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[WebAssembly] Fix the order of destructors in the LowerGlobalDtors pass.
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Fix the LowerGlobalDtors pass to run destructors in the same order as the
regular LLVM destructor lowering -- in reverse order. Adjacent
destructors with the same associated object are grouped, but destructors
are not reordered based on associated objects.

Differential Revision: https://reviews.llvm.org/D70685
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@sunfishcode
sunfishcode committed Mar 26, 2020
1 parent 5db37f3 commit d865437
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Showing 2 changed files with 115 additions and 35 deletions.
30 changes: 24 additions & 6 deletions llvm/lib/Target/WebAssembly/WebAssemblyLowerGlobalDtors.cpp
View file
Expand Up @@ -76,9 +76,13 @@ bool LowerGlobalDtors::runOnModule(Module &M) {
!ETy->getTypeAtIndex(2U)->isPointerTy())
return false; // Not (int, ptr, ptr).

// Collect the contents of @llvm.global_dtors, collated by priority and
// associated symbol.
std::map<uint16_t, MapVector<Constant *, std::vector<Constant *>>> DtorFuncs;
// Collect the contents of @llvm.global_dtors, ordered by priority. Within a
// priority, sequences of destructors with the same associated object are
// recorded so that we can register them as a group.
std::map<
uint16_t,
std::vector<std::pair<Constant *, std::vector<Constant *>>>
> DtorFuncs;
for (Value *O : InitList->operands()) {
auto *CS = dyn_cast<ConstantStruct>(O);
if (!CS)
Expand All @@ -96,7 +100,14 @@ bool LowerGlobalDtors::runOnModule(Module &M) {
Constant *Associated = CS->getOperand(2);
Associated = cast<Constant>(Associated->stripPointerCasts());

DtorFuncs[PriorityValue][Associated].push_back(DtorFunc);
auto &AtThisPriority = DtorFuncs[PriorityValue];
if (AtThisPriority.empty() || AtThisPriority.back().first != Associated) {
std::vector<Constant *> NewList;
NewList.push_back(DtorFunc);
AtThisPriority.push_back(std::make_pair(Associated, NewList));
} else {
AtThisPriority.back().second.push_back(DtorFunc);
}
}
if (DtorFuncs.empty())
return false;
Expand Down Expand Up @@ -131,22 +142,27 @@ bool LowerGlobalDtors::runOnModule(Module &M) {
// first function with __cxa_atexit.
for (auto &PriorityAndMore : DtorFuncs) {
uint16_t Priority = PriorityAndMore.first;
for (auto &AssociatedAndMore : PriorityAndMore.second) {
uint64_t Id = 0;
auto &AtThisPriority = PriorityAndMore.second;
for (auto &AssociatedAndMore : AtThisPriority) {
Constant *Associated = AssociatedAndMore.first;
auto ThisId = Id++;

Function *CallDtors = Function::Create(
AtExitFuncTy, Function::PrivateLinkage,
"call_dtors" +
(Priority != UINT16_MAX ? (Twine(".") + Twine(Priority))
: Twine()) +
(AtThisPriority.size() > 1 ? Twine("$") + Twine(ThisId)
: Twine()) +
(!Associated->isNullValue() ? (Twine(".") + Associated->getName())
: Twine()),
&M);
BasicBlock *BB = BasicBlock::Create(C, "body", CallDtors);
FunctionType *VoidVoid = FunctionType::get(Type::getVoidTy(C),
/*isVarArg=*/false);

for (auto Dtor : AssociatedAndMore.second)
for (auto Dtor : reverse(AssociatedAndMore.second))
CallInst::Create(VoidVoid, Dtor, "", BB);
ReturnInst::Create(C, BB);

