[llvm] r193749 - Remove the --shrink-wrap option.
Rafael Espindola
rafael.espindola at gmail.com
Thu Oct 31 07:08:00 PDT 2013
Author: rafael
Date: Thu Oct 31 09:07:59 2013
New Revision: 193749
URL: http://llvm.org/viewvc/llvm-project?rev=193749&view=rev
Log:
Remove the --shrink-wrap option.
It had no tests, was unused and was "experimental at best".
Removed:
llvm/trunk/lib/CodeGen/ShrinkWrapping.cpp
Modified:
llvm/trunk/lib/CodeGen/CMakeLists.txt
llvm/trunk/lib/CodeGen/PrologEpilogInserter.cpp
llvm/trunk/lib/CodeGen/PrologEpilogInserter.h
Modified: llvm/trunk/lib/CodeGen/CMakeLists.txt
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/CMakeLists.txt?rev=193749&r1=193748&r2=193749&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/CMakeLists.txt (original)
+++ llvm/trunk/lib/CodeGen/CMakeLists.txt Thu Oct 31 09:07:59 2013
@@ -89,7 +89,6 @@ add_llvm_library(LLVMCodeGen
ScheduleDAGPrinter.cpp
ScoreboardHazardRecognizer.cpp
ShadowStackGC.cpp
- ShrinkWrapping.cpp
SjLjEHPrepare.cpp
SlotIndexes.cpp
SpillPlacement.cpp
Modified: llvm/trunk/lib/CodeGen/PrologEpilogInserter.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/PrologEpilogInserter.cpp?rev=193749&r1=193748&r2=193749&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/PrologEpilogInserter.cpp (original)
+++ llvm/trunk/lib/CodeGen/PrologEpilogInserter.cpp Thu Oct 31 09:07:59 2013
@@ -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 f
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(MachineFu
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(MachineFu
<< ") in " << Fn.getName() << ".\n";
delete RS;
- clearAllSets();
+ ReturnBlocks.clear();
return true;
}
@@ -283,7 +308,7 @@ void PEI::calculateCalleeSavedRegisters(
}
/// 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(Mac
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;
-
- 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;
- }
- }
+ // 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;
@@ -436,21 +361,21 @@ void PEI::insertCSRSpillsAndRestores(Mac
// 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;
+ }
}
}
}
Modified: llvm/trunk/lib/CodeGen/PrologEpilogInserter.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/PrologEpilogInserter.h?rev=193749&r1=193748&r2=193749&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/PrologEpilogInserter.h (original)
+++ llvm/trunk/lib/CodeGen/PrologEpilogInserter.h Thu Oct 31 09:07:59 2013
@@ -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
Removed: llvm/trunk/lib/CodeGen/ShrinkWrapping.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/ShrinkWrapping.cpp?rev=193748&view=auto
==============================================================================
--- llvm/trunk/lib/CodeGen/ShrinkWrapping.cpp (original)
+++ llvm/trunk/lib/CodeGen/ShrinkWrapping.cpp (removed)
@@ -1,1152 +0,0 @@
-//===-- ShrinkWrapping.cpp - Reduce spills/restores of callee-saved regs --===//
-//
-// The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-//
-// This file implements a shrink wrapping variant of prolog/epilog insertion:
-// - Spills and restores of callee-saved registers (CSRs) are placed in the
-// machine CFG to tightly surround their uses so that execution paths that
-// do not use CSRs do not pay the spill/restore penalty.
-//
-// - Avoiding placment of spills/restores in loops: if a CSR is used inside a
-// loop the spills are placed in the loop preheader, and restores are
-// placed in the loop exit nodes (the successors of loop _exiting_ nodes).
-//
-// - Covering paths without CSR uses:
-// If a region in a CFG uses CSRs and has multiple entry and/or exit points,
-// the use info for the CSRs inside the region is propagated outward in the
-// CFG to ensure validity of the spill/restore placements. This decreases
-// the effectiveness of shrink wrapping but does not require edge splitting
-// in the machine CFG.
-//
-// This shrink wrapping implementation uses an iterative analysis to determine
-// which basic blocks require spills and restores for CSRs.
-//
-// This pass uses MachineDominators and MachineLoopInfo. Loop information
-// is used to prevent placement of callee-saved register spills/restores
-// in the bodies of loops.
-//
-//===----------------------------------------------------------------------===//
-
-#define DEBUG_TYPE "shrink-wrap"
-
-#include "PrologEpilogInserter.h"
-#include "llvm/ADT/DenseMap.h"
-#include "llvm/ADT/PostOrderIterator.h"
-#include "llvm/ADT/STLExtras.h"
-#include "llvm/ADT/SparseBitVector.h"
-#include "llvm/ADT/Statistic.h"
-#include "llvm/CodeGen/MachineDominators.h"
-#include "llvm/CodeGen/MachineFrameInfo.h"
-#include "llvm/CodeGen/MachineInstr.h"
-#include "llvm/CodeGen/MachineLoopInfo.h"
-#include "llvm/CodeGen/MachineRegisterInfo.h"
-#include "llvm/Support/CommandLine.h"
-#include "llvm/Support/Compiler.h"
-#include "llvm/Support/Debug.h"
-#include "llvm/Target/TargetMachine.h"
-#include "llvm/Target/TargetRegisterInfo.h"
-#include <sstream>
-
-using namespace llvm;
-
-STATISTIC(numSRReduced, "Number of CSR spills+restores reduced.");
-
-// Shrink Wrapping:
-static cl::opt<bool>
-ShrinkWrapping("shrink-wrap",
- cl::desc("Shrink wrap callee-saved register spills/restores"));
-
-// Shrink wrap only the specified function, a debugging aid.
-static cl::opt<std::string>
-ShrinkWrapFunc("shrink-wrap-func", cl::Hidden,
- cl::desc("Shrink wrap the specified function"),
- cl::value_desc("funcname"),
- cl::init(""));
-
-// Debugging level for shrink wrapping.
