-//===-- PPCBranchSelector.cpp - Emit long conditional branches-----*- C++ -*-=//
+//===-- PPCBranchSelector.cpp - Emit long conditional branches ------------===//
//
// The LLVM Compiler Infrastructure
//
-// This file was developed by Nate Baegeman and is distributed under the
-// University of Illinois Open Source License. See LICENSE.TXT for details.
+// 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
+// positions pass, and a branch pseudo op to machine branch opcode pass. This
// pass should be run last, just before the assembly printer.
//
//===----------------------------------------------------------------------===//
#include "PPC.h"
+#include "MCTargetDesc/PPCPredicates.h"
#include "PPCInstrBuilder.h"
#include "PPCInstrInfo.h"
-#include "PPCPredicates.h"
-#include "llvm/CodeGen/MachineFunctionPass.h"
-#include "llvm/Target/TargetMachine.h"
-#include "llvm/Target/TargetAsmInfo.h"
#include "llvm/ADT/Statistic.h"
-#include "llvm/Support/Compiler.h"
+#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/Support/MathExtras.h"
+#include "llvm/Target/TargetMachine.h"
+#include "llvm/Target/TargetSubtargetInfo.h"
using namespace llvm;
-static Statistic NumExpanded("ppc-branch-select",
- "Num branches expanded to long format");
+#define DEBUG_TYPE "ppc-branch-select"
+
+STATISTIC(NumExpanded, "Number of branches expanded to long format");
+
+namespace llvm {
+ void initializePPCBSelPass(PassRegistry&);
+}
namespace {
- struct VISIBILITY_HIDDEN PPCBSel : public MachineFunctionPass {
+ struct PPCBSel : public MachineFunctionPass {
+ static char ID;
+ PPCBSel() : MachineFunctionPass(ID) {
+ initializePPCBSelPass(*PassRegistry::getPassRegistry());
+ }
+
/// BlockSizes - The sizes of the basic blocks in the function.
std::vector<unsigned> BlockSizes;
- virtual bool runOnMachineFunction(MachineFunction &Fn);
+ bool runOnMachineFunction(MachineFunction &Fn) override;
- virtual const char *getPassName() const {
+ const char *getPassName() const override {
return "PowerPC Branch Selector";
}
};
+ char PPCBSel::ID = 0;
}
+INITIALIZE_PASS(PPCBSel, "ppc-branch-select", "PowerPC Branch Selector",
+ false, false)
+
/// createPPCBranchSelectionPass - returns an instance of the Branch Selection
/// Pass
///
return new PPCBSel();
}
-/// getNumBytesForInstruction - Return the number of bytes of code the specified
-/// instruction may be. This returns the maximum number of bytes.
-///
-static unsigned getNumBytesForInstruction(MachineInstr *MI) {
- switch (MI->getOpcode()) {
- case PPC::IMPLICIT_DEF_GPRC: // no asm emitted
- case PPC::IMPLICIT_DEF_G8RC: // no asm emitted
- case PPC::IMPLICIT_DEF_F4: // no asm emitted
- case PPC::IMPLICIT_DEF_F8: // no asm emitted
- case PPC::IMPLICIT_DEF_VRRC: // no asm emitted
- return 0;
- case PPC::INLINEASM: { // Inline Asm: Variable size.
- MachineFunction *MF = MI->getParent()->getParent();
- const char *AsmStr = MI->getOperand(0).getSymbolName();
- return MF->getTarget().getTargetAsmInfo()->getInlineAsmLength(AsmStr);
- }
- default:
- return 4; // PowerPC instructions are all 4 bytes
- }
-}
-
-
bool PPCBSel::runOnMachineFunction(MachineFunction &Fn) {
- const TargetInstrInfo *TII = Fn.getTarget().getInstrInfo();
+ const PPCInstrInfo *TII =
+ static_cast<const PPCInstrInfo *>(Fn.getSubtarget().getInstrInfo());
// Give the blocks of the function a dense, in-order, numbering.
Fn.RenumberBlocks();
BlockSizes.resize(Fn.getNumBlockIDs());
+ auto GetAlignmentAdjustment =
+ [TII](MachineBasicBlock &MBB, unsigned Offset) -> unsigned {
+ unsigned Align = MBB.getAlignment();
+ if (!Align)
+ return 0;
+
+ unsigned AlignAmt = 1 << Align;
+ unsigned ParentAlign = MBB.getParent()->getAlignment();
+
+ if (Align <= ParentAlign)
+ return OffsetToAlignment(Offset, AlignAmt);
+
+ // The alignment of this MBB is larger than the function's alignment, so we
+ // can't tell whether or not it will insert nops. Assume that it will.
