[llvm-commits] [llvm] r90353 - in /llvm/trunk: include/llvm/CodeGen/MachineSSAUpdater.h lib/CodeGen/MachineSSAUpdater.cpp
Evan Cheng
evan.cheng at apple.com
Wed Dec 2 14:02:53 PST 2009
Author: evancheng
Date: Wed Dec 2 16:02:52 2009
New Revision: 90353
URL: http://llvm.org/viewvc/llvm-project?rev=90353&view=rev
Log:
Skeleton for MachineInstr level SSA updater.
Added:
llvm/trunk/include/llvm/CodeGen/MachineSSAUpdater.h
llvm/trunk/lib/CodeGen/MachineSSAUpdater.cpp
Added: llvm/trunk/include/llvm/CodeGen/MachineSSAUpdater.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/CodeGen/MachineSSAUpdater.h?rev=90353&view=auto
==============================================================================
--- llvm/trunk/include/llvm/CodeGen/MachineSSAUpdater.h (added)
+++ llvm/trunk/include/llvm/CodeGen/MachineSSAUpdater.h Wed Dec 2 16:02:52 2009
@@ -0,0 +1,99 @@
+//===-- MachineSSAUpdater.h - Unstructured SSA Update Tool ------*- C++ -*-===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file declares the MachineSSAUpdater class.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CODEGEN_MACHINESSAUPDATER_H
+#define LLVM_CODEGEN_MACHINESSAUPDATER_H
+
+namespace llvm {
+ class MachineBasicBlock;
+ class MachineInstr;
+ template<typename T> class SmallVectorImpl;
+
+/// SSAUpdater - This class updates SSA form for a set of values defined in
+/// multiple blocks. This is used when code duplication or another unstructured
+/// transformation wants to rewrite a set of uses of one value with uses of a
+/// set of values.
+class MachineSSAUpdater {
+ /// AvailableVals - This keeps track of which value to use on a per-block
+ /// basis. When we insert PHI nodes, we keep track of them here.
+ //typedef DenseMap<MachineBasicBlock*, unsigned > AvailableValsTy;
+ void *AV;
+
+ /// IncomingPredInfo - We use this as scratch space when doing our recursive
+ /// walk. This should only be used in GetValueInBlockInternal, normally it
+ /// should be empty.
+ //std::vector<std::pair<MachineBasicBlock*, unsigned > > IncomingPredInfo;
+ void *IPI;
+
+ /// InsertedPHIs - If this is non-null, the MachineSSAUpdater adds all PHI
+ /// nodes that it creates to the vector.
+ SmallVectorImpl<MachineInstr*> *InsertedPHIs;
+public:
+ /// MachineSSAUpdater constructor. If InsertedPHIs is specified, it will be
+ /// filled in with all PHI Nodes created by rewriting.
+ explicit MachineSSAUpdater(SmallVectorImpl<MachineInstr*> *InsertedPHIs = 0);
+ ~MachineSSAUpdater();
+
+ /// Initialize - Reset this object to get ready for a new set of SSA
+ /// updates.
+ void Initialize();
+
+ /// AddAvailableValue - Indicate that a rewritten value is available at the
+ /// end of the specified block with the specified value.
+ void AddAvailableValue(MachineBasicBlock *BB, unsigned V);
+
+ /// HasValueForBlock - Return true if the MachineSSAUpdater already has a
+ /// value for the specified block.
+ bool HasValueForBlock(MachineBasicBlock *BB) const;
+
+ /// GetValueAtEndOfBlock - Construct SSA form, materializing a value that is
+ /// live at the end of the specified block.
+ unsigned GetValueAtEndOfBlock(MachineBasicBlock *BB);
+
+ /// GetValueInMiddleOfBlock - Construct SSA form, materializing a value that
+ /// is live in the middle of the specified block.
+ ///
+ /// GetValueInMiddleOfBlock is the same as GetValueAtEndOfBlock except in one
+ /// important case: if there is a definition of the rewritten value after the
+ /// 'use' in BB. Consider code like this:
+ ///
+ /// X1 = ...
+ /// SomeBB:
+ /// use(X)
+ /// X2 = ...
+ /// br Cond, SomeBB, OutBB
+ ///
+ /// In this case, there are two values (X1 and X2) added to the AvailableVals
+ /// set by the client of the rewriter, and those values are both live out of
+ /// their respective blocks. However, the use of X happens in the *middle* of
+ /// a block. Because of this, we need to insert a new PHI node in SomeBB to
+ /// merge the appropriate values, and this value isn't live out of the block.
+ ///
+ unsigned GetValueInMiddleOfBlock(MachineBasicBlock *BB);
+
+ /// RewriteUse - Rewrite a use of the symbolic value. This handles PHI nodes,
+ /// which use their value in the corresponding predecessor. Note that this
+ /// will not work if the use is supposed to be rewritten to a value defined in
+ /// the same block as the use, but above it. Any 'AddAvailableValue's added
+ /// for the use's block will be considered to be below it.
