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Fix tailcall regression with compiled F#
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This change skips instantiating stubs for direct tailcalls and instead passes the inst argument directly to the target method.

Fixes dotnet#40864
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@jkotas
jkotas committed Aug 25, 2020
1 parent c0862a5 commit 9b73547
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Showing 11 changed files with 160 additions and 192 deletions.
12 changes: 6 additions & 6 deletions .../src/System.Private.CoreLib/src/System/Runtime/CompilerServices/RuntimeHelpers.CoreCLR.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -286,9 +286,6 @@ public static IntPtr AllocateTypeAssociatedMemory(Type type, int size)
[MethodImpl(MethodImplOptions.InternalCall)]
private static extern IntPtr AllocTailCallArgBuffer(int size, IntPtr gcDesc);

[MethodImpl(MethodImplOptions.InternalCall)]
private static extern void FreeTailCallArgBuffer();

[MethodImpl(MethodImplOptions.InternalCall)]
private static unsafe extern TailCallTls* GetTailCallInfo(IntPtr retAddrSlot, IntPtr* retAddr);

Expand Down Expand Up @@ -323,6 +320,12 @@ private static unsafe void DispatchTailCalls(
finally
{
tls->Frame = prevFrame;

// If the arg buffer is reporting inst argument, it is safe to abandon it now
if (tls->ArgBuffer != IntPtr.Zero && *(int*)tls->ArgBuffer == 1 /* TAILCALLARGBUFFER_INSTARG_ONLY */)
{
*(int*)tls->ArgBuffer = 2 /* TAILCALLARGBUFFER_ABANDONED */;
}
}
}

Expand Down Expand Up @@ -481,9 +484,6 @@ internal unsafe struct TailCallTls
{
public PortableTailCallFrame* Frame;
public IntPtr ArgBuffer;
private IntPtr _argBufferSize;
private IntPtr _argBufferGCDesc;
private fixed byte _argBufferInline[64];
}

}
1 change: 0 additions & 1 deletion src/coreclr/src/jit/compiler.h
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Original file line number Diff line number Diff line change
Expand Up @@ -5579,7 +5579,6 @@ class Compiler
GenTree* fgCreateCallDispatcherAndGetResult(GenTreeCall* origCall,
CORINFO_METHOD_HANDLE callTargetStubHnd,
CORINFO_METHOD_HANDLE dispatcherHnd);
GenTree* getMethodPointerTree(CORINFO_RESOLVED_TOKEN* pResolvedToken, CORINFO_CALL_INFO* pCallInfo);
GenTree* getLookupTree(CORINFO_RESOLVED_TOKEN* pResolvedToken,
CORINFO_LOOKUP* pLookup,
unsigned handleFlags,
Expand Down
89 changes: 28 additions & 61 deletions src/coreclr/src/jit/morph.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -7700,6 +7700,8 @@ GenTree* Compiler::fgMorphTailCallViaHelpers(GenTreeCall* call, CORINFO_TAILCALL
assert(!call->IsImplicitTailCall());
assert(!fgCanFastTailCall(call, nullptr));

bool virtualCall = call->IsVirtual();

// If VSD then get rid of arg to VSD since we turn this into a direct call.
// The extra arg will be the first arg so this needs to be done before we
// handle the retbuf below.
Expand Down Expand Up @@ -7734,41 +7736,39 @@ GenTree* Compiler::fgMorphTailCallViaHelpers(GenTreeCall* call, CORINFO_TAILCALL
// where we pass instantiating stub.
if ((help.flags & CORINFO_TAILCALL_STORE_TARGET) != 0)
{
// If asked to store target and we have a type arg we will store
// instantiating stub, so in that case we should not pass the type arg.
if (call->tailCallInfo->GetSig()->hasTypeArg())
JITDUMP("Adding target since VM requested it\n");
GenTree* target;
if (!virtualCall)
{
JITDUMP("Removing type arg");

assert(call->gtCallArgs != nullptr);
if (Target::g_tgtArgOrder == Target::ARG_ORDER_R2L)
if (call->gtCallType == CT_INDIRECT)
{
// Generic context is first arg
call->gtCallArgs = call->gtCallArgs->GetNext();
noway_assert(call->gtCallAddr != nullptr);
target = call->gtCallAddr;
}
else
{
// Generic context is last arg
GenTreeCall::Use** lastArgSlot = &call->gtCallArgs;
while ((*lastArgSlot)->GetNext() != nullptr)
CORINFO_CONST_LOOKUP addrInfo;
info.compCompHnd->getFunctionEntryPoint(call->gtCallMethHnd, &addrInfo);

CORINFO_GENERIC_HANDLE handle = nullptr;
void* pIndirection = nullptr;
assert(addrInfo.accessType != IAT_PPVALUE && addrInfo.accessType != IAT_RELPVALUE);

if (addrInfo.accessType == IAT_VALUE)
{
lastArgSlot = &(*lastArgSlot)->NextRef();
handle = addrInfo.handle;
}