Expand All @@ -155,6 +171,8 @@ bool LowerGlobalDtors::runOnModule(Module &M) {
"register_call_dtors" +
(Priority != UINT16_MAX ? (Twine(".") + Twine(Priority))
: Twine()) +
(AtThisPriority.size() > 1 ? Twine("$") + Twine(ThisId)
: Twine()) +
(!Associated->isNullValue() ? (Twine(".") + Associated->getName())
: Twine()),
&M);
Expand Down
120 changes: 91 additions & 29 deletions llvm/test/CodeGen/WebAssembly/lower-global-dtors.ll
View file
Expand Up @@ -13,11 +13,18 @@ declare void @orig_dtor1b()
declare void @orig_dtor1c0()
declare void @orig_dtor1c1a()
declare void @orig_dtor1c1b()
declare void @orig_dtor65536()
declare void @orig_dtor1c2a()
declare void @orig_dtor1c2b()
declare void @orig_dtor1c3()
declare void @orig_dtor1d()
declare void @orig_dtor65535()
declare void @orig_dtor65535c0()
declare void @after_the_null()

@associated1c0 = external global i8
@associated1c1 = external global i8
@associatedc0 = external global i8
@associatedc1 = external global i8
@associatedc2 = global i8 42
@associatedc3 = global i8 84

@llvm.global_ctors = appending global
[1 x { i32, void ()*, i8* }]
Expand All @@ -26,15 +33,20 @@ declare void @after_the_null()
]

@llvm.global_dtors = appending global
[9 x { i32, void ()*, i8* }]
[14 x { i32, void ()*, i8* }]
[
{ i32, void ()*, i8* } { i32 0, void ()* @orig_dtor0, i8* null },
{ i32, void ()*, i8* } { i32 1, void ()* @orig_dtor1a, i8* null },
{ i32, void ()*, i8* } { i32 1, void ()* @orig_dtor1b, i8* null },
{ i32, void ()*, i8* } { i32 1, void ()* @orig_dtor1c0, i8* @associated1c0 },
{ i32, void ()*, i8* } { i32 1, void ()* @orig_dtor1c1a, i8* @associated1c1 },
{ i32, void ()*, i8* } { i32 1, void ()* @orig_dtor1c1b, i8* @associated1c1 },
{ i32, void ()*, i8* } { i32 65535, void ()* @orig_dtor65536, i8* null },
{ i32, void ()*, i8* } { i32 1, void ()* @orig_dtor1c0, i8* @associatedc0 },
{ i32, void ()*, i8* } { i32 1, void ()* @orig_dtor1c1a, i8* @associatedc1 },
{ i32, void ()*, i8* } { i32 1, void ()* @orig_dtor1c1b, i8* @associatedc1 },
{ i32, void ()*, i8* } { i32 1, void ()* @orig_dtor1c2a, i8* @associatedc2 },
{ i32, void ()*, i8* } { i32 1, void ()* @orig_dtor1c2b, i8* @associatedc2 },
{ i32, void ()*, i8* } { i32 1, void ()* @orig_dtor1c3, i8* @associatedc3 },
{ i32, void ()*, i8* } { i32 1, void ()* @orig_dtor1d, i8* null },
{ i32, void ()*, i8* } { i32 65535, void ()* @orig_dtor65535c0, i8* @associatedc0 },
{ i32, void ()*, i8* } { i32 65535, void ()* @orig_dtor65535, i8* null },
{ i32, void ()*, i8* } { i32 65535, void ()* null, i8* null },
{ i32, void ()*, i8* } { i32 65535, void ()* @after_the_null, i8* null }
]
Expand All @@ -54,14 +66,14 @@ declare void @after_the_null()
; CHECK-NEXT: unreachable
; CHECK: end_block

; CHECK-LABEL: .Lcall_dtors.1:
; CHECK-NEXT: .functype .Lcall_dtors.1 (i32) -> (){{$}}
; CHECK-NEXT: call orig_dtor1a{{$}}
; CHECK-LABEL: .Lcall_dtors.1$0:
; CHECK-NEXT: .functype .Lcall_dtors.1$0 (i32) -> (){{$}}
; CHECK-NEXT: call orig_dtor1b{{$}}
; CHECK-NEXT: call orig_dtor1a{{$}}

