[llvm] r231818 - [LAA-memchecks 3/3] Introduce pointer partitions for memchecks
Adam Nemet
anemet at apple.com
Tue Mar 10 11:54:26 PDT 2015
Author: anemet
Date: Tue Mar 10 13:54:26 2015
New Revision: 231818
URL: http://llvm.org/viewvc/llvm-project?rev=231818&view=rev
Log:
[LAA-memchecks 3/3] Introduce pointer partitions for memchecks
This is the final patch that actually introduces the new parameter of
partition mapping to RuntimePointerCheck::needsChecking.
Another API (LAI::getInstructionsForAccess) is also exposed that helps
to map pointers to instructions because ultimately we partition
instructions.
The WIP version of the Loop Distribution pass in D6930 has been adapted
to use all this. See for example, how
InstrPartitionContainer::computePartitionSetForPointers sets up the
partitions using the above API and then calls to LAI::addRuntimeCheck
with the pointer partitions.
Modified:
llvm/trunk/include/llvm/Analysis/LoopAccessAnalysis.h
llvm/trunk/lib/Analysis/LoopAccessAnalysis.cpp
Modified: llvm/trunk/include/llvm/Analysis/LoopAccessAnalysis.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Analysis/LoopAccessAnalysis.h?rev=231818&r1=231817&r2=231818&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Analysis/LoopAccessAnalysis.h (original)
+++ llvm/trunk/include/llvm/Analysis/LoopAccessAnalysis.h Tue Mar 10 13:54:26 2015
@@ -231,6 +231,10 @@ public:
return InstMap;
}
+ /// \brief Find the set of instructions that read or write via \p Ptr.
+ SmallVector<Instruction *, 4> getInstructionsForAccess(Value *Ptr,
+ bool isWrite) const;
+
private:
ScalarEvolution *SE;
const Loop *InnermostLoop;
@@ -328,10 +332,20 @@ public:
/// \brief Decide whether we need to issue a run-time check for pointer at
/// index \p I and \p J to prove their independence.
- bool needsChecking(unsigned I, unsigned J) const;
+ ///
+ /// If \p PtrPartition is set, it contains the partition number for
+ /// pointers (-1 if the pointer belongs to multiple partitions). In this
+ /// case omit checks between pointers belonging to the same partition.
+ bool needsChecking(unsigned I, unsigned J,
+ const SmallVectorImpl<int> *PtrPartition) const;
/// \brief Print the list run-time memory checks necessary.
- void print(raw_ostream &OS, unsigned Depth = 0) const;
+ ///
+ /// If \p PtrPartition is set, it contains the partition number for
+ /// pointers (-1 if the pointer belongs to multiple partitions). In this
+ /// case omit checks between pointers belonging to the same partition.
+ void print(raw_ostream &OS, unsigned Depth = 0,
+ const SmallVectorImpl<int> *PtrPartition = nullptr) const;
/// This flag indicates if we need to add the runtime check.
bool Need;
@@ -383,8 +397,13 @@ public:
/// Returns a pair of instructions where the first element is the first
/// instruction generated in possibly a sequence of instructions and the
/// second value is the final comparator value or NULL if no check is needed.
+ ///
+ /// If \p PtrPartition is set, it contains the partition number for pointers
+ /// (-1 if the pointer belongs to multiple partitions). In this case omit
+ /// checks between pointers belonging to the same partition.
std::pair<Instruction *, Instruction *>
- addRuntimeCheck(Instruction *Loc) const;
+ addRuntimeCheck(Instruction *Loc,
+ const SmallVectorImpl<int> *PtrPartition = nullptr) const;
/// \brief The diagnostics report generated for the analysis. E.g. why we
/// couldn't analyze the loop.
@@ -394,6 +413,13 @@ public:
/// loop-independent and loop-carried dependences between memory accesses.
const MemoryDepChecker &getDepChecker() const { return DepChecker; }
+ /// \brief Return the list of instructions that use \p Ptr to read or write
+ /// memory.
