[llvm-branch-commits] [llvm-branch] r86910 - in /llvm/branches/Apple/Leela: lib/CodeGen/ lib/Target/Alpha/ lib/Target/Blackfin/ lib/Target/CellSPU/ lib/Target/MSP430/ lib/Target/Sparc/ lib/Target/XCore/ lib/Transforms/Utils/ test/CodeGen/Thumb2/ test/CodeGen/X86/ test/Transforms/LCSSA/
Dan Gohman
gohman at apple.com
Wed Nov 11 16:39:53 PST 2009
Author: djg
Date: Wed Nov 11 18:39:53 2009
New Revision: 86910
URL: http://llvm.org/viewvc/llvm-project?rev=86910&view=rev
Log:
$ svn merge -c 86569 https://djg@llvm.org/svn/llvm-project/llvm/trunk
--- Merging r86569 into '.':
A test/Transforms/LCSSA/indirectbr.ll
U lib/Transforms/Utils/LCSSA.cpp
$ svn merge -c 86641 https://djg@llvm.org/svn/llvm-project/llvm/trunk
--- Merging r86641 into '.':
U lib/CodeGen/BranchFolding.cpp
$ svn merge -c 86642 https://djg@llvm.org/svn/llvm-project/llvm/trunk
--- Merging r86642 into '.':
G lib/CodeGen/BranchFolding.cpp
$ svn merge -c 86732 https://djg@llvm.org/svn/llvm-project/llvm/trunk
--- Merging r86732 into '.':
U lib/Target/CellSPU/SPUInstrInfo.td
$ svn merge -c 86851 https://djg@llvm.org/svn/llvm-project/llvm/trunk
--- Merging r86851 into '.':
U lib/Target/XCore/XCoreInstrInfo.td
U lib/Target/Alpha/AlphaInstrInfo.td
U lib/Target/MSP430/MSP430InstrInfo.td
U lib/Target/Sparc/SparcInstrInfo.td
U lib/Target/Blackfin/BlackfinInstrInfo.td
$ svn merge -c 86853 https://djg@llvm.org/svn/llvm-project/llvm/trunk
--- Merging r86853 into '.':
G lib/CodeGen/BranchFolding.cpp
$ svn merge -c 86854 https://djg@llvm.org/svn/llvm-project/llvm/trunk
--- Merging r86854 into '.':
G lib/CodeGen/BranchFolding.cpp
$ svn merge -c 86855 https://djg@llvm.org/svn/llvm-project/llvm/trunk
--- Merging r86855 into '.':
G lib/CodeGen/BranchFolding.cpp
$ svn merge -c 86856 https://djg@llvm.org/svn/llvm-project/llvm/trunk
--- Merging r86856 into '.':
G lib/CodeGen/BranchFolding.cpp
$ svn merge -c 86871 https://djg@llvm.org/svn/llvm-project/llvm/trunk
--- Merging r86871 into '.':
U test/CodeGen/X86/loop-blocks.ll
A test/CodeGen/X86/tail-opts.ll
U test/CodeGen/Thumb2/thumb2-cbnz.ll
U test/CodeGen/Thumb2/thumb2-ifcvt3.ll
G lib/CodeGen/BranchFolding.cpp
U lib/CodeGen/MachineBasicBlock.cpp
$ svn merge -c 86873 https://djg@llvm.org/svn/llvm-project/llvm/trunk
--- Merging r86873 into '.':
U lib/CodeGen/BranchFolding.h
$ svn merge -c 86875 https://djg@llvm.org/svn/llvm-project/llvm/trunk
--- Merging r86875 into '.':
G lib/CodeGen/BranchFolding.cpp
Added:
llvm/branches/Apple/Leela/test/CodeGen/X86/tail-opts.ll
- copied unchanged from r86871, llvm/trunk/test/CodeGen/X86/tail-opts.ll
llvm/branches/Apple/Leela/test/Transforms/LCSSA/indirectbr.ll
- copied unchanged from r86569, llvm/trunk/test/Transforms/LCSSA/indirectbr.ll
Modified:
llvm/branches/Apple/Leela/lib/CodeGen/BranchFolding.cpp
llvm/branches/Apple/Leela/lib/CodeGen/BranchFolding.h
llvm/branches/Apple/Leela/lib/CodeGen/MachineBasicBlock.cpp
llvm/branches/Apple/Leela/lib/Target/Alpha/AlphaInstrInfo.td
llvm/branches/Apple/Leela/lib/Target/Blackfin/BlackfinInstrInfo.td
llvm/branches/Apple/Leela/lib/Target/CellSPU/SPUInstrInfo.td
llvm/branches/Apple/Leela/lib/Target/MSP430/MSP430InstrInfo.td
llvm/branches/Apple/Leela/lib/Target/Sparc/SparcInstrInfo.td
llvm/branches/Apple/Leela/lib/Target/XCore/XCoreInstrInfo.td
llvm/branches/Apple/Leela/lib/Transforms/Utils/LCSSA.cpp
llvm/branches/Apple/Leela/test/CodeGen/Thumb2/thumb2-cbnz.ll
llvm/branches/Apple/Leela/test/CodeGen/Thumb2/thumb2-ifcvt3.ll
llvm/branches/Apple/Leela/test/CodeGen/X86/loop-blocks.ll
Modified: llvm/branches/Apple/Leela/lib/CodeGen/BranchFolding.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/branches/Apple/Leela/lib/CodeGen/BranchFolding.cpp?rev=86910&r1=86909&r2=86910&view=diff
==============================================================================
--- llvm/branches/Apple/Leela/lib/CodeGen/BranchFolding.cpp (original)
+++ llvm/branches/Apple/Leela/lib/CodeGen/BranchFolding.cpp Wed Nov 11 18:39:53 2009
@@ -32,6 +32,7 @@
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/ADT/SmallSet.h"
+#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/STLExtras.h"
#include <algorithm>
@@ -40,18 +41,24 @@
STATISTIC(NumDeadBlocks, "Number of dead blocks removed");
STATISTIC(NumBranchOpts, "Number of branches optimized");
STATISTIC(NumTailMerge , "Number of block tails merged");
-static cl::opt<cl::boolOrDefault> FlagEnableTailMerge("enable-tail-merge",
+static cl::opt<cl::boolOrDefault> FlagEnableTailMerge("enable-tail-merge",
cl::init(cl::BOU_UNSET), cl::Hidden);
// Throttle for huge numbers of predecessors (compile speed problems)
static cl::opt<unsigned>
-TailMergeThreshold("tail-merge-threshold",
+TailMergeThreshold("tail-merge-threshold",
cl::desc("Max number of predecessors to consider tail merging"),
cl::init(150), cl::Hidden);
+// Heuristic for tail merging (and, inversely, tail duplication).
+// TODO: This should be replaced with a target query.
+static cl::opt<unsigned>
+TailMergeSize("tail-merge-size",
+ cl::desc("Min number of instructions to consider tail merging"),
+ cl::init(3), cl::Hidden);
char BranchFolderPass::ID = 0;
-FunctionPass *llvm::createBranchFoldingPass(bool DefaultEnableTailMerge) {
+FunctionPass *llvm::createBranchFoldingPass(bool DefaultEnableTailMerge) {
return new BranchFolderPass(DefaultEnableTailMerge);
}
@@ -63,7 +70,6 @@
}
-
BranchFolder::BranchFolder(bool defaultEnableTailMerge) {
switch (FlagEnableTailMerge) {
case cl::BOU_UNSET: EnableTailMerge = defaultEnableTailMerge; break;
@@ -77,12 +83,12 @@
void BranchFolder::RemoveDeadBlock(MachineBasicBlock *MBB) {
assert(MBB->pred_empty() && "MBB must be dead!");
DEBUG(errs() << "\nRemoving MBB: " << *MBB);
-
+
MachineFunction *MF = MBB->getParent();
// drop all successors.
while (!MBB->succ_empty())
MBB->removeSuccessor(MBB->succ_end()-1);
-
+
// If there are any labels in the basic block, unregister them from
// MachineModuleInfo.
if (MMI && !MBB->empty()) {
@@ -93,7 +99,7 @@
MMI->InvalidateLabel(I->getOperand(0).getImm());
}
}
-
+
// Remove the block.
MF->erase(MBB);
}
@@ -190,7 +196,7 @@
// Figure out how these jump tables should be merged.
std::vector<unsigned> JTMapping;
JTMapping.reserve(JTs.size());
-
+
// We always keep the 0th jump table.