-enum ShrinkWrapDebugLevel {
- Disabled, BasicInfo, Iterations, Details
-};
-
-static cl::opt<enum ShrinkWrapDebugLevel>
-ShrinkWrapDebugging("shrink-wrap-dbg", cl::Hidden,
- cl::desc("Print shrink wrapping debugging information"),
- cl::values(
- clEnumVal(Disabled , "disable debug output"),
- clEnumVal(BasicInfo , "print basic DF sets"),
- clEnumVal(Iterations, "print SR sets for each iteration"),
- clEnumVal(Details , "print all DF sets"),
- clEnumValEnd));
-
-
-void PEI::getAnalysisUsage(AnalysisUsage &AU) const {
- AU.setPreservesCFG();
- if (ShrinkWrapping || ShrinkWrapFunc != "") {
- AU.addRequired<MachineLoopInfo>();
- AU.addRequired<MachineDominatorTree>();
- }
- AU.addPreserved<MachineLoopInfo>();
- AU.addPreserved<MachineDominatorTree>();
- AU.addRequired<TargetPassConfig>();
- MachineFunctionPass::getAnalysisUsage(AU);
-}
-
-//===----------------------------------------------------------------------===//
-// ShrinkWrapping implementation
-//===----------------------------------------------------------------------===//
-
-// Convienences for dealing with machine loops.
-MachineBasicBlock* PEI::getTopLevelLoopPreheader(MachineLoop* LP) {
- assert(LP && "Machine loop is NULL.");
- MachineBasicBlock* PHDR = LP->getLoopPreheader();
- MachineLoop* PLP = LP->getParentLoop();
- while (PLP) {
- PHDR = PLP->getLoopPreheader();
- PLP = PLP->getParentLoop();
- }
- return PHDR;
-}
-
-MachineLoop* PEI::getTopLevelLoopParent(MachineLoop *LP) {
- if (LP == 0)
- return 0;
- MachineLoop* PLP = LP->getParentLoop();
- while (PLP) {
- LP = PLP;
- PLP = PLP->getParentLoop();
- }
- return LP;
-}
-
-bool PEI::isReturnBlock(MachineBasicBlock* MBB) {
- return (MBB && !MBB->empty() && MBB->back().isReturn());
-}
-
-// Initialize shrink wrapping DFA sets, called before iterations.
-void PEI::clearAnticAvailSets() {
- AnticIn.clear();
- AnticOut.clear();
- AvailIn.clear();
- AvailOut.clear();
-}
-
-// Clear all sets constructed by shrink wrapping.
-void PEI::clearAllSets() {
- ReturnBlocks.clear();
- clearAnticAvailSets();
- UsedCSRegs.clear();
- CSRUsed.clear();
- TLLoops.clear();
- CSRSave.clear();
- CSRRestore.clear();
-}
-
-// Initialize all shrink wrapping data.
-void PEI::initShrinkWrappingInfo() {
- clearAllSets();
- EntryBlock = 0;
-#ifndef NDEBUG
- HasFastExitPath = false;
-#endif
- ShrinkWrapThisFunction = ShrinkWrapping;
- // DEBUG: enable or disable shrink wrapping for the current function
- // via --shrink-wrap-func=<funcname>.
-#ifndef NDEBUG
- if (ShrinkWrapFunc != "") {
- std::string MFName = MF->getName().str();
- ShrinkWrapThisFunction = (MFName == ShrinkWrapFunc);
- }
-#endif
-}
-
-
-/// placeCSRSpillsAndRestores - determine which MBBs of the function
-/// need save, restore code for callee-saved registers by doing a DF analysis
-/// similar to the one used in code motion (GVNPRE). This produces maps of MBBs
-/// to sets of registers (CSRs) for saves and restores. MachineLoopInfo
-/// is used to ensure that CSR save/restore code is not placed inside loops.
-/// This function computes the maps of MBBs -> CSRs to spill and restore
-/// in CSRSave, CSRRestore.
-///
-/// If shrink wrapping is not being performed, place all spills in
-/// the entry block, all restores in return blocks. In this case,
-/// CSRSave has a single mapping, CSRRestore has mappings for each
-/// return block.
-///
-void PEI::placeCSRSpillsAndRestores(MachineFunction &Fn) {
-
- DEBUG(MF = &Fn);
-
- initShrinkWrappingInfo();
-
- DEBUG(if (ShrinkWrapThisFunction) {
- dbgs() << "Place CSR spills/restores for "
- << MF->getName() << "\n";
- });
-
- if (calculateSets(Fn))
- placeSpillsAndRestores(Fn);
-}
-
-/// calcAnticInOut - calculate the anticipated in/out reg sets
-/// for the given MBB by looking forward in the MCFG at MBB's
-/// successors.
-///
-bool PEI::calcAnticInOut(MachineBasicBlock* MBB) {
- bool changed = false;
-
- // AnticOut[MBB] = INTERSECT(AnticIn[S] for S in SUCCESSORS(MBB))
- SmallVector<MachineBasicBlock*, 4> successors;
- for (MachineBasicBlock::succ_iterator SI = MBB->succ_begin(),
- SE = MBB->succ_end(); SI != SE; ++SI) {
- MachineBasicBlock* SUCC = *SI;
- if (SUCC != MBB)
- successors.push_back(SUCC);
- }
-
- unsigned i = 0, e = successors.size();
- if (i != e) {
- CSRegSet prevAnticOut = AnticOut[MBB];
- MachineBasicBlock* SUCC = successors[i];
-
- AnticOut[MBB] = AnticIn[SUCC];
- for (++i; i != e; ++i) {
- SUCC = successors[i];
- AnticOut[MBB] &= AnticIn[SUCC];
- }
- if (prevAnticOut != AnticOut[MBB])
- changed = true;
- }
-
- // AnticIn[MBB] = UNION(CSRUsed[MBB], AnticOut[MBB]);
- CSRegSet prevAnticIn = AnticIn[MBB];
- AnticIn[MBB] = CSRUsed[MBB] | AnticOut[MBB];
- if (prevAnticIn != AnticIn[MBB])
- changed = true;
- return changed;
-}
-
-/// calcAvailInOut - calculate the available in/out reg sets
-/// for the given MBB by looking backward in the MCFG at MBB's
-/// predecessors.
