[llvm-commits] [llvm] r50020 - in /llvm/trunk: include/llvm/Transforms/Utils/BasicBlockUtils.h lib/Transforms/Utils/BasicBlockUtils.cpp lib/Transforms/Utils/LoopSimplify.cpp
Chris Lattner
sabre at nondot.org
Sun Apr 20 18:28:02 PDT 2008
Author: lattner
Date: Sun Apr 20 20:28:02 2008
New Revision: 50020
URL: http://llvm.org/viewvc/llvm-project?rev=50020&view=rev
Log:
Move SplitBlockPredecessors out of loopsimplify into BasicBlockUtils.h
as a global helper function. At the same type, switch it from taking
a vector of predecessors to an arbitrary sequential input. This allows
us to switch LoopSimplify to use a SmallVector for various temporary
vectors that it passed into SplitBlockPredecessors.
Modified:
llvm/trunk/include/llvm/Transforms/Utils/BasicBlockUtils.h
llvm/trunk/lib/Transforms/Utils/BasicBlockUtils.cpp
llvm/trunk/lib/Transforms/Utils/LoopSimplify.cpp
Modified: llvm/trunk/include/llvm/Transforms/Utils/BasicBlockUtils.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Transforms/Utils/BasicBlockUtils.h?rev=50020&r1=50019&r2=50020&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Transforms/Utils/BasicBlockUtils.h (original)
+++ llvm/trunk/include/llvm/Transforms/Utils/BasicBlockUtils.h Sun Apr 20 20:28:02 2008
@@ -120,6 +120,19 @@
/// the loop info is updated.
///
BasicBlock *SplitBlock(BasicBlock *Old, Instruction *SplitPt, Pass *P);
+
+/// SplitBlockPredecessors - This method transforms BB by introducing a new
+/// basic block into the function, and moving some of the predecessors of BB to
+/// be predecessors of the new block. The new predecessors are indicated by the
+/// Preds array, which has NumPreds elements in it. The new block is given a
+/// suffix of 'Suffix'. This function returns the new block.
+///
+/// This currently updates the LLVM IR, AliasAnalysis, DominatorTree and
+/// DominanceFrontier, but no other analyses.
+BasicBlock *SplitBlockPredecessors(BasicBlock *BB, BasicBlock *const *Preds,
+ unsigned NumPreds, const char *Suffix,
+ Pass *P = 0);
+
} // End llvm namespace
#endif
Modified: llvm/trunk/lib/Transforms/Utils/BasicBlockUtils.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/BasicBlockUtils.cpp?rev=50020&r1=50019&r2=50020&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/BasicBlockUtils.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/BasicBlockUtils.cpp Sun Apr 20 20:28:02 2008
@@ -17,6 +17,7 @@
#include "llvm/Instructions.h"
#include "llvm/Constant.h"
#include "llvm/Type.h"
+#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/Dominators.h"
#include <algorithm>
@@ -187,3 +188,103 @@
return New;
}
+
+
+/// SplitBlockPredecessors - This method transforms BB by introducing a new
+/// basic block into the function, and moving some of the predecessors of BB to
+/// be predecessors of the new block. The new predecessors are indicated by the
+/// Preds array, which has NumPreds elements in it. The new block is given a
+/// suffix of 'Suffix'.
+///
+/// This currently updates the LLVM IR, AliasAnalysis, DominatorTree and
+/// DominanceFrontier, but no other analyses.
+BasicBlock *llvm::SplitBlockPredecessors(BasicBlock *BB,
+ BasicBlock *const *Preds,
+ unsigned NumPreds, const char *Suffix,
+ Pass *P) {
+ // Create new basic block, insert right before the original block.
+ BasicBlock *NewBB =
+ BasicBlock::Create(BB->getName()+Suffix, BB->getParent(), BB);
+
+ // The new block unconditionally branches to the old block.
+ BranchInst *BI = BranchInst::Create(BB, NewBB);
+
+ // Move the edges from Preds to point to NewBB instead of BB.