JTMapping.push_back(0);
@@ -202,7 +208,7 @@
else
JTMapping.push_back(JTI->getJumpTableIndex(JTs[i].MBBs));
}
-
+
// If a jump table was merge with another one, walk the function rewriting
// references to jump tables to reference the new JT ID's. Keep track of
// whether we see a jump table idx, if not, we can delete the JT.
@@ -221,7 +227,7 @@
JTIsLive.set(NewIdx);
}
}
-
+
// Finally, remove dead jump tables. This happens either because the
// indirect jump was unreachable (and thus deleted) or because the jump
// table was merged with some other one.
@@ -245,7 +251,7 @@
unsigned Hash = MI->getOpcode();
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
const MachineOperand &Op = MI->getOperand(i);
-
+
// Merge in bits from the operand if easy.
unsigned OperandHash = 0;
switch (Op.getType()) {
@@ -267,31 +273,30 @@
break;
default: break;
}
-
+
Hash += ((OperandHash << 3) | Op.getType()) << (i&31);
}
return Hash;
}
/// HashEndOfMBB - Hash the last few instructions in the MBB. For blocks
-/// with no successors, we hash two instructions, because cross-jumping
-/// only saves code when at least two instructions are removed (since a
+/// with no successors, we hash two instructions, because cross-jumping
+/// only saves code when at least two instructions are removed (since a
/// branch must be inserted). For blocks with a successor, one of the
/// two blocks to be tail-merged will end with a branch already, so
/// it gains to cross-jump even for one instruction.
-
static unsigned HashEndOfMBB(const MachineBasicBlock *MBB,
unsigned minCommonTailLength) {
MachineBasicBlock::const_iterator I = MBB->end();
if (I == MBB->begin())
return 0; // Empty MBB.
-
+
--I;
unsigned Hash = HashMachineInstr(I);
-
+
if (I == MBB->begin() || minCommonTailLength == 1)
return Hash; // Single instr MBB.
-
+
--I;
// Hash in the second-to-last instruction.
Hash ^= HashMachineInstr(I) << 2;
@@ -307,11 +312,11 @@
MachineBasicBlock::iterator &I2) {
I1 = MBB1->end();
I2 = MBB2->end();
-
+
unsigned TailLen = 0;
while (I1 != MBB1->begin() && I2 != MBB2->begin()) {
--I1; --I2;
- if (!I1->isIdenticalTo(I2) ||
+ if (!I1->isIdenticalTo(I2) ||
// FIXME: This check is dubious. It's used to get around a problem where
// people incorrectly expect inline asm directives to remain in the same
// relative order. This is untenable because normal compiler
@@ -332,11 +337,11 @@
void BranchFolder::ReplaceTailWithBranchTo(MachineBasicBlock::iterator OldInst,
MachineBasicBlock *NewDest) {
MachineBasicBlock *OldBB = OldInst->getParent();
-
+
// Remove all the old successors of OldBB from the CFG.
while (!OldBB->succ_empty())
OldBB->removeSuccessor(OldBB->succ_begin());
-
+
// Remove all the dead instructions from the end of OldBB.
OldBB->erase(OldInst, OldBB->end());
@@ -361,10 +366,10 @@
// Move all the successors of this block to the specified block.
NewMBB->transferSuccessors(&CurMBB);
-
+
// Add an edge from CurMBB to NewMBB for the fall-through.
CurMBB.addSuccessor(NewMBB);
-
+
// Splice the code over.
NewMBB->splice(NewMBB->end(), &CurMBB, BBI1, CurMBB.end());
@@ -404,7 +409,6 @@
// branches temporarily for tail merging). In the case where CurMBB ends
// with a conditional branch to the next block, optimize by reversing the
// test and conditionally branching to SuccMBB instead.
-
static void FixTail(MachineBasicBlock* CurMBB, MachineBasicBlock *SuccBB,
const TargetInstrInfo *TII) {
MachineFunction *MF = CurMBB->getParent();
@@ -445,6 +449,25 @@
}
}
+/// CountTerminators - Count the number of terminators in the given
+/// block and set I to the position of the first non-terminator, if there
+/// is one, or MBB->end() otherwise.
+static unsigned CountTerminators(MachineBasicBlock *MBB,
+ MachineBasicBlock::iterator &I) {
+ I = MBB->end();
+ unsigned NumTerms = 0;
+ for (;;) {
+ if (I == MBB->begin()) {
+ I = MBB->end();
+ break;
+ }
+ --I;
+ if (!I->getDesc().isTerminator()) break;
+ ++NumTerms;
+ }
+ return NumTerms;
+}
+
/// ProfitableToMerge - Check if two machine basic blocks have a common tail
/// and decide if it would be profitable to merge those tails. Return the
/// length of the common tail and iterators to the first common instruction
@@ -454,16 +477,35 @@
unsigned minCommonTailLength,
unsigned &CommonTailLen,
MachineBasicBlock::iterator &I1,
- MachineBasicBlock::iterator &I2) {
+ MachineBasicBlock::iterator &I2,
+ MachineBasicBlock *SuccBB,
+ MachineBasicBlock *PredBB) {
CommonTailLen = ComputeCommonTailLength(MBB1, MBB2, I1, I2);
MachineFunction *MF = MBB1->getParent();
- if (CommonTailLen >= minCommonTailLength)
- return true;
-
if (CommonTailLen == 0)
return false;
+ // It's almost always profitable to merge any number of non-terminator
+ // instructions with the block that falls through into the common successor.
+ if (MBB1 == PredBB || MBB2 == PredBB) {
+ MachineBasicBlock::iterator I;
+ unsigned NumTerms = CountTerminators(MBB1 == PredBB ? MBB2 : MBB1, I);
+ if (CommonTailLen > NumTerms)
+ return true;
+ }
+
+ // If both blocks have an unconditional branch temporarily stripped out,
+ // treat that as an additional common instruction.
+ if (MBB1 != PredBB && MBB2 != PredBB &&
+ !MBB1->back().getDesc().isBarrier() &&
+ !MBB2->back().getDesc().isBarrier())
+ --minCommonTailLength;
+
+ // Check if the common tail is long enough to be worthwhile.
+ if (CommonTailLen >= minCommonTailLength)
+ return true;
+
// If we are optimizing for code size, 1 instruction in common is enough if
// we don't have to split a block. At worst we will be replacing a
// fallthrough into the common tail with a branch, which at worst breaks
@@ -476,29 +518,32 @@
}
/// ComputeSameTails - Look through all the blocks in MergePotentials that have
-/// hash CurHash (guaranteed to match the last element). Build the vector
+/// hash CurHash (guaranteed to match the last element). Build the vector
/// SameTails of all those that have the (same) largest number of instructions
/// in common of any pair of these blocks. SameTails entries contain an
-/// iterator into MergePotentials (from which the MachineBasicBlock can be
-/// found) and a MachineBasicBlock::iterator into that MBB indicating the
+/// iterator into MergePotentials (from which the MachineBasicBlock can be
+/// found) and a MachineBasicBlock::iterator into that MBB indicating the
/// instruction where the matching code sequence begins.
/// Order of elements in SameTails is the reverse of the order in which
/// those blocks appear in MergePotentials (where they are not necessarily
/// consecutive).
-unsigned BranchFolder::ComputeSameTails(unsigned CurHash,
- unsigned minCommonTailLength) {
+unsigned BranchFolder::ComputeSameTails(unsigned CurHash,
+ unsigned minCommonTailLength,
+ MachineBasicBlock *SuccBB,
+ MachineBasicBlock *PredBB) {
unsigned maxCommonTailLength = 0U;
SameTails.clear();
MachineBasicBlock::iterator TrialBBI1, TrialBBI2;
MPIterator HighestMPIter = prior(MergePotentials.end());
for (MPIterator CurMPIter = prior(MergePotentials.end()),
- B = MergePotentials.begin();
- CurMPIter!=B && CurMPIter->first==CurHash;
+ B = MergePotentials.begin();
+ CurMPIter!=B && CurMPIter->first == CurHash;
--CurMPIter) {
- for (MPIterator I = prior(CurMPIter); I->first==CurHash ; --I) {
+ for (MPIterator I = prior(CurMPIter); I->first == CurHash ; --I) {
unsigned CommonTailLen;
if (ProfitableToMerge(CurMPIter->second, I->second, minCommonTailLength,
- CommonTailLen, TrialBBI1, TrialBBI2)) {
+ CommonTailLen, TrialBBI1, TrialBBI2,
+ SuccBB, PredBB)) {
if (CommonTailLen > maxCommonTailLength) {
SameTails.clear();
maxCommonTailLength = CommonTailLen;
@@ -509,7 +554,7 @@
CommonTailLen == maxCommonTailLength)
SameTails.push_back(std::make_pair(I, TrialBBI2));
}
- if (I==B)
+ if (I == B)
break;
}
}
@@ -518,18 +563,18 @@
/// RemoveBlocksWithHash - Remove all blocks with hash CurHash from
/// MergePotentials, restoring branches at ends of blocks as appropriate.
