Remove the --shrink-wrap option.

It had no tests, was unused and was "experimental at best".

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@193749 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/CMakeLists.txt

@@ -89,7 +89,6 @@ add_llvm_library(LLVMCodeGen
   ScheduleDAGPrinter.cpp
   ScoreboardHazardRecognizer.cpp
   ShadowStackGC.cpp
-  ShrinkWrapping.cpp
   SjLjEHPrepare.cpp
   SlotIndexes.cpp
   SpillPlacement.cpp

lib/CodeGen/PrologEpilogInserter.cpp

@@ -14,9 +14,6 @@
 // This pass must be run after register allocation.  After this pass is
 // executed, it is illegal to construct MO_FrameIndex operands.
 //
-// This pass provides an optional shrink wrapping variant of prolog/epilog
-// insertion, enabled via --shrink-wrap. See ShrinkWrapping.cpp.
-//
 //===----------------------------------------------------------------------===//
 
 #define DEBUG_TYPE "pei"
@@ -66,6 +63,38 @@ STATISTIC(NumScavengedRegs, "Number of frame index regs scavenged");
 STATISTIC(NumBytesStackSpace,
           "Number of bytes used for stack in all functions");
 
+void PEI::getAnalysisUsage(AnalysisUsage &AU) const {
+  AU.setPreservesCFG();
+  AU.addPreserved<MachineLoopInfo>();
+  AU.addPreserved<MachineDominatorTree>();
+  AU.addRequired<TargetPassConfig>();
+  MachineFunctionPass::getAnalysisUsage(AU);
+}
+
+bool PEI::isReturnBlock(MachineBasicBlock* MBB) {
+  return (MBB && !MBB->empty() && MBB->back().isReturn());
+}
+
+/// Compute the set of return blocks
+void PEI::calculateSets(MachineFunction &Fn) {
+  // Sets used to compute spill, restore placement sets.
+  const std::vector<CalleeSavedInfo> &CSI =
+    Fn.getFrameInfo()->getCalleeSavedInfo();
+
+  // If no CSRs used, we are done.
+  if (CSI.empty())
+    return;
+
+  // Save refs to entry and return blocks.
+  EntryBlock = Fn.begin();
+  for (MachineFunction::iterator MBB = Fn.begin(), E = Fn.end();
+       MBB != E; ++MBB)
+    if (isReturnBlock(MBB))
+      ReturnBlocks.push_back(MBB);
+
+  return;
+}
+
 /// runOnMachineFunction - Insert prolog/epilog code and replace abstract
 /// frame indexes with appropriate references.
 ///
@@ -93,12 +122,8 @@ bool PEI::runOnMachineFunction(MachineFunction &Fn) {
   calculateCalleeSavedRegisters(Fn);
 
   // Determine placement of CSR spill/restore code:
-  //  - With shrink wrapping, place spills and restores to tightly
-  //    enclose regions in the Machine CFG of the function where
-  //    they are used.
-  //  - Without shink wrapping (default), place all spills in the
-  //    entry block, all restores in return blocks.
-  placeCSRSpillsAndRestores(Fn);
+  // place all spills in the entry block, all restores in return blocks.
+  calculateSets(Fn);
 
   // Add the code to save and restore the callee saved registers
   if (!F->hasFnAttribute(Attribute::Naked))
@@ -141,7 +166,7 @@ bool PEI::runOnMachineFunction(MachineFunction &Fn) {
            << ") in " << Fn.getName()  << ".\n";
 
   delete RS;
-  clearAllSets();
+  ReturnBlocks.clear();
   return true;
 }
 
@@ -283,7 +308,7 @@ void PEI::calculateCalleeSavedRegisters(MachineFunction &F) {
 }
 
 /// insertCSRSpillsAndRestores - Insert spill and restore code for
-/// callee saved registers used in the function, handling shrink wrapping.
+/// callee saved registers used in the function.
 ///
 void PEI::insertCSRSpillsAndRestores(MachineFunction &Fn) {
   // Get callee saved register information.
@@ -301,133 +326,33 @@ void PEI::insertCSRSpillsAndRestores(MachineFunction &Fn) {
   const TargetRegisterInfo *TRI = Fn.getTarget().getRegisterInfo();
   MachineBasicBlock::iterator I;
 