+ void RewriteUse(unsigned &U);
+
+private:
+ unsigned GetValueAtEndOfBlockInternal(MachineBasicBlock *BB);
+ void operator=(const MachineSSAUpdater&); // DO NOT IMPLEMENT
+ MachineSSAUpdater(const MachineSSAUpdater&); // DO NOT IMPLEMENT
+};
+
+} // End llvm namespace
+
+#endif
Added: llvm/trunk/lib/CodeGen/MachineSSAUpdater.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/MachineSSAUpdater.cpp?rev=90353&view=auto
==============================================================================
--- llvm/trunk/lib/CodeGen/MachineSSAUpdater.cpp (added)
+++ llvm/trunk/lib/CodeGen/MachineSSAUpdater.cpp Wed Dec 2 16:02:52 2009
@@ -0,0 +1,108 @@
+//===- MachineSSAUpdater.cpp - Unstructured SSA Update Tool ---------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the MachineSSAUpdater class.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/CodeGen/MachineSSAUpdater.h"
+#include "llvm/CodeGen/MachineInstr.h"
+#include "llvm/ADT/DenseMap.h"
+using namespace llvm;
+
+typedef DenseMap<MachineBasicBlock*, unsigned > AvailableValsTy;
+typedef std::vector<std::pair<MachineBasicBlock*, unsigned> >
+ IncomingPredInfoTy;
+
+static AvailableValsTy &getAvailableVals(void *AV) {
+ return *static_cast<AvailableValsTy*>(AV);
+}
+
+static IncomingPredInfoTy &getIncomingPredInfo(void *IPI) {
+ return *static_cast<IncomingPredInfoTy*>(IPI);
+}
+
+
+MachineSSAUpdater::MachineSSAUpdater(SmallVectorImpl<MachineInstr*> *NewPHI)
+ : AV(0), IPI(0), InsertedPHIs(NewPHI) {}
+
+MachineSSAUpdater::~MachineSSAUpdater() {
+ delete &getAvailableVals(AV);
+ delete &getIncomingPredInfo(IPI);
+}
+
+/// Initialize - Reset this object to get ready for a new set of SSA
+/// updates. ProtoValue is the value used to name PHI nodes.
+void MachineSSAUpdater::Initialize() {
+ if (AV == 0)
+ AV = new AvailableValsTy();
+ else
+ getAvailableVals(AV).clear();
+
+ if (IPI == 0)
+ IPI = new IncomingPredInfoTy();
+ else
+ getIncomingPredInfo(IPI).clear();
+}
+
+/// HasValueForBlock - Return true if the MachineSSAUpdater already has a value for
+/// the specified block.
+bool MachineSSAUpdater::HasValueForBlock(MachineBasicBlock *BB) const {
+ return getAvailableVals(AV).count(BB);
+}
+
+/// AddAvailableValue - Indicate that a rewritten value is available in the
+/// specified block with the specified value.
+void MachineSSAUpdater::AddAvailableValue(MachineBasicBlock *BB, unsigned V) {
+ getAvailableVals(AV)[BB] = V;
+}
+
+/// GetValueAtEndOfBlock - Construct SSA form, materializing a value that is
+/// live at the end of the specified block.
+unsigned MachineSSAUpdater::GetValueAtEndOfBlock(MachineBasicBlock *BB) {
+ return GetValueAtEndOfBlockInternal(BB);
+}
+
+/// GetValueInMiddleOfBlock - Construct SSA form, materializing a value that
+/// is live in the middle of the specified block.
+///
+/// GetValueInMiddleOfBlock is the same as GetValueAtEndOfBlock except in one
+/// important case: if there is a definition of the rewritten value after the
+/// 'use' in BB. Consider code like this:
+///
+/// X1 = ...
+/// SomeBB:
+/// use(X)
+/// X2 = ...
+/// br Cond, SomeBB, OutBB
+///
+/// In this case, there are two values (X1 and X2) added to the AvailableVals
+/// set by the client of the rewriter, and those values are both live out of
+/// their respective blocks. However, the use of X happens in the *middle* of
+/// a block. Because of this, we need to insert a new PHI node in SomeBB to
+/// merge the appropriate values, and this value isn't live out of the block.
+///
+unsigned MachineSSAUpdater::GetValueInMiddleOfBlock(MachineBasicBlock *BB) {
+ return 0;
+}
+
+/// RewriteUse - Rewrite a use of the symbolic value. This handles PHI nodes,
+/// which use their value in the corresponding predecessor.
+void MachineSSAUpdater::RewriteUse(unsigned &U) {
+}
+
+
+/// GetValueAtEndOfBlockInternal - Check to see if AvailableVals has an entry
+/// for the specified BB and if so, return it. If not, construct SSA form by
+/// walking predecessors inserting PHI nodes as needed until we get to a block
+/// where the value is available.
+///
+unsigned MachineSSAUpdater::GetValueAtEndOfBlockInternal(MachineBasicBlock *BB){
+ return 0;
+}
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