diff options
| -rw-r--r-- | llvm/lib/CodeGen/CodeGenPrepare.cpp | 17 |
1 files changed, 13 insertions, 4 deletions
diff --git a/llvm/lib/CodeGen/CodeGenPrepare.cpp b/llvm/lib/CodeGen/CodeGenPrepare.cpp index 45dc13d58de..dc02a00e0fc 100644 --- a/llvm/lib/CodeGen/CodeGenPrepare.cpp +++ b/llvm/lib/CodeGen/CodeGenPrepare.cpp @@ -4016,14 +4016,18 @@ static bool IsOperandAMemoryOperand(CallInst *CI, InlineAsm *IA, Value *OpVal, return true; } +// Max number of memory uses to look at before aborting the search to conserve +// compile time. +static constexpr int MaxMemoryUsesToScan = 20; + /// Recursively walk all the uses of I until we find a memory use. /// If we find an obviously non-foldable instruction, return true. /// Add the ultimately found memory instructions to MemoryUses. static bool FindAllMemoryUses( Instruction *I, SmallVectorImpl<std::pair<Instruction *, unsigned>> &MemoryUses, - SmallPtrSetImpl<Instruction *> &ConsideredInsts, - const TargetLowering &TLI, const TargetRegisterInfo &TRI) { + SmallPtrSetImpl<Instruction *> &ConsideredInsts, const TargetLowering &TLI, + const TargetRegisterInfo &TRI, int SeenInsts = 0) { // If we already considered this instruction, we're done. if (!ConsideredInsts.insert(I).second) return false; @@ -4036,8 +4040,12 @@ static bool FindAllMemoryUses( // Loop over all the uses, recursively processing them. for (Use &U : I->uses()) { - Instruction *UserI = cast<Instruction>(U.getUser()); + // Conservatively return true if we're seeing a large number or a deep chain + // of users. This avoids excessive compilation times in pathological cases. + if (SeenInsts++ >= MaxMemoryUsesToScan) + return true; + Instruction *UserI = cast<Instruction>(U.getUser()); if (LoadInst *LI = dyn_cast<LoadInst>(UserI)) { MemoryUses.push_back(std::make_pair(LI, U.getOperandNo())); continue; @@ -4082,7 +4090,8 @@ static bool FindAllMemoryUses( continue; } - if (FindAllMemoryUses(UserI, MemoryUses, ConsideredInsts, TLI, TRI)) + if (FindAllMemoryUses(UserI, MemoryUses, ConsideredInsts, TLI, TRI, + SeenInsts)) return true; } |
