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[PlaceSafepoints] Entry safepoint location doesn't need to be a terminator

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Long ago, the poll insertion code assumed that the insertion site was a terminator.  As a result, the entry selection code would split a basic block to ensure it could pass a terminator.  The insertion code was updated quite a while ago - possibly before it ever landed upstream - but the now redundant work was never removed.  

While I'm at it, remove a comment which doesn't apply to the upstreamed code.  

NFC intended.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@238254 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Philip Reames 2015-05-26 21:16:42 +00:00
parent d59f970668
commit 90b5eb2319
1 changed files with 1 additions and 17 deletions
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18
lib/Transforms/Scalar/PlaceSafepoints.cpp
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@ -417,12 +417,6 @@ static Instruction *findLocationForEntrySafepoint(Function &F,
// that can grow the stack. This, combined with backedge polls,
// give us all the progress guarantees we need.
// Due to the way the frontend generates IR, we may have a couple of initial
// basic blocks before the first bytecode. These will be single-entry
// single-exit blocks which conceptually are just part of the first 'real
// basic block'. Since we don't have deopt state until the first bytecode,
// walk forward until we've found the first unconditional branch or merge.
// hasNextInstruction and nextInstruction are used to iterate
// through a "straight line" execution sequence.
@ -465,17 +459,7 @@ static Instruction *findLocationForEntrySafepoint(Function &F,
assert((hasNextInstruction(cursor) || cursor->isTerminator()) &&
"either we stopped because of a call, or because of terminator");
if (cursor->isTerminator()) {
return cursor;
}
BasicBlock *BB = cursor->getParent();
SplitBlock(BB, cursor, &DT);
// SplitBlock updates the DT
DEBUG(DT.verifyDomTree());
return BB->getTerminator();
return cursor;
}
/// Identify the list of call sites which need to be have parseable state