[Mlir-commits] [mlir] [MLIR][Affine] NFC. Fix/improve debug messages for affine analysis/fusion utils (PR #127164)
Uday Bondhugula
llvmlistbot at llvm.org
Fri Feb 14 19:32:22 PST 2025
https://github.com/bondhugula updated https://github.com/llvm/llvm-project/pull/127164
>From cbf94927fbf86090ee362f644b1adb1645a8278a Mon Sep 17 00:00:00 2001
From: Uday Bondhugula <uday at polymagelabs.com>
Date: Fri, 14 Feb 2025 08:26:50 +0530
Subject: [PATCH] [MLIR][Affine] NFC. Fix/improve debug messages for affine
analysis/fusion utils
Improve debug messages and API signatures for affine
analysis/fusion utils.
Move some warnings under LLVM_DEBUG. These weren't meant to be exposed
during compilation.
Add dump pretty methods for FlatLinearConstraints.
NFC.
---
.../Analysis/FlatLinearValueConstraints.h | 7 ++
.../mlir/Dialect/Affine/Analysis/Utils.h | 8 +--
.../Analysis/FlatLinearValueConstraints.cpp | 70 ++++++++++++++++---
.../Dialect/Affine/Analysis/LoopAnalysis.cpp | 7 +-
mlir/lib/Dialect/Affine/Analysis/Utils.cpp | 48 ++++++-------
.../Dialect/Affine/Transforms/LoopFusion.cpp | 15 +++-
.../Dialect/Affine/Utils/LoopFusionUtils.cpp | 8 +--
7 files changed, 115 insertions(+), 48 deletions(-)
diff --git a/mlir/include/mlir/Analysis/FlatLinearValueConstraints.h b/mlir/include/mlir/Analysis/FlatLinearValueConstraints.h
index 63305e0cbf8d7..c8167014b5300 100644
--- a/mlir/include/mlir/Analysis/FlatLinearValueConstraints.h
+++ b/mlir/include/mlir/Analysis/FlatLinearValueConstraints.h
@@ -194,6 +194,13 @@ class FlatLinearConstraints : public presburger::IntegerPolyhedron {
return appendVar(VarKind::Local, num);
}
+ /// A more human-readable version of dump().
+ void dumpPretty() const;
+ /// An easier to read dump of a `row` of the same width as the number of
+ /// columns. `fixedColWidth` ensure that even with a zero coefficient, we
+ /// print spaces so that variables are aligned.
+ void dumpRow(ArrayRef<int64_t> row, bool fixedColWidth = true) const;
+
protected:
using VarKind = presburger::VarKind;
diff --git a/mlir/include/mlir/Dialect/Affine/Analysis/Utils.h b/mlir/include/mlir/Dialect/Affine/Analysis/Utils.h
index 5b386868cb004..de9ed6a683c24 100644
--- a/mlir/include/mlir/Dialect/Affine/Analysis/Utils.h
+++ b/mlir/include/mlir/Dialect/Affine/Analysis/Utils.h
@@ -416,10 +416,10 @@ struct ComputationSliceState {
// %v = affine.load %0[%i1] : memref<100xf32> // 'depSinkAccess'
// }
//
-void getComputationSliceState(Operation *depSourceOp, Operation *depSinkOp,
- FlatAffineValueConstraints *dependenceConstraints,
- unsigned loopDepth, bool isBackwardSlice,
- ComputationSliceState *sliceState);
+void getComputationSliceState(
+ Operation *depSourceOp, Operation *depSinkOp,
+ const FlatAffineValueConstraints &dependenceConstraints, unsigned loopDepth,
+ bool isBackwardSlice, ComputationSliceState *sliceState);
/// Return the number of iterations for