*lastArgSlot = nullptr;
else if (addrInfo.accessType == IAT_PVALUE)
{
pIndirection = addrInfo.addr;
}
target = gtNewIconEmbHndNode(handle, pIndirection, GTF_ICON_FTN_ADDR, call->gtCallMethHnd);
}
call->fgArgInfo = nullptr;
}

JITDUMP("Adding target since VM requested it\n");
GenTree* target;
if (call->tailCallInfo->IsCalli())
{
noway_assert(call->gtCallType == CT_INDIRECT && call->gtCallAddr != nullptr);
target = call->gtCallAddr;
}
else
{
assert(!call->tailCallInfo->GetSig()->hasTypeArg());

CORINFO_CALL_INFO callInfo;
unsigned flags = CORINFO_CALLINFO_LDFTN;
if (call->tailCallInfo->IsCallvirt())
Expand All @@ -7778,19 +7778,10 @@ GenTree* Compiler::fgMorphTailCallViaHelpers(GenTreeCall* call, CORINFO_TAILCALL

eeGetCallInfo(call->tailCallInfo->GetToken(), nullptr, (CORINFO_CALLINFO_FLAGS)flags, &callInfo);

if (!call->tailCallInfo->IsCallvirt() ||
((callInfo.methodFlags & (CORINFO_FLG_FINAL | CORINFO_FLG_STATIC)) != 0) ||
((callInfo.methodFlags & CORINFO_FLG_VIRTUAL) == 0))
{
target = getMethodPointerTree(call->tailCallInfo->GetToken(), &callInfo);
}
else
{
assert(call->gtCallThisArg != nullptr);
// TODO: Proper cloning of the this pointer.
target = getVirtMethodPointerTree(gtCloneExpr(call->gtCallThisArg->GetNode()),
call->tailCallInfo->GetToken(), &callInfo);
}
assert(call->gtCallThisArg != nullptr);
// TODO: Proper cloning of the this pointer.
target = getVirtMethodPointerTree(gtCloneExpr(call->gtCallThisArg->GetNode()),
call->tailCallInfo->GetToken(), &callInfo);
}

// Insert target as last arg
Expand Down Expand Up @@ -8044,30 +8035,6 @@ GenTree* Compiler::fgCreateCallDispatcherAndGetResult(GenTreeCall* orig
return finalTree;
}

//------------------------------------------------------------------------
// getMethodPointerTree: get a method pointer tree
//
// Arguments:
// pResolvedToken - resolved token of the call
// pCallInfo - the call info of the call
//
// Return Value:
// A node representing the method pointer
//
GenTree* Compiler::getMethodPointerTree(CORINFO_RESOLVED_TOKEN* pResolvedToken, CORINFO_CALL_INFO* pCallInfo)
{
switch (pCallInfo->kind)
{
case CORINFO_CALL:
return new (this, GT_FTN_ADDR) GenTreeFptrVal(TYP_I_IMPL, pCallInfo->hMethod);
case CORINFO_CALL_CODE_POINTER:
return getLookupTree(pResolvedToken, &pCallInfo->codePointerLookup, GTF_ICON_FTN_ADDR, pCallInfo->hMethod);
default:
noway_assert(!"unknown call kind");
return nullptr;
}
}

//------------------------------------------------------------------------
// getLookupTree: get a lookup tree
//
Expand Down
8 changes: 0 additions & 8 deletions src/coreclr/src/vm/corelib.h
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Original file line number Diff line number Diff line change
Expand Up @@ -708,7 +708,6 @@ DEFINE_METHOD(RUNTIME_HELPERS, ENUM_EQUALS, EnumEquals, NoSig)
DEFINE_METHOD(RUNTIME_HELPERS, ENUM_COMPARE_TO, EnumCompareTo, NoSig)
DEFINE_METHOD(RUNTIME_HELPERS, ALLOC_TAILCALL_ARG_BUFFER, AllocTailCallArgBuffer, SM_Int_IntPtr_RetIntPtr)
DEFINE_METHOD(RUNTIME_HELPERS, GET_TAILCALL_INFO, GetTailCallInfo, NoSig)
DEFINE_METHOD(RUNTIME_HELPERS, FREE_TAILCALL_ARG_BUFFER, FreeTailCallArgBuffer, SM_RetVoid)
DEFINE_METHOD(RUNTIME_HELPERS, DISPATCH_TAILCALLS, DispatchTailCalls, NoSig)

DEFINE_CLASS(UNSAFE, InternalCompilerServices, Unsafe)
Expand Down Expand Up @@ -760,9 +759,6 @@ DEFINE_FIELD(PORTABLE_TAIL_CALL_FRAME, NEXT_CALL, NextCall)
DEFINE_CLASS(TAIL_CALL_TLS, CompilerServices, TailCallTls)
DEFINE_FIELD(TAIL_CALL_TLS, FRAME, Frame)
DEFINE_FIELD(TAIL_CALL_TLS, ARG_BUFFER, ArgBuffer)
DEFINE_FIELD(TAIL_CALL_TLS, ARG_BUFFER_SIZE, _argBufferSize)
DEFINE_FIELD(TAIL_CALL_TLS, ARG_BUFFER_GC_DESC, _argBufferGCDesc)
DEFINE_FIELD(TAIL_CALL_TLS, ARG_BUFFER_INLINE, _argBufferInline)

