Hexagon backend support
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@146412 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/Hexagon/HexagonCFGOptimizer.cpp b/lib/Target/Hexagon/HexagonCFGOptimizer.cpp
new file mode 100644
index 0000000..38000e7
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+++ b/lib/Target/Hexagon/HexagonCFGOptimizer.cpp
@@ -0,0 +1,240 @@
+//===---- HexagonCFGOptimizer.cpp - CFG optimizations ---------------------===//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+
+#define DEBUG_TYPE "hexagon_cfg"
+#include "llvm/CodeGen/Passes.h"
+#include "llvm/CodeGen/MachineDominators.h"
+#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineLoopInfo.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/Target/TargetMachine.h"
+#include "llvm/Target/TargetInstrInfo.h"
+#include "llvm/Target/TargetRegisterInfo.h"
+#include "llvm/Support/Compiler.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/Support/MathExtras.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
+#include "HexagonTargetMachine.h"
+#include "HexagonSubtarget.h"
+#include "HexagonMachineFunctionInfo.h"
+#include <iostream>
+
+#include "llvm/Support/CommandLine.h"
+
+using namespace llvm;
+
+namespace {
+
+class HexagonCFGOptimizer : public MachineFunctionPass {
+
+private:
+ HexagonTargetMachine& QTM;
+ const HexagonSubtarget &QST;
+
+ void InvertAndChangeJumpTarget(MachineInstr*, MachineBasicBlock*);
+
+ public:
+ static char ID;
+ HexagonCFGOptimizer(HexagonTargetMachine& TM) : MachineFunctionPass(ID),
+ QTM(TM),
+ QST(*TM.getSubtargetImpl()) {}
+
+ const char *getPassName() const {
+ return "Hexagon CFG Optimizer";
+ }
+ bool runOnMachineFunction(MachineFunction &Fn);
+};
+
+
+char HexagonCFGOptimizer::ID = 0;
+
+static bool IsConditionalBranch(int Opc) {
+ return (Opc == Hexagon::JMP_Pred) || (Opc == Hexagon::JMP_PredNot)
+ || (Opc == Hexagon::JMP_PredPt) || (Opc == Hexagon::JMP_PredNotPt);
+}
+
+
+static bool IsUnconditionalJump(int Opc) {
+ return (Opc == Hexagon::JMP);
+}
+
+
+void
+HexagonCFGOptimizer::InvertAndChangeJumpTarget(MachineInstr* MI,
+ MachineBasicBlock* NewTarget) {
+ const HexagonInstrInfo *QII = QTM.getInstrInfo();
+ int NewOpcode = 0;
+ switch(MI->getOpcode()) {
+ case Hexagon::JMP_Pred:
+ NewOpcode = Hexagon::JMP_PredNot;
+ break;
+
+ case Hexagon::JMP_PredNot:
+ NewOpcode = Hexagon::JMP_Pred;
+ break;
+
+ case Hexagon::JMP_PredPt:
+ NewOpcode = Hexagon::JMP_PredNotPt;
+ break;
+
+ case Hexagon::JMP_PredNotPt:
+ NewOpcode = Hexagon::JMP_PredPt;
+ break;
+
+ default:
+ assert(0 && "Cannot handle this case");
+ }
+
+ MI->setDesc(QII->get(NewOpcode));
+ MI->getOperand(1).setMBB(NewTarget);
+}
+
+
+bool HexagonCFGOptimizer::runOnMachineFunction(MachineFunction &Fn) {
+
+ // Loop over all of the basic blocks.
+ for (MachineFunction::iterator MBBb = Fn.begin(), MBBe = Fn.end();
+ MBBb != MBBe; ++MBBb) {
+ MachineBasicBlock* MBB = MBBb;
+
+ // Traverse the basic block.
+ MachineBasicBlock::iterator MII = MBB->getFirstTerminator();
+ if (MII != MBB->end()) {
+ MachineInstr *MI = MII;
+ int Opc = MI->getOpcode();
+ if (IsConditionalBranch(Opc)) {
+
+ //
+ // (Case 1) Transform the code if the following condition occurs:
+ // BB1: if (p0) jump BB3
+ // ...falls-through to BB2 ...
+ // BB2: jump BB4
+ // ...next block in layout is BB3...
+ // BB3: ...
+ //
+ // Transform this to:
+ // BB1: if (!p0) jump BB4
+ // Remove BB2
+ // BB3: ...
+ //
+ // (Case 2) A variation occurs when BB3 contains a JMP to BB4:
+ // BB1: if (p0) jump BB3
+ // ...falls-through to BB2 ...
+ // BB2: jump BB4
+ // ...other basic blocks ...
