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Improve constant folding for some frozen objects #86318

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merged 4 commits into from
May 17, 2023
Merged

Improve constant folding for some frozen objects #86318

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eb1a0fb
Make jit fold bool.parse("true")
EgorBo May 16, 2023
546f545
Fix typo
EgorBo May 16, 2023
ca93999
Use target_ssize_t
EgorBo May 16, 2023
71439a2
Update valuenum.cpp
EgorBo May 16, 2023
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42 changes: 23 additions & 19 deletions src/coreclr/jit/valuenum.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -5796,6 +5796,11 @@ bool ValueNumStore::IsVNConstant(ValueNum vn)
}
}

bool ValueNumStore::IsVNConstantNonHandle(ValueNum vn)
{
return IsVNConstant(vn) && !IsVNHandle(vn);
}

bool ValueNumStore::IsVNInt32Constant(ValueNum vn)
{
if (!IsVNConstant(vn))
Expand Down Expand Up @@ -10379,38 +10384,37 @@ static bool GetObjectHandleAndOffset(ValueNumStore* vnStore,
ssize_t* byteOffset,
CORINFO_OBJECT_HANDLE* pObj)
{

if (!tree->gtVNPair.BothEqual())
{
return false;
}

ValueNum treeVN = tree->gtVNPair.GetLiberal();
VNFuncApp funcApp;
if (vnStore->GetVNFunc(treeVN, &funcApp) && (funcApp.m_func == (VNFunc)GT_ADD))
ValueNum treeVN = tree->gtVNPair.GetLiberal();
VNFuncApp funcApp;
target_ssize_t offset = 0;
while (vnStore->GetVNFunc(treeVN, &funcApp) && (funcApp.m_func == (VNFunc)GT_ADD))
{
// [objHandle + offset]
if (vnStore->IsVNObjHandle(funcApp.m_args[0]) && vnStore->IsVNConstant(funcApp.m_args[1]))
if (vnStore->IsVNConstantNonHandle(funcApp.m_args[0]) && (vnStore->TypeOfVN(funcApp.m_args[0]) == TYP_I_IMPL))
{
*pObj = vnStore->ConstantObjHandle(funcApp.m_args[0]);
*byteOffset = vnStore->ConstantValue<ssize_t>(funcApp.m_args[1]);
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@jakobbotsch jakobbotsch May 17, 2023 •
edited
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I'm surprised we haven't hit this assert with this previous code:

runtime/src/coreclr/jit/valuenum.h

Lines 1080 to 1099 in bda1f6c

T val1 = reinterpret_cast<T*>(c->m_defs)[offset];
T val2 = SafeGetConstantValue<T>(c, offset);
// Detect if there is a mismatch between the VN storage type and explicitly
// passed-in type T.
bool mismatch = false;
if (varTypeIsFloating(c->m_typ))
{
mismatch = (memcmp(&val1, &val2, sizeof(val1)) != 0);
}
else
{
mismatch = (val1 != val2);
}
if (mismatch)
{
assert(
!"Called ConstantValue<T>(vn), but type(T) != type(vn); Use CoercedConstantValue instead.");
}

I would expect it to hit for 64-bit to 32-bit crossgen2 compilations. It seems to indicate that this code is never hit for crossgen2 32-bit compilations? Is that expected?

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I would expect it to hit for 64-bit to 32-bit crossgen2 compilations.

That's correct - it will be hit if you replay a 32 bit collection with a cross-targeting Jit today. Evidently, we just don't have people (or machines) doing that.

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crossgen doesn't have frozen objects so this path indeed has never been executed, but we could see it on NativeAOT, but I'm not sure we cover the cross compilation case on CI for it

return true;
offset += vnStore->ConstantValue<target_ssize_t>(funcApp.m_args[0]);
treeVN = funcApp.m_args[1];
}

// [offset + objHandle]
// TODO: Introduce a general helper to accumulate offsets for
// shapes such as (((X + CNS1) + CNS2) + CNS3) etc.
if (vnStore->IsVNObjHandle(funcApp.m_args[1]) && vnStore->IsVNConstant(funcApp.m_args[0]))
else if (vnStore->IsVNConstantNonHandle(funcApp.m_args[1]) &&
(vnStore->TypeOfVN(funcApp.m_args[1]) == TYP_I_IMPL))
{
*pObj = vnStore->ConstantObjHandle(funcApp.m_args[1]);
*byteOffset = vnStore->ConstantValue<ssize_t>(funcApp.m_args[0]);
return true;
offset += vnStore->ConstantValue<target_ssize_t>(funcApp.m_args[1]);
treeVN = funcApp.m_args[0];
}
else
{
return false;
}
}
else if (vnStore->IsVNObjHandle(treeVN))

if (vnStore->IsVNObjHandle(treeVN))
{
*pObj = vnStore->ConstantObjHandle(treeVN);
*byteOffset = 0;
*byteOffset = offset;
return true;
}
return false;
Expand Down
5 changes: 4 additions & 1 deletion src/coreclr/jit/valuenum.h
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Original file line number Diff line number Diff line change
Expand Up @@ -858,9 +858,12 @@ class ValueNumStore
// Returns BasicBlock::MAX_LOOP_NUM if the given value number's loop nest is unknown or ill-defined.
BasicBlock::loopNumber LoopOfVN(ValueNum vn);

// Returns true iff the VN represents a (non-handle) constant.
// Returns true iff the VN represents a constant.
bool IsVNConstant(ValueNum vn);

// Returns true iff the VN represents a (non-handle) constant.
bool IsVNConstantNonHandle(ValueNum vn);

// Returns true iff the VN represents an integer constant.
bool IsVNInt32Constant(ValueNum vn);

Expand Down
11 changes: 9 additions & 2 deletions src/libraries/System.Private.CoreLib/src/System/Boolean.cs
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Expand Up @@ -236,8 +236,14 @@ public static bool Parse(string value)
return Parse(value.AsSpan());
}

public static bool Parse(ReadOnlySpan<char> value) =>
TryParse(value, out bool result) ? result : throw new FormatException(SR.Format(SR.Format_BadBoolean, new string(value)));
public static bool Parse(ReadOnlySpan<char> value)
{
if (!TryParse(value, out bool result))
{
ThrowHelper.ThrowFormatException_BadBoolean(value);
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Replaced throw with a throw helper to make it inlineable (at least for constant input)

}
return result;
}

// Determines whether a String represents true or false.
//
Expand Down Expand Up @@ -267,6 +273,7 @@ public static bool TryParse(ReadOnlySpan<char> value, out bool result)

return TryParseUncommon(value, out result);

[MethodImpl(MethodImplOptions.NoInlining)]
static bool TryParseUncommon(ReadOnlySpan<char> value, out bool result)
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TryParseUncommon used to be inlineable in some cases (e.g. without pgo data)

{
// With "true" being 4 characters, even if we trim something from <= 4 chars,
Expand Down
6 changes: 6 additions & 0 deletions src/libraries/System.Private.CoreLib/src/System/ThrowHelper.cs
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Expand Up @@ -539,6 +539,12 @@ internal static void ThrowFormatException_NeedSingleChar()
throw new FormatException(SR.Format_NeedSingleChar);
}

[DoesNotReturn]
internal static void ThrowFormatException_BadBoolean(ReadOnlySpan<char> value)
{
throw new FormatException(SR.Format(SR.Format_BadBoolean, new string(value)));
}

[DoesNotReturn]
internal static void ThrowArgumentOutOfRangeException_PrecisionTooLarge()
{
Expand Down