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Fix unwind info generation for EH funclets #1923

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merged 2 commits into from
Jul 1, 2022
Merged

Fix unwind info generation for EH funclets #1923

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3659a5f
Fix unwind info generation for EH funclets
Jul 1, 2022
2d6da1a
Fix allocUnwindInfo call for cold funclets
Jul 1, 2022
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28 changes: 27 additions & 1 deletion src/coreclr/jit/flowgraph.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -3443,6 +3443,8 @@ PhaseStatus Compiler::fgDetermineFirstColdBlock()
}
else
{
bool inFuncletSection = false;

for (lblk = nullptr, block = fgFirstBB; block != nullptr; lblk = block, block = block->bbNext)
{
bool blockMustBeInHotSection = false;
Expand All @@ -3454,6 +3456,15 @@ PhaseStatus Compiler::fgDetermineFirstColdBlock()
}
#endif // HANDLER_ENTRY_MUST_BE_IN_HOT_SECTION

#ifdef FEATURE_EH_FUNCLETS
// Make note of if we're in the funclet section,
// so we can stop the search early.
if (block == fgFirstFuncletBB)
{
inFuncletSection = true;
}
#endif // FEATURE_EH_FUNCLETS

// Do we have a candidate for the first cold block?
if (firstColdBlock != nullptr)
{
Expand All @@ -3465,6 +3476,21 @@ PhaseStatus Compiler::fgDetermineFirstColdBlock()
// We have to restart the search for the first cold block
firstColdBlock = nullptr;
prevToFirstColdBlock = nullptr;

#ifdef FEATURE_EH_FUNCLETS
// If we're already in the funclet section, try to split
// at fgFirstFuncletBB, and stop the search.
if (inFuncletSection)
{
if (fgFuncletsAreCold())
{
firstColdBlock = fgFirstFuncletBB;
prevToFirstColdBlock = fgFirstFuncletBB->bbPrev;
}

break;
}
#endif // FEATURE_EH_FUNCLETS
}
}
else // (firstColdBlock == NULL) -- we don't have a candidate for first cold block
Expand All @@ -3476,7 +3502,7 @@ PhaseStatus Compiler::fgDetermineFirstColdBlock()
// consider splitting at the first funclet; do not consider splitting between funclets,
// as this may break unwind info.
//
if (block == fgFirstFuncletBB)
if (inFuncletSection)
{
if (fgFuncletsAreCold())
{
Expand Down
10 changes: 9 additions & 1 deletion src/coreclr/jit/unwind.cpp
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Expand Up @@ -102,7 +102,15 @@ void Compiler::unwindGetFuncLocations(FuncInfoDsc* func,
assert(fgFirstColdBlock != nullptr); // There better be a cold section!

*ppStartLoc = new (this, CMK_UnwindInfo) emitLocation(ehEmitCookie(fgFirstColdBlock));
*ppEndLoc = nullptr; // nullptr end location means the end of the code

if (fgFirstFuncletBB != nullptr)
{
*ppEndLoc = new (this, CMK_UnwindInfo) emitLocation(ehEmitCookie(fgFirstFuncletBB));
}
else
{
*ppEndLoc = nullptr; // nullptr end location means the end of the code
}
}
}
else
Expand Down
111 changes: 74 additions & 37 deletions src/coreclr/jit/unwindamd64.cpp
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Expand Up @@ -656,17 +656,34 @@ void Compiler::unwindReserve()
//
void Compiler::unwindReserveFunc(FuncInfoDsc* func)
{
unwindReserveFuncHelper(func, true);

if (fgFirstColdBlock != nullptr)
{
#ifdef DEBUG
if (!JitConfig.JitFakeProcedureSplitting())
// If fake-splitting, treat all unwind info as hot.
if (JitConfig.JitFakeProcedureSplitting())
{
unwindReserveFuncHelper(func, true);
return;
}
#endif // DEBUG

if (func->funKind == FUNC_ROOT)
{
unwindReserveFuncHelper(func, true);

// If the function's main body is split, reserve unwind info of size 0 for the cold section.
// If only funclets are cold, the main body is hot, so don't make a second call.
const bool isFunctionSplit = ((fgFirstColdBlock != nullptr) && (fgFirstColdBlock != fgFirstFuncletBB));
if (isFunctionSplit)
{
unwindReserveFuncHelper(func, false);
}
}
else
{
// Make only one call for funclets.
// If function is split and has EH, the funclets will be cold.
const bool isFuncletHot = (fgFirstColdBlock == nullptr);
unwindReserveFuncHelper(func, isFuncletHot);
}
}