+ for (unsigned i = 0; i != NumPreds; ++i) {
+ Preds[i]->getTerminator()->replaceUsesOfWith(BB, NewBB);
+
+ if (Preds[i]->getUnwindDest() == BB)
+ Preds[i]->setUnwindDest(NewBB);
+ }
+
+ // Update dominator tree and dominator frontier if available.
+ DominatorTree *DT = P ? P->getAnalysisToUpdate<DominatorTree>() : 0;
+ if (DT)
+ DT->splitBlock(NewBB);
+ if (DominanceFrontier *DF = P ? P->getAnalysisToUpdate<DominanceFrontier>():0)
+ DF->splitBlock(NewBB);
+ AliasAnalysis *AA = P ? P->getAnalysisToUpdate<AliasAnalysis>() : 0;
+
+
+ // Insert a new PHI node into NewBB for every PHI node in BB and that new PHI
+ // node becomes an incoming value for BB's phi node. However, if the Preds
+ // list is empty, we need to insert dummy entries into the PHI nodes in BB to
+ // account for the newly created predecessor.
+ if (NumPreds == 0) {
+ // Insert dummy values as the incoming value.
+ for (BasicBlock::iterator I = BB->begin(); isa<PHINode>(I); ++I)
+ cast<PHINode>(I)->addIncoming(UndefValue::get(I->getType()), NewBB);
+ return NewBB;
+ }
+
+ // Otherwise, create a new PHI node in NewBB for each PHI node in BB.
+ for (BasicBlock::iterator I = BB->begin(); isa<PHINode>(I); ) {
+ PHINode *PN = cast<PHINode>(I++);
+
+ // Check to see if all of the values coming in are the same. If so, we
+ // don't need to create a new PHI node.
+ Value *InVal = PN->getIncomingValueForBlock(Preds[0]);
+ for (unsigned i = 1; i != NumPreds; ++i)
+ if (InVal != PN->getIncomingValueForBlock(Preds[i])) {
+ InVal = 0;
+ break;
+ }
+
+ if (InVal) {
+ // If all incoming values for the new PHI would be the same, just don't
+ // make a new PHI. Instead, just remove the incoming values from the old
+ // PHI.
+ for (unsigned i = 0; i != NumPreds; ++i)
+ PN->removeIncomingValue(Preds[i], false);
+ } else {
+ // If the values coming into the block are not the same, we need a PHI.
+ // Create the new PHI node, insert it into NewBB at the end of the block
+ PHINode *NewPHI =
+ PHINode::Create(PN->getType(), PN->getName()+".ph", BI);
+ if (AA) AA->copyValue(PN, NewPHI);
+
+ // Move all of the PHI values for 'Preds' to the new PHI.
+ for (unsigned i = 0; i != NumPreds; ++i) {
+ Value *V = PN->removeIncomingValue(Preds[i], false);
+ NewPHI->addIncoming(V, Preds[i]);
+ }
+ InVal = NewPHI;
+ }
+
+ // Add an incoming value to the PHI node in the loop for the preheader
+ // edge.
+ PN->addIncoming(InVal, NewBB);
+
+ // Check to see if we can eliminate this phi node.
+ if (Value *V = PN->hasConstantValue(DT != 0)) {
+ Instruction *I = dyn_cast<Instruction>(V);
+ if (!I || DT == 0 || DT->dominates(I, PN)) {
+ PN->replaceAllUsesWith(V);
+ if (AA) AA->deleteValue(PN);
+ PN->eraseFromParent();
+ }
+ }
+ }
+
+ return NewBB;
+}
Modified: llvm/trunk/lib/Transforms/Utils/LoopSimplify.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/LoopSimplify.cpp?rev=50020&r1=50019&r2=50020&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/LoopSimplify.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/LoopSimplify.cpp Sun Apr 20 20:28:02 2008
@@ -41,6 +41,7 @@
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/Dominators.h"
#include "llvm/Analysis/LoopInfo.h"
+#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Support/CFG.h"
#include "llvm/Support/Compiler.h"
#include "llvm/ADT/SetOperations.h"
@@ -86,14 +87,12 @@
private:
bool ProcessLoop(Loop *L);
- BasicBlock *SplitBlockPredecessors(BasicBlock *BB, const char *Suffix,
- const std::vector<BasicBlock*> &Preds);
BasicBlock *RewriteLoopExitBlock(Loop *L, BasicBlock *Exit);
void InsertPreheaderForLoop(Loop *L);
Loop *SeparateNestedLoop(Loop *L);
void InsertUniqueBackedgeBlock(Loop *L);
void PlaceSplitBlockCarefully(BasicBlock *NewBB,
- std::vector<BasicBlock*> &SplitPreds,
+ SmallVectorImpl<BasicBlock*> &SplitPreds,
Loop *L);
};
@@ -260,103 +259,6 @@
return Changed;
}
-/// SplitBlockPredecessors - Split the specified block into two blocks. We want
-/// to move the predecessors specified in the Preds list to point to the new
-/// block, leaving the remaining predecessors pointing to BB. This method
-/// updates the SSA PHINode's, AliasAnalysis, DominatorTree and
-/// DominanceFrontier, but no other analyses.
