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Implement FixupPrecode for Arm64 #7015

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Sep 3, 2016
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Implement FixupPrecode for Arm64 #7015

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2 changes: 1 addition & 1 deletion src/inc/jithelpers.h
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Original file line number Diff line number Diff line change
Expand Up @@ -315,7 +315,7 @@

JITHELPER(CORINFO_HELP_EE_PRESTUB, ThePreStub, CORINFO_HELP_SIG_NO_ALIGN_STUB)

#if defined(_TARGET_X86_) || defined(_TARGET_AMD64_) || defined(_TARGET_ARM_)
#if defined(HAS_FIXUP_PRECODE)
JITHELPER(CORINFO_HELP_EE_PRECODE_FIXUP, PrecodeFixupThunk, CORINFO_HELP_SIG_NO_ALIGN_STUB)
#else
JITHELPER(CORINFO_HELP_EE_PRECODE_FIXUP, NULL, CORINFO_HELP_SIG_NO_ALIGN_STUB)
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13 changes: 13 additions & 0 deletions src/vm/arm64/asmconstants.h
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Expand Up @@ -147,6 +147,19 @@ ASMCONSTANTS_C_ASSERT(CONTEXT_Pc == offsetof(T_CONTEXT,Pc))
ASMCONSTANTS_C_ASSERT(SIZEOF__FaultingExceptionFrame == sizeof(FaultingExceptionFrame));
ASMCONSTANTS_C_ASSERT(FaultingExceptionFrame__m_fFilterExecuted == offsetof(FaultingExceptionFrame, m_fFilterExecuted));

#define SIZEOF__FixupPrecode 24
#define Offset_PrecodeChunkIndex 15
#define Offset_MethodDescChunkIndex 14
#define MethodDesc_ALIGNMENT_SHIFT 3
#define FixupPrecode_ALIGNMENT_SHIFT_1 3
#define FixupPrecode_ALIGNMENT_SHIFT_2 4

ASMCONSTANTS_C_ASSERT(SIZEOF__FixupPrecode == sizeof(FixupPrecode));
ASMCONSTANTS_C_ASSERT(Offset_PrecodeChunkIndex == offsetof(FixupPrecode, m_PrecodeChunkIndex));
ASMCONSTANTS_C_ASSERT(Offset_MethodDescChunkIndex == offsetof(FixupPrecode, m_MethodDescChunkIndex));
ASMCONSTANTS_C_ASSERT(MethodDesc_ALIGNMENT_SHIFT == MethodDesc::ALIGNMENT_SHIFT);
ASMCONSTANTS_C_ASSERT((1<<FixupPrecode_ALIGNMENT_SHIFT_1) + (1<<FixupPrecode_ALIGNMENT_SHIFT_2) == sizeof(FixupPrecode));

#ifndef CROSSGEN_COMPILE
#define ResolveCacheElem__target 0x10
#define ResolveCacheElem__pNext 0x18
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20 changes: 18 additions & 2 deletions src/vm/arm64/asmhelpers.asm
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Expand Up @@ -193,9 +193,25 @@ Done
NESTED_END

; ------------------------------------------------------------------
; ARM64TODO: Implement PrecodeFixupThunk when PreCode is Enabled
; The call in fixup precode initally points to this function.
; The pupose of this function is to load the MethodDesc and forward the call to prestub.
NESTED_ENTRY PrecodeFixupThunk
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@rahku rahku Sep 3, 2016 •
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in comment forward the call to prestub

brk #0

; x12 = FixupPrecode *
; On Exit
; x12 = MethodDesc*
; x13, x14 Trashed
; Inline computation done by FixupPrecode::GetMethodDesc()
ldrb w13, [x12, #Offset_PrecodeChunkIndex] ; m_PrecodeChunkIndex
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Is this the disassembly of FixupPrecode::GetMethodDesc()

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@ramarag ramarag Sep 3, 2016 •
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NO the assembly for FixupPrecode::GetMethodDesc() generated by C++ compiler is actually

39403c08 ldrb        w8,[x0,#0xF]
d280030a mov         x10,#0x18
11000508 add         w8,w8,#1
93407d09 sxtw        x9,w8
9b0a7d29 mul         x9,x9,x10
f860692a ldr         x10,[x9,x0]
b500006a cbnz        x10,coreclr!FixupPrecode::GetMethodDesc+0x24 (00000001`80145004)
d2800000 mov         x0,#0
14000004 b           coreclr!FixupPrecode::GetMethodDesc+0x30 (00000001`80145010)
39403808 ldrb        w8,[x0,#0xE]
531d7108 lsl         w8,w8,#3
8b28c140 add         x0,x10,w8 sxtw
d65f03c0 ret         lr