-void BranchFolder::RemoveBlocksWithHash(unsigned CurHash,
+void BranchFolder::RemoveBlocksWithHash(unsigned CurHash,
MachineBasicBlock* SuccBB,
MachineBasicBlock* PredBB) {
MPIterator CurMPIter, B;
- for (CurMPIter = prior(MergePotentials.end()), B = MergePotentials.begin();
- CurMPIter->first==CurHash;
+ for (CurMPIter = prior(MergePotentials.end()), B = MergePotentials.begin();
+ CurMPIter->first == CurHash;
--CurMPIter) {
// Put the unconditional branch back, if we need one.
MachineBasicBlock *CurMBB = CurMPIter->second;
if (SuccBB && CurMBB != PredBB)
FixTail(CurMBB, SuccBB, TII);
- if (CurMPIter==B)
+ if (CurMPIter == B)
break;
}
if (CurMPIter->first!=CurHash)
@@ -545,15 +590,15 @@
unsigned TimeEstimate = ~0U;
for (i=0, commonTailIndex=0; i<SameTails.size(); i++) {
// Use PredBB if possible; that doesn't require a new branch.
- if (SameTails[i].first->second==PredBB) {
+ if (SameTails[i].first->second == PredBB) {
commonTailIndex = i;
break;
}
// Otherwise, make a (fairly bogus) choice based on estimate of
// how long it will take the various blocks to execute.
- unsigned t = EstimateRuntime(SameTails[i].first->second->begin(),
+ unsigned t = EstimateRuntime(SameTails[i].first->second->begin(),
SameTails[i].second);
- if (t<=TimeEstimate) {
+ if (t <= TimeEstimate) {
TimeEstimate = t;
commonTailIndex = i;
}
@@ -562,14 +607,15 @@
MachineBasicBlock::iterator BBI = SameTails[commonTailIndex].second;
MachineBasicBlock *MBB = SameTails[commonTailIndex].first->second;
- DEBUG(errs() << "\nSplitting " << MBB->getNumber() << ", size "
+ DEBUG(errs() << "\nSplitting BB#" << MBB->getNumber() << ", size "
<< maxCommonTailLength);
MachineBasicBlock *newMBB = SplitMBBAt(*MBB, BBI);
SameTails[commonTailIndex].first->second = newMBB;
SameTails[commonTailIndex].second = newMBB->begin();
+
// If we split PredBB, newMBB is the new predecessor.
- if (PredBB==MBB)
+ if (PredBB == MBB)
PredBB = newMBB;
return commonTailIndex;
@@ -579,20 +625,66 @@
// successor, or all have no successor) can be tail-merged. If there is a
// successor, any blocks in MergePotentials that are not tail-merged and
// are not immediately before Succ must have an unconditional branch to
-// Succ added (but the predecessor/successor lists need no adjustment).
+// Succ added (but the predecessor/successor lists need no adjustment).
// The lone predecessor of Succ that falls through into Succ,
// if any, is given in PredBB.
-bool BranchFolder::TryMergeBlocks(MachineBasicBlock *SuccBB,
- MachineBasicBlock* PredBB) {
+bool BranchFolder::TryTailMergeBlocks(MachineBasicBlock *SuccBB,
+ MachineBasicBlock* PredBB) {
bool MadeChange = false;
- // It doesn't make sense to save a single instruction since tail merging
- // will add a jump.
- // FIXME: Ask the target to provide the threshold?
- unsigned minCommonTailLength = (SuccBB ? 1 : 2) + 1;
-
- DEBUG(errs() << "\nTryMergeBlocks " << MergePotentials.size() << '\n');
+ // Except for the special cases below, tail-merge if there are at least
+ // this many instructions in common.
+ unsigned minCommonTailLength = TailMergeSize;
+
+ // If there's a successor block, there are some cases which don't require
+ // new branching and as such are very likely to be profitable.
+ if (SuccBB) {
+ if (SuccBB->pred_size() == MergePotentials.size() &&
+ !MergePotentials[0].second->empty()) {
+ // If all the predecessors have at least one tail instruction in common,
+ // merging is very likely to be a win since it won't require an increase
+ // in static branches, and it will decrease the static instruction count.
+ bool AllPredsMatch = true;
+ MachineBasicBlock::iterator FirstNonTerm;
+ unsigned MinNumTerms = CountTerminators(MergePotentials[0].second,
+ FirstNonTerm);
+ if (FirstNonTerm != MergePotentials[0].second->end()) {
+ for (unsigned i = 1, e = MergePotentials.size(); i != e; ++i) {
+ MachineBasicBlock::iterator OtherFirstNonTerm;
+ unsigned NumTerms = CountTerminators(MergePotentials[0].second,
+ OtherFirstNonTerm);
+ if (NumTerms < MinNumTerms)
+ MinNumTerms = NumTerms;
+ if (OtherFirstNonTerm == MergePotentials[i].second->end() ||
+ OtherFirstNonTerm->isIdenticalTo(FirstNonTerm)) {
+ AllPredsMatch = false;
+ break;
+ }
+ }
+
+ // If they all have an instruction in common, do any amount of merging.
+ if (AllPredsMatch)
+ minCommonTailLength = MinNumTerms + 1;
+ }
+ }
+ }
+
+ DEBUG(errs() << "\nTryTailMergeBlocks: ";
+ for (unsigned i = 0, e = MergePotentials.size(); i != e; ++i)
+ errs() << "BB#" << MergePotentials[i].second->getNumber()
+ << (i == e-1 ? "" : ", ");
+ errs() << "\n";
+ if (SuccBB) {
+ errs() << " with successor BB#" << SuccBB->getNumber() << '\n';
+ if (PredBB)
+ errs() << " which has fall-through from BB#"
+ << PredBB->getNumber() << "\n";
+ }
+ errs() << "Looking for common tails of at least "
+ << minCommonTailLength << " instruction"
+ << (minCommonTailLength == 1 ? "" : "s") << '\n';
+ );
// Sort by hash value so that blocks with identical end sequences sort
// together.
@@ -600,14 +692,15 @@
// Walk through equivalence sets looking for actual exact matches.
while (MergePotentials.size() > 1) {
- unsigned CurHash = prior(MergePotentials.end())->first;
-
+ unsigned CurHash = MergePotentials.back().first;
+
// Build SameTails, identifying the set of blocks with this hash code
// and with the maximum number of instructions in common.
- unsigned maxCommonTailLength = ComputeSameTails(CurHash,
- minCommonTailLength);
+ unsigned maxCommonTailLength = ComputeSameTails(CurHash,
+ minCommonTailLength,
+ SuccBB, PredBB);
- // If we didn't find any pair that has at least minCommonTailLength
+ // If we didn't find any pair that has at least minCommonTailLength
// instructions in common, remove all blocks with this hash code and retry.
if (SameTails.empty()) {
RemoveBlocksWithHash(CurHash, SuccBB, PredBB);
@@ -623,27 +716,35 @@
unsigned int commonTailIndex, i;
for (commonTailIndex=SameTails.size(), i=0; i<SameTails.size(); i++) {
MachineBasicBlock *MBB = SameTails[i].first->second;
- if (MBB->begin() == SameTails[i].second && MBB != EntryBB) {
+ if (MBB == EntryBB)
+ continue;
+ if (MBB == PredBB) {
commonTailIndex = i;
- if (MBB==PredBB)
- break;
+ break;
}
+ if (MBB->begin() == SameTails[i].second)
+ commonTailIndex = i;
}
- if (commonTailIndex==SameTails.size()) {
+ if (commonTailIndex == SameTails.size() ||
+ (SameTails[commonTailIndex].first->second == PredBB &&
+ SameTails[commonTailIndex].first->second->begin() !=
+ SameTails[i].second)) {
// None of the blocks consist entirely of the common tail.
// Split a block so that one does.
- commonTailIndex = CreateCommonTailOnlyBlock(PredBB, maxCommonTailLength);
+ commonTailIndex = CreateCommonTailOnlyBlock(PredBB, maxCommonTailLength);
}
MachineBasicBlock *MBB = SameTails[commonTailIndex].first->second;
// MBB is common tail. Adjust all other BB's to jump to this one.
