X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FCodeGen%2FPrologEpilogInserter.cpp;h=76583f0de888cef8c84d5fab4a45cb15c74ec6b0;hb=e903f64b10dc61461b135425460efb63346f0fed;hp=5334a633ead77c922a9d5ccfb88d8f9bfc7e1b38;hpb=0a8ff297adf36a0a01d1e2dce80857e6b258a023;p=oota-llvm.git diff --git a/lib/CodeGen/PrologEpilogInserter.cpp b/lib/CodeGen/PrologEpilogInserter.cpp index 5334a633ead..76583f0de88 100644 --- a/lib/CodeGen/PrologEpilogInserter.cpp +++ b/lib/CodeGen/PrologEpilogInserter.cpp @@ -71,9 +71,9 @@ private: // stack frame indexes. unsigned MinCSFrameIndex, MaxCSFrameIndex; - // Entry and return blocks of the current function. - MachineBasicBlock *EntryBlock; - SmallVector ReturnBlocks; + // Save and Restore blocks of the current function. + MachineBasicBlock *SaveBlock; + SmallVector RestoreBlocks; // Flag to control whether to use the register scavenger to resolve // frame index materialization registers. Set according to @@ -133,20 +133,26 @@ bool PEI::isReturnBlock(MachineBasicBlock* MBB) { /// Compute the set of return blocks void PEI::calculateSets(MachineFunction &Fn) { - // Sets used to compute spill, restore placement sets. - const std::vector &CSI = - Fn.getFrameInfo()->getCalleeSavedInfo(); + const MachineFrameInfo *MFI = Fn.getFrameInfo(); - // If no CSRs used, we are done. - if (CSI.empty()) + // Even when we do not change any CSR, we still want to insert the + // prologue and epilogue of the function. + // So set the save points for those. + + // Use the points found by shrink-wrapping, if any. + if (MFI->getSavePoint()) { + SaveBlock = MFI->getSavePoint(); + assert(MFI->getRestorePoint() && "Both restore and save must be set"); + RestoreBlocks.push_back(MFI->getRestorePoint()); return; + } // Save refs to entry and return blocks. - EntryBlock = Fn.begin(); + SaveBlock = Fn.begin(); for (MachineFunction::iterator MBB = Fn.begin(), E = Fn.end(); MBB != E; ++MBB) if (isReturnBlock(MBB)) - ReturnBlocks.push_back(MBB); + RestoreBlocks.push_back(MBB); return; } @@ -226,7 +232,7 @@ bool PEI::runOnMachineFunction(MachineFunction &Fn) { } delete RS; - ReturnBlocks.clear(); + RestoreBlocks.clear(); return true; } @@ -242,12 +248,12 @@ void PEI::calculateCallsInformation(MachineFunction &Fn) { bool AdjustsStack = MFI->adjustsStack(); // Get the function call frame set-up and tear-down instruction opcode - int FrameSetupOpcode = TII.getCallFrameSetupOpcode(); - int FrameDestroyOpcode = TII.getCallFrameDestroyOpcode(); + unsigned FrameSetupOpcode = TII.getCallFrameSetupOpcode(); + unsigned FrameDestroyOpcode = TII.getCallFrameDestroyOpcode(); // Early exit for targets which have no call frame setup/destroy pseudo // instructions. - if (FrameSetupOpcode == -1 && FrameDestroyOpcode == -1) + if (FrameSetupOpcode == ~0u && FrameDestroyOpcode == ~0u) return; std::vector FrameSDOps; @@ -372,6 +378,61 @@ void PEI::calculateCalleeSavedRegisters(MachineFunction &F) { MFI->setCalleeSavedInfo(CSI); } +/// Helper function to update the liveness information for the callee-saved +/// registers. +static void updateLiveness(MachineFunction &MF) { + MachineFrameInfo *MFI = MF.getFrameInfo(); + // Visited will contain all the basic blocks that are in the region + // where the callee saved registers are alive: + // - Anything that is not Save or Restore -> LiveThrough. + // - Save -> LiveIn. + // - Restore -> LiveOut. + // The live-out is not attached to the block, so no need to keep + // Restore in this set. + SmallPtrSet Visited; + SmallVector WorkList; + MachineBasicBlock *Entry = &MF.front(); + MachineBasicBlock *Save = MFI->getSavePoint(); + + if (!Save) + Save = Entry; + + if (Entry != Save) { + WorkList.push_back(Entry); + Visited.insert(Entry); + } + Visited.insert(Save); + + MachineBasicBlock *Restore = MFI->getRestorePoint(); + if (Restore) + // By construction Restore cannot be visited, otherwise it + // means there exists a path to Restore that does not go + // through Save. + WorkList.push_back(Restore); + + while (!WorkList.empty()) { + const MachineBasicBlock *CurBB = WorkList.pop_back_val(); + // By construction, the region that is after the save point is + // dominated by the