diff options
Diffstat (limited to 'llvm/lib/CodeGen/TailDuplicator.cpp')
| -rw-r--r-- | llvm/lib/CodeGen/TailDuplicator.cpp | 18 |
1 files changed, 11 insertions, 7 deletions
diff --git a/llvm/lib/CodeGen/TailDuplicator.cpp b/llvm/lib/CodeGen/TailDuplicator.cpp index a88c57f..5d720fb 100644 --- a/llvm/lib/CodeGen/TailDuplicator.cpp +++ b/llvm/lib/CodeGen/TailDuplicator.cpp @@ -604,12 +604,21 @@ bool TailDuplicator::shouldTailDuplicate(bool IsSimple, bool HasComputedGoto = false; if (!TailBB.empty()) { HasIndirectbr = TailBB.back().isIndirectBranch(); - HasComputedGoto = TailBB.terminatorIsComputedGoto(); + HasComputedGoto = TailBB.terminatorIsComputedGotoWithSuccessors(); } if (HasIndirectbr && PreRegAlloc) MaxDuplicateCount = TailDupIndirectBranchSize; + // Allow higher limits when the block has computed-gotos and running after + // register allocation. NB. This basically unfactors computed gotos that were + // factored early on in the compilation process to speed up edge based data + // flow. If we do not unfactor them again, it can seriously pessimize code + // with many computed jumps in the source code, such as interpreters. + // Therefore we do not restrict the computed gotos. + if (HasComputedGoto && !PreRegAlloc) + MaxDuplicateCount = std::max(MaxDuplicateCount, 10u); + // Check the instructions in the block to determine whether tail-duplication // is invalid or unlikely to be profitable. unsigned InstrCount = 0; @@ -663,12 +672,7 @@ bool TailDuplicator::shouldTailDuplicate(bool IsSimple, // Duplicating a BB which has both multiple predecessors and successors will // may cause huge amount of PHI nodes. If we want to remove this limitation, // we have to address https://github.com/llvm/llvm-project/issues/78578. - // NB. This basically unfactors computed gotos that were factored early on in - // the compilation process to speed up edge based data flow. If we do not - // unfactor them again, it can seriously pessimize code with many computed - // jumps in the source code, such as interpreters. Therefore we do not - // restrict the computed gotos. - if (!HasComputedGoto && TailBB.pred_size() > TailDupPredSize && + if (PreRegAlloc && TailBB.pred_size() > TailDupPredSize && TailBB.succ_size() > TailDupSuccSize) { // If TailBB or any of its successors contains a phi, we may have to add a // large number of additional phis with additional incoming values. |