I replaced the mul with two add instructions. The assembly code here is similar to what is found in arm

ldrb w14, [x12, #Offset_MethodDescChunkIndex] ; m_MethodDescChunkIndex

add x12,x12,w13,uxtw #FixupPrecode_ALIGNMENT_SHIFT_1
add x13,x12,w13,uxtw #FixupPrecode_ALIGNMENT_SHIFT_2
ldr x13, [x13,#SIZEOF__FixupPrecode]
add x12,x13,w14,uxtw #MethodDesc_ALIGNMENT_SHIFT

b ThePreStub

NESTED_END
; ------------------------------------------------------------------

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60 changes: 46 additions & 14 deletions src/vm/arm64/cgencpu.h
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Expand Up @@ -38,8 +38,8 @@ class ComCallMethodDesc;

#define USE_INDIRECT_CODEHEADER

//#define HAS_FIXUP_PRECODE 1
//#define HAS_FIXUP_PRECODE_CHUNKS 1
#define HAS_FIXUP_PRECODE 1
#define HAS_FIXUP_PRECODE_CHUNKS 1

// ThisPtrRetBufPrecode one is necessary for closed delegates over static methods with return buffer
#define HAS_THISPTR_RETBUF_PRECODE 1
Expand Down Expand Up @@ -613,44 +613,76 @@ typedef DPTR(NDirectImportPrecode) PTR_NDirectImportPrecode;

struct FixupPrecode {

static const int Type = 0xfc;
static const int Type = 0x0C;

// mov r12, pc
// ldr pc, [pc, #4] ; =m_pTarget
// adr x12, #0
// ldr x11, [pc, #12] ; =m_pTarget
// br x11
// dcb m_MethodDescChunkIndex
// dcb m_PrecodeChunkIndex
// 2 byte padding
// dcd m_pTarget
WORD m_rgCode[3];


UINT32 m_rgCode[3];
BYTE padding[2];
BYTE m_MethodDescChunkIndex;
BYTE m_PrecodeChunkIndex;
TADDR m_pTarget;

void Init(MethodDesc* pMD, LoaderAllocator *pLoaderAllocator, int iMethodDescChunkIndex = 0, int iPrecodeChunkIndex = 0);
void InitCommon()
{
WRAPPER_NO_CONTRACT;
int n = 0;

m_rgCode[n++] = 0x1000000C; // adr x12, #0
m_rgCode[n++] = 0x5800006B; // ldr x11, [pc, #12] ; =m_pTarget

_ASSERTE((UINT32*)&m_pTarget == &m_rgCode[n + 2]);

m_rgCode[n++] = 0xD61F0160; // br x11

_ASSERTE(n == _countof(m_rgCode));
}

TADDR GetBase()
{
_ASSERTE(!"ARM64:NYI");
return NULL;
LIMITED_METHOD_CONTRACT;
SUPPORTS_DAC;

return dac_cast<TADDR>(this) + (m_PrecodeChunkIndex + 1) * sizeof(FixupPrecode);
}

TADDR GetMethodDesc();

PCODE GetTarget()
{
_ASSERTE(!"ARM64:NYI");
return NULL;
LIMITED_METHOD_DAC_CONTRACT;
return m_pTarget;
}

BOOL SetTargetInterlocked(TADDR target, TADDR expected)
{
_ASSERTE(!"ARM64:NYI");
return NULL;
CONTRACTL
{
THROWS;
GC_TRIGGERS;
}
CONTRACTL_END;

EnsureWritableExecutablePages(&m_pTarget);
return (TADDR)InterlockedCompareExchange64(
(LONGLONG*)&m_pTarget, (TADDR)target, (TADDR)expected) == expected;
}

static BOOL IsFixupPrecodeByASM(PCODE addr)
{
_ASSERTE(!"ARM64:NYI");
return NULL;
PTR_DWORD pInstr = dac_cast<PTR_DWORD>(PCODEToPINSTR(addr));
return
(pInstr[0] == 0x1000000C) &&
(pInstr[1] == 0x5800006B) &&
(pInstr[2] == 0xD61F0160);
}

#ifdef FEATURE_PREJIT
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99 changes: 91 additions & 8 deletions src/vm/arm64/stubs.cpp
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Expand Up @@ -494,14 +494,22 @@ void HelperMethodFrame::UpdateRegDisplay(const PREGDISPLAY pRD)

TADDR FixupPrecode::GetMethodDesc()
{
_ASSERTE(!"ARM64:NYI");
return NULL;
LIMITED_METHOD_DAC_CONTRACT;

// This lookup is also manually inlined in PrecodeFixupThunk assembly code
TADDR base = *PTR_TADDR(GetBase());
if (base == NULL)
return NULL;
return base + (m_MethodDescChunkIndex * MethodDesc::ALIGNMENT);
}

#ifdef DACCESS_COMPILE
void FixupPrecode::EnumMemoryRegions(CLRDataEnumMemoryFlags flags)
{
_ASSERTE(!"ARM64:NYI");
SUPPORTS_DAC;
DacEnumMemoryRegion(dac_cast<TADDR>(this), sizeof(FixupPrecode));

DacEnumMemoryRegion(GetBase(), sizeof(TADDR));
}
#endif // DACCESS_COMPILE

Expand Down Expand Up @@ -574,19 +582,78 @@ void NDirectImportPrecode::Fixup(DataImage *image)

void FixupPrecode::Init(MethodDesc* pMD, LoaderAllocator *pLoaderAllocator, int iMethodDescChunkIndex /*=0*/, int iPrecodeChunkIndex /*=0*/)
{
_ASSERTE(!"ARM64:NYI");
WRAPPER_NO_CONTRACT;