-  if (!ShrinkWrapThisFunction) {
-    // Spill using target interface.
-    I = EntryBlock->begin();
-    if (!TFI->spillCalleeSavedRegisters(*EntryBlock, 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(), RC, TRI);
-      }
-    }
-
-    // Restore using target interface.
-    for (unsigned ri = 0, re = ReturnBlocks.size(); ri != re; ++ri) {
-      MachineBasicBlock* MBB = ReturnBlocks[ri];
-      I = MBB->end(); --I;
-
-      // Skip over all terminator instructions, which are part of the return
-      // sequence.
-      MachineBasicBlock::iterator I2 = I;
-      while (I2 != MBB->begin() && (--I2)->isTerminator())
-        I = I2;
-
-      bool AtStart = I == MBB->begin();
-      MachineBasicBlock::iterator BeforeI = I;
-      if (!AtStart)
-        --BeforeI;
-
-      // Restore all registers immediately before the return and any
-      // terminators that precede it.
-      if (!TFI->restoreCalleeSavedRegisters(*MBB, I, CSI, TRI)) {
-        for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
-          unsigned Reg = CSI[i].getReg();
-          const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg);
-          TII.loadRegFromStackSlot(*MBB, I, Reg,
-                                   CSI[i].getFrameIdx(),
-                                   RC, TRI);
-          assert(I != MBB->begin() &&
-                 "loadRegFromStackSlot didn't insert any code!");
-          // Insert in reverse order.  loadRegFromStackSlot can insert
-          // multiple instructions.
-          if (AtStart)
-            I = MBB->begin();
-          else {
-            I = BeforeI;
-            ++I;
-          }
-        }
-      }
-    }
-    return;
-  }
-
-  // Insert spills.
-  std::vector<CalleeSavedInfo> blockCSI;
-  for (CSRegBlockMap::iterator BI = CSRSave.begin(),
-         BE = CSRSave.end(); BI != BE; ++BI) {
-    MachineBasicBlock* MBB = BI->first;
-    CSRegSet save = BI->second;
-
-    if (save.empty())
-      continue;
-
-    blockCSI.clear();
-    for (CSRegSet::iterator RI = save.begin(),
-           RE = save.end(); RI != RE; ++RI) {
-      blockCSI.push_back(CSI[*RI]);
-    }
-    assert(blockCSI.size() > 0 &&
-           "Could not collect callee saved register info");
-
-    I = MBB->begin();
-
-    // When shrink wrapping, use stack slot stores/loads.
-    for (unsigned i = 0, e = blockCSI.size(); i != e; ++i) {
+  // Spill using target interface.
+  I = EntryBlock->begin();
+  if (!TFI->spillCalleeSavedRegisters(*EntryBlock, 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.
-      MBB->addLiveIn(blockCSI[i].getReg());
+      EntryBlock->addLiveIn(CSI[i].getReg());
 
       // Insert the spill to the stack frame.
-      unsigned Reg = blockCSI[i].getReg();
+      unsigned Reg = CSI[i].getReg();
       const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg);
-      TII.storeRegToStackSlot(*MBB, I, Reg,
-                              true,
-                              blockCSI[i].getFrameIdx(),
+      TII.storeRegToStackSlot(*EntryBlock, I, Reg, true, CSI[i].getFrameIdx(),
                               RC, TRI);
     }
   }
 
-  for (CSRegBlockMap::iterator BI = CSRRestore.begin(),
-         BE = CSRRestore.end(); BI != BE; ++BI) {
-    MachineBasicBlock* MBB = BI->first;
-    CSRegSet restore = BI->second;
+  // Restore using target interface.
+  for (unsigned ri = 0, re = ReturnBlocks.size(); ri != re; ++ri) {
+    MachineBasicBlock *MBB = ReturnBlocks[ri];
+    I = MBB->end();
+    --I;
 
