diff options
Diffstat (limited to 'llvm/lib')
| -rw-r--r-- | llvm/lib/CodeGen/TailDuplication.cpp | 11 | ||||
| -rw-r--r-- | llvm/lib/Transforms/Utils/SimplifyCFG.cpp | 7 |
2 files changed, 13 insertions, 5 deletions
diff --git a/llvm/lib/CodeGen/TailDuplication.cpp b/llvm/lib/CodeGen/TailDuplication.cpp index ce4b1be8541..15aed3436c7 100644 --- a/llvm/lib/CodeGen/TailDuplication.cpp +++ b/llvm/lib/CodeGen/TailDuplication.cpp @@ -465,9 +465,12 @@ TailDuplicatePass::TailDuplicate(MachineBasicBlock *TailBB, MachineFunction &MF, MaxDuplicateCount = TailDuplicateSize; if (PreRegAlloc) { - // Pre-regalloc tail duplication hurts compile time and doesn't help - // much except for indirect branches. - if (TailBB->empty() || !TailBB->back().getDesc().isIndirectBranch()) + if (TailBB->empty()) + return false; + const TargetInstrDesc &TID = TailBB->back().getDesc(); + // Pre-regalloc tail duplication hurts compile time and doesn't help + // much except for indirect branches and returns. + if (!TID.isIndirectBranch() && !TID.isReturn()) return false; // If the target has hardware branch prediction that can handle indirect // branches, duplicating them can often make them predictable when there @@ -502,7 +505,7 @@ TailDuplicatePass::TailDuplicate(MachineBasicBlock *TailBB, MachineFunction &MF, } // Heuristically, don't tail-duplicate calls if it would expand code size, // as it's less likely to be worth the extra cost. - if (InstrCount > 1 && HasCall) + if (InstrCount > 1 && (PreRegAlloc && HasCall)) return false; DEBUG(dbgs() << "\n*** Tail-duplicating BB#" << TailBB->getNumber() << '\n'); diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp index f6d7d76dbf6..37e6d28d7b0 100644 --- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp +++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp @@ -28,6 +28,7 @@ #include "llvm/ADT/Statistic.h" #include "llvm/ADT/STLExtras.h" #include "llvm/Support/CFG.h" +#include "llvm/Support/CommandLine.h" #include "llvm/Support/ConstantRange.h" #include "llvm/Support/Debug.h" #include "llvm/Support/raw_ostream.h" @@ -36,6 +37,10 @@ #include <map> using namespace llvm; +static cl::opt<bool> +DupRet("simplifycfg-dup-ret", cl::Hidden, cl::init(false), + cl::desc("Duplicate return instructions into unconditional branches")); + STATISTIC(NumSpeculations, "Number of speculative executed instructions"); namespace { @@ -2027,7 +2032,7 @@ bool SimplifyCFGOpt::SimplifyReturn(ReturnInst *RI) { } // If we found some, do the transformation! - if (!UncondBranchPreds.empty()) { + if (!UncondBranchPreds.empty() && DupRet) { while (!UncondBranchPreds.empty()) { BasicBlock *Pred = UncondBranchPreds.pop_back_val(); DEBUG(dbgs() << "FOLDING: " << *BB |