InitCommon();

// Initialize chunk indices only if they are not initialized yet. This is necessary to make MethodDesc::Reset work.
if (m_PrecodeChunkIndex == 0)
{
_ASSERTE(FitsInU1(iPrecodeChunkIndex));
m_PrecodeChunkIndex = static_cast<BYTE>(iPrecodeChunkIndex);
}

if (iMethodDescChunkIndex != -1)
{
if (m_MethodDescChunkIndex == 0)
{
_ASSERTE(FitsInU1(iMethodDescChunkIndex));
m_MethodDescChunkIndex = static_cast<BYTE>(iMethodDescChunkIndex);
}

if (*(void**)GetBase() == NULL)
*(void**)GetBase() = (BYTE*)pMD - (iMethodDescChunkIndex * MethodDesc::ALIGNMENT);
}

_ASSERTE(GetMethodDesc() == (TADDR)pMD);

if (pLoaderAllocator != NULL)
{
m_pTarget = GetEEFuncEntryPoint(PrecodeFixupThunk);
}
}

#ifdef FEATURE_NATIVE_IMAGE_GENERATION
// Partial initialization. Used to save regrouped chunks.
void FixupPrecode::InitForSave(int iPrecodeChunkIndex)
{
_ASSERTE(!"ARM64:NYI");
STANDARD_VM_CONTRACT;

InitCommon();

_ASSERTE(FitsInU1(iPrecodeChunkIndex));
m_PrecodeChunkIndex = static_cast<BYTE>(iPrecodeChunkIndex);
// The rest is initialized in code:FixupPrecode::Fixup
}

void FixupPrecode::Fixup(DataImage *image, MethodDesc * pMD)
{
_ASSERTE(!"ARM64:NYI");
STANDARD_VM_CONTRACT;

// Note that GetMethodDesc() does not return the correct value because of
// regrouping of MethodDescs into hot and cold blocks. That's why the caller
// has to supply the actual MethodDesc

SSIZE_T mdChunkOffset;
ZapNode * pMDChunkNode = image->GetNodeForStructure(pMD, &mdChunkOffset);
ZapNode * pHelperThunk = image->GetHelperThunk(CORINFO_HELP_EE_PRECODE_FIXUP);

image->FixupFieldToNode(this, offsetof(FixupPrecode, m_pTarget), pHelperThunk);

// Set the actual chunk index
FixupPrecode * pNewPrecode = (FixupPrecode *)image->GetImagePointer(this);

size_t mdOffset = mdChunkOffset - sizeof(MethodDescChunk);
size_t chunkIndex = mdOffset / MethodDesc::ALIGNMENT;
_ASSERTE(FitsInU1(chunkIndex));
pNewPrecode->m_MethodDescChunkIndex = (BYTE)chunkIndex;

// Fixup the base of MethodDescChunk
if (m_PrecodeChunkIndex == 0)
{
image->FixupFieldToNode(this, (BYTE *)GetBase() - (BYTE *)this,
pMDChunkNode, sizeof(MethodDescChunk));
}
}
#endif // FEATURE_NATIVE_IMAGE_GENERATION

Expand Down Expand Up @@ -618,7 +685,20 @@ BOOL DoesSlotCallPrestub(PCODE pCode)
{
PTR_DWORD pInstr = dac_cast<PTR_DWORD>(PCODEToPINSTR(pCode));

// ARM64TODO: Check for FixupPrecode
//FixupPrecode
#if defined(HAS_FIXUP_PRECODE)
if (FixupPrecode::IsFixupPrecodeByASM(pCode))
{
PCODE pTarget = dac_cast<PTR_FixupPrecode>(pInstr)->m_pTarget;

if (isJump(pTarget))
{
pTarget = decodeJump(pTarget);
}

return pTarget == (TADDR)PrecodeFixupThunk;
}
#endif

// StubPrecode
if (pInstr[0] == 0x10000089 && // adr x9, #16
Expand All @@ -627,7 +707,10 @@ BOOL DoesSlotCallPrestub(PCODE pCode)
{
PCODE pTarget = dac_cast<PTR_StubPrecode>(pInstr)->m_pTarget;

// ARM64TODO: implement for NGen case
if (isJump(pTarget))
{
pTarget = decodeJump(pTarget);
}

return pTarget == GetPreStubEntryPoint();
}
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2 changes: 1 addition & 1 deletion src/vm/precode.cpp
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Expand Up @@ -433,7 +433,7 @@ BOOL Precode::SetTargetInterlocked(PCODE target)
// SetTargetInterlocked does not modify code on ARM so the flush instruction cache is
// not necessary.
//
#if !defined(_TARGET_ARM_)
#if !defined(_TARGET_ARM_) && !defined(_TARGET_ARM64_)
if (ret) {
FlushInstructionCache(GetCurrentProcess(),this,SizeOf());
}
Expand Down