From d1ffc739c1f88352c79a63ff17b828b3a529777e Mon Sep 17 00:00:00 2001 From: Pete Cooper Date: Thu, 3 Nov 2011 00:56:36 +0000 Subject: Treat objc selector reference globals as invariant so that MachineLICM can hoist them out of loops. Fixes git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@143600 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/CodeGen/MachineInstr.cpp | 15 +++++++++++++++ 1 file changed, 15 insertions(+) (limited to 'lib/CodeGen/MachineInstr.cpp') diff --git a/lib/CodeGen/MachineInstr.cpp b/lib/CodeGen/MachineInstr.cpp index a240667f7d..a2fd3c46bf 100644 --- a/lib/CodeGen/MachineInstr.cpp +++ b/lib/CodeGen/MachineInstr.cpp @@ -1232,6 +1232,19 @@ bool MachineInstr::hasVolatileMemoryRef() const { return false; } +/// pointsToRuntimeConstantMemory - Return true if this value points to data +/// which does never changes once the program starts running +static bool pointsToRuntimeConstantMemory(const Value *V) { + if (const GlobalVariable *GV = dyn_cast(V)) { + StringRef Name = GV->getName(); + // These special values are known to be constant at runtime + // TODO: a new linkage type for these would be far better than this check + if (Name.startswith("\01L_OBJC_SELECTOR_REFERENCES_")) + return true; + } + return false; +} + /// isInvariantLoad - Return true if this instruction is loading from a /// location whose value is invariant across the function. For example, /// loading a value from the constant pool or from the argument area @@ -1259,6 +1272,8 @@ bool MachineInstr::isInvariantLoad(AliasAnalysis *AA) const { if (const PseudoSourceValue *PSV = dyn_cast(V)) if (PSV->isConstant(MFI)) continue; + if (pointsToRuntimeConstantMemory(V)) + continue; // If we have an AliasAnalysis, ask it whether the memory is constant. if (AA && AA->pointsToConstantMemory( AliasAnalysis::Location(V, (*I)->getSize(), -- cgit v1.2.3-70-g09d2