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[WebAssembly] Make rethrow take an except_ref type argument 

Summary:
In the new wasm EH proposal, `rethrow` takes an `except_ref` argument.
This change was missing in r352598.

This patch adds `llvm.wasm.rethrow.in.catch` intrinsic. This is an
intrinsic that's gonna eventually be lowered to wasm `rethrow`
instruction, but this intrinsic can appear only within a catchpad or a
cleanuppad scope. Also this intrinsic needs to be invokable - otherwise
EH pad successor for it will not be correctly generated in clang.

This also adds lowering logic for this intrinsic in
`SelectionDAGBuilder::visitInvoke`. This routine is basically a
specialized and simplified version of
`SelectionDAGBuilder::visitTargetIntrinsic`, but we can't use it
because if is only for `CallInst`s.

This deletes the previous `llvm.wasm.rethrow` intrinsic and related
tests, which was meant to be used within a `__cxa_rethrow` library
function. Turned out this needs some more logic, so the intrinsic for
this purpose will be added later.

LateEHPrepare takes a result value of `catch` and inserts it into
matching `rethrow` as an argument.

`RETHROW_IN_CATCH` is a pseudo instruction that serves as a link between
`llvm.wasm.rethrow.in.catch` and the real wasm `rethrow` instruction. To
generate a `rethrow` instruction, we need an `except_ref` argument,
which is generated from `catch` instruction. But `catch` instrutions are
added in LateEHPrepare pass, so we use `RETHROW_IN_CATCH`, which takes
no argument, until we are able to correctly lower it to `rethrow` in
LateEHPrepare.

Reviewers: dschuff

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

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D59352

llvm-svn: 356316
This commit is contained in:
Heejin Ahn 2019-03-16 05:38:57 +00:00
parent b47a18cd4b
commit 66ce419468
9 changed files with 85 additions and 102 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
llvm/include/llvm/IR/IntrinsicsWebAssembly.td
View File

@ -41,7 +41,7 @@ def int_wasm_trunc_saturate_unsigned : Intrinsic<[llvm_anyint_ty],
// throw / rethrow
def int_wasm_throw : Intrinsic<[], [llvm_i32_ty, llvm_ptr_ty],
[Throws, IntrNoReturn]>;
def int_wasm_rethrow : Intrinsic<[], [], [Throws, IntrNoReturn]>;
def int_wasm_rethrow_in_catch : Intrinsic<[], [], [Throws, IntrNoReturn]>;
// Since wasm does not use landingpad instructions, these instructions return
// exception pointer and selector values until we lower them in WasmEHPrepare.

14
llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
View File

@ -2697,6 +2697,20 @@ void SelectionDAGBuilder::visitInvoke(const InvokeInst &I) {
case Intrinsic::experimental_gc_statepoint:
LowerStatepoint(ImmutableStatepoint(&I), EHPadBB);
break;
case Intrinsic::wasm_rethrow_in_catch: {
// This is usually done in visitTargetIntrinsic, but this intrinsic is
// special because it can be invoked, so we manually lower it to a DAG
// node here.
SmallVector<SDValue, 8> Ops;
Ops.push_back(getRoot()); // inchain
const TargetLowering &TLI = DAG.getTargetLoweringInfo();
Ops.push_back(
DAG.getTargetConstant(Intrinsic::wasm_rethrow_in_catch, getCurSDLoc(),
TLI.getPointerTy(DAG.getDataLayout())));
SDVTList VTs = DAG.getVTList(ArrayRef<EVT>({MVT::Other})); // outchain
DAG.setRoot(DAG.getNode(ISD::INTRINSIC_VOID, getCurSDLoc(), VTs, Ops));
break;
}
}
} else if (I.countOperandBundlesOfType(LLVMContext::OB_deopt)) {
// Currently we do not lower any intrinsic calls with deopt operand bundles.