-///
-bool PEI::calcAvailInOut(MachineBasicBlock* MBB) {
- bool changed = false;
-
- // AvailIn[MBB] = INTERSECT(AvailOut[P] for P in PREDECESSORS(MBB))
- SmallVector<MachineBasicBlock*, 4> predecessors;
- for (MachineBasicBlock::pred_iterator PI = MBB->pred_begin(),
- PE = MBB->pred_end(); PI != PE; ++PI) {
- MachineBasicBlock* PRED = *PI;
- if (PRED != MBB)
- predecessors.push_back(PRED);
- }
-
- unsigned i = 0, e = predecessors.size();
- if (i != e) {
- CSRegSet prevAvailIn = AvailIn[MBB];
- MachineBasicBlock* PRED = predecessors[i];
-
- AvailIn[MBB] = AvailOut[PRED];
- for (++i; i != e; ++i) {
- PRED = predecessors[i];
- AvailIn[MBB] &= AvailOut[PRED];
- }
- if (prevAvailIn != AvailIn[MBB])
- changed = true;
- }
-
- // AvailOut[MBB] = UNION(CSRUsed[MBB], AvailIn[MBB]);
- CSRegSet prevAvailOut = AvailOut[MBB];
- AvailOut[MBB] = CSRUsed[MBB] | AvailIn[MBB];
- if (prevAvailOut != AvailOut[MBB])
- changed = true;
- return changed;
-}
-
-/// calculateAnticAvail - build the sets anticipated and available
-/// registers in the MCFG of the current function iteratively,
-/// doing a combined forward and backward analysis.
-///
-void PEI::calculateAnticAvail(MachineFunction &Fn) {
- // Initialize data flow sets.
- clearAnticAvailSets();
-
- // Calculate Antic{In,Out} and Avail{In,Out} iteratively on the MCFG.
- bool changed = true;
- unsigned iterations = 0;
- while (changed) {
- changed = false;
- ++iterations;
- for (MachineFunction::iterator MBBI = Fn.begin(), MBBE = Fn.end();
- MBBI != MBBE; ++MBBI) {
- MachineBasicBlock* MBB = MBBI;
-
- // Calculate anticipated in, out regs at MBB from
- // anticipated at successors of MBB.
- changed |= calcAnticInOut(MBB);
-
- // Calculate available in, out regs at MBB from
- // available at predecessors of MBB.
- changed |= calcAvailInOut(MBB);
- }
- }
-
- DEBUG({
- if (ShrinkWrapDebugging >= Details) {
- dbgs()
- << "-----------------------------------------------------------\n"
- << " Antic/Avail Sets:\n"
- << "-----------------------------------------------------------\n"
- << "iterations = " << iterations << "\n"
- << "-----------------------------------------------------------\n"
- << "MBB | USED | ANTIC_IN | ANTIC_OUT | AVAIL_IN | AVAIL_OUT\n"
- << "-----------------------------------------------------------\n";
-
- for (MachineFunction::iterator MBBI = Fn.begin(), MBBE = Fn.end();
- MBBI != MBBE; ++MBBI) {
- MachineBasicBlock* MBB = MBBI;
- dumpSets(MBB);
- }
-
- dbgs()
- << "-----------------------------------------------------------\n";
- }
- });
-}
-
-/// propagateUsesAroundLoop - copy used register info from MBB to all blocks
-/// of the loop given by LP and its parent loops. This prevents spills/restores
-/// from being placed in the bodies of loops.
-///
-void PEI::propagateUsesAroundLoop(MachineBasicBlock* MBB, MachineLoop* LP) {
- if (! MBB || !LP)
- return;
-
- std::vector<MachineBasicBlock*> loopBlocks = LP->getBlocks();
- for (unsigned i = 0, e = loopBlocks.size(); i != e; ++i) {
- MachineBasicBlock* LBB = loopBlocks[i];
- if (LBB == MBB)
- continue;
- if (CSRUsed[LBB].contains(CSRUsed[MBB]))
- continue;
- CSRUsed[LBB] |= CSRUsed[MBB];
- }
-}
-
-/// calculateSets - collect the CSRs used in this function, compute
-/// the DF sets that describe the initial minimal regions in the
-/// Machine CFG around which CSR spills and restores must be placed.
-///
-/// Additionally, this function decides if shrink wrapping should
-/// be disabled for the current function, checking the following:
-/// 1. the current function has more than 500 MBBs: heuristic limit
-/// on function size to reduce compile time impact of the current
-/// iterative algorithm.
-/// 2. all CSRs are used in the entry block.
-/// 3. all CSRs are used in all immediate successors of the entry block.
-/// 4. all CSRs are used in a subset of blocks, each of which dominates
-/// all return blocks. These blocks, taken as a subgraph of the MCFG,
-/// are equivalent to the entry block since all execution paths pass
-/// through them.
-///
-bool 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()) {
- DEBUG(if (ShrinkWrapThisFunction)
- dbgs() << "DISABLED: " << Fn.getName()
- << ": uses no callee-saved registers\n");
- return false;
- }
-
- // 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);
-
- // Determine if this function has fast exit paths.
- DEBUG(if (ShrinkWrapThisFunction)
- findFastExitPath());
-
- // Limit shrink wrapping via the current iterative bit vector
- // implementation to functions with <= 500 MBBs.
- if (Fn.size() > 500) {
- DEBUG(if (ShrinkWrapThisFunction)
- dbgs() << "DISABLED: " << Fn.getName()
- << ": too large (" << Fn.size() << " MBBs)\n");
- ShrinkWrapThisFunction = false;
- }
-
- // Return now if not shrink wrapping.
- if (! ShrinkWrapThisFunction)
- return false;
-
- // Collect set of used CSRs.
- for (unsigned inx = 0, e = CSI.size(); inx != e; ++inx) {
- UsedCSRegs.set(inx);
- }
-
- // Walk instructions in all MBBs, create CSRUsed[] sets, choose
- // whether or not to shrink wrap this function.
- MachineLoopInfo &LI = getAnalysis<MachineLoopInfo>();
- MachineDominatorTree &DT = getAnalysis<MachineDominatorTree>();
- const TargetRegisterInfo *TRI = Fn.getTarget().getRegisterInfo();
-
- bool allCSRUsesInEntryBlock = true;
- for (MachineFunction::iterator MBBI = Fn.begin(), MBBE = Fn.end();
- MBBI != MBBE; ++MBBI) {
- MachineBasicBlock* MBB = MBBI;
- for (MachineBasicBlock::iterator I = MBB->begin(); I != MBB->end(); ++I) {
- for (unsigned inx = 0, e = CSI.size(); inx != e; ++inx) {
- unsigned Reg = CSI[inx].getReg();
- // If instruction I reads or modifies Reg, add it to UsedCSRegs,
- // CSRUsed map for the current block.