-///
-BasicBlock *LoopSimplify::SplitBlockPredecessors(BasicBlock *BB,
- const char *Suffix,
- const std::vector<BasicBlock*> &Preds) {
-
- // Create new basic block, insert right before the original block.
- BasicBlock *NewBB =
- BasicBlock::Create(BB->getName()+Suffix, BB->getParent(), BB);
-
- // The preheader first gets an unconditional branch to the loop header.
- BranchInst *BI = BranchInst::Create(BB, NewBB);
-
- // Move the edges from Preds to point to NewBB instead of BB.
- for (unsigned i = 0, e = Preds.size(); i != e; ++i) {
- Preds[i]->getTerminator()->replaceUsesOfWith(BB, NewBB);
-
- if (Preds[i]->getUnwindDest() == BB)
- Preds[i]->setUnwindDest(NewBB);
- }
-
- // Update dominator tree and dominator frontier if available.
- DT->splitBlock(NewBB);
- if (DominanceFrontier *DF = getAnalysisToUpdate<DominanceFrontier>())
- DF->splitBlock(NewBB);
-
- // For every PHI node in the block, insert a PHI node into NewBB where the
- // incoming values from the out of loop edges are moved to NewBB. We have two
- // possible cases here. If the loop is dead, we just insert dummy entries
- // into the PHI nodes for the new edge. If the loop is not dead, we move the
- // incoming edges in BB into new PHI nodes in NewBB.
- //
- if (Preds.empty()) { // Is the loop obviously dead?
- // Insert dummy values as the incoming value.
- for (BasicBlock::iterator I = BB->begin(); isa<PHINode>(I); ++I)
- cast<PHINode>(I)->addIncoming(UndefValue::get(I->getType()), NewBB);
-
- return NewBB;
- }
-
- // Check to see if the values being merged into the new block need PHI
- // nodes. If so, insert them.
- for (BasicBlock::iterator I = BB->begin(); isa<PHINode>(I); ) {
- PHINode *PN = cast<PHINode>(I);
- ++I;
-
- // Check to see if all of the values coming in are the same. If so, we
- // don't need to create a new PHI node.
- Value *InVal = PN->getIncomingValueForBlock(Preds[0]);
- for (unsigned i = 1, e = Preds.size(); i != e; ++i)
- if (InVal != PN->getIncomingValueForBlock(Preds[i])) {
- InVal = 0;
- break;
- }
-
- // If the values coming into the block are not the same, we need a PHI.
- if (InVal == 0) {
- // Create the new PHI node, insert it into NewBB at the end of the block
- PHINode *NewPHI =
- PHINode::Create(PN->getType(), PN->getName()+".ph", BI);
- if (AA) AA->copyValue(PN, NewPHI);
-
- // Move all of the edges from blocks outside the loop to the new PHI
- for (unsigned i = 0, e = Preds.size(); i != e; ++i) {
- Value *V = PN->removeIncomingValue(Preds[i], false);
- NewPHI->addIncoming(V, Preds[i]);
- }
- InVal = NewPHI;
- } else {
- // Remove all of the edges coming into the PHI nodes from outside of the
- // block.