55
llvm/lib/CodeGen/WasmEHPrepare.cpp
View File

@ -104,15 +104,14 @@ class WasmEHPrepare : public FunctionPass {
Value *LSDAField = nullptr; // lsda field
Value *SelectorField = nullptr; // selector
Function *ThrowF = nullptr; // wasm.throw() intrinsic
Function *RethrowF = nullptr; // wasm.rethrow() intrinsic
Function *LPadIndexF = nullptr; // wasm.landingpad.index() intrinsic
Function *LSDAF = nullptr; // wasm.lsda() intrinsic
Function *GetExnF = nullptr; // wasm.get.exception() intrinsic
Function *ExtractExnF = nullptr; // wasm.extract.exception() intrinsic
Function *GetSelectorF = nullptr; // wasm.get.ehselector() intrinsic
Function *ThrowF = nullptr; // wasm.throw() intrinsic
Function *LPadIndexF = nullptr; // wasm.landingpad.index() intrinsic
Function *LSDAF = nullptr; // wasm.lsda() intrinsic
Function *GetExnF = nullptr; // wasm.get.exception() intrinsic
Function *ExtractExnF = nullptr; // wasm.extract.exception() intrinsic
Function *GetSelectorF = nullptr; // wasm.get.ehselector() intrinsic
FunctionCallee CallPersonalityF =
nullptr; // _Unwind_CallPersonality() wrapper
nullptr; // _Unwind_CallPersonality() wrapper
bool prepareEHPads(Function &F);
bool prepareThrows(Function &F);
@ -177,29 +176,23 @@ bool WasmEHPrepare::prepareThrows(Function &F) {
// wasm.throw() intinsic, which will be lowered to wasm 'throw' instruction.
ThrowF = Intrinsic::getDeclaration(&M, Intrinsic::wasm_throw);
// wasm.rethrow() intinsic, which will be lowered to wasm 'rethrow'
// instruction.
RethrowF = Intrinsic::getDeclaration(&M, Intrinsic::wasm_rethrow);
// Insert an unreachable instruction after a call to @llvm.wasm.throw /
// @llvm.wasm.rethrow and delete all following instructions within the BB, and
// delete all the dead children of the BB as well.
for (auto L : {ThrowF->users(), RethrowF->users()}) {
for (User *U : L) {
// A call to @llvm.wasm.throw() is only generated from __cxa_throw()
// builtin call within libcxxabi, and cannot be an InvokeInst.
auto *ThrowI = cast<CallInst>(U);
if (ThrowI->getFunction() != &F)
continue;
Changed = true;
auto *BB = ThrowI->getParent();
SmallVector<BasicBlock *, 4> Succs(succ_begin(BB), succ_end(BB));
auto &InstList = BB->getInstList();
InstList.erase(std::next(BasicBlock::iterator(ThrowI)), InstList.end());
IRB.SetInsertPoint(BB);
IRB.CreateUnreachable();
eraseDeadBBsAndChildren(Succs);
}
// Insert an unreachable instruction after a call to @llvm.wasm.throw and
// delete all following instructions within the BB, and delete all the dead
// children of the BB as well.
for (User *U : ThrowF->users()) {
// A call to @llvm.wasm.throw() is only generated from __cxa_throw()
// builtin call within libcxxabi, and cannot be an InvokeInst.
auto *ThrowI = cast<CallInst>(U);
if (ThrowI->getFunction() != &F)
continue;
Changed = true;
auto *BB = ThrowI->getParent();
SmallVector<BasicBlock *, 4> Succs(succ_begin(BB), succ_end(BB));
auto &InstList = BB->getInstList();
InstList.erase(std::next(BasicBlock::iterator(ThrowI)), InstList.end());
IRB.SetInsertPoint(BB);
IRB.CreateUnreachable();
eraseDeadBBsAndChildren(Succs);
}
return Changed;

3
llvm/lib/IR/Verifier.cpp
View File

@ -4026,7 +4026,8 @@ void Verifier::visitInstruction(Instruction &I) {
F->getIntrinsicID() == Intrinsic::coro_destroy ||
F->getIntrinsicID() == Intrinsic::experimental_patchpoint_void ||
F->getIntrinsicID() == Intrinsic::experimental_patchpoint_i64 ||
F->getIntrinsicID() == Intrinsic::experimental_gc_statepoint,
F->getIntrinsicID() == Intrinsic::experimental_gc_statepoint ||
F->getIntrinsicID() == Intrinsic::wasm_rethrow_in_catch,
"Cannot invoke an intrinsic other than donothing, patchpoint, "
"statepoint, coro_resume or coro_destroy",
&I);

8
llvm/lib/Target/WebAssembly/WebAssemblyInstrControl.td
View File

@ -144,7 +144,13 @@ defm THROW : I<(outs), (ins event_op:$tag, variable_ops),
(outs), (ins event_op:$tag),
[(WebAssemblythrow (WebAssemblywrapper texternalsym:$tag))],
"throw \t$tag", "throw \t$tag", 0x08>;
defm RETHROW : NRI<(outs), (ins), [(int_wasm_rethrow)], "rethrow", 0x09>;
defm RETHROW : I<(outs), (ins EXCEPT_REF:$exn), (outs), (ins),
[], "rethrow \t$exn", "rethrow", 0x09>;
// Pseudo instruction to be the lowering target of int_wasm_rethrow_in_catch
// intrinsic. Will be converted to the real rethrow instruction later.
let isPseudo = 1 in
defm RETHROW_IN_CATCH : NRI<(outs), (ins), [(int_wasm_rethrow_in_catch)],
"rethrow_in_catch", 0>;
} // isTerminator = 1, hasCtrlDep = 1, isBarrier = 1
// Region within which an exception is caught: try / end_try