//------------------------------------------------------------------------
Expand All @@ -679,8 +696,10 @@ void Compiler::unwindReserveFunc(FuncInfoDsc* func)
//
void Compiler::unwindReserveFuncHelper(FuncInfoDsc* func, bool isHotCode)
{
DWORD unwindCodeBytes = 0;
if (isHotCode)
const bool isFunclet = (func->funKind != FUNC_ROOT);
DWORD unwindCodeBytes = 0;

if (isHotCode || isFunclet)
{
#ifdef UNIX_AMD64_ABI
if (generateCFIUnwindCodes())
Expand Down Expand Up @@ -717,9 +736,7 @@ void Compiler::unwindReserveFuncHelper(FuncInfoDsc* func, bool isHotCode)
}
}

bool isFunclet = (func->funKind != FUNC_ROOT);
bool isColdCode = !isHotCode;

const bool isColdCode = !isHotCode;
eeReserveUnwindInfo(isFunclet, isColdCode, unwindCodeBytes);
}

Expand Down Expand Up @@ -779,7 +796,32 @@ void Compiler::unwindEmitFuncHelper(FuncInfoDsc* func, void* pHotCode, void* pCo
{
endOffset = func->endLoc->CodeOffset(GetEmitter());
}
}
else
{
assert(fgFirstColdBlock != nullptr);

if (func->coldStartLoc == nullptr)
{
startOffset = 0;
}
else
{
startOffset = func->coldStartLoc->CodeOffset(GetEmitter());
}

if (func->coldEndLoc == nullptr)
{
endOffset = info.compNativeCodeSize;
}
else
{
endOffset = func->coldEndLoc->CodeOffset(GetEmitter());
}
}

if (isHotCode || (func->funKind != FUNC_ROOT))
{
#ifdef UNIX_AMD64_ABI
if (generateCFIUnwindCodes())
{
Expand Down Expand Up @@ -807,28 +849,6 @@ void Compiler::unwindEmitFuncHelper(FuncInfoDsc* func, void* pHotCode, void* pCo
pUnwindBlock = &func->unwindCodes[func->unwindCodeSlot];
}
}
else
{
assert(fgFirstColdBlock != nullptr);

if (func->coldStartLoc == nullptr)
{
startOffset = 0;
}
else
{
startOffset = func->coldStartLoc->CodeOffset(GetEmitter());
}

if (func->coldEndLoc == nullptr)
{
endOffset = info.compNativeCodeSize;
}
else
{
endOffset = func->coldEndLoc->CodeOffset(GetEmitter());
}
}

#ifdef DEBUG
if (opts.dspUnwind)
Expand Down Expand Up @@ -894,17 +914,34 @@ void Compiler::unwindEmitFunc(FuncInfoDsc* func, void* pHotCode, void* pColdCode
static_assert_no_msg(FUNC_HANDLER == (FuncKind)CORJIT_FUNC_HANDLER);
static_assert_no_msg(FUNC_FILTER == (FuncKind)CORJIT_FUNC_FILTER);

unwindEmitFuncHelper(func, pHotCode, pColdCode, true);

if (pColdCode != nullptr)
{
#ifdef DEBUG
if (!JitConfig.JitFakeProcedureSplitting())
// If fake-splitting, treat all unwind info as hot.
if (JitConfig.JitFakeProcedureSplitting())
{
unwindEmitFuncHelper(func, pHotCode, pColdCode, true);
return;
}
#endif // DEBUG

if (func->funKind == FUNC_ROOT)
{
unwindEmitFuncHelper(func, pHotCode, pColdCode, true);

// If the function's main body is split, reserve unwind info of size 0 for the cold section.
// If only funclets are cold, the main body is hot, so don't make a second call.
const bool isFunctionSplit = ((fgFirstColdBlock != nullptr) && (fgFirstColdBlock != fgFirstFuncletBB));
if (isFunctionSplit)
{
unwindEmitFuncHelper(func, pHotCode, pColdCode, false);
}
}
else
{
// Make only one call for funclets.
// If function is split and has EH, the funclets will be cold.
const bool isFuncletHot = (fgFirstColdBlock == nullptr);
unwindEmitFuncHelper(func, pHotCode, pColdCode, isFuncletHot);
}
}

#endif // TARGET_AMD64