- for (unsigned opInx = 0, opEnd = I->getNumOperands();
- opInx != opEnd; ++opInx) {
- const MachineOperand &MO = I->getOperand(opInx);
- if (! (MO.isReg() && (MO.isUse() || MO.isDef())))
- continue;
- unsigned MOReg = MO.getReg();
- if (!MOReg)
- continue;
- if (MOReg == Reg ||
- (TargetRegisterInfo::isPhysicalRegister(MOReg) &&
- TargetRegisterInfo::isPhysicalRegister(Reg) &&
- TRI->isSubRegister(Reg, MOReg))) {
- // CSR Reg is defined/used in block MBB.
- CSRUsed[MBB].set(inx);
- // Check for uses in EntryBlock.
- if (MBB != EntryBlock)
- allCSRUsesInEntryBlock = false;
- }
- }
- }
- }
-
- if (CSRUsed[MBB].empty())
- continue;
-
- // Propagate CSRUsed[MBB] in loops
- if (MachineLoop* LP = LI.getLoopFor(MBB)) {
- // Add top level loop to work list.
- MachineBasicBlock* HDR = getTopLevelLoopPreheader(LP);
- MachineLoop* PLP = getTopLevelLoopParent(LP);
-
- if (! HDR) {
- HDR = PLP->getHeader();
- assert(HDR->pred_size() > 0 && "Loop header has no predecessors?");
- MachineBasicBlock::pred_iterator PI = HDR->pred_begin();
- HDR = *PI;
- }
- TLLoops[HDR] = PLP;
-
- // Push uses from inside loop to its parent loops,
- // or to all other MBBs in its loop.
- if (LP->getLoopDepth() > 1) {
- for (MachineLoop* PLP = LP->getParentLoop(); PLP;
- PLP = PLP->getParentLoop()) {
- propagateUsesAroundLoop(MBB, PLP);
- }
- } else {
- propagateUsesAroundLoop(MBB, LP);
- }
- }
- }
-
- if (allCSRUsesInEntryBlock) {
- DEBUG(dbgs() << "DISABLED: " << Fn.getName()
- << ": all CSRs used in EntryBlock\n");
- ShrinkWrapThisFunction = false;
- } else {
- bool allCSRsUsedInEntryFanout = true;
- for (MachineBasicBlock::succ_iterator SI = EntryBlock->succ_begin(),
- SE = EntryBlock->succ_end(); SI != SE; ++SI) {
- MachineBasicBlock* SUCC = *SI;
- if (CSRUsed[SUCC] != UsedCSRegs)
- allCSRsUsedInEntryFanout = false;
- }
- if (allCSRsUsedInEntryFanout) {
- DEBUG(dbgs() << "DISABLED: " << Fn.getName()
- << ": all CSRs used in imm successors of EntryBlock\n");
- ShrinkWrapThisFunction = false;
- }
- }
-
- if (ShrinkWrapThisFunction) {
- // Check if MBB uses CSRs and dominates all exit nodes.
- // Such nodes are equiv. to the entry node w.r.t.
- // CSR uses: every path through the function must
- // pass through this node. If each CSR is used at least
- // once by these nodes, shrink wrapping is disabled.
- CSRegSet CSRUsedInChokePoints;
- for (MachineFunction::iterator MBBI = Fn.begin(), MBBE = Fn.end();
- MBBI != MBBE; ++MBBI) {
- MachineBasicBlock* MBB = MBBI;
- if (MBB == EntryBlock || CSRUsed[MBB].empty() || MBB->succ_size() < 1)
- continue;
- bool dominatesExitNodes = true;
- for (unsigned ri = 0, re = ReturnBlocks.size(); ri != re; ++ri)
- if (! DT.dominates(MBB, ReturnBlocks[ri])) {
- dominatesExitNodes = false;
- break;
- }
- if (dominatesExitNodes) {
- CSRUsedInChokePoints |= CSRUsed[MBB];
- if (CSRUsedInChokePoints == UsedCSRegs) {
- DEBUG(dbgs() << "DISABLED: " << Fn.getName()
- << ": all CSRs used in choke point(s) at "
- << getBasicBlockName(MBB) << "\n");
- ShrinkWrapThisFunction = false;
- break;
- }
- }
- }
- }
-
- // Return now if we have decided not to apply shrink wrapping
- // to the current function.
- if (! ShrinkWrapThisFunction)
- return false;
-
- DEBUG({
- dbgs() << "ENABLED: " << Fn.getName();
- if (HasFastExitPath)
- dbgs() << " (fast exit path)";
- dbgs() << "\n";
- if (ShrinkWrapDebugging >= BasicInfo) {
- dbgs() << "------------------------------"
- << "-----------------------------\n";
- dbgs() << "UsedCSRegs = " << stringifyCSRegSet(UsedCSRegs) << "\n";
- if (ShrinkWrapDebugging >= Details) {
- dbgs() << "------------------------------"
- << "-----------------------------\n";
- dumpAllUsed();
- }
- }
- });
-
- // Build initial DF sets to determine minimal regions in the
- // Machine CFG around which CSRs must be spilled and restored.
- calculateAnticAvail(Fn);
-
- return true;
-}
-
-/// addUsesForMEMERegion - add uses of CSRs spilled or restored in
-/// multi-entry, multi-exit (MEME) regions so spill and restore
-/// placement will not break code that enters or leaves a
-/// shrink-wrapped region by inducing spills with no matching
-/// restores or restores with no matching spills. A MEME region
-/// is a subgraph of the MCFG with multiple entry edges, multiple
-/// exit edges, or both. This code propagates use information
-/// through the MCFG until all paths requiring spills and restores
-/// _outside_ the computed minimal placement regions have been covered.