19
llvm/lib/Target/WebAssembly/WebAssemblyLateEHPrepare.cpp
View File

@ -161,9 +161,17 @@ bool WebAssemblyLateEHPrepare::replaceFuncletReturns(MachineFunction &MF) {
Changed = true;
break;
}
case WebAssembly::CLEANUPRET: {
// Replace a cleanupret with a rethrow
BuildMI(MBB, TI, TI->getDebugLoc(), TII.get(WebAssembly::RETHROW));
case WebAssembly::CLEANUPRET:
case WebAssembly::RETHROW_IN_CATCH: {
// Replace a cleanupret/rethrow_in_catch with a rethrow
auto *EHPad = getMatchingEHPad(TI);
auto CatchPos = EHPad->begin();
if (CatchPos->isEHLabel()) // EH pad starts with an EH label
++CatchPos;
MachineInstr *Catch = &*CatchPos;
unsigned ExnReg = Catch->getOperand(0).getReg();
BuildMI(MBB, TI, TI->getDebugLoc(), TII.get(WebAssembly::RETHROW))
.addReg(ExnReg);
TI->eraseFromParent();
Changed = true;
break;
@ -191,7 +199,8 @@ bool WebAssemblyLateEHPrepare::removeUnnecessaryUnreachables(
SmallVector<MachineBasicBlock *, 8> Succs(MBB.succ_begin(),
MBB.succ_end());
for (auto *Succ : Succs)
MBB.removeSuccessor(Succ);
if (!Succ->isEHPad())
MBB.removeSuccessor(Succ);
eraseDeadBBsAndChildren(Succs);
}
}
@ -337,7 +346,7 @@ bool WebAssemblyLateEHPrepare::addExceptionExtraction(MachineFunction &MF) {
BuildMI(ElseMBB, DL, TII.get(WebAssembly::UNREACHABLE));
} else {
BuildMI(ElseMBB, DL, TII.get(WebAssembly::RETHROW));
BuildMI(ElseMBB, DL, TII.get(WebAssembly::RETHROW)).addReg(ExnReg);
if (EHInfo->hasEHPadUnwindDest(EHPad))
ElseMBB->addSuccessor(EHInfo->getEHPadUnwindDest(EHPad));
}