+ SmallVector<Instruction *, 4> getInstructionsForAccess(Value *Ptr,
+ bool isWrite) const {
+ return DepChecker.getInstructionsForAccess(Ptr, isWrite);
+ }
+
/// \brief Print the information about the memory accesses in the loop.
void print(raw_ostream &OS, unsigned Depth = 0) const;
Modified: llvm/trunk/lib/Analysis/LoopAccessAnalysis.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/LoopAccessAnalysis.cpp?rev=231818&r1=231817&r2=231818&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/LoopAccessAnalysis.cpp (original)
+++ llvm/trunk/lib/Analysis/LoopAccessAnalysis.cpp Tue Mar 10 13:54:26 2015
@@ -127,8 +127,8 @@ void LoopAccessInfo::RuntimePointerCheck
AliasSetId.push_back(ASId);
}
-bool LoopAccessInfo::RuntimePointerCheck::needsChecking(unsigned I,
- unsigned J) const {
+bool LoopAccessInfo::RuntimePointerCheck::needsChecking(
+ unsigned I, unsigned J, const SmallVectorImpl<int> *PtrPartition) const {
// No need to check if two readonly pointers intersect.
if (!IsWritePtr[I] && !IsWritePtr[J])
return false;
@@ -141,11 +141,19 @@ bool LoopAccessInfo::RuntimePointerCheck
if (AliasSetId[I] != AliasSetId[J])
return false;
+ // If PtrPartition is set omit checks between pointers of the same partition.
+ // Partition number -1 means that the pointer is used in multiple partitions.
+ // In this case we can't omit the check.
+ if (PtrPartition && (*PtrPartition)[I] != -1 &&
+ (*PtrPartition)[I] == (*PtrPartition)[J])
+ return false;
+
return true;
}
-void LoopAccessInfo::RuntimePointerCheck::print(raw_ostream &OS,
- unsigned Depth) const {
+void LoopAccessInfo::RuntimePointerCheck::print(
+ raw_ostream &OS, unsigned Depth,
+ const SmallVectorImpl<int> *PtrPartition) const {
unsigned NumPointers = Pointers.size();
if (NumPointers == 0)
return;
@@ -154,10 +162,16 @@ void LoopAccessInfo::RuntimePointerCheck
unsigned N = 0;
for (unsigned I = 0; I < NumPointers; ++I)
for (unsigned J = I + 1; J < NumPointers; ++J)
- if (needsChecking(I, J)) {
+ if (needsChecking(I, J, PtrPartition)) {
OS.indent(Depth) << N++ << ":\n";
- OS.indent(Depth + 2) << *Pointers[I] << "\n";
- OS.indent(Depth + 2) << *Pointers[J] << "\n";
+ OS.indent(Depth + 2) << *Pointers[I];
+ if (PtrPartition)
+ OS << " (Partition: " << (*PtrPartition)[I] << ")";
+ OS << "\n";
+ OS.indent(Depth + 2) << *Pointers[J];
+ if (PtrPartition)
+ OS << " (Partition: " << (*PtrPartition)[J] << ")";
+ OS << "\n";
}
}
@@ -835,6 +849,18 @@ bool MemoryDepChecker::areDepsSafe(DepCa
return SafeForVectorization;
}
+SmallVector<Instruction *, 4>
+MemoryDepChecker::getInstructionsForAccess(Value *Ptr, bool isWrite) const {
+ MemAccessInfo Access(Ptr, isWrite);
+ auto &IndexVector = Accesses.find(Access)->second;
+
+ SmallVector<Instruction *, 4> Insts;
+ std::transform(IndexVector.begin(), IndexVector.end(),
+ std::back_inserter(Insts),
+ [&](unsigned Idx) { return this->InstMap[Idx]; });
+ return Insts;
+}
+
const char *MemoryDepChecker::Dependence::DepName[] = {
"NoDep", "Unknown", "Forward", "ForwardButPreventsForwarding", "Backward",
"BackwardVectorizable", "BackwardVectorizableButPreventsForwarding"};
@@ -1169,8 +1195,8 @@ static Instruction *getFirstInst(Instruc
return nullptr;
}
-std::pair<Instruction *, Instruction *>
-LoopAccessInfo::addRuntimeCheck(Instruction *Loc) const {
+std::pair<Instruction *, Instruction *> LoopAccessInfo::addRuntimeCheck(
+ Instruction *Loc, const SmallVectorImpl<int> *PtrPartition) const {
Instruction *tnullptr = nullptr;
if (!PtrRtCheck.Need)
return std::pair<Instruction *, Instruction *>(tnullptr, tnullptr);
@@ -1211,7 +1237,7 @@ LoopAccessInfo::addRuntimeCheck(Instruct
Value *MemoryRuntimeCheck = nullptr;
for (unsigned i = 0; i < NumPointers; ++i) {
for (unsigned j = i+1; j < NumPointers; ++j) {
- if (!PtrRtCheck.needsChecking(i, j))
+ if (!PtrRtCheck.needsChecking(i, j, PtrPartition))
continue;
unsigned AS0 = Starts[i]->getType()->getPointerAddressSpace();
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