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[CGP] Do not eliminate blocks which have their address taken #163962

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[CGP] Do not eliminate blocks which have their address taken #163962

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6 changes: 6 additions & 0 deletions llvm/lib/CodeGen/CodeGenPrepare.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -954,6 +954,12 @@ bool CodeGenPrepare::eliminateMostlyEmptyBlocks(Function &F) {
bool CodeGenPrepare::isMergingEmptyBlockProfitable(BasicBlock *BB,
BasicBlock *DestBB,
bool isPreheader) {
// Do not eliminate blocks which have their address taken.
// This could lead to updates across functions which is problematic in a
// function pass like codegenprepare. The update to a blockaddress in a
// function defined before the function with the eliminated block is lost.
if(BB->hasAddressTaken()) return false;

// Do not delete loop preheaders if doing so would create a critical edge.
// Loop preheaders can be good locations to spill registers. If the
// preheader is deleted and we create a critical edge, registers may be
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