22
llvm/test/CodeGen/WebAssembly/cfg-stackify-eh.ll
View File

@ -33,7 +33,7 @@ target triple = "wasm32-unknown-unknown"
; CHECK: call __cxa_end_catch
; CHECK: br 1 # 1: down to label0
; CHECK: end_block # label3:
; CHECK: call __cxa_rethrow
; CHECK: rethrow {{.*}} # to caller
; CHECK: end_try # label0:
define void @test0() personality i8* bitcast (i32 (...)* @__gxx_wasm_personality_v0 to i8*) {
entry:
@ -67,7 +67,7 @@ catch: ; preds = %catch.fallthrough
catchret from %1 to label %try.cont
rethrow: ; preds = %catch.fallthrough
call void @__cxa_rethrow() [ "funclet"(token %1) ]
call void @llvm.wasm.rethrow.in.catch() [ "funclet"(token %1) ]
unreachable
try.cont: ; preds = %entry, %catch, %catch2
@ -108,21 +108,19 @@ try.cont: ; preds = %entry, %catch, %cat
; CHECK: br 2 # 2: down to label9
; CHECK: catch
; CHECK: call __cxa_end_catch
; CHECK: rethrow # down to catch3
; CHECK: rethrow {{.*}} # down to catch3
; CHECK: end_try
; CHECK: end_block # label11:
; CHECK: call __cxa_rethrow
; CHECK: unreachable
; CHECK: rethrow {{.*}} # down to catch3
; CHECK: catch {{.*}} # catch3:
; CHECK: call __cxa_end_catch
; CHECK: rethrow # to caller
; CHECK: rethrow {{.*}} # to caller
; CHECK: end_try # label9:
; CHECK: call __cxa_end_catch
; CHECK: br 2 # 2: down to label6
; CHECK: end_try
; CHECK: end_block # label7:
; CHECK: call __cxa_rethrow
; CHECK: unreachable
; CHECK: rethrow {{.*}} # to caller
; CHECK: end_block # label6:
; CHECK: call __cxa_end_catch
; CHECK: end_try
@ -172,7 +170,7 @@ invoke.cont8: ; preds = %catch6
catchret from %9 to label %try.cont
rethrow5: ; preds = %catch.start3
invoke void @__cxa_rethrow() [ "funclet"(token %9) ]
invoke void @llvm.wasm.rethrow.in.catch() [ "funclet"(token %9) ]
to label %unreachable unwind label %ehcleanup9
try.cont: ; preds = %catch, %invoke.cont8
@ -180,7 +178,7 @@ try.cont: ; preds = %catch, %invoke.cont
catchret from %1 to label %try.cont11
rethrow: ; preds = %catch.start
call void @__cxa_rethrow() [ "funclet"(token %1) ]
call void @llvm.wasm.rethrow.in.catch() [ "funclet"(token %1) ]
unreachable
try.cont11: ; preds = %entry, %try.cont
@ -229,7 +227,7 @@ unreachable: ; preds = %rethrow5
; CHECK: call __clang_call_terminate
; CHECK: unreachable
; CHECK: end_try
; CHECK: rethrow # to caller
; CHECK: rethrow {{.*}} # to caller
; CHECK: end_try
; CHECK: end_block # label17:
; CHECK: call __cxa_end_catch
@ -293,9 +291,9 @@ declare void @bar()
declare i32 @__gxx_wasm_personality_v0(...)
declare i8* @llvm.wasm.get.exception(token)
declare i32 @llvm.wasm.get.ehselector(token)
declare void @llvm.wasm.rethrow.in.catch()
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*)
declare void @_ZSt9terminatev()

25
llvm/test/CodeGen/WebAssembly/exception.ll
View File

@ -17,14 +17,6 @@ define void @test_throw(i8* %p) {
ret void
}
; CHECK-LABEL: test_rethrow:
; CHECK: rethrow
; CHECK-NOT: unreachable
define void @test_rethrow(i8* %p) {
call void @llvm.wasm.rethrow()
ret void
}
; Simple test with a try-catch
;
; void foo();
@ -43,7 +35,7 @@ define void @test_rethrow(i8* %p) {
; CHECK: global.set __stack_pointer
; CHECK: block i32
; CHECK: br_on_exn 0, __cpp_exception, $[[EXCEPT_REF]]
; CHECK: rethrow
; CHECK: rethrow $[[EXCEPT_REF]]
; CHECK: end_block
; CHECK: extract_exception $[[EXN:[0-9]+]]=
; CHECK-DAG: i32.store __wasm_lpad_context
@ -55,7 +47,7 @@ define void @test_rethrow(i8* %p) {
; CHECK: call __cxa_end_catch
; CHECK: br 1
; CHECK: end_block
; CHECK: call __cxa_rethrow
; CHECK: rethrow $[[EXCEPT_REF]]
; CHECK: end_try
define void @test_catch() personality i8* bitcast (i32 (...)* @__gxx_wasm_personality_v0 to i8*) {
entry:
@ -79,7 +71,7 @@ catch: ; preds = %catch.start
catchret from %1 to label %try.cont
rethrow: ; preds = %catch.start
call void @__cxa_rethrow() [ "funclet"(token %1) ]
call void @llvm.wasm.rethrow.in.catch() [ "funclet"(token %1) ]
unreachable
try.cont: ; preds = %entry, %catch
@ -100,10 +92,10 @@ try.cont: ; preds = %entry, %catch
; CHECK-LABEL: test_cleanup:
; CHECK: try
; CHECK: call foo
; CHECK: catch
; CHECK: catch $[[EXCEPT_REF:[0-9]+]]=
; CHECK: global.set __stack_pointer
; CHECK: i32.call $drop=, _ZN4TempD2Ev
; CHECK: rethrow
; CHECK: rethrow $[[EXCEPT_REF]]
; CHECK: end_try
define void @test_cleanup() personality i8* bitcast (i32 (...)* @__gxx_wasm_personality_v0 to i8*) {
entry:
@ -231,7 +223,7 @@ terminate: ; preds = %ehcleanup
; CHECK-NOT: global.set __stack_pointer, $pop{{.+}}
; CHECK: end_try
; CHECK: end_block
; CHECK: call __cxa_rethrow
; CHECK: rethrow
; CHECK: end_block
; CHECK-NOT: global.set __stack_pointer, $pop{{.+}}
; CHECK: call __cxa_end_catch
@ -266,7 +258,7 @@ invoke.cont1: ; preds = %catch
catchret from %1 to label %try.cont
rethrow: ; preds = %catch.start
call void @__cxa_rethrow() [ "funclet"(token %1) ]
call void @llvm.wasm.rethrow.in.catch() [ "funclet"(token %1) ]
unreachable
try.cont: ; preds = %entry, %invoke.cont1
@ -342,13 +334,12 @@ declare void @foo()
declare void @bar(i32*)
declare i32 @__gxx_wasm_personality_v0(...)
declare void @llvm.wasm.throw(i32, i8*)
declare void @llvm.wasm.rethrow()
declare i8* @llvm.wasm.get.exception(token)
declare i32 @llvm.wasm.get.ehselector(token)
declare void @llvm.wasm.rethrow.in.catch()
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*)
declare %struct.Temp* @_ZN4TempD2Ev(%struct.Temp* returned)