-///
-bool PEI::addUsesForMEMERegion(MachineBasicBlock* MBB,
- SmallVectorImpl<MachineBasicBlock *> &blks) {
- if (MBB->succ_size() < 2 && MBB->pred_size() < 2) {
- bool processThisBlock = false;
- for (MachineBasicBlock::succ_iterator SI = MBB->succ_begin(),
- SE = MBB->succ_end(); SI != SE; ++SI) {
- MachineBasicBlock* SUCC = *SI;
- if (SUCC->pred_size() > 1) {
- processThisBlock = true;
- break;
- }
- }
- if (!CSRRestore[MBB].empty() && MBB->succ_size() > 0) {
- for (MachineBasicBlock::pred_iterator PI = MBB->pred_begin(),
- PE = MBB->pred_end(); PI != PE; ++PI) {
- MachineBasicBlock* PRED = *PI;
- if (PRED->succ_size() > 1) {
- processThisBlock = true;
- break;
- }
- }
- }
- if (! processThisBlock)
- return false;
- }
-
- CSRegSet prop;
- if (!CSRSave[MBB].empty())
- prop = CSRSave[MBB];
- else if (!CSRRestore[MBB].empty())
- prop = CSRRestore[MBB];
- else
- prop = CSRUsed[MBB];
- if (prop.empty())
- return false;
-
- // Propagate selected bits to successors, predecessors of MBB.
- bool addedUses = false;
- for (MachineBasicBlock::succ_iterator SI = MBB->succ_begin(),
- SE = MBB->succ_end(); SI != SE; ++SI) {
- MachineBasicBlock* SUCC = *SI;
- // Self-loop
- if (SUCC == MBB)
- continue;
- if (! CSRUsed[SUCC].contains(prop)) {
- CSRUsed[SUCC] |= prop;
- addedUses = true;
- blks.push_back(SUCC);
- DEBUG(if (ShrinkWrapDebugging >= Iterations)
- dbgs() << getBasicBlockName(MBB)
- << "(" << stringifyCSRegSet(prop) << ")->"
- << "successor " << getBasicBlockName(SUCC) << "\n");
- }
- }
- for (MachineBasicBlock::pred_iterator PI = MBB->pred_begin(),
- PE = MBB->pred_end(); PI != PE; ++PI) {
- MachineBasicBlock* PRED = *PI;
- // Self-loop
- if (PRED == MBB)
- continue;
- if (! CSRUsed[PRED].contains(prop)) {
- CSRUsed[PRED] |= prop;
- addedUses = true;
- blks.push_back(PRED);
- DEBUG(if (ShrinkWrapDebugging >= Iterations)
- dbgs() << getBasicBlockName(MBB)
- << "(" << stringifyCSRegSet(prop) << ")->"
- << "predecessor " << getBasicBlockName(PRED) << "\n");
- }
- }
- return addedUses;
-}
-
-/// addUsesForTopLevelLoops - add uses for CSRs used inside top
-/// level loops to the exit blocks of those loops.
-///
-bool PEI::addUsesForTopLevelLoops(SmallVectorImpl<MachineBasicBlock *> &blks) {
- bool addedUses = false;
-
- // Place restores for top level loops where needed.
- for (DenseMap<MachineBasicBlock*, MachineLoop*>::iterator
- I = TLLoops.begin(), E = TLLoops.end(); I != E; ++I) {
- MachineBasicBlock* MBB = I->first;
- MachineLoop* LP = I->second;
- MachineBasicBlock* HDR = LP->getHeader();
- SmallVector<MachineBasicBlock*, 4> exitBlocks;
- CSRegSet loopSpills;
-
- loopSpills = CSRSave[MBB];
- if (CSRSave[MBB].empty()) {
- loopSpills = CSRUsed[HDR];
- assert(!loopSpills.empty() && "No CSRs used in loop?");
- } else if (CSRRestore[MBB].contains(CSRSave[MBB]))
- continue;
-
- LP->getExitBlocks(exitBlocks);
- assert(exitBlocks.size() > 0 && "Loop has no top level exit blocks?");
- for (unsigned i = 0, e = exitBlocks.size(); i != e; ++i) {
- MachineBasicBlock* EXB = exitBlocks[i];
- if (! CSRUsed[EXB].contains(loopSpills)) {
- CSRUsed[EXB] |= loopSpills;
- addedUses = true;
- DEBUG(if (ShrinkWrapDebugging >= Iterations)
- dbgs() << "LOOP " << getBasicBlockName(MBB)
- << "(" << stringifyCSRegSet(loopSpills) << ")->"
- << getBasicBlockName(EXB) << "\n");
- if (EXB->succ_size() > 1 || EXB->pred_size() > 1)
- blks.push_back(EXB);
- }
- }
- }
- return addedUses;
-}
-
-/// calcSpillPlacements - determine which CSRs should be spilled
-/// in MBB using AnticIn sets of MBB's predecessors, keeping track
-/// of changes to spilled reg sets. Add MBB to the set of blocks
-/// that need to be processed for propagating use info to cover
-/// multi-entry/exit regions.
-///
-bool PEI::calcSpillPlacements(MachineBasicBlock* MBB,
- SmallVectorImpl<MachineBasicBlock *> &blks,
- CSRegBlockMap &prevSpills) {
- bool placedSpills = false;
- // Intersect (CSRegs - AnticIn[P]) for P in Predecessors(MBB)
- CSRegSet anticInPreds;
- SmallVector<MachineBasicBlock*, 4> predecessors;
- for (MachineBasicBlock::pred_iterator PI = MBB->pred_begin(),
- PE = MBB->pred_end(); PI != PE; ++PI) {
- MachineBasicBlock* PRED = *PI;
- if (PRED != MBB)
- predecessors.push_back(PRED);
- }
- unsigned i = 0, e = predecessors.size();
- if (i != e) {
- MachineBasicBlock* PRED = predecessors[i];
- anticInPreds = UsedCSRegs - AnticIn[PRED];
- for (++i; i != e; ++i) {
- PRED = predecessors[i];
- anticInPreds &= (UsedCSRegs - AnticIn[PRED]);
- }
- } else {
- // Handle uses in entry blocks (which have no predecessors).
- // This is necessary because the DFA formulation assumes the
- // entry and (multiple) exit nodes cannot have CSR uses, which
- // is not the case in the real world.