// Traversal must be forwards so erases work.
- DEBUG(errs() << "\nUsing common tail " << MBB->getNumber() << " for ");
- for (unsigned int i=0; i<SameTails.size(); ++i) {
- if (commonTailIndex==i)
+ DEBUG(errs() << "\nUsing common tail in BB#" << MBB->getNumber()
+ << " for ");
+ for (unsigned int i=0, e = SameTails.size(); i != e; ++i) {
+ if (commonTailIndex == i)
continue;
- DEBUG(errs() << SameTails[i].first->second->getNumber() << ",");
+ DEBUG(errs() << "BB#" << SameTails[i].first->second->getNumber()
+ << (i == e-1 ? "" : ", "));
// Hack the end off BB i, making it jump to BB commonTailIndex instead.
ReplaceTailWithBranchTo(SameTails[i].second, MBB);
// BB i is no longer a predecessor of SuccBB; remove it from the worklist.
@@ -660,7 +761,7 @@
bool BranchFolder::TailMergeBlocks(MachineFunction &MF) {
if (!EnableTailMerge) return false;
-
+
bool MadeChange = false;
// First find blocks with no successors.
@@ -669,17 +770,18 @@
if (I->succ_empty())
MergePotentials.push_back(std::make_pair(HashEndOfMBB(I, 2U), I));
}
+
// See if we can do any tail merging on those.
if (MergePotentials.size() < TailMergeThreshold &&
MergePotentials.size() >= 2)
- MadeChange |= TryMergeBlocks(NULL, NULL);
+ MadeChange |= TryTailMergeBlocks(NULL, NULL);
// Look at blocks (IBB) with multiple predecessors (PBB).
// We change each predecessor to a canonical form, by
// (1) temporarily removing any unconditional branch from the predecessor
// to IBB, and
// (2) alter conditional branches so they branch to the other block
- // not IBB; this may require adding back an unconditional branch to IBB
+ // not IBB; this may require adding back an unconditional branch to IBB
// later, where there wasn't one coming in. E.g.
// Bcc IBB
// fallthrough to QBB
@@ -693,18 +795,19 @@
// a compile-time infinite loop repeatedly doing and undoing the same
// transformations.)
- for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I) {
+ for (MachineFunction::iterator I = next(MF.begin()), E = MF.end();
+ I != E; ++I) {
if (I->pred_size() >= 2 && I->pred_size() < TailMergeThreshold) {
SmallPtrSet<MachineBasicBlock *, 8> UniquePreds;
MachineBasicBlock *IBB = I;
MachineBasicBlock *PredBB = prior(I);
MergePotentials.clear();
- for (MachineBasicBlock::pred_iterator P = I->pred_begin(),
+ for (MachineBasicBlock::pred_iterator P = I->pred_begin(),
E2 = I->pred_end();
P != E2; ++P) {
MachineBasicBlock* PBB = *P;
// Skip blocks that loop to themselves, can't tail merge these.
- if (PBB==IBB)
+ if (PBB == IBB)
continue;
// Visit each predecessor only once.
if (!UniquePreds.insert(PBB))
@@ -715,7 +818,7 @@
// Failing case: IBB is the target of a cbr, and
// we cannot reverse the branch.
SmallVector<MachineOperand, 4> NewCond(Cond);
- if (!Cond.empty() && TBB==IBB) {
+ if (!Cond.empty() && TBB == IBB) {
if (TII->ReverseBranchCondition(NewCond))
continue;
// This is the QBB case described above
@@ -730,7 +833,7 @@
MachineBasicBlock* PredNextBB = NULL;
if (IP!=MF.end())
PredNextBB = IP;
- if (TBB==NULL) {
+ if (TBB == NULL) {
if (IBB!=PredNextBB) // fallthrough
continue;
} else if (FBB) {
@@ -749,19 +852,19 @@
TII->RemoveBranch(*PBB);
if (!Cond.empty())
// reinsert conditional branch only, for now
- TII->InsertBranch(*PBB, (TBB==IBB) ? FBB : TBB, 0, NewCond);
+ TII->InsertBranch(*PBB, (TBB == IBB) ? FBB : TBB, 0, NewCond);
}
MergePotentials.push_back(std::make_pair(HashEndOfMBB(PBB, 1U), *P));
}
}
- if (MergePotentials.size() >= 2)
- MadeChange |= TryMergeBlocks(I, PredBB);
- // Reinsert an unconditional branch if needed.
- // The 1 below can occur as a result of removing blocks in TryMergeBlocks.
- PredBB = prior(I); // this may have been changed in TryMergeBlocks
- if (MergePotentials.size()==1 &&
- MergePotentials.begin()->second != PredBB)
- FixTail(MergePotentials.begin()->second, I, TII);
+ if (MergePotentials.size() >= 2)
+ MadeChange |= TryTailMergeBlocks(IBB, PredBB);
+ // Reinsert an unconditional branch if needed.
+ // The 1 below can occur as a result of removing blocks in TryTailMergeBlocks.
+ PredBB = prior(I); // this may have been changed in TryTailMergeBlocks
+ if (MergePotentials.size() == 1 &&
+ MergePotentials.begin()->second != PredBB)
+ FixTail(MergePotentials.begin()->second, IBB, TII);
}
}
return MadeChange;
@@ -773,14 +876,14 @@
bool BranchFolder::OptimizeBranches(MachineFunction &MF) {
bool MadeChange = false;
-
+
// Make sure blocks are numbered in order
MF.RenumberBlocks();
for (MachineFunction::iterator I = ++MF.begin(), E = MF.end(); I != E; ) {
MachineBasicBlock *MBB = I++;
MadeChange |= OptimizeBlock(MBB);
-
+
// If it is dead, remove it.
if (MBB->pred_empty()) {
RemoveDeadBlock(MBB);
@@ -801,7 +904,7 @@
///
bool BranchFolder::CanFallThrough(MachineBasicBlock *CurBB,
bool BranchUnAnalyzable,
- MachineBasicBlock *TBB,
+ MachineBasicBlock *TBB,
MachineBasicBlock *FBB,
const SmallVectorImpl<MachineOperand> &Cond) {
MachineFunction::iterator Fallthrough = CurBB;
@@ -809,13 +912,21 @@
// If FallthroughBlock is off the end of the function, it can't fall through.
if (Fallthrough == CurBB->getParent()->end())
return false;
-
+
// If FallthroughBlock isn't a successor of CurBB, no fallthrough is possible.
if (!CurBB->isSuccessor(Fallthrough))
return false;
-
- // If we couldn't analyze the branch, assume it could fall through.
- if (BranchUnAnalyzable) return true;
+
+ // If we couldn't analyze the branch, examine the last instruction.
+ // If the block doesn't end in a known control barrier, assume fallthrough
+ // is possible. The isPredicable check is needed because this code can be
+ // called during IfConversion, where an instruction which is normally a
+ // Barrier is predicated and thus no longer an actual control barrier. This
+ // is over-conservative though, because if an instruction isn't actually
+ // predicated we could still treat it like a barrier.
+ if (BranchUnAnalyzable)
+ return CurBB->empty() || !CurBB->back().getDesc().isBarrier() ||
+ CurBB->back().getDesc().isPredicable();
// If there is no branch, control always falls through.
if (TBB == 0) return true;
@@ -825,11 +936,11 @@
if (MachineFunction::iterator(TBB) == Fallthrough ||
MachineFunction::iterator(FBB) == Fallthrough)
return true;
-
- // If it's an unconditional branch to some block not the fall through, it
+
+ // If it's an unconditional branch to some block not the fall through, it
// doesn't fall through.
if (Cond.empty()) return false;
-
+
// Otherwise, if it is conditional and has no explicit false block, it falls
// through.
return FBB == 0;
@@ -853,14 +964,14 @@
/// fall-through to MBB1 than to fall through into MBB2. This has to return
/// a strict ordering, returning true for both (MBB1,MBB2) and (MBB2,MBB1) will
/// result in infinite loops.
-static bool IsBetterFallthrough(MachineBasicBlock *MBB1,
+static bool IsBetterFallthrough(MachineBasicBlock *MBB1,
MachineBasicBlock *MBB2) {
// Right now, we use a simple heuristic. If MBB2 ends with a call, and
// MBB1 doesn't, we prefer to fall through into MBB1. This allows us to
// optimize branches that branch to either a return block or an assert block
// into a fallthrough to the return.
if (MBB1->empty() || MBB2->empty()) return false;
-
+
// If there is a clear successor ordering we make sure that one block
// will fall through to the next
if (MBB1->isSuccessor(MBB2)) return true;
@@ -871,14 +982,112 @@
return MBB2I->getDesc().isCall() && !MBB1I->getDesc().isCall();
}
+/// TailDuplicate - MBB unconditionally branches to SuccBB. If it is profitable,
+/// duplicate SuccBB's contents in MBB to eliminate the branch.