39
llvm/test/CodeGen/WebAssembly/wasmehprepare.ll
View File

@ -54,7 +54,7 @@ catch: ; preds = %catch.start
; CHECK-NEXT: call i8* @__cxa_begin_catch(i8* %[[EXN]])
rethrow: ; preds = %catch.start
call void @__cxa_rethrow() [ "funclet"(token %1) ]
call void @llvm.wasm.rethrow.in.catch() [ "funclet"(token %1) ]
unreachable
try.cont: ; preds = %entry, %catch
@ -125,7 +125,7 @@ catch4: ; preds = %catch.start3
catchret from %6 to label %try.cont7
rethrow: ; preds = %catch.start3
call void @__cxa_rethrow() [ "funclet"(token %6) ]
call void @llvm.wasm.rethrow.in.catch() [ "funclet"(token %6) ]
unreachable
try.cont7: ; preds = %try.cont, %catch4
@ -189,7 +189,7 @@ catch6: ; preds = %catch.start3
catchret from %7 to label %try.cont
rethrow5: ; preds = %catch.start3
invoke void @__cxa_rethrow() [ "funclet"(token %7) ]
invoke void @llvm.wasm.rethrow.in.catch() [ "funclet"(token %7) ]
to label %unreachable unwind label %ehcleanup
try.cont: ; preds = %catch, %catch6
@ -197,7 +197,7 @@ try.cont: ; preds = %catch, %catch6
catchret from %1 to label %try.cont9
rethrow: ; preds = %catch.start
call void @__cxa_rethrow() [ "funclet"(token %1) ]
call void @llvm.wasm.rethrow.in.catch() [ "funclet"(token %1) ]
unreachable
try.cont9: ; preds = %entry, %try.cont
@ -392,34 +392,6 @@ merge: ; preds = %bb.true.0, %bb.fals
ret i32 0
}
; Tests if instructions after a call to @llvm.wasm.rethrow are deleted and the
; BB's dead children are deleted.
; CHECK-LABEL: @test6
define i32 @test6(i1 %b, i8* %p) {
entry:
br i1 %b, label %bb.true, label %bb.false
; CHECK: bb.true:
; CHECK-NEXT: call void @llvm.wasm.rethrow()
; CHECK-NEXT: unreachable
bb.true: ; preds = %entry
call void @llvm.wasm.rethrow()
br label %bb.true.0
; CHECK-NOT: bb.true.0
bb.true.0: ; preds = %bb.true
br label %merge
; CHECK: bb.false
bb.false: ; preds = %entry
br label %merge
; CHECK: merge
merge: ; preds = %bb.true.0, %bb.false
ret i32 0
}
declare void @foo()
declare void @bar(i32)
declare %struct.Temp* @_ZN4TempD2Ev(%struct.Temp* returned)
@ -428,10 +400,9 @@ declare i8* @llvm.wasm.get.exception(token)
declare i32 @llvm.wasm.get.ehselector(token)
declare i32 @llvm.eh.typeid.for(i8*)
declare void @llvm.wasm.throw(i32, i8*)
declare void @llvm.wasm.rethrow()
declare void @llvm.wasm.rethrow.in.catch()
declare i8* @__cxa_begin_catch(i8*)
declare void @__cxa_end_catch()
declare void @__cxa_rethrow()
declare void @__clang_call_terminate(i8*)
; CHECK-DAG: declare void @llvm.wasm.landingpad.index(token, i32)