; CHECK-LABEL: .Lregister_call_dtors.1:
; CHECK-LABEL: .Lregister_call_dtors.1$0:
; CHECK: block
; CHECK-NEXT: i32.const $push2=, .Lcall_dtors.1{{$}}
; CHECK-NEXT: i32.const $push2=, .Lcall_dtors.1$0{{$}}
; CHECK-NEXT: i32.const $push1=, 0
; CHECK-NEXT: i32.const $push0=, __dso_handle
; CHECK-NEXT: call $push3=, __cxa_atexit, $pop2, $pop1, $pop0{{$}}
Expand All @@ -70,42 +82,89 @@ declare void @after_the_null()
; CHECK-NEXT: unreachable
; CHECK: end_block

; CHECK-LABEL: .Lcall_dtors.1.associated1c0:
; CHECK-NEXT: .functype .Lcall_dtors.1.associated1c0 (i32) -> (){{$}}
; CHECK-LABEL: .Lcall_dtors.1$1.associatedc0:
; CHECK-NEXT: .functype .Lcall_dtors.1$1.associatedc0 (i32) -> (){{$}}
; CHECK-NEXT: call orig_dtor1c0{{$}}

; CHECK-LABEL: .Lregister_call_dtors.1.associated1c0:
; CHECK-LABEL: .Lregister_call_dtors.1$1.associatedc0:
; CHECK: block
; CHECK-NEXT: i32.const $push2=, .Lcall_dtors.1.associated1c0{{$}}
; CHECK-NEXT: i32.const $push2=, .Lcall_dtors.1$1.associatedc0{{$}}
; CHECK-NEXT: i32.const $push1=, 0
; CHECK-NEXT: i32.const $push0=, __dso_handle
; CHECK-NEXT: call $push3=, __cxa_atexit, $pop2, $pop1, $pop0{{$}}
; CHECK-NEXT: i32.eqz $push4=, $pop3
; CHECK-NEXT: br_if 0, $pop4
; CHECK-NEXT: unreachable

; CHECK-LABEL: .Lcall_dtors.1.associated1c1:
; CHECK-NEXT: .functype .Lcall_dtors.1.associated1c1 (i32) -> (){{$}}
; CHECK-NEXT: call orig_dtor1c1a{{$}}
; CHECK-LABEL: .Lcall_dtors.1$2.associatedc1:
; CHECK-NEXT: .functype .Lcall_dtors.1$2.associatedc1 (i32) -> (){{$}}
; CHECK-NEXT: call orig_dtor1c1b{{$}}
; CHECK-NEXT: call orig_dtor1c1a{{$}}

; CHECK-LABEL: .Lregister_call_dtors.1$2.associatedc1:
; CHECK: block
; CHECK-NEXT: i32.const $push2=, .Lcall_dtors.1$2.associatedc1{{$}}
; CHECK-NEXT: i32.const $push1=, 0
; CHECK-NEXT: i32.const $push0=, __dso_handle
; CHECK-NEXT: call $push3=, __cxa_atexit, $pop2, $pop1, $pop0{{$}}
; CHECK-NEXT: i32.eqz $push4=, $pop3
; CHECK-NEXT: br_if 0, $pop4
; CHECK-NEXT: unreachable

; CHECK-LABEL: .Lcall_dtors.1$3.associatedc2:
; CHECK-NEXT: .functype .Lcall_dtors.1$3.associatedc2 (i32) -> (){{$}}
; CHECK-NEXT: call orig_dtor1c2b{{$}}
; CHECK-NEXT: call orig_dtor1c2a{{$}}

; CHECK-LABEL: .Lregister_call_dtors.1$3.associatedc2:
; CHECK: block
; CHECK-NEXT: i32.const $push2=, .Lcall_dtors.1$3.associatedc2{{$}}
; CHECK-NEXT: i32.const $push1=, 0
; CHECK-NEXT: i32.const $push0=, __dso_handle
; CHECK-NEXT: call $push3=, __cxa_atexit, $pop2, $pop1, $pop0{{$}}
; CHECK-NEXT: i32.eqz $push4=, $pop3
; CHECK-NEXT: br_if 0, $pop4
; CHECK-NEXT: unreachable

; CHECK-LABEL: .Lcall_dtors.1$4.associatedc3:
; CHECK-NEXT: .functype .Lcall_dtors.1$4.associatedc3 (i32) -> (){{$}}
; CHECK-NEXT: call orig_dtor1c3{{$}}