-    if (restore.empty())
-      continue;
-
-    blockCSI.clear();
-    for (CSRegSet::iterator RI = restore.begin(),
-           RE = restore.end(); RI != RE; ++RI) {
-      blockCSI.push_back(CSI[*RI]);
-    }
-    assert(blockCSI.size() > 0 &&
-           "Could not find callee saved register info");
-
-    // If MBB is empty and needs restores, insert at the _beginning_.
-    if (MBB->empty()) {
-      I = MBB->begin();
-    } else {
-      I = MBB->end();
-      --I;
-
-      // Skip over all terminator instructions, which are part of the
-      // return sequence.
-      if (! I->isTerminator()) {
-        ++I;
-      } else {
-        MachineBasicBlock::iterator I2 = I;
-        while (I2 != MBB->begin() && (--I2)->isTerminator())
-          I = I2;
-      }
-    }
+    // Skip over all terminator instructions, which are part of the return
+    // sequence.
+    MachineBasicBlock::iterator I2 = I;
+    while (I2 != MBB->begin() && (--I2)->isTerminator())
+      I = I2;
 
     bool AtStart = I == MBB->begin();
     MachineBasicBlock::iterator BeforeI = I;
@@ -436,21 +361,21 @@ void PEI::insertCSRSpillsAndRestores(MachineFunction &Fn) {
 
     // Restore all registers immediately before the return and any
     // terminators that precede it.
-    for (unsigned i = 0, e = blockCSI.size(); i != e; ++i) {
-      unsigned Reg = blockCSI[i].getReg();
-      const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg);
-      TII.loadRegFromStackSlot(*MBB, I, Reg,
-                               blockCSI[i].getFrameIdx(),
-                               RC, TRI);
-      assert(I != MBB->begin() &&
-             "loadRegFromStackSlot didn't insert any code!");
-      // Insert in reverse order.  loadRegFromStackSlot can insert
-      // multiple instructions.
-      if (AtStart)
-        I = MBB->begin();
-      else {
-        I = BeforeI;
-        ++I;
+    if (!TFI->restoreCalleeSavedRegisters(*MBB, I, CSI, TRI)) {
+      for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
+        unsigned Reg = CSI[i].getReg();
+        const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg);
+        TII.loadRegFromStackSlot(*MBB, I, Reg, CSI[i].getFrameIdx(), RC, TRI);
+        assert(I != MBB->begin() &&
+               "loadRegFromStackSlot didn't insert any code!");
+        // Insert in reverse order.  loadRegFromStackSlot can insert
+        // multiple instructions.
+        if (AtStart)
+          I = MBB->begin();
+        else {
+          I = BeforeI;
+          ++I;
+        }
       }
     }
   }

lib/CodeGen/PrologEpilogInserter.h

@@ -14,9 +14,6 @@
 // This pass must be run after register allocation.  After this pass is
 // executed, it is illegal to construct MO_FrameIndex operands.
 //
-// This pass also implements a shrink wrapping variant of prolog/epilog
-// insertion.
-//
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_CODEGEN_PEI_H
@@ -54,74 +51,16 @@ namespace llvm {
     // stack frame indexes.
     unsigned MinCSFrameIndex, MaxCSFrameIndex;
 
-    // Analysis info for spill/restore placement.
-    // "CSR": "callee saved register".
-
-    // CSRegSet contains indices into the Callee Saved Register Info
-    // vector built by calculateCalleeSavedRegisters() and accessed
-    // via MF.getFrameInfo()->getCalleeSavedInfo().
-    typedef SparseBitVector<> CSRegSet;
-
-    // CSRegBlockMap maps MachineBasicBlocks to sets of callee
-    // saved register indices.
-    typedef DenseMap<MachineBasicBlock*, CSRegSet> CSRegBlockMap;
-
-    // Set and maps for computing CSR spill/restore placement:
-    //  used in function (UsedCSRegs)
-    //  used in a basic block (CSRUsed)
-    //  anticipatable in a basic block (Antic{In,Out})
-    //  available in a basic block (Avail{In,Out})
-    //  to be spilled at the entry to a basic block (CSRSave)
-    //  to be restored at the end of a basic block (CSRRestore)
-    CSRegSet UsedCSRegs;
-    CSRegBlockMap CSRUsed;
-    CSRegBlockMap AnticIn, AnticOut;
-    CSRegBlockMap AvailIn, AvailOut;
-    CSRegBlockMap CSRSave;
-    CSRegBlockMap CSRRestore;
-
     // Entry and return blocks of the current function.
     MachineBasicBlock* EntryBlock;
     SmallVector<MachineBasicBlock*, 4> ReturnBlocks;
 
