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JIT: Fix reordering of call args on x86 #70931

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Merged
jakobbotsch merged 2 commits into from
Jun 21, 2022
Merged

JIT: Fix reordering of call args on x86 #70931

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JIT: Fix reordering of call args on x86
jakobbotsch Jun 18, 2022
d3ce5b7
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jakobbotsch Jun 18, 2022
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67 changes: 45 additions & 22 deletions src/coreclr/jit/morph.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -746,15 +746,14 @@ void CallArgs::ArgsComplete(Compiler* comp, GenTreeCall* call)
continue;
}

bool canEvalToTemp = true;
if (arg.AbiInfo.GetRegNum() == REG_STK)
{
assert(m_hasStackArgs);
#if !FEATURE_FIXED_OUT_ARGS
// On x86 we use push instructions to pass arguments:
// The non-register arguments are evaluated and pushed in order
// and they are never evaluated into temps
//
continue;
// Non-register arguments are evaluated and pushed in order; they
// should never go in the late arg list.
canEvalToTemp = false;
#endif
}
#if FEATURE_ARG_SPLIT
Expand Down Expand Up @@ -787,17 +786,20 @@ void CallArgs::ArgsComplete(Compiler* comp, GenTreeCall* call)

if (argx->gtFlags & GTF_ASG)
{
// If this is not the only argument, or it's a copyblk, or it already evaluates the expression to
// a tmp, then we need a temp in the late arg list.
if ((argCount > 1) || argx->OperIsCopyBlkOp()
#ifdef FEATURE_FIXED_OUT_ARGS
|| arg.m_isTmp // Protect this by "FEATURE_FIXED_OUT_ARGS" to preserve the property
// that we only have late non-register args when that feature is on.
#endif
Comment on lines -793 to -796
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@jakobbotsch jakobbotsch Jun 18, 2022

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FEATURE_FIXED_OUT_ARGS is defined even on x86, just with value 0, so this #ifdef was always true. The point of this check is to catch when fgMakeOutgoingStructArgCopy has left a non-value node, and it only does this for FEATURE_FIXED_OUT_ARGS, so I have fixed the logic.

)
// If this is not the only argument, or it's a copyblk, or it
// already evaluates the expression to a tmp then we need a temp in
// the late arg list.
// In the latter case this might not even be a value;
// fgMakeOutgoingStructArgCopy will leave the copying nodes here
// for FEATURE_FIXED_OUT_ARGS.
if (canEvalToTemp && ((argCount > 1) || argx->OperIsCopyBlkOp() || (FEATURE_FIXED_OUT_ARGS && arg.m_isTmp)))
{
SetNeedsTemp(&arg);
}
else
{
assert(argx->IsValue());
}

// For all previous arguments, unless they are a simple constant
// we require that they be evaluated into temps
Expand All @@ -808,6 +810,16 @@ void CallArgs::ArgsComplete(Compiler* comp, GenTreeCall* call)
break;
}

#if !FEATURE_FIXED_OUT_ARGS
if (prevArg.AbiInfo.GetRegNum() == REG_STK)
{
// All stack args are already evaluated and placed in order
// in this case; we only need to check this for register
// args.
break;
}
#endif

if ((prevArg.GetEarlyNode() != nullptr) && !prevArg.GetEarlyNode()->IsInvariant())
{
SetNeedsTemp(&prevArg);
Expand Down Expand Up @@ -853,14 +865,17 @@ void CallArgs::ArgsComplete(Compiler* comp, GenTreeCall* call)

if (treatLikeCall)
{
if (argCount > 1) // If this is not the only argument
if (canEvalToTemp)
{
SetNeedsTemp(&arg);
}
else if (varTypeIsFloating(argx->TypeGet()) && (argx->OperGet() == GT_CALL))
{
// Spill all arguments that are floating point calls
SetNeedsTemp(&arg);
if (argCount > 1) // If this is not the only argument
{
SetNeedsTemp(&arg);
}
else if (varTypeIsFloating(argx->TypeGet()) && (argx->OperGet() == GT_CALL))
{
// Spill all arguments that are floating point calls
SetNeedsTemp(&arg);
}
}

// All previous arguments may need to be evaluated into temps
Expand All @@ -871,6 +886,15 @@ void CallArgs::ArgsComplete(Compiler* comp, GenTreeCall* call)
break;
}

#if !FEATURE_FIXED_OUT_ARGS
if (prevArg.AbiInfo.GetRegNum() == REG_STK)
{
// All stack args are already evaluated and placed in order
// in this case.
break;
}
#endif

// For all previous arguments, if they have any GTF_ALL_EFFECT
// we require that they be evaluated into a temp
if ((prevArg.GetEarlyNode() != nullptr) && ((prevArg.GetEarlyNode()->gtFlags & GTF_ALL_EFFECT) != 0))
Expand All @@ -879,8 +903,7 @@ void CallArgs::ArgsComplete(Compiler* comp, GenTreeCall* call)
}
#if FEATURE_FIXED_OUT_ARGS
// Or, if they are stored into the FIXED_OUT_ARG area
// we require that they be moved to the gtCallLateArgs
// and replaced with a placeholder node
// we require that they be moved to the late list
else if (prevArg.AbiInfo.GetRegNum() == REG_STK)
{
prevArg.m_needPlace = true;
Expand Down