diff options
Diffstat (limited to 'release_23/lib/Target/PowerPC/PPCBranchSelector.cpp')
| -rw-r--r-- | release_23/lib/Target/PowerPC/PPCBranchSelector.cpp | 173 |
1 files changed, 0 insertions, 173 deletions
diff --git a/release_23/lib/Target/PowerPC/PPCBranchSelector.cpp b/release_23/lib/Target/PowerPC/PPCBranchSelector.cpp deleted file mode 100644 index ab988ba823ee..000000000000 --- a/release_23/lib/Target/PowerPC/PPCBranchSelector.cpp +++ /dev/null @@ -1,173 +0,0 @@ -//===-- PPCBranchSelector.cpp - Emit long conditional branches-----*- C++ -*-=// -// -// The LLVM Compiler Infrastructure -// -// This file is distributed under the University of Illinois Open Source -// License. See LICENSE.TXT for details. -// -//===----------------------------------------------------------------------===// -// -// This file contains a pass that scans a machine function to determine which -// conditional branches need more than 16 bits of displacement to reach their -// target basic block. It does this in two passes; a calculation of basic block -// positions pass, and a branch psuedo op to machine branch opcode pass. This -// pass should be run last, just before the assembly printer. -// -//===----------------------------------------------------------------------===// - -#define DEBUG_TYPE "ppc-branch-select" -#include "PPC.h" -#include "PPCInstrBuilder.h" -#include "PPCInstrInfo.h" -#include "PPCPredicates.h" -#include "llvm/CodeGen/MachineFunctionPass.h" -#include "llvm/Target/TargetMachine.h" -#include "llvm/ADT/Statistic.h" -#include "llvm/Support/Compiler.h" -#include "llvm/Support/MathExtras.h" -using namespace llvm; - -STATISTIC(NumExpanded, "Number of branches expanded to long format"); - -namespace { - struct VISIBILITY_HIDDEN PPCBSel : public MachineFunctionPass { - static char ID; - PPCBSel() : MachineFunctionPass((intptr_t)&ID) {} - - /// BlockSizes - The sizes of the basic blocks in the function. - std::vector<unsigned> BlockSizes; - - virtual bool runOnMachineFunction(MachineFunction &Fn); - - virtual const char *getPassName() const { - return "PowerPC Branch Selector"; - } - }; - char PPCBSel::ID = 0; -} - -/// createPPCBranchSelectionPass - returns an instance of the Branch Selection -/// Pass -/// -FunctionPass *llvm::createPPCBranchSelectionPass() { - return new PPCBSel(); -} - -bool PPCBSel::runOnMachineFunction(MachineFunction &Fn) { - const TargetInstrInfo *TII = Fn.getTarget().getInstrInfo(); - // Give the blocks of the function a dense, in-order, numbering. - Fn.RenumberBlocks(); - BlockSizes.resize(Fn.getNumBlockIDs()); - - // Measure each MBB and compute a size for the entire function. - unsigned FuncSize = 0; - for (MachineFunction::iterator MFI = Fn.begin(), E = Fn.end(); MFI != E; - ++MFI) { - MachineBasicBlock *MBB = MFI; - - unsigned BlockSize = 0; - for (MachineBasicBlock::iterator MBBI = MBB->begin(), EE = MBB->end(); - MBBI != EE; ++MBBI) - BlockSize += TII->GetInstSizeInBytes(MBBI); - - BlockSizes[MBB->getNumber()] = BlockSize; - FuncSize += BlockSize; - } - - // If the entire function is smaller than the displacement of a branch field, - // we know we don't need to shrink any branches in this function. This is a - // common case. - if (FuncSize < (1 << 15)) { - BlockSizes.clear(); - return false; - } - - // For each conditional branch, if the offset to its destination is larger - // than the offset field allows, transform it into a long branch sequence - // like this: - // short branch: - // bCC MBB - // long branch: - // b!CC $PC+8 - // b MBB - // - bool MadeChange = true; - bool EverMadeChange = false; - while (MadeChange) { - // Iteratively expand branches until we reach a fixed point. - MadeChange = false; - - for (MachineFunction::iterator MFI = Fn.begin(), E = Fn.end(); MFI != E; - ++MFI) { - MachineBasicBlock &MBB = *MFI; - unsigned MBBStartOffset = 0; - for (MachineBasicBlock::iterator I = MBB.begin(), E = MBB.end(); - I != E; ++I) { - if (I->getOpcode() != PPC::BCC || I->getOperand(2).isImmediate()) { - MBBStartOffset += TII->GetInstSizeInBytes(I); - continue; - } - - // Determine the offset from the current branch to the destination - // block. - MachineBasicBlock *Dest = I->getOperand(2).getMBB(); - - int BranchSize; - if (Dest->getNumber() <= MBB.getNumber()) { - // If this is a backwards branch, the delta is the offset from the - // start of this block to this branch, plus the sizes of all blocks - // from this block to the dest. - BranchSize = MBBStartOffset; - - for (unsigned i = Dest->getNumber(), e = MBB.getNumber(); i != e; ++i) - BranchSize += BlockSizes[i]; - } else { - // Otherwise, add the size of the blocks between this block and the - // dest to the number of bytes left in this block. - BranchSize = -MBBStartOffset; - - for (unsigned i = MBB.getNumber(), e = Dest->getNumber(); i != e; ++i) - BranchSize += BlockSizes[i]; - } - - // If this branch is in range, ignore it. - if (isInt16(BranchSize)) { - MBBStartOffset += 4; - continue; - } - - // Otherwise, we have to expand it to a long branch. - // The BCC operands are: - // 0. PPC branch predicate - // 1. CR register - // 2. Target MBB - PPC::Predicate Pred = (PPC::Predicate)I->getOperand(0).getImm(); - unsigned CRReg = I->getOperand(1).getReg(); - - MachineInstr *OldBranch = I; - - // Jump over the uncond branch inst (i.e. $PC+8) on opposite condition. - BuildMI(MBB, I, TII->get(PPC::BCC)) - .addImm(PPC::InvertPredicate(Pred)).addReg(CRReg).addImm(2); - - // Uncond branch to the real destination. - I = BuildMI(MBB, I, TII->get(PPC::B)).addMBB(Dest); - - // Remove the old branch from the function. - OldBranch->eraseFromParent(); - - // Remember that this instruction is 8-bytes, increase the size of the - // block by 4, remember to iterate. - BlockSizes[MBB.getNumber()] += 4; - MBBStartOffset += 8; - ++NumExpanded; - MadeChange = true; - } - } - EverMadeChange |= MadeChange; - } - - BlockSizes.clear(); - return true; -} - |