+bool BranchFolder::TailDuplicate(MachineBasicBlock *TailBB,
+ bool PrevFallsThrough,
+ MachineFunction &MF) {
+ // Don't try to tail-duplicate single-block loops.
+ if (TailBB->isSuccessor(TailBB))
+ return false;
+
+ // Don't tail-duplicate a block which will soon be folded into its successor.
+ if (TailBB->succ_size() == 1 &&
+ TailBB->succ_begin()[0]->pred_size() == 1)
+ return false;
+
+ // Duplicate up to one less that the tail-merge threshold, so that we don't
+ // get into an infinite loop between duplicating and merging. When optimizing
+ // for size, duplicate only one, because one branch instruction can be
+ // eliminated to compensate for the duplication.
+ unsigned MaxDuplicateCount =
+ MF.getFunction()->hasFnAttr(Attribute::OptimizeForSize) ?
+ 1 : (TailMergeSize - 1);
+
+ // Check the instructions in the block to determine whether tail-duplication
+ // is invalid or unlikely to be unprofitable.
+ unsigned i = 0;
+ bool HasCall = false;
+ for (MachineBasicBlock::iterator I = TailBB->begin();
+ I != TailBB->end(); ++I, ++i) {
+ // Non-duplicable things shouldn't be tail-duplicated.
+ if (I->getDesc().isNotDuplicable()) return false;
+ // Don't duplicate more than the threshold.
+ if (i == MaxDuplicateCount) return false;
+ // Remember if we saw a call.
+ if (I->getDesc().isCall()) HasCall = true;
+ }
+ // Heuristically, don't tail-duplicate calls if it would expand code size,
+ // as it's less likely to be worth the extra cost.
+ if (i > 1 && HasCall)
+ return false;
+
+ // Iterate through all the unique predecessors and tail-duplicate this
+ // block into them, if possible. Copying the list ahead of time also
+ // avoids trouble with the predecessor list reallocating.
+ bool Changed = false;
+ SmallSetVector<MachineBasicBlock *, 8> Preds(TailBB->pred_begin(),
+ TailBB->pred_end());
+ for (SmallSetVector<MachineBasicBlock *, 8>::iterator PI = Preds.begin(),
+ PE = Preds.end(); PI != PE; ++PI) {
+ MachineBasicBlock *PredBB = *PI;
+
+ assert(TailBB != PredBB &&
+ "Single-block loop should have been rejected earlier!");
+ if (PredBB->succ_size() > 1) continue;
+
+ MachineBasicBlock *PredTBB, *PredFBB;
+ SmallVector<MachineOperand, 4> PredCond;
+ if (TII->AnalyzeBranch(*PredBB, PredTBB, PredFBB, PredCond, true))
+ continue;
+ if (!PredCond.empty())
+ continue;
+ // EH edges are ignored by AnalyzeBranch.
+ if (PredBB->succ_size() != 1)
+ continue;
+ // Don't duplicate into a fall-through predecessor unless its the
+ // only predecessor.
+ if (&*next(MachineFunction::iterator(PredBB)) == TailBB &&
+ PrevFallsThrough &&
+ TailBB->pred_size() != 1)
+ continue;
+
+ DEBUG(errs() << "\nTail-duplicating into PredBB: " << *PredBB
+ << "From Succ: " << *TailBB);
+
+ // Remove PredBB's unconditional branch.
+ TII->RemoveBranch(*PredBB);
+ // Clone the contents of TailBB into PredBB.
+ for (MachineBasicBlock::iterator I = TailBB->begin(), E = TailBB->end();
+ I != E; ++I) {
+ MachineInstr *NewMI = MF.CloneMachineInstr(I);
+ PredBB->insert(PredBB->end(), NewMI);
+ }
+
+ // Update the CFG.
+ PredBB->removeSuccessor(PredBB->succ_begin());
+ assert(PredBB->succ_empty() &&
+ "TailDuplicate called on block with multiple successors!");
+ for (MachineBasicBlock::succ_iterator I = TailBB->succ_begin(),
+ E = TailBB->succ_end(); I != E; ++I)
+ PredBB->addSuccessor(*I);
+
+ Changed = true;
+ }
+
+ return Changed;
+}
+
/// OptimizeBlock - Analyze and optimize control flow related to the specified
/// block. This is never called on the entry block.
bool BranchFolder::OptimizeBlock(MachineBasicBlock *MBB) {
bool MadeChange = false;
+ MachineFunction &MF = *MBB->getParent();
+ReoptimizeBlock:
MachineFunction::iterator FallThrough = MBB;
++FallThrough;
-
+
// If this block is empty, make everyone use its fall-through, not the block
// explicitly. Landing pads should not do this since the landing-pad table
// points to this block. Blocks with their addresses taken shouldn't be
@@ -886,8 +1095,8 @@
if (MBB->empty() && !MBB->isLandingPad() && !MBB->hasAddressTaken()) {
// Dead block? Leave for cleanup later.
if (MBB->pred_empty()) return MadeChange;
-
- if (FallThrough == MBB->getParent()->end()) {
+
+ if (FallThrough == MF.end()) {
// TODO: Simplify preds to not branch here if possible!
} else {
// Rewrite all predecessors of the old block to go to the fallthrough
@@ -898,8 +1107,7 @@
}
// If MBB was the target of a jump table, update jump tables to go to the
// fallthrough instead.
- MBB->getParent()->getJumpTableInfo()->
- ReplaceMBBInJumpTables(MBB, FallThrough);
+ MF.getJumpTableInfo()->ReplaceMBBInJumpTables(MBB, FallThrough);
MadeChange = true;
}
return MadeChange;
@@ -917,18 +1125,38 @@
// If the CFG for the prior block has extra edges, remove them.
MadeChange |= PrevBB.CorrectExtraCFGEdges(PriorTBB, PriorFBB,
!PriorCond.empty());
-
+
// If the previous branch is conditional and both conditions go to the same
// destination, remove the branch, replacing it with an unconditional one or
// a fall-through.
if (PriorTBB && PriorTBB == PriorFBB) {
TII->RemoveBranch(PrevBB);
- PriorCond.clear();
+ PriorCond.clear();
if (PriorTBB != MBB)
TII->InsertBranch(PrevBB, PriorTBB, 0, PriorCond);
MadeChange = true;
++NumBranchOpts;
- return OptimizeBlock(MBB);
+ goto ReoptimizeBlock;
+ }
+
+ // If the previous block unconditionally falls through to this block and
+ // this block has no other predecessors, move the contents of this block
+ // into the prior block. This doesn't usually happen when SimplifyCFG
+ // has been used, but it can happen tail duplication eliminates all the
+ // non-branch predecessors of a block leaving only the fall-through edge.
+ // This has to check PrevBB->succ_size() because EH edges are ignored by
+ // AnalyzeBranch.
+ if (PriorCond.empty() && !PriorTBB && MBB->pred_size() == 1 &&
+ PrevBB.succ_size() == 1 &&
+ !MBB->hasAddressTaken()) {
+ DEBUG(errs() << "\nMerging into block: " << PrevBB
+ << "From MBB: " << *MBB);
+ PrevBB.splice(PrevBB.end(), MBB, MBB->begin(), MBB->end());
+ PrevBB.removeSuccessor(PrevBB.succ_begin());;
+ assert(PrevBB.succ_empty());
+ PrevBB.transferSuccessors(MBB);
+ MadeChange = true;
+ return MadeChange;
}
// If the previous branch *only* branches to *this* block (conditional or
@@ -937,9 +1165,9 @@
TII->RemoveBranch(PrevBB);
MadeChange = true;
++NumBranchOpts;
- return OptimizeBlock(MBB);
+ goto ReoptimizeBlock;
}
-
+
// If the prior block branches somewhere else on the condition and here if
// the condition is false, remove the uncond second branch.
if (PriorFBB == MBB) {
@@ -947,9 +1175,9 @@
TII->InsertBranch(PrevBB, PriorTBB, 0, PriorCond);
MadeChange = true;
++NumBranchOpts;
- return OptimizeBlock(MBB);
+ goto ReoptimizeBlock;
}
-
+
// If the prior block branches here on true and somewhere else on false, and
// if the branch condition is reversible, reverse the branch to create a
// fall-through.