DEFINE_CLASS_U(CompilerServices, PortableTailCallFrame, PortableTailCallFrame)
DEFINE_FIELD_U(Prev, PortableTailCallFrame, Prev)
Expand All @@ -772,10 +768,6 @@ DEFINE_FIELD_U(NextCall, PortableTailCallFrame, NextCall)
DEFINE_CLASS_U(CompilerServices, TailCallTls, TailCallTls)
DEFINE_FIELD_U(Frame, TailCallTls, m_frame)
DEFINE_FIELD_U(ArgBuffer, TailCallTls, m_argBuffer)
DEFINE_FIELD_U(_argBufferSize, TailCallTls, m_argBufferSize)
DEFINE_FIELD_U(_argBufferGCDesc, TailCallTls, m_argBufferGCDesc)
DEFINE_FIELD_U(_argBufferInline, TailCallTls, m_argBufferInline)


DEFINE_CLASS(RUNTIME_WRAPPED_EXCEPTION, CompilerServices, RuntimeWrappedException)
DEFINE_METHOD(RUNTIME_WRAPPED_EXCEPTION, OBJ_CTOR, .ctor, IM_Obj_RetVoid)
Expand Down
1 change: 0 additions & 1 deletion src/coreclr/src/vm/ecalllist.h
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Original file line number Diff line number Diff line change
Expand Up @@ -881,7 +881,6 @@ FCFuncStart(gRuntimeHelpers)
FCFuncElement("GetUninitializedObjectInternal", ReflectionSerialization::GetUninitializedObject)
QCFuncElement("AllocateTypeAssociatedMemoryInternal", RuntimeTypeHandle::AllocateTypeAssociatedMemory)
FCFuncElement("AllocTailCallArgBuffer", TailCallHelp::AllocTailCallArgBuffer)
FCFuncElement("FreeTailCallArgBuffer", TailCallHelp::FreeTailCallArgBuffer)
FCFuncElement("GetTailCallInfo", TailCallHelp::GetTailCallInfo)
FCFuncElement("GetILBytesJitted", GetJittedBytes)
FCFuncElement("GetMethodsJittedCount", GetJittedMethodsCount)
Expand Down
20 changes: 13 additions & 7 deletions src/coreclr/src/vm/gcenv.ee.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -157,27 +157,33 @@ static void ScanStackRoots(Thread * pThread, promote_func* fn, ScanContext* sc)

static void ScanTailCallArgBufferRoots(Thread* pThread, promote_func* fn, ScanContext* sc)
{
void* gcDesc;
char* argBuffer = pThread->GetTailCallTls()->GetArgBuffer(&gcDesc);
if (gcDesc == NULL)
TailCallArgBuffer* argBuffer = pThread->GetTailCallTls()->GetArgBuffer();
if (argBuffer == NULL || argBuffer->GCDesc == NULL)
return;

GCRefMapDecoder decoder(static_cast<PTR_BYTE>(gcDesc));
if (argBuffer->State == TAILCALLARGBUFFER_ABANDONED)
return;

bool instArgOnly = argBuffer->State == TAILCALLARGBUFFER_INSTARG_ONLY;

GCRefMapDecoder decoder(static_cast<PTR_BYTE>(argBuffer->GCDesc));
while (!decoder.AtEnd())
{
int pos = decoder.CurrentPos();
int token = decoder.ReadToken();

PTR_TADDR ppObj = dac_cast<PTR_TADDR>(argBuffer + pos * sizeof(TADDR));
PTR_TADDR ppObj = dac_cast<PTR_TADDR>(((BYTE*)argBuffer->Args) + pos * sizeof(TADDR));
switch (token)
{
case GCREFMAP_SKIP:
break;
case GCREFMAP_REF:
fn(dac_cast<PTR_PTR_Object>(ppObj), sc, CHECK_APP_DOMAIN);
if (!instArgOnly)
fn(dac_cast<PTR_PTR_Object>(ppObj), sc, CHECK_APP_DOMAIN);
break;
case GCREFMAP_INTERIOR:
PromoteCarefully(fn, dac_cast<PTR_PTR_Object>(ppObj), sc, GC_CALL_INTERIOR);
if (!instArgOnly)
PromoteCarefully(fn, dac_cast<PTR_PTR_Object>(ppObj), sc, GC_CALL_INTERIOR);
break;
case GCREFMAP_METHOD_PARAM:
if (sc->promotion)
Expand Down
2 changes: 1 addition & 1 deletion src/coreclr/src/vm/jitinterface.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -13952,7 +13952,7 @@ bool CEEInfo::getTailCallHelpersInternal(CORINFO_RESOLVED_TOKEN* callToken,

TailCallHelp::CreateTailCallHelperStubs(
m_pMethodBeingCompiled, pTargetMD,
msig, isCallvirt, isThisArgByRef,
msig, isCallvirt, isThisArgByRef, sig->hasTypeArg(),
&pStoreArgsMD, &needsTarget,
&pCallTargetMD);

Expand Down
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