; CHECK-LABEL: .Lregister_call_dtors.1$4.associatedc3:
; CHECK: block
; CHECK-NEXT: i32.const $push2=, .Lcall_dtors.1$4.associatedc3{{$}}
; CHECK-NEXT: i32.const $push1=, 0
; CHECK-NEXT: i32.const $push0=, __dso_handle
; CHECK-NEXT: call $push3=, __cxa_atexit, $pop2, $pop1, $pop0{{$}}
; CHECK-NEXT: i32.eqz $push4=, $pop3
; CHECK-NEXT: br_if 0, $pop4
; CHECK-NEXT: unreachable

; CHECK-LABEL: .Lregister_call_dtors.1.associated1c1:
; CHECK-LABEL: .Lcall_dtors.1$5:
; CHECK-NEXT: .functype .Lcall_dtors.1$5 (i32) -> (){{$}}
; CHECK-NEXT: call orig_dtor1d{{$}}

; CHECK-LABEL: .Lregister_call_dtors.1$5:
; CHECK: block
; CHECK-NEXT: i32.const $push2=, .Lcall_dtors.1.associated1c1{{$}}
; CHECK-NEXT: i32.const $push2=, .Lcall_dtors.1$5{{$}}
; CHECK-NEXT: i32.const $push1=, 0
; CHECK-NEXT: i32.const $push0=, __dso_handle
; CHECK-NEXT: call $push3=, __cxa_atexit, $pop2, $pop1, $pop0{{$}}
; CHECK-NEXT: i32.eqz $push4=, $pop3
; CHECK-NEXT: br_if 0, $pop4
; CHECK-NEXT: unreachable

; CHECK-LABEL: .Lcall_dtors:
; CHECK-NEXT: .functype .Lcall_dtors (i32) -> (){{$}}
; CHECK-NEXT: call orig_dtor65536{{$}}
; CHECK-LABEL: .Lcall_dtors$0.associatedc0:
; CHECK-NEXT: .functype .Lcall_dtors$0.associatedc0 (i32) -> (){{$}}
; CHECK-NEXT: call orig_dtor65535c0

; CHECK-LABEL: .Lcall_dtors$1:
; CHECK-NEXT: .functype .Lcall_dtors$1 (i32) -> (){{$}}
; CHECK-NEXT: call orig_dtor65535{{$}}

; CHECK-LABEL: .Lregister_call_dtors:
; CHECK-LABEL: .Lregister_call_dtors$1:
; CHECK: block
; CHECK-NEXT: i32.const $push2=, .Lcall_dtors{{$}}
; CHECK-NEXT: i32.const $push2=, .Lcall_dtors$1{{$}}
; CHECK-NEXT: i32.const $push1=, 0
; CHECK-NEXT: i32.const $push0=, __dso_handle
; CHECK-NEXT: call $push3=, __cxa_atexit, $pop2, $pop1, $pop0{{$}}
Expand All @@ -116,11 +175,14 @@ declare void @after_the_null()
; CHECK-LABEL: .section .init_array.0,"",@
; CHECK: .int32 .Lregister_call_dtors.0{{$}}
; CHECK-LABEL: .section .init_array.1,"",@
; CHECK: .int32 .Lregister_call_dtors.1{{$}}
; CHECK: .int32 .Lregister_call_dtors.1$0{{$}}
; CHECK-NEXT: .int32 .Lregister_call_dtors.1$3.associatedc2{{$}}
; CHECK-NEXT: .int32 .Lregister_call_dtors.1$4.associatedc3{{$}}
; CHECK-NEXT: .int32 .Lregister_call_dtors.1$5{{$}}
; CHECK-LABEL: .section .init_array.200,"",@
; CHECK: .int32 orig_ctor{{$}}
; CHECK-LABEL: .section .init_array,"",@
; CHECK: .int32 .Lregister_call_dtors{{$}}
; CHECK: .int32 .Lregister_call_dtors$1{{$}}

; CHECK-LABEL: .weak __dso_handle

Expand Down

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