Save and post-dominated by the Restore. + if (CurBB == Save) + continue; + // Enqueue all the successors not already visited. + // Those are by construction either before Save or after Restore. + for (MachineBasicBlock *SuccBB : CurBB->successors()) + if (Visited.insert(SuccBB).second) + WorkList.push_back(SuccBB); + } + + const std::vector &CSI = MFI->getCalleeSavedInfo(); + + for (unsigned i = 0, e = CSI.size(); i != e; ++i) { + for (MachineBasicBlock *MBB : Visited) + // Add the callee-saved register as live-in. + // It's killed at the spill. + MBB->addLiveIn(CSI[i].getReg()); + } +} + /// insertCSRSpillsAndRestores - Insert spill and restore code for /// callee saved registers used in the function. /// @@ -392,26 +453,22 @@ void PEI::insertCSRSpillsAndRestores(MachineFunction &Fn) { MachineBasicBlock::iterator I; // Spill using target interface. - I = EntryBlock->begin(); - if (!TFI->spillCalleeSavedRegisters(*EntryBlock, I, CSI, TRI)) { + I = SaveBlock->begin(); + if (!TFI->spillCalleeSavedRegisters(*SaveBlock, I, CSI, TRI)) { for (unsigned i = 0, e = CSI.size(); i != e; ++i) { - // Add the callee-saved register as live-in. - // It's killed at the spill. - EntryBlock->addLiveIn(CSI[i].getReg()); - // Insert the spill to the stack frame. unsigned Reg = CSI[i].getReg(); const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg); - TII.storeRegToStackSlot(*EntryBlock, I, Reg, true, CSI[i].getFrameIdx(), + TII.storeRegToStackSlot(*SaveBlock, I, Reg, true, CSI[i].getFrameIdx(), RC, TRI); } } + // Update the live-in information of all the blocks up to the save point. + updateLiveness(Fn); // Restore using target interface. - for (unsigned ri = 0, re = ReturnBlocks.size(); ri != re; ++ri) { - MachineBasicBlock *MBB = ReturnBlocks[ri]; + for (MachineBasicBlock *MBB : RestoreBlocks) { I = MBB->end(); - --I; // Skip over all terminator instructions, which are part of the return // sequence. @@ -721,21 +778,18 @@ void PEI::insertPrologEpilogCode(MachineFunction &Fn) { const TargetFrameLowering &TFI = *Fn.getSubtarget().getFrameLowering(); // Add prologue to the function... - TFI.emitPrologue(Fn); + TFI.emitPrologue(Fn, *SaveBlock); - // Add epilogue to restore the callee-save registers in each exiting block - for (MachineFunction::iterator I = Fn.begin(), E = Fn.end(); I != E; ++I) { - // If last instruction is a return instruction, add an epilogue - if (!I->empty() && I->back().isReturn()) - TFI.emitEpilogue(Fn, *I); - } + // Add epilogue to restore the callee-save registers in each exiting block. + for (MachineBasicBlock *RestoreBlock : RestoreBlocks) + TFI.emitEpilogue(Fn, *RestoreBlock); // Emit additional code that is required to support segmented stacks, if // we've been asked for it. This, when linked with a runtime with support // for segmented stacks (libgcc is one), will result in allocating stack // space in small chunks instead of one large contiguous block. if (Fn.shouldSplitStack()) - TFI.adjustForSegmentedStacks(Fn); + TFI.adjustForSegmentedStacks(Fn, *SaveBlock); // Emit additional code that is required to explicitly handle the stack in // HiPE native code (if needed) when loaded in the Erlang/OTP runtime. The @@ -743,7 +797,7 @@ void PEI::insertPrologEpilogCode(MachineFunction &Fn) { // different conditional check and another BIF for allocating more stack // space. if (Fn.getFunction()->getCallingConv() == CallingConv::HiPE) - TFI.adjustForHiPEPrologue(Fn); + TFI.adjustForHiPEPrologue(Fn, *SaveBlock); } /// replaceFrameIndices - Replace all MO_FrameIndex operands with physical @@ -810,8 +864,8 @@ void PEI::replaceFrameIndices(MachineBasicBlock *BB, MachineFunction &Fn, const TargetInstrInfo &TII = *Fn.getSubtarget().getInstrInfo(); const TargetRegisterInfo &TRI = *Fn.getSubtarget().getRegisterInfo(); const TargetFrameLowering *TFI = Fn.getSubtarget().getFrameLowering(); - int FrameSetupOpcode = TII.getCallFrameSetupOpcode(); - int FrameDestroyOpcode = TII.getCallFrameDestroyOpcode(); + unsigned FrameSetupOpcode = TII.getCallFrameSetupOpcode(); + unsigned FrameDestroyOpcode = TII.getCallFrameDestroyOpcode(); if (RS && !FrameIndexVirtualScavenging) RS->enterBasicBlock(BB);