@@ -960,10 +1188,10 @@
TII->InsertBranch(PrevBB, PriorFBB, 0, NewPriorCond);
MadeChange = true;
++NumBranchOpts;
- return OptimizeBlock(MBB);
+ goto ReoptimizeBlock;
}
}
-
+
// If this block has no successors (e.g. it is a return block or ends with
// a call to a no-return function like abort or __cxa_throw) and if the pred
// falls through into this block, and if it would otherwise fall through
@@ -976,13 +1204,13 @@
MachineFunction::iterator(PriorTBB) == FallThrough &&
!CanFallThrough(MBB)) {
bool DoTransform = true;
-
+
// We have to be careful that the succs of PredBB aren't both no-successor
// blocks. If neither have successors and if PredBB is the second from
// last block in the function, we'd just keep swapping the two blocks for
// last. Only do the swap if one is clearly better to fall through than
// the other.
- if (FallThrough == --MBB->getParent()->end() &&
+ if (FallThrough == --MF.end() &&
!IsBetterFallthrough(PriorTBB, MBB))
DoTransform = false;
@@ -1000,20 +1228,20 @@
if (DoTransform && !MBB->succ_empty() &&
(!CanFallThrough(PriorTBB) || PriorTBB->empty()))
DoTransform = false;
-
-
+
+
if (DoTransform) {
// Reverse the branch so we will fall through on the previous true cond.
SmallVector<MachineOperand, 4> NewPriorCond(PriorCond);
if (!TII->ReverseBranchCondition(NewPriorCond)) {
DEBUG(errs() << "\nMoving MBB: " << *MBB
<< "To make fallthrough to: " << *PriorTBB << "\n");
-
+
TII->RemoveBranch(PrevBB);
TII->InsertBranch(PrevBB, MBB, 0, NewPriorCond);
// Move this block to the end of the function.
- MBB->moveAfter(--MBB->getParent()->end());
+ MBB->moveAfter(--MF.end());
MadeChange = true;
++NumBranchOpts;
return MadeChange;
@@ -1021,7 +1249,7 @@
}
}
}
-
+
// Analyze the branch in the current block.
MachineBasicBlock *CurTBB = 0, *CurFBB = 0;
SmallVector<MachineOperand, 4> CurCond;
@@ -1030,7 +1258,7 @@
// If the CFG for the prior block has extra edges, remove them.
MadeChange |= MBB->CorrectExtraCFGEdges(CurTBB, CurFBB, !CurCond.empty());
- // If this is a two-way branch, and the FBB branches to this block, reverse
+ // If this is a two-way branch, and the FBB branches to this block, reverse
// the condition so the single-basic-block loop is faster. Instead of:
// Loop: xxx; jcc Out; jmp Loop
// we want:
@@ -1042,14 +1270,14 @@
TII->InsertBranch(*MBB, CurFBB, CurTBB, NewCond);
MadeChange = true;
++NumBranchOpts;
- return OptimizeBlock(MBB);
+ goto ReoptimizeBlock;
}
}
-
-
+
+
// If this branch is the only thing in its block, see if we can forward
// other blocks across it.
- if (CurTBB && CurCond.empty() && CurFBB == 0 &&
+ if (CurTBB && CurCond.empty() && CurFBB == 0 &&
MBB->begin()->getDesc().isBranch() && CurTBB != MBB &&
!MBB->hasAddressTaken()) {
// This block may contain just an unconditional branch. Because there can
@@ -1068,7 +1296,7 @@
!PrevBB.isSuccessor(MBB)) {
// If the prior block falls through into us, turn it into an
// explicit branch to us to make updates simpler.
- if (!PredHasNoFallThrough && PrevBB.isSuccessor(MBB) &&
+ if (!PredHasNoFallThrough && PrevBB.isSuccessor(MBB) &&
PriorTBB != MBB && PriorFBB != MBB) {
if (PriorTBB == 0) {
assert(PriorCond.empty() && PriorFBB == 0 &&
@@ -1104,18 +1332,17 @@
NewCurFBB, NewCurCond, true);
if (!NewCurUnAnalyzable && NewCurTBB && NewCurTBB == NewCurFBB) {
TII->RemoveBranch(*PMBB);
- NewCurCond.clear();
+ NewCurCond.clear();
TII->InsertBranch(*PMBB, NewCurTBB, 0, NewCurCond);
MadeChange = true;
++NumBranchOpts;
- PMBB->CorrectExtraCFGEdges(NewCurTBB, NewCurFBB, false);
+ PMBB->CorrectExtraCFGEdges(NewCurTBB, 0, false);
}
}
}
// Change any jumptables to go to the new MBB.
- MBB->getParent()->getJumpTableInfo()->
- ReplaceMBBInJumpTables(MBB, CurTBB);
+ MF.getJumpTableInfo()->ReplaceMBBInJumpTables(MBB, CurTBB);
if (DidChange) {
++NumBranchOpts;
MadeChange = true;
@@ -1123,22 +1350,32 @@
}
}
}
-
+
// Add the branch back if the block is more than just an uncond branch.
TII->InsertBranch(*MBB, CurTBB, 0, CurCond);
}
}
+ // Now we know that there was no fall-through into this block, check to
+ // see if it has a fall-through into its successor.
+ bool CurFallsThru = CanFallThrough(MBB, CurUnAnalyzable, CurTBB, CurFBB,
+ CurCond);
+ bool PrevFallsThru = CanFallThrough(&PrevBB, PriorUnAnalyzable,
+ PriorTBB, PriorFBB, PriorCond);
+
+ // If this block is small, unconditionally branched to, and does not
+ // fall through, tail-duplicate its instructions into its predecessors
+ // to eliminate a (dynamic) branch.
+ if (!CurFallsThru)
+ if (TailDuplicate(MBB, PrevFallsThru, MF)) {
+ MadeChange = true;
+ return MadeChange;
+ }
+
// If the prior block doesn't fall through into this block, and if this
// block doesn't fall through into some other block, see if we can find a
// place to move this block where a fall-through will happen.
- if (!CanFallThrough(&PrevBB, PriorUnAnalyzable,
- PriorTBB, PriorFBB, PriorCond)) {
- // Now we know that there was no fall-through into this block, check to
- // see if it has a fall-through into its successor.
- bool CurFallsThru = CanFallThrough(MBB, CurUnAnalyzable, CurTBB, CurFBB,
- CurCond);
-
+ if (!PrevFallsThru) {
if (!MBB->isLandingPad()) {
// Check all the predecessors of this block. If one of them has no fall
// throughs, move this block right after it.
@@ -1147,12 +1384,15 @@
// Analyze the branch at the end of the pred.
MachineBasicBlock *PredBB = *PI;
MachineFunction::iterator PredFallthrough = PredBB; ++PredFallthrough;
- if (PredBB != MBB && !CanFallThrough(PredBB)
+ MachineBasicBlock *PredTBB, *PredFBB;
+ SmallVector<MachineOperand, 4> PredCond;
+ if (PredBB != MBB && !CanFallThrough(PredBB) &&
+ !TII->AnalyzeBranch(*PredBB, PredTBB, PredFBB, PredCond, true)
&& (!CurFallsThru || !CurTBB || !CurFBB)
&& (!CurFallsThru || MBB->getNumber() >= PredBB->getNumber())) {
// If the current block doesn't fall through, just move it.
// If the current block can fall through and does not end with a
- // conditional branch, we need to append an unconditional jump to
+ // conditional branch, we need to append an unconditional jump to
// the (current) next block. To avoid a possible compile-time
// infinite loop, move blocks only backward in this case.
// Also, if there are already 2 branches here, we cannot add a third;
@@ -1167,11 +1407,11 @@
}
MBB->moveAfter(PredBB);
MadeChange = true;
- return OptimizeBlock(MBB);
+ goto ReoptimizeBlock;
}
}
}
-
+
if (!CurFallsThru) {
// Check all successors to see if we can move this block before it.
for (MachineBasicBlock::succ_iterator SI = MBB->succ_begin(),
@@ -1179,26 +1419,29 @@
// Analyze the branch at the end of the block before the succ.
MachineBasicBlock *SuccBB = *SI;
MachineFunction::iterator SuccPrev = SuccBB; --SuccPrev;
- std::vector<MachineOperand> SuccPrevCond;
-
+
// If this block doesn't already fall-through to that successor, and if
// the succ doesn't already have a block that can fall through into it,
// and if the successor isn't an EH destination, we can arrange for the
// fallthrough to happen.