- anticInPreds = UsedCSRegs;
- }
- // Compute spills required at MBB:
- CSRSave[MBB] |= (AnticIn[MBB] - AvailIn[MBB]) & anticInPreds;
-
- if (! CSRSave[MBB].empty()) {
- if (MBB == EntryBlock) {
- for (unsigned ri = 0, re = ReturnBlocks.size(); ri != re; ++ri)
- CSRRestore[ReturnBlocks[ri]] |= CSRSave[MBB];
- } else {
- // Reset all regs spilled in MBB that are also spilled in EntryBlock.
- if (CSRSave[EntryBlock].intersects(CSRSave[MBB])) {
- CSRSave[MBB] = CSRSave[MBB] - CSRSave[EntryBlock];
- }
- }
- }
- placedSpills = (CSRSave[MBB] != prevSpills[MBB]);
- prevSpills[MBB] = CSRSave[MBB];
- // Remember this block for adding restores to successor
- // blocks for multi-entry region.
- if (placedSpills)
- blks.push_back(MBB);
-
- DEBUG(if (! CSRSave[MBB].empty() && ShrinkWrapDebugging >= Iterations)
- dbgs() << "SAVE[" << getBasicBlockName(MBB) << "] = "
- << stringifyCSRegSet(CSRSave[MBB]) << "\n");
-
- return placedSpills;
-}
-
-/// calcRestorePlacements - determine which CSRs should be restored
-/// in MBB using AvailOut sets of MBB's succcessors, keeping track
-/// of changes to restored reg sets. Add MBB to the set of blocks
-/// that need to be processed for propagating use info to cover
-/// multi-entry/exit regions.
-///
-bool PEI::calcRestorePlacements(MachineBasicBlock* MBB,
- SmallVectorImpl<MachineBasicBlock *> &blks,
- CSRegBlockMap &prevRestores) {
- bool placedRestores = false;
- // Intersect (CSRegs - AvailOut[S]) for S in Successors(MBB)
- CSRegSet availOutSucc;
- SmallVector<MachineBasicBlock*, 4> successors;
- for (MachineBasicBlock::succ_iterator SI = MBB->succ_begin(),
- SE = MBB->succ_end(); SI != SE; ++SI) {
- MachineBasicBlock* SUCC = *SI;
- if (SUCC != MBB)
- successors.push_back(SUCC);
- }
- unsigned i = 0, e = successors.size();
- if (i != e) {
- MachineBasicBlock* SUCC = successors[i];
- availOutSucc = UsedCSRegs - AvailOut[SUCC];
- for (++i; i != e; ++i) {
- SUCC = successors[i];
- availOutSucc &= (UsedCSRegs - AvailOut[SUCC]);
- }
- } else {
- if (! CSRUsed[MBB].empty() || ! AvailOut[MBB].empty()) {
- // Handle uses in return blocks (which have no successors).
- // This is necessary because the DFA formulation assumes the
- // entry and (multiple) exit nodes cannot have CSR uses, which
- // is not the case in the real world.
- availOutSucc = UsedCSRegs;
- }
- }
- // Compute restores required at MBB:
- CSRRestore[MBB] |= (AvailOut[MBB] - AnticOut[MBB]) & availOutSucc;
-
- // Postprocess restore placements at MBB.
- // Remove the CSRs that are restored in the return blocks.
- // Lest this be confusing, note that:
- // CSRSave[EntryBlock] == CSRRestore[B] for all B in ReturnBlocks.
- if (MBB->succ_size() && ! CSRRestore[MBB].empty()) {
- if (! CSRSave[EntryBlock].empty())
- CSRRestore[MBB] = CSRRestore[MBB] - CSRSave[EntryBlock];
- }
- placedRestores = (CSRRestore[MBB] != prevRestores[MBB]);
- prevRestores[MBB] = CSRRestore[MBB];
- // Remember this block for adding saves to predecessor
- // blocks for multi-entry region.
- if (placedRestores)
- blks.push_back(MBB);
-
- DEBUG(if (! CSRRestore[MBB].empty() && ShrinkWrapDebugging >= Iterations)
- dbgs() << "RESTORE[" << getBasicBlockName(MBB) << "] = "
- << stringifyCSRegSet(CSRRestore[MBB]) << "\n");
-
- return placedRestores;
-}
-
-/// placeSpillsAndRestores - place spills and restores of CSRs
-/// used in MBBs in minimal regions that contain the uses.
-///
-void PEI::placeSpillsAndRestores(MachineFunction &Fn) {
- CSRegBlockMap prevCSRSave;
- CSRegBlockMap prevCSRRestore;
- SmallVector<MachineBasicBlock*, 4> cvBlocks, ncvBlocks;
- bool changed = true;
- unsigned iterations = 0;
-
- // Iterate computation of spill and restore placements in the MCFG until:
- // 1. CSR use info has been fully propagated around the MCFG, and
- // 2. computation of CSRSave[], CSRRestore[] reach fixed points.
- while (changed) {
- changed = false;
- ++iterations;
-
- DEBUG(if (ShrinkWrapDebugging >= Iterations)
- dbgs() << "iter " << iterations
- << " --------------------------------------------------\n");
-
- // Calculate CSR{Save,Restore} sets using Antic, Avail on the MCFG,
- // which determines the placements of spills and restores.
- // Keep track of changes to spills, restores in each iteration to
- // minimize the total iterations.
- bool SRChanged = false;
- for (MachineFunction::iterator MBBI = Fn.begin(), MBBE = Fn.end();
- MBBI != MBBE; ++MBBI) {
- MachineBasicBlock* MBB = MBBI;
-
- // Place spills for CSRs in MBB.
- SRChanged |= calcSpillPlacements(MBB, cvBlocks, prevCSRSave);
-
- // Place restores for CSRs in MBB.
- SRChanged |= calcRestorePlacements(MBB, cvBlocks, prevCSRRestore);
- }
-
- // Add uses of CSRs used inside loops where needed.
- changed |= addUsesForTopLevelLoops(cvBlocks);
-
- // Add uses for CSRs spilled or restored at branch, join points.
