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JIT: Don't move EH entry block to enable branch reversal during flow opts #117618

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Merged
merged 1 commit into from
Jul 14, 2025
Merged

JIT: Don't move EH entry block to enable branch reversal during flow opts #117618

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2 changes: 0 additions & 2 deletions src/coreclr/jit/compiler.h
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Original file line number Diff line number Diff line change
Expand Up @@ -6152,8 +6152,6 @@ class Compiler

bool fgExpandRarelyRunBlocks();

bool fgEhAllowsMoveBlock(BasicBlock* bBefore, BasicBlock* bAfter);

void fgMoveBlocksAfter(BasicBlock* bStart, BasicBlock* bEnd, BasicBlock* insertAfterBlk);

PhaseStatus fgHeadTailMerge(bool early);
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12 changes: 0 additions & 12 deletions src/coreclr/jit/fgbasic.cpp
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Expand Up @@ -5309,18 +5309,6 @@ bool Compiler::fgIsForwardBranch(BasicBlock* bJump, BasicBlock* bDest, BasicBloc
return result;
}

/*****************************************************************************
*
* Returns true if it is allowable (based upon the EH regions)
* to place block bAfter immediately after bBefore. It is allowable
* if the 'bBefore' and 'bAfter' blocks are in the exact same EH region.
*/

bool Compiler::fgEhAllowsMoveBlock(BasicBlock* bBefore, BasicBlock* bAfter)
{
return BasicBlock::sameEHRegion(bBefore, bAfter);
}

/*****************************************************************************
*
* Function called to move the range of blocks [bStart .. bEnd].
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4 changes: 3 additions & 1 deletion src/coreclr/jit/fgopt.cpp
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Expand Up @@ -4517,8 +4517,10 @@ bool Compiler::fgUpdateFlowGraph(bool doTailDuplication /* = false */, bool isPh
{
// In the join free case, we also need to move bDest right after bNext
// to create same flow as in the isJumpAroundEmpty case.
// However, we cannot move bDest if it will break EH invariants.
//
if (!fgEhAllowsMoveBlock(bNext, bDest) || bDest->isBBCallFinallyPair())
if (!BasicBlock::sameEHRegion(bNext, bDest) || bbIsTryBeg(bDest) || bbIsHandlerBeg(bDest) ||
bDest->isBBCallFinallyPair())
{
optimizeJump = false;
}
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