-    // Map of MBBs to top level MachineLoops.
-    DenseMap<MachineBasicBlock*, MachineLoop*> TLLoops;
-
-    // Flag to control shrink wrapping per-function:
-    // may choose to skip shrink wrapping for certain
-    // functions.
-    bool ShrinkWrapThisFunction;
-
     // Flag to control whether to use the register scavenger to resolve
     // frame index materialization registers. Set according to
     // TRI->requiresFrameIndexScavenging() for the curren function.
     bool FrameIndexVirtualScavenging;
 
-#ifndef NDEBUG
-    // Machine function handle.
-    MachineFunction* MF;
-
-    // Flag indicating that the current function
-    // has at least one "short" path in the machine
-    // CFG from the entry block to an exit block.
-    bool HasFastExitPath;
-#endif
-
-    bool calculateSets(MachineFunction &Fn);
-    bool calcAnticInOut(MachineBasicBlock* MBB);
-    bool calcAvailInOut(MachineBasicBlock* MBB);
-    void calculateAnticAvail(MachineFunction &Fn);
-    bool addUsesForMEMERegion(MachineBasicBlock* MBB,
-                              SmallVectorImpl<MachineBasicBlock *> &blks);
-    bool addUsesForTopLevelLoops(SmallVectorImpl<MachineBasicBlock *> &blks);
-    bool calcSpillPlacements(MachineBasicBlock* MBB,
-                             SmallVectorImpl<MachineBasicBlock *> &blks,
-                             CSRegBlockMap &prevSpills);
-    bool calcRestorePlacements(MachineBasicBlock* MBB,
-                               SmallVectorImpl<MachineBasicBlock *> &blks,
-                               CSRegBlockMap &prevRestores);
-    void placeSpillsAndRestores(MachineFunction &Fn);
-    void placeCSRSpillsAndRestores(MachineFunction &Fn);
+    void calculateSets(MachineFunction &Fn);
     void calculateCallsInformation(MachineFunction &Fn);
     void calculateCalleeSavedRegisters(MachineFunction &Fn);
     void insertCSRSpillsAndRestores(MachineFunction &Fn);
@@ -132,44 +71,8 @@ namespace llvm {
     void scavengeFrameVirtualRegs(MachineFunction &Fn);
     void insertPrologEpilogCode(MachineFunction &Fn);
 
-    // Initialize DFA sets, called before iterations.
-    void clearAnticAvailSets();
-    // Clear all sets constructed by shrink wrapping.
-    void clearAllSets();
-
-    // Initialize all shrink wrapping data.
-    void initShrinkWrappingInfo();
-
-    // Convienences for dealing with machine loops.
-    MachineBasicBlock* getTopLevelLoopPreheader(MachineLoop* LP);
-    MachineLoop* getTopLevelLoopParent(MachineLoop *LP);
-
-    // Propgate CSRs used in MBB to all MBBs of loop LP.
-    void propagateUsesAroundLoop(MachineBasicBlock* MBB, MachineLoop* LP);
-
     // Convenience for recognizing return blocks.
     bool isReturnBlock(MachineBasicBlock* MBB);
-
-#ifndef NDEBUG
-    // Debugging methods.
-
-    // Mark this function as having fast exit paths.
-    void findFastExitPath();
-
-    // Verify placement of spills/restores.
-    void verifySpillRestorePlacement();
-
-    std::string getBasicBlockName(const MachineBasicBlock* MBB);
-    std::string stringifyCSRegSet(const CSRegSet& s);
-    void dumpSet(const CSRegSet& s);
-    void dumpUsed(MachineBasicBlock* MBB);
-    void dumpAllUsed();
-    void dumpSets(MachineBasicBlock* MBB);
-    void dumpSets1(MachineBasicBlock* MBB);
-    void dumpAllSets();
-    void dumpSRSets();
-#endif
-
   };
 } // End llvm namespace
 #endif