- if (changed || SRChanged) {
- while (! cvBlocks.empty()) {
- MachineBasicBlock* MBB = cvBlocks.pop_back_val();
- changed |= addUsesForMEMERegion(MBB, ncvBlocks);
- }
- if (! ncvBlocks.empty()) {
- cvBlocks = ncvBlocks;
- ncvBlocks.clear();
- }
- }
-
- if (changed) {
- calculateAnticAvail(Fn);
- CSRSave.clear();
- CSRRestore.clear();
- }
- }
-
- // Check for effectiveness:
- // SR0 = {r | r in CSRSave[EntryBlock], CSRRestore[RB], RB in ReturnBlocks}
- // numSRReduced = |(UsedCSRegs - SR0)|, approx. SR0 by CSRSave[EntryBlock]
- // Gives a measure of how many CSR spills have been moved from EntryBlock
- // to minimal regions enclosing their uses.
- CSRegSet notSpilledInEntryBlock = (UsedCSRegs - CSRSave[EntryBlock]);
- unsigned numSRReducedThisFunc = notSpilledInEntryBlock.count();
- numSRReduced += numSRReducedThisFunc;
- DEBUG(if (ShrinkWrapDebugging >= BasicInfo) {
- dbgs() << "-----------------------------------------------------------\n";
- dbgs() << "total iterations = " << iterations << " ( "
- << Fn.getName()
- << " " << numSRReducedThisFunc
- << " " << Fn.size()
- << " )\n";
- dbgs() << "-----------------------------------------------------------\n";
- dumpSRSets();
- dbgs() << "-----------------------------------------------------------\n";
- if (numSRReducedThisFunc)
- verifySpillRestorePlacement();
- });
-}
-
-// Debugging methods.
-#ifndef NDEBUG
-/// findFastExitPath - debugging method used to detect functions
-/// with at least one path from the entry block to a return block
-/// directly or which has a very small number of edges.
-///
-void PEI::findFastExitPath() {
- if (! EntryBlock)
- return;
- // Fina a path from EntryBlock to any return block that does not branch:
- // Entry
- // | ...
- // v |
- // B1<-----+
- // |
- // v
- // Return
- for (MachineBasicBlock::succ_iterator SI = EntryBlock->succ_begin(),
- SE = EntryBlock->succ_end(); SI != SE; ++SI) {
- MachineBasicBlock* SUCC = *SI;
-
- // Assume positive, disprove existence of fast path.
- HasFastExitPath = true;
-
- // Check the immediate successors.
- if (isReturnBlock(SUCC)) {
- if (ShrinkWrapDebugging >= BasicInfo)
- dbgs() << "Fast exit path: " << getBasicBlockName(EntryBlock)
- << "->" << getBasicBlockName(SUCC) << "\n";
- break;
- }
- // Traverse df from SUCC, look for a branch block.
- std::string exitPath = getBasicBlockName(SUCC);
- for (df_iterator<MachineBasicBlock*> BI = df_begin(SUCC),
- BE = df_end(SUCC); BI != BE; ++BI) {
- MachineBasicBlock* SBB = *BI;
- // Reject paths with branch nodes.
- if (SBB->succ_size() > 1) {
- HasFastExitPath = false;
- break;
- }
- exitPath += "->" + getBasicBlockName(SBB);
- }
- if (HasFastExitPath) {
- if (ShrinkWrapDebugging >= BasicInfo)
- dbgs() << "Fast exit path: " << getBasicBlockName(EntryBlock)
- << "->" << exitPath << "\n";
- break;
- }
- }
-}
-
-/// verifySpillRestorePlacement - check the current spill/restore
-/// sets for safety. Attempt to find spills without restores or
-/// restores without spills.
-/// Spills: walk df from each MBB in spill set ensuring that
-/// all CSRs spilled at MMBB are restored on all paths
-/// from MBB to all exit blocks.
-/// Restores: walk idf from each MBB in restore set ensuring that
-/// all CSRs restored at MBB are spilled on all paths
-/// reaching MBB.
-///
-void PEI::verifySpillRestorePlacement() {
- unsigned numReturnBlocks = 0;
- for (MachineFunction::iterator MBBI = MF->begin(), MBBE = MF->end();
- MBBI != MBBE; ++MBBI) {
- MachineBasicBlock* MBB = MBBI;
- if (isReturnBlock(MBB) || MBB->succ_size() == 0)
- ++numReturnBlocks;
- }
- for (CSRegBlockMap::iterator BI = CSRSave.begin(),
- BE = CSRSave.end(); BI != BE; ++BI) {
- MachineBasicBlock* MBB = BI->first;
- CSRegSet spilled = BI->second;
- CSRegSet restored;
-
- if (spilled.empty())
- continue;
-
- DEBUG(dbgs() << "SAVE[" << getBasicBlockName(MBB) << "] = "
- << stringifyCSRegSet(spilled)
- << " RESTORE[" << getBasicBlockName(MBB) << "] = "
- << stringifyCSRegSet(CSRRestore[MBB]) << "\n");
-
- if (CSRRestore[MBB].intersects(spilled)) {
- restored |= (CSRRestore[MBB] & spilled);
- }
-
- // Walk depth first from MBB to find restores of all CSRs spilled at MBB:
- // we must find restores for all spills w/no intervening spills on all
- // paths from MBB to all return blocks.
- for (df_iterator<MachineBasicBlock*> BI = df_begin(MBB),
- BE = df_end(MBB); BI != BE; ++BI) {
- MachineBasicBlock* SBB = *BI;
- if (SBB == MBB)
- continue;
- // Stop when we encounter spills of any CSRs spilled at MBB that
- // have not yet been seen to be restored.
- if (CSRSave[SBB].intersects(spilled) &&
- !restored.contains(CSRSave[SBB] & spilled))
- break;
- // Collect the CSRs spilled at MBB that are restored
- // at this DF successor of MBB.
- if (CSRRestore[SBB].intersects(spilled))
- restored |= (CSRRestore[SBB] & spilled);
- // If we are at a retun block, check that the restores
- // we have seen so far exhaust the spills at MBB, then
- // reset the restores.
- if (isReturnBlock(SBB) || SBB->succ_size() == 0) {
- if (restored != spilled) {
- CSRegSet notRestored = (spilled - restored);
- DEBUG(dbgs() << MF->getName() << ": "
- << stringifyCSRegSet(notRestored)
- << " spilled at " << getBasicBlockName(MBB)
- << " are never restored on path to return "
- << getBasicBlockName(SBB) << "\n");
- }
- restored.clear();
- }
- }
- }
-
- // Check restore placements.
