diff options
| -rw-r--r-- | llvm/lib/Transforms/Utils/PromoteMemoryToRegister.cpp | 54 |
1 files changed, 31 insertions, 23 deletions
diff --git a/llvm/lib/Transforms/Utils/PromoteMemoryToRegister.cpp b/llvm/lib/Transforms/Utils/PromoteMemoryToRegister.cpp index f703481e4ba..5ee812bbe88 100644 --- a/llvm/lib/Transforms/Utils/PromoteMemoryToRegister.cpp +++ b/llvm/lib/Transforms/Utils/PromoteMemoryToRegister.cpp @@ -339,9 +339,15 @@ static void removeLifetimeIntrinsicUsers(AllocaInst *AI) { } } -/// If there is only a single store to this value, replace any loads of it that -/// are directly dominated by the definition with the value stored. -static void rewriteSingleStoreAlloca(AllocaInst *AI, AllocaInfo &Info, +/// \brief Rewrite as many loads as possible given a single store. +/// +/// When there is only a single store, we can use the domtree to trivially +/// replace all of the dominated loads with the stored value. Do so, and return +/// true if this has successfully promoted the alloca entirely. If this returns +/// false there were some loads which were not dominated by the single store +/// and thus must be phi-ed with undef. We fall back to the standard alloca +/// promotion algorithm in that case. +static bool rewriteSingleStoreAlloca(AllocaInst *AI, AllocaInfo &Info, LargeBlockInfo &LBI, DominatorTree &DT, AliasSetTracker *AST) { @@ -401,6 +407,27 @@ static void rewriteSingleStoreAlloca(AllocaInst *AI, AllocaInfo &Info, LI->eraseFromParent(); LBI.deleteValue(LI); } + + // Finally, after the scan, check to see if the store is all that is left. + if (!Info.UsingBlocks.empty()) + return false; // If not, we'll have to fall back for the remainder. + + // Record debuginfo for the store and remove the declaration's + // debuginfo. + if (DbgDeclareInst *DDI = Info.DbgDeclare) { + DIBuilder DIB(*AI->getParent()->getParent()->getParent()); + ConvertDebugDeclareToDebugValue(DDI, Info.OnlyStore, DIB); + DDI->eraseFromParent(); + } + // Remove the (now dead) store and alloca. + Info.OnlyStore->eraseFromParent(); + LBI.deleteValue(Info.OnlyStore); + + if (AST) + AST->deleteValue(AI); + AI->eraseFromParent(); + LBI.deleteValue(AI); + return true; } namespace { @@ -537,28 +564,9 @@ void PromoteMem2Reg::run() { // If there is only a single store to this value, replace any loads of // it that are directly dominated by the definition with the value stored. if (Info.DefiningBlocks.size() == 1) { - rewriteSingleStoreAlloca(AI, Info, LBI, DT, AST); - - // Finally, after the scan, check to see if the store is all that is left. - if (Info.UsingBlocks.empty()) { - // Record debuginfo for the store and remove the declaration's - // debuginfo. - if (DbgDeclareInst *DDI = Info.DbgDeclare) { - ConvertDebugDeclareToDebugValue(DDI, Info.OnlyStore, DIB); - DDI->eraseFromParent(); - } - // Remove the (now dead) store and alloca. - Info.OnlyStore->eraseFromParent(); - LBI.deleteValue(Info.OnlyStore); - - if (AST) - AST->deleteValue(AI); - AI->eraseFromParent(); - LBI.deleteValue(AI); - + if (rewriteSingleStoreAlloca(AI, Info, LBI, DT, AST)) { // The alloca has been processed, move on. RemoveFromAllocasList(AllocaNum); - ++NumSingleStore; continue; } |
