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JIT: Allow early prop to reorder null checks #71435

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JIT: Allow early prop to reorder null checks #71435

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5 changes: 1 addition & 4 deletions src/coreclr/jit/compiler.h
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Original file line number Diff line number Diff line change
Expand Up @@ -6914,10 +6914,7 @@ class Compiler
GenTree* nullCheckTree,
GenTree** nullCheckParent,
Statement** nullCheckStmt);
bool optCanMoveNullCheckPastTree(GenTree* tree,
unsigned nullCheckLclNum,
bool isInsideTry,
bool checkSideEffectSummary);
bool optCanMoveNullCheckPastTree(GenTree* tree, unsigned nullCheckLclNum, bool isInsideTry, bool checkWholeTree);
#if DEBUG
void optCheckFlagsAreSet(unsigned methodFlag,
const char* methodFlagStr,
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17 changes: 9 additions & 8 deletions src/coreclr/jit/earlyprop.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -721,28 +721,29 @@ bool Compiler::optIsNullCheckFoldingLegal(GenTree* tree,
// tree - The tree to check.
// nullCheckLclNum - The local variable that GT_NULLCHECK checks.
// isInsideTry - True if tree is inside try, false otherwise.
// checkSideEffectSummary -If true, check side effect summary flags only,
// otherwise check the side effects of the operation itself.
// checkWholeTree - If true, check the tree and child nodes for interference.
// If false, check only 'tree' in anticipation of the children being checked separately.
//
// Return Value:
// True if nullcheck may be folded into a node that is after tree in execution order,
// false otherwise.

//
bool Compiler::optCanMoveNullCheckPastTree(GenTree* tree,
unsigned nullCheckLclNum,
bool isInsideTry,
bool checkSideEffectSummary)
bool checkWholeTree)
{
bool result = true;

if ((tree->gtFlags & GTF_CALL) != 0)
{
result = !checkSideEffectSummary && !tree->OperRequiresCallFlag(this);
result = !checkWholeTree && !tree->OperRequiresCallFlag(this);
}

if (result && (tree->gtFlags & GTF_EXCEPT) != 0)
{
result = !checkSideEffectSummary && !tree->OperMayThrow(this);
ExceptionSetFlags flags = checkWholeTree ? gtCollectExceptions(tree) : tree->OperExceptions(this);
result = (flags == ExceptionSetFlags::None) || (flags == ExceptionSetFlags::NullReferenceException);
}

if (result && ((tree->gtFlags & GTF_ASG) != 0))
Expand All @@ -751,7 +752,7 @@ bool Compiler::optCanMoveNullCheckPastTree(GenTree* tree,
{
GenTree* lhs = tree->gtGetOp1();
GenTree* rhs = tree->gtGetOp2();
if (checkSideEffectSummary && ((rhs->gtFlags & GTF_ASG) != 0))
if (checkWholeTree && ((rhs->gtFlags & GTF_ASG) != 0))
{
result = false;
}
Expand All @@ -767,7 +768,7 @@ bool Compiler::optCanMoveNullCheckPastTree(GenTree* tree,
result = ((lhs->gtFlags & GTF_GLOB_REF) == 0);
}
}
else if (checkSideEffectSummary)
else if (checkWholeTree)
{
result = !isInsideTry && ((tree->gtFlags & GTF_GLOB_REF) == 0);
}
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