- for (CSRegBlockMap::iterator BI = CSRRestore.begin(),
- BE = CSRRestore.end(); BI != BE; ++BI) {
- MachineBasicBlock* MBB = BI->first;
- CSRegSet restored = BI->second;
- CSRegSet spilled;
-
- if (restored.empty())
- continue;
-
- DEBUG(dbgs() << "SAVE[" << getBasicBlockName(MBB) << "] = "
- << stringifyCSRegSet(CSRSave[MBB])
- << " RESTORE[" << getBasicBlockName(MBB) << "] = "
- << stringifyCSRegSet(restored) << "\n");
-
- if (CSRSave[MBB].intersects(restored)) {
- spilled |= (CSRSave[MBB] & restored);
- }
- // Walk inverse depth first from MBB to find spills of all
- // CSRs restored at MBB:
- for (idf_iterator<MachineBasicBlock*> BI = idf_begin(MBB),
- BE = idf_end(MBB); BI != BE; ++BI) {
- MachineBasicBlock* PBB = *BI;
- if (PBB == MBB)
- continue;
- // Stop when we encounter restores of any CSRs restored at MBB that
- // have not yet been seen to be spilled.
- if (CSRRestore[PBB].intersects(restored) &&
- !spilled.contains(CSRRestore[PBB] & restored))
- break;
- // Collect the CSRs restored at MBB that are spilled
- // at this DF predecessor of MBB.
- if (CSRSave[PBB].intersects(restored))
- spilled |= (CSRSave[PBB] & restored);
- }
- if (spilled != restored) {
- CSRegSet notSpilled = (restored - spilled);
- DEBUG(dbgs() << MF->getName() << ": "
- << stringifyCSRegSet(notSpilled)
- << " restored at " << getBasicBlockName(MBB)
- << " are never spilled\n");
- }
- }
-}
-
-// Debugging print methods.
-std::string PEI::getBasicBlockName(const MachineBasicBlock* MBB) {
- if (!MBB)
- return "";
-
- if (MBB->getBasicBlock())
- return MBB->getBasicBlock()->getName().str();
-
- std::ostringstream name;
- name << "_MBB_" << MBB->getNumber();
- return name.str();
-}
-
-std::string PEI::stringifyCSRegSet(const CSRegSet& s) {
- const TargetRegisterInfo* TRI = MF->getTarget().getRegisterInfo();
- const std::vector<CalleeSavedInfo> &CSI =
- MF->getFrameInfo()->getCalleeSavedInfo();
-
- std::ostringstream srep;
- if (CSI.size() == 0) {
- srep << "[]";
- return srep.str();
- }
- srep << "[";
- CSRegSet::iterator I = s.begin(), E = s.end();
- if (I != E) {
- unsigned reg = CSI[*I].getReg();
- srep << TRI->getName(reg);
- for (++I; I != E; ++I) {
- reg = CSI[*I].getReg();
- srep << ",";
- srep << TRI->getName(reg);
- }
- }
- srep << "]";
- return srep.str();
-}
-
-void PEI::dumpSet(const CSRegSet& s) {
- DEBUG(dbgs() << stringifyCSRegSet(s) << "\n");
-}
-
-void PEI::dumpUsed(MachineBasicBlock* MBB) {
- DEBUG({
- if (MBB)
- dbgs() << "CSRUsed[" << getBasicBlockName(MBB) << "] = "
- << stringifyCSRegSet(CSRUsed[MBB]) << "\n";
- });
-}
-
-void PEI::dumpAllUsed() {
- for (MachineFunction::iterator MBBI = MF->begin(), MBBE = MF->end();
- MBBI != MBBE; ++MBBI) {
- MachineBasicBlock* MBB = MBBI;
- dumpUsed(MBB);
- }
-}
-
-void PEI::dumpSets(MachineBasicBlock* MBB) {
- DEBUG({
- if (MBB)
- dbgs() << getBasicBlockName(MBB) << " | "
- << stringifyCSRegSet(CSRUsed[MBB]) << " | "
- << stringifyCSRegSet(AnticIn[MBB]) << " | "
- << stringifyCSRegSet(AnticOut[MBB]) << " | "
- << stringifyCSRegSet(AvailIn[MBB]) << " | "
- << stringifyCSRegSet(AvailOut[MBB]) << "\n";
- });
-}
-
-void PEI::dumpSets1(MachineBasicBlock* MBB) {
- DEBUG({
- if (MBB)
- dbgs() << getBasicBlockName(MBB) << " | "
- << stringifyCSRegSet(CSRUsed[MBB]) << " | "
- << stringifyCSRegSet(AnticIn[MBB]) << " | "
- << stringifyCSRegSet(AnticOut[MBB]) << " | "
- << stringifyCSRegSet(AvailIn[MBB]) << " | "
- << stringifyCSRegSet(AvailOut[MBB]) << " | "
- << stringifyCSRegSet(CSRSave[MBB]) << " | "
- << stringifyCSRegSet(CSRRestore[MBB]) << "\n";
- });
-}
-
-void PEI::dumpAllSets() {
- for (MachineFunction::iterator MBBI = MF->begin(), MBBE = MF->end();
- MBBI != MBBE; ++MBBI) {
- MachineBasicBlock* MBB = MBBI;
- dumpSets1(MBB);
- }
-}
-
-void PEI::dumpSRSets() {
- DEBUG({
- for (MachineFunction::iterator MBB = MF->begin(), E = MF->end();
- MBB != E; ++MBB) {
- if (!CSRSave[MBB].empty()) {
- dbgs() << "SAVE[" << getBasicBlockName(MBB) << "] = "
- << stringifyCSRegSet(CSRSave[MBB]);
- if (CSRRestore[MBB].empty())
- dbgs() << '\n';
- }
-
- if (!CSRRestore[MBB].empty() && !CSRSave[MBB].empty())
- dbgs() << " "
- << "RESTORE[" << getBasicBlockName(MBB) << "] = "
- << stringifyCSRegSet(CSRRestore[MBB]) << "\n";
- }
- });
-}
-#endif
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