- if (SuccBB != MBB && !CanFallThrough(SuccPrev) &&
+ if (SuccBB != MBB && &*SuccPrev != MBB &&
+ !CanFallThrough(SuccPrev) && !CurUnAnalyzable &&
!SuccBB->isLandingPad()) {
MBB->moveBefore(SuccBB);
MadeChange = true;
- return OptimizeBlock(MBB);
+ goto ReoptimizeBlock;
}
}
-
+
// Okay, there is no really great place to put this block. If, however,
// the block before this one would be a fall-through if this block were
// removed, move this block to the end of the function.
- if (FallThrough != MBB->getParent()->end() &&
+ MachineBasicBlock *PrevTBB, *PrevFBB;
+ SmallVector<MachineOperand, 4> PrevCond;
+ if (FallThrough != MF.end() &&
+ !TII->AnalyzeBranch(PrevBB, PrevTBB, PrevFBB, PrevCond, true) &&
PrevBB.isSuccessor(FallThrough)) {
- MBB->moveAfter(--MBB->getParent()->end());
+ MBB->moveAfter(--MF.end());
MadeChange = true;
return MadeChange;
}
Modified: llvm/branches/Apple/Leela/lib/CodeGen/BranchFolding.h
URL: http://llvm.org/viewvc/llvm-project/llvm/branches/Apple/Leela/lib/CodeGen/BranchFolding.h?rev=86910&r1=86909&r2=86910&view=diff
==============================================================================
--- llvm/branches/Apple/Leela/lib/CodeGen/BranchFolding.h (original)
+++ llvm/branches/Apple/Leela/lib/CodeGen/BranchFolding.h Wed Nov 11 18:39:53 2009
@@ -44,18 +44,24 @@
RegScavenger *RS;
bool TailMergeBlocks(MachineFunction &MF);
- bool TryMergeBlocks(MachineBasicBlock* SuccBB,
- MachineBasicBlock* PredBB);
+ bool TryTailMergeBlocks(MachineBasicBlock* SuccBB,
+ MachineBasicBlock* PredBB);
void ReplaceTailWithBranchTo(MachineBasicBlock::iterator OldInst,
MachineBasicBlock *NewDest);
MachineBasicBlock *SplitMBBAt(MachineBasicBlock &CurMBB,
MachineBasicBlock::iterator BBI1);
- unsigned ComputeSameTails(unsigned CurHash, unsigned minCommonTailLength);
+ unsigned ComputeSameTails(unsigned CurHash, unsigned minCommonTailLength,
+ MachineBasicBlock *SuccBB,
+ MachineBasicBlock *PredBB);
void RemoveBlocksWithHash(unsigned CurHash, MachineBasicBlock* SuccBB,
MachineBasicBlock* PredBB);
unsigned CreateCommonTailOnlyBlock(MachineBasicBlock *&PredBB,
unsigned maxCommonTailLength);
+ bool TailDuplicate(MachineBasicBlock *TailBB,
+ bool PrevFallsThrough,
+ MachineFunction &MF);
+
bool OptimizeBranches(MachineFunction &MF);
bool OptimizeBlock(MachineBasicBlock *MBB);
void RemoveDeadBlock(MachineBasicBlock *MBB);
Modified: llvm/branches/Apple/Leela/lib/CodeGen/MachineBasicBlock.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/branches/Apple/Leela/lib/CodeGen/MachineBasicBlock.cpp?rev=86910&r1=86909&r2=86910&view=diff
==============================================================================
--- llvm/branches/Apple/Leela/lib/CodeGen/MachineBasicBlock.cpp (original)
+++ llvm/branches/Apple/Leela/lib/CodeGen/MachineBasicBlock.cpp Wed Nov 11 18:39:53 2009
@@ -371,10 +371,7 @@
MachineBasicBlock::succ_iterator SI = succ_begin();
MachineBasicBlock *OrigDestA = DestA, *OrigDestB = DestB;
while (SI != succ_end()) {
- if (*SI == DestA && DestA == DestB) {
- DestA = DestB = 0;
- ++SI;
- } else if (*SI == DestA) {
+ if (*SI == DestA) {
DestA = 0;
++SI;
} else if (*SI == DestB) {
Modified: llvm/branches/Apple/Leela/lib/Target/Alpha/AlphaInstrInfo.td
URL: http://llvm.org/viewvc/llvm-project/llvm/branches/Apple/Leela/lib/Target/Alpha/AlphaInstrInfo.td?rev=86910&r1=86909&r2=86910&view=diff
==============================================================================
--- llvm/branches/Apple/Leela/lib/Target/Alpha/AlphaInstrInfo.td (original)
+++ llvm/branches/Apple/Leela/lib/Target/Alpha/AlphaInstrInfo.td Wed Nov 11 18:39:53 2009
@@ -391,7 +391,7 @@
def : Pat<(setune GPRC:$X, immUExt8:$Y), (CMPEQi (CMPEQ GPRC:$X, immUExt8:$Y), 0)>;
-let isReturn = 1, isTerminator = 1, Ra = 31, Rb = 26, disp = 1, Uses = [R26] in {
+let isReturn = 1, isTerminator = 1, isBarrier = 1, Ra = 31, Rb = 26, disp = 1, Uses = [R26] in {
def RETDAG : MbrForm< 0x1A, 0x02, (ops), "ret $$31,($$26),1", s_jsr>; //Return from subroutine
def RETDAGp : MbrpForm< 0x1A, 0x02, (ops), "ret $$31,($$26),1", [(retflag)], s_jsr>; //Return from subroutine
}
Modified: llvm/branches/Apple/Leela/lib/Target/Blackfin/BlackfinInstrInfo.td
URL: http://llvm.org/viewvc/llvm-project/llvm/branches/Apple/Leela/lib/Target/Blackfin/BlackfinInstrInfo.td?rev=86910&r1=86909&r2=86910&view=diff
==============================================================================
--- llvm/branches/Apple/Leela/lib/Target/Blackfin/BlackfinInstrInfo.td (original)
+++ llvm/branches/Apple/Leela/lib/Target/Blackfin/BlackfinInstrInfo.td Wed Nov 11 18:39:53 2009
@@ -174,6 +174,7 @@
let isReturn = 1,
isTerminator = 1,
+ isBarrier = 1,
Uses = [RETS] in
def RTS: F1<(outs), (ins), "rts;", [(BfinRet)]>;
Modified: llvm/branches/Apple/Leela/lib/Target/CellSPU/SPUInstrInfo.td
URL: http://llvm.org/viewvc/llvm-project/llvm/branches/Apple/Leela/lib/Target/CellSPU/SPUInstrInfo.td?rev=86910&r1=86909&r2=86910&view=diff
==============================================================================
--- llvm/branches/Apple/Leela/lib/Target/CellSPU/SPUInstrInfo.td (original)
+++ llvm/branches/Apple/Leela/lib/Target/CellSPU/SPUInstrInfo.td Wed Nov 11 18:39:53 2009
@@ -3601,21 +3601,23 @@
(BRASL texternalsym:$func)>;
// Unconditional branches:
-let isBranch = 1, isTerminator = 1, hasCtrlDep = 1, isBarrier = 1 in {
- def BR :
- UncondBranch<0b001001100, (outs), (ins brtarget:$dest),
- "br\t$dest",
- [(br bb:$dest)]>;
-
- // Unconditional, absolute address branch
- def BRA:
- UncondBranch<0b001100000, (outs), (ins brtarget:$dest),
- "bra\t$dest",
- [/* no pattern */]>;
-
- // Indirect branch
- def BI:
- BIForm<0b00010101100, "bi\t$func", [(brind R32C:$func)]>;
+let isBranch = 1, isTerminator = 1, hasCtrlDep = 1 in {
+ let isBarrier = 1 in {
+ def BR :
+ UncondBranch<0b001001100, (outs), (ins brtarget:$dest),
+ "br\t$dest",
+ [(br bb:$dest)]>;
+
+ // Unconditional, absolute address branch
+ def BRA:
+ UncondBranch<0b001100000, (outs), (ins brtarget:$dest),
+ "bra\t$dest",
+ [/* no pattern */]>;
+
+ // Indirect branch
+ def BI:
+ BIForm<0b00010101100, "bi\t$func", [(brind R32C:$func)]>;
+ }
// Conditional branches:
class BRNZInst<dag IOL, list<dag> pattern>:
Modified: llvm/branches/Apple/Leela/lib/Target/MSP430/MSP430InstrInfo.td
URL: http://llvm.org/viewvc/llvm-project/llvm/branches/Apple/Leela/lib/Target/MSP430/MSP430InstrInfo.td?rev=86910&r1=86909&r2=86910&view=diff
==============================================================================
--- llvm/branches/Apple/Leela/lib/Target/MSP430/MSP430InstrInfo.td (original)
+++ llvm/branches/Apple/Leela/lib/Target/MSP430/MSP430InstrInfo.td Wed Nov 11 18:39:53 2009
@@ -127,7 +127,7 @@
//
// FIXME: Provide proper encoding!