- for (unsigned i = 0, e = Preds.size(); i != e; ++i)
- PN->removeIncomingValue(Preds[i], false);
- }
-
- // Add an incoming value to the PHI node in the loop for the preheader
- // edge.
- PN->addIncoming(InVal, NewBB);
-
- // Can we eliminate this phi node now?
- if (Value *V = PN->hasConstantValue(true)) {
- Instruction *I = dyn_cast<Instruction>(V);
- if (!I || DT->dominates(I, PN)) {
- PN->replaceAllUsesWith(V);
- if (AA) AA->deleteValue(PN);
- PN->eraseFromParent();
- }
- }
- }
-
- return NewBB;
-}
-
/// InsertPreheaderForLoop - Once we discover that a loop doesn't have a
/// preheader, this method is called to insert one. This method has two phases:
/// preheader insertion and analysis updating.
@@ -365,7 +267,7 @@
BasicBlock *Header = L->getHeader();
// Compute the set of predecessors of the loop that are not in the loop.
- std::vector<BasicBlock*> OutsideBlocks;
+ SmallVector<BasicBlock*, 8> OutsideBlocks;
for (pred_iterator PI = pred_begin(Header), PE = pred_end(Header);
PI != PE; ++PI)
if (!L->contains(*PI)) // Coming in from outside the loop?
@@ -373,7 +275,8 @@
// Split out the loop pre-header.
BasicBlock *NewBB =
- SplitBlockPredecessors(Header, ".preheader", OutsideBlocks);
+ SplitBlockPredecessors(Header, &OutsideBlocks[0], OutsideBlocks.size(),
+ ".preheader", this);
//===--------------------------------------------------------------------===//
@@ -393,13 +296,15 @@
/// blocks. This method is used to split exit blocks that have predecessors
/// outside of the loop.
BasicBlock *LoopSimplify::RewriteLoopExitBlock(Loop *L, BasicBlock *Exit) {
- std::vector<BasicBlock*> LoopBlocks;
+ SmallVector<BasicBlock*, 8> LoopBlocks;
for (pred_iterator I = pred_begin(Exit), E = pred_end(Exit); I != E; ++I)
if (L->contains(*I))
LoopBlocks.push_back(*I);
assert(!LoopBlocks.empty() && "No edges coming in from outside the loop?");
- BasicBlock *NewBB = SplitBlockPredecessors(Exit, ".loopexit", LoopBlocks);
+ BasicBlock *NewBB = SplitBlockPredecessors(Exit, &LoopBlocks[0],
+ LoopBlocks.size(), ".loopexit",
+ this);
// Update Loop Information - we know that the new block will be in whichever
// loop the Exit block is in. Note that it may not be in that immediate loop,
@@ -464,7 +369,7 @@
// right after some 'outside block' block. This prevents the preheader from
// being placed inside the loop body, e.g. when the loop hasn't been rotated.
void LoopSimplify::PlaceSplitBlockCarefully(BasicBlock *NewBB,
- std::vector<BasicBlock*>&SplitPreds,
+ SmallVectorImpl<BasicBlock*> &SplitPreds,
Loop *L) {
// Check to see if NewBB is already well placed.
Function::iterator BBI = NewBB; --BBI;
@@ -522,14 +427,16 @@
// Pull out all predecessors that have varying values in the loop. This
// handles the case when a PHI node has multiple instances of itself as
// arguments.
- std::vector<BasicBlock*> OuterLoopPreds;
+ SmallVector<BasicBlock*, 8> OuterLoopPreds;
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
if (PN->getIncomingValue(i) != PN ||
!L->contains(PN->getIncomingBlock(i)))
OuterLoopPreds.push_back(PN->getIncomingBlock(i));
BasicBlock *Header = L->getHeader();
- BasicBlock *NewBB = SplitBlockPredecessors(Header, ".outer", OuterLoopPreds);
+ BasicBlock *NewBB = SplitBlockPredecessors(Header, &OuterLoopPreds[0],
+ OuterLoopPreds.size(),
+ ".outer", this);
// Make sure that NewBB is put someplace intelligent, which doesn't mess up
// code layout too horribly.
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