+ return AlignAmt + OffsetToAlignment(Offset, AlignAmt);
+ };
+
// 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;
+ // The end of the previous block may have extra nops if this block has an
+ // alignment requirement.
+ if (MBB->getNumber() > 0) {
+ unsigned AlignExtra = GetAlignmentAdjustment(*MBB, FuncSize);
+ BlockSizes[MBB->getNumber()-1] += AlignExtra;
+ FuncSize += AlignExtra;
+ }
+
unsigned BlockSize = 0;
for (MachineBasicBlock::iterator MBBI = MBB->begin(), EE = MBB->end();
MBBI != EE; ++MBBI)
- BlockSize += getNumBytesForInstruction(MBBI);
+ BlockSize += TII->GetInstSizeInBytes(MBBI);
BlockSizes[MBB->getNumber()] = BlockSize;
FuncSize += BlockSize;
unsigned MBBStartOffset = 0;
for (MachineBasicBlock::iterator I = MBB.begin(), E = MBB.end();
I != E; ++I) {
- if (I->getOpcode() != PPC::BCC || I->getOperand(2).isImm()) {
- MBBStartOffset += getNumBytesForInstruction(I);
+ MachineBasicBlock *Dest = nullptr;
+ if (I->getOpcode() == PPC::BCC && !I->getOperand(2).isImm())
+ Dest = I->getOperand(2).getMBB();
+ else if ((I->getOpcode() == PPC::BC || I->getOpcode() == PPC::BCn) &&
+ !I->getOperand(1).isImm())
+ Dest = I->getOperand(1).getMBB();
+ else if ((I->getOpcode() == PPC::BDNZ8 || I->getOpcode() == PPC::BDNZ ||
+ I->getOpcode() == PPC::BDZ8 || I->getOpcode() == PPC::BDZ) &&
+ !I->getOperand(0).isImm())
+ Dest = I->getOperand(0).getMBB();
+
+ if (!Dest) {
+ MBBStartOffset += TII->GetInstSizeInBytes(I);
continue;
}
// Determine the offset from the current branch to the destination
// block.
- MachineBasicBlock *Dest = I->getOperand(2).getMachineBasicBlock();
-
int BranchSize;
if (Dest->getNumber() <= MBB.getNumber()) {
// If this is a backwards branch, the delta is the offset from the
}
// If this branch is in range, ignore it.
- if (isInt16(BranchSize)) {
+ if (isInt<16>(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);
+ DebugLoc dl = OldBranch->getDebugLoc();
+
+ if (I->getOpcode() == PPC::BCC) {
+ // 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();
+
+ // Jump over the uncond branch inst (i.e. $PC+8) on opposite condition.
+ BuildMI(MBB, I, dl, TII->get(PPC::BCC))
+ .addImm(PPC::InvertPredicate(Pred)).addReg(CRReg).addImm(2);
+ } else if (I->getOpcode() == PPC::BC) {
+ unsigned CRBit = I->getOperand(0).getReg();
+ BuildMI(MBB, I, dl, TII->get(PPC::BCn)).addReg(CRBit).addImm(2);
+ } else if (I->getOpcode() == PPC::BCn) {
+ unsigned CRBit = I->getOperand(0).getReg();
+ BuildMI(MBB, I, dl, TII->get(PPC::BC)).addReg(CRBit).addImm(2);
+ } else if (I->getOpcode() == PPC::BDNZ) {
+ BuildMI(MBB, I, dl, TII->get(PPC::BDZ)).addImm(2);
+ } else if (I->getOpcode() == PPC::BDNZ8) {
+ BuildMI(MBB, I, dl, TII->get(PPC::BDZ8)).addImm(2);
+ } else if (I->getOpcode() == PPC::BDZ) {
+ BuildMI(MBB, I, dl, TII->get(PPC::BDNZ)).addImm(2);
+ } else if (I->getOpcode() == PPC::BDZ8) {
+ BuildMI(MBB, I, dl, TII->get(PPC::BDNZ8)).addImm(2);
+ } else {
+ llvm_unreachable("Unhandled branch type!");
+ }
// Uncond branch to the real destination.
- I = BuildMI(MBB, I, TII->get(PPC::B)).addMBB(Dest);
+ I = BuildMI(MBB, I, dl, TII->get(PPC::B)).addMBB(Dest);
// Remove the old branch from the function.
OldBranch->eraseFromParent();
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