-let isReturn = 1, isTerminator = 1 in {
+let isReturn = 1, isTerminator = 1, isBarrier = 1 in {
def RET : Pseudo<(outs), (ins), "ret", [(MSP430retflag)]>;
}
Modified: llvm/branches/Apple/Leela/lib/Target/Sparc/SparcInstrInfo.td
URL: http://llvm.org/viewvc/llvm-project/llvm/branches/Apple/Leela/lib/Target/Sparc/SparcInstrInfo.td?rev=86910&r1=86909&r2=86910&view=diff
==============================================================================
--- llvm/branches/Apple/Leela/lib/Target/Sparc/SparcInstrInfo.td (original)
+++ llvm/branches/Apple/Leela/lib/Target/Sparc/SparcInstrInfo.td Wed Nov 11 18:39:53 2009
@@ -277,7 +277,7 @@
// Section A.3 - Synthetic Instructions, p. 85
// special cases of JMPL:
-let isReturn = 1, isTerminator = 1, hasDelaySlot = 1 in {
+let isReturn = 1, isTerminator = 1, hasDelaySlot = 1, isBarrier = 1 in {
let rd = O7.Num, rs1 = G0.Num, simm13 = 8 in
def RETL: F3_2<2, 0b111000, (outs), (ins), "retl", [(retflag)]>;
}
Modified: llvm/branches/Apple/Leela/lib/Target/XCore/XCoreInstrInfo.td
URL: http://llvm.org/viewvc/llvm-project/llvm/branches/Apple/Leela/lib/Target/XCore/XCoreInstrInfo.td?rev=86910&r1=86909&r2=86910&view=diff
==============================================================================
--- llvm/branches/Apple/Leela/lib/Target/XCore/XCoreInstrInfo.td (original)
+++ llvm/branches/Apple/Leela/lib/Target/XCore/XCoreInstrInfo.td Wed Nov 11 18:39:53 2009
@@ -617,7 +617,7 @@
let mayStore = 1 in
defm ENTSP : FU6_LU6_np<"entsp">;
-let isReturn = 1, isTerminator = 1, mayLoad = 1 in {
+let isReturn = 1, isTerminator = 1, mayLoad = 1, isBarrier = 1 in {
defm RETSP : FU6_LU6<"retsp", XCoreRetsp>;
}
}
Modified: llvm/branches/Apple/Leela/lib/Transforms/Utils/LCSSA.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/branches/Apple/Leela/lib/Transforms/Utils/LCSSA.cpp?rev=86910&r1=86909&r2=86910&view=diff
==============================================================================
--- llvm/branches/Apple/Leela/lib/Transforms/Utils/LCSSA.cpp (original)
+++ llvm/branches/Apple/Leela/lib/Transforms/Utils/LCSSA.cpp Wed Nov 11 18:39:53 2009
@@ -63,6 +63,9 @@
///
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesCFG();
+
+ // LCSSA doesn't actually require LoopSimplify, but the PassManager
+ // doesn't know how to schedule LoopSimplify by itself.
AU.addRequiredID(LoopSimplifyID);
AU.addPreservedID(LoopSimplifyID);
AU.addRequiredTransitive<LoopInfo>();
@@ -214,7 +217,7 @@
SSAUpdate.Initialize(Inst);
// Insert the LCSSA phi's into all of the exit blocks dominated by the
- // value., and add them to the Phi's map.
+ // value, and add them to the Phi's map.
for (SmallVectorImpl<BasicBlock*>::const_iterator BBI = ExitBlocks.begin(),
BBE = ExitBlocks.end(); BBI != BBE; ++BBI) {
BasicBlock *ExitBB = *BBI;
@@ -228,8 +231,17 @@
PN->reserveOperandSpace(PredCache.GetNumPreds(ExitBB));
// Add inputs from inside the loop for this PHI.
- for (BasicBlock **PI = PredCache.GetPreds(ExitBB); *PI; ++PI)
+ for (BasicBlock **PI = PredCache.GetPreds(ExitBB); *PI; ++PI) {
PN->addIncoming(Inst, *PI);
+
+ // If the exit block has a predecessor not within the loop, arrange for
+ // the incomging value use corresponding to that predecessor to be
+ // rewritten in terms of a different LCSSA PHI.
+ if (!inLoop(*PI))
+ UsesToRewrite.push_back(
+ &PN->getOperandUse(
+ PN->getOperandNumForIncomingValue(PN->getNumIncomingValues()-1)));
+ }
// Remember that this phi makes the value alive in this block.
SSAUpdate.AddAvailableValue(ExitBB, PN);
Modified: llvm/branches/Apple/Leela/test/CodeGen/Thumb2/thumb2-cbnz.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/branches/Apple/Leela/test/CodeGen/Thumb2/thumb2-cbnz.ll?rev=86910&r1=86909&r2=86910&view=diff
==============================================================================
--- llvm/branches/Apple/Leela/test/CodeGen/Thumb2/thumb2-cbnz.ll (original)
+++ llvm/branches/Apple/Leela/test/CodeGen/Thumb2/thumb2-cbnz.ll Wed Nov 11 18:39:53 2009
@@ -20,7 +20,8 @@
br i1 %a, label %bb11, label %bb9
bb9: ; preds = %bb7
-; CHECK: @ BB#2:
+; CHECK: cmp r0, #0
+; CHECK-NEXT: cmp r0, #0
; CHECK-NEXT: cbnz
%0 = tail call arm_apcscc double @floor(double %b) nounwind readnone ; <double> [#uses=0]
br label %bb11
Modified: llvm/branches/Apple/Leela/test/CodeGen/Thumb2/thumb2-ifcvt3.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/branches/Apple/Leela/test/CodeGen/Thumb2/thumb2-ifcvt3.ll?rev=86910&r1=86909&r2=86910&view=diff
==============================================================================
--- llvm/branches/Apple/Leela/test/CodeGen/Thumb2/thumb2-ifcvt3.ll (original)
+++ llvm/branches/Apple/Leela/test/CodeGen/Thumb2/thumb2-ifcvt3.ll Wed Nov 11 18:39:53 2009
@@ -23,7 +23,7 @@
; CHECK: movne
; CHECK: moveq
; CHECK: pop
-; CHECK-NEXT: LBB1_2:
+; CHECK-NEXT: LBB1_1:
%0 = load i64* @posed, align 4 ; <i64> [#uses=3]
%1 = sub i64 %0, %.reload78 ; <i64> [#uses=1]
%2 = ashr i64 %1, 1 ; <i64> [#uses=3]
Modified: llvm/branches/Apple/Leela/test/CodeGen/X86/loop-blocks.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/branches/Apple/Leela/test/CodeGen/X86/loop-blocks.ll?rev=86910&r1=86909&r2=86910&view=diff
==============================================================================
--- llvm/branches/Apple/Leela/test/CodeGen/X86/loop-blocks.ll (original)
+++ llvm/branches/Apple/Leela/test/CodeGen/X86/loop-blocks.ll Wed Nov 11 18:39:53 2009
@@ -74,16 +74,16 @@
; CHECK: yet_more_involved:
; CHECK: jmp .LBB3_1
; CHECK-NEXT: align
-; CHECK-NEXT: .LBB3_3:
+; CHECK-NEXT: .LBB3_4:
; CHECK-NEXT: call bar99
; CHECK-NEXT: call get
; CHECK-NEXT: cmpl $2999, %eax
-; CHECK-NEXT: jg .LBB3_5
+; CHECK-NEXT: jg .LBB3_6
; CHECK-NEXT: call block_a_true_func
-; CHECK-NEXT: jmp .LBB3_6
-; CHECK-NEXT: .LBB3_5:
-; CHECK-NEXT: call block_a_false_func
+; CHECK-NEXT: jmp .LBB3_7
; CHECK-NEXT: .LBB3_6:
+; CHECK-NEXT: call block_a_false_func
+; CHECK-NEXT: .LBB3_7:
; CHECK-NEXT: call block_a_merge_func
; CHECK-NEXT: .LBB3_1:
; CHECK-NEXT: call body
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