+ // BB4:
+ // ...not a fall-thru
+ // BB3: ...
+ // jump BB4
+ //
+ // Transform this to:
+ // BB1: if (!p0) jump BB4
+ // Remove BB2
+ // BB3: ...
+ // BB4: ...
+ //
+ unsigned NumSuccs = MBB->succ_size();
+ MachineBasicBlock::succ_iterator SI = MBB->succ_begin();
+ MachineBasicBlock* FirstSucc = *SI;
+ MachineBasicBlock* SecondSucc = *(++SI);
+ MachineBasicBlock* LayoutSucc = NULL;
+ MachineBasicBlock* JumpAroundTarget = NULL;
+
+ if (MBB->isLayoutSuccessor(FirstSucc)) {
+ LayoutSucc = FirstSucc;
+ JumpAroundTarget = SecondSucc;
+ } else if (MBB->isLayoutSuccessor(SecondSucc)) {
+ LayoutSucc = SecondSucc;
+ JumpAroundTarget = FirstSucc;
+ } else {
+ // Odd case...cannot handle.
+ }
+
+ // The target of the unconditional branch must be JumpAroundTarget.
+ // TODO: If not, we should not invert the unconditional branch.
+ MachineBasicBlock* CondBranchTarget = NULL;
+ if ((MI->getOpcode() == Hexagon::JMP_Pred) ||
+ (MI->getOpcode() == Hexagon::JMP_PredNot)) {
+ CondBranchTarget = MI->getOperand(1).getMBB();
+ }
+
+ if (!LayoutSucc || (CondBranchTarget != JumpAroundTarget)) {
+ continue;
+ }
+
+ if ((NumSuccs == 2) && LayoutSucc && (LayoutSucc->pred_size() == 1)) {
+
+ // Ensure that BB2 has one instruction -- an unconditional jump.
+ if ((LayoutSucc->size() == 1) &&
+ IsUnconditionalJump(LayoutSucc->front().getOpcode())) {
+ MachineBasicBlock* UncondTarget =
+ LayoutSucc->front().getOperand(0).getMBB();
+ // Check if the layout successor of BB2 is BB3.
+ bool case1 = LayoutSucc->isLayoutSuccessor(JumpAroundTarget);
+ bool case2 = JumpAroundTarget->isSuccessor(UncondTarget) &&
+ JumpAroundTarget->size() >= 1 &&
+ IsUnconditionalJump(JumpAroundTarget->back().getOpcode()) &&
+ JumpAroundTarget->pred_size() == 1 &&
+ JumpAroundTarget->succ_size() == 1;
+
+ if (case1 || case2) {
+ InvertAndChangeJumpTarget(MI, UncondTarget);
+ MBB->removeSuccessor(JumpAroundTarget);
+ MBB->addSuccessor(UncondTarget);
+
+ // Remove the unconditional branch in LayoutSucc.
+ LayoutSucc->erase(LayoutSucc->begin());
+ LayoutSucc->removeSuccessor(UncondTarget);
+ LayoutSucc->addSuccessor(JumpAroundTarget);
+
+ // This code performs the conversion for case 2, which moves
+ // the block to the fall-thru case (BB3 in the code above).
+ if (case2 && !case1) {
+ JumpAroundTarget->moveAfter(LayoutSucc);
+ // only move a block if it doesn't have a fall-thru. otherwise
+ // the CFG will be incorrect.
+ if (!UncondTarget->canFallThrough()) {
+ UncondTarget->moveAfter(JumpAroundTarget);
+ }
+ }
+
+ //
+ // Correct live-in information. Is used by post-RA scheduler
+ // The live-in to LayoutSucc is now all values live-in to
+ // JumpAroundTarget.
+ //
+ std::vector<unsigned> OrigLiveIn(LayoutSucc->livein_begin(),
+ LayoutSucc->livein_end());
+ std::vector<unsigned> NewLiveIn(JumpAroundTarget->livein_begin(),
+ JumpAroundTarget->livein_end());
+ for (unsigned i = 0; i < OrigLiveIn.size(); ++i) {
+ LayoutSucc->removeLiveIn(OrigLiveIn[i]);
+ }
+ for (unsigned i = 0; i < NewLiveIn.size(); ++i) {
+ LayoutSucc->addLiveIn(NewLiveIn[i]);
+ }
+ }
+ }
+ }
+ }
+ }
+ }
+ return true;
+}
+}
+
+
+//===----------------------------------------------------------------------===//
+// Public Constructor Functions
+//===----------------------------------------------------------------------===//
+
+FunctionPass *llvm::createHexagonCFGOptimizer(HexagonTargetMachine &TM) {
+ return new HexagonCFGOptimizer(TM);
+}