscriptenEHSjLj::createSetTempRet0Function(Module &M) {
LLVMContext &C = M.getContext();
IRBuilder<> IRB(C);
if (M.getNamedGlobal("setTempRet0"))
report_fatal_error("setTempRet0 already exists");
Type *Params[] = {IRB.getInt32Ty()};
FunctionType *FTy = FunctionType::get(IRB.getVoidTy(), Params, false);
Function *F =
Function::Create(FTy, GlobalValue::WeakODRLinkage, "setTempRet0", &M);
F->arg_begin()->setName("value");
BasicBlock *EntryBB = BasicBlock::Create(C, "entry", F);
IRB.SetInsertPoint(EntryBB);
IRB.CreateStore(&*F->arg_begin(), TempRet0GV);
IRB.CreateRetVoid();
}
void WebAssemblyLowerEmscriptenEHSjLj::rebuildSSA(Function &F) {
DominatorTree &DT = getAnalysis<DominatorTreeWrapperPass>(F).getDomTree();
DT.recalculate(F); // CFG has been changed
@ -688,11 +628,12 @@ bool WebAssemblyLowerEmscriptenEHSjLj::runOnModule(Module &M) {
bool LongjmpUsed = LongjmpF && !LongjmpF->use_empty();
bool DoSjLj = EnableSjLj && (SetjmpUsed || LongjmpUsed);
// Create global variables __THREW__, threwValue, and __tempRet0, which are
// used in common for both exception handling and setjmp/longjmp handling
ThrewGV = createGlobalVariableI32(M, IRB, "__THREW__");
ThrewValueGV = createGlobalVariableI32(M, IRB, "__threwValue");
TempRet0GV = createGlobalVariableI32(M, IRB, "__tempRet0");
// Declare (or get) global variables __THREW__, __threwValue, and __tempRet0,
// which are used in common for both exception handling and setjmp/longjmp
// handling
ThrewGV = getGlobalVariableI32(M, IRB, "__THREW__");
ThrewValueGV = getGlobalVariableI32(M, IRB, "__threwValue");
TempRet0GV = getGlobalVariableI32(M, IRB, "__tempRet0");
bool Changed = false;
@ -764,9 +705,6 @@ bool WebAssemblyLowerEmscriptenEHSjLj::runOnModule(Module &M) {
if (!Changed) {
// Delete unused global variables and functions
ThrewGV->eraseFromParent();
ThrewValueGV->eraseFromParent();
TempRet0GV->eraseFromParent();
if (ResumeF)
ResumeF->eraseFromParent();
if (EHTypeIDF)
@ -780,12 +718,6 @@ bool WebAssemblyLowerEmscriptenEHSjLj::runOnModule(Module &M) {
return false;
}
// If we have made any changes while doing exception handling or
// setjmp/longjmp handling, we have to create these functions for JavaScript
// to call.
createSetThrewFunction(M);
createSetTempRet0Function(M);
return true;
}

27
llvm/test/CodeGen/WebAssembly/lower-em-exceptions.ll
View File

@ -5,9 +5,9 @@ target triple = "wasm32-unknown-unknown"
@_ZTIi = external constant i8*
@_ZTIc = external constant i8*
; CHECK-DAG: __THREW__ = weak_odr global i32 0
; CHECK-DAG: __threwValue = weak_odr global i32 0
; CHECK-DAG: __tempRet0 = weak_odr global i32 0
; CHECK-DAG: __THREW__ = external global i32
; CHECK-DAG: __threwValue = external global i32
; CHECK-DAG: __tempRet0 = external global i32
; Test invoke instruction with clauses (try-catch block)
define void @clause() personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*) {
@ -171,24 +171,3 @@ declare void @__cxa_call_unexpected(i8*)
; CHECK-DAG: declare void @__resumeException(i8*)
; CHECK-DAG: declare void @__invoke_void_i32(void (i32)*, i32)
; CHECK-DAG: declare i8* @__cxa_find_matching_catch_4(i8*, i8*)
; setThrew function creation
; CHECK-LABEL: define weak_odr void @setThrew(i32 %threw, i32 %value) {
; CHECK: entry:
; CHECK-NEXT: %__THREW__.val = load i32, i32* @__THREW__
; CHECK-NEXT: %cmp = icmp eq i32 %__THREW__.val, 0
; CHECK-NEXT: br i1 %cmp, label %if.then, label %if.end
; CHECK: if.then:
; CHECK-NEXT: store i32 %threw, i32* @__THREW__
; CHECK-NEXT: store i32 %value, i32* @__threwValue
; CHECK-NEXT: br label %if.end
; CHECK: if.end:
; CHECK-NEXT: ret void
; CHECK: }
; setTempRet0 function creation
; CHECK-LABEL: define weak_odr void @setTempRet0(i32 %value) {
; CHECK: entry:
; CHECK-NEXT: store i32 %value, i32* @__tempRet0
; CHECK-NEXT: ret void
; CHECK: }

6
llvm/test/CodeGen/WebAssembly/lower-em-sjlj.ll
View File

@ -6,9 +6,9 @@ target triple = "wasm32-unknown-unknown"
%struct.__jmp_buf_tag = type { [6 x i32], i32, [32 x i32] }
@global_var = hidden global i32 0, align 4
; CHECK-DAG: __THREW__ = weak_odr global i32 0
; CHECK-DAG: __threwValue = weak_odr global i32 0
; CHECK-DAG: __tempRet0 = weak_odr global i32 0
; CHECK-DAG: __THREW__ = external global i32
; CHECK-DAG: __threwValue = external global i32
; CHECK-DAG: __tempRet0 = external global i32
; Test a simple setjmp - longjmp sequence
define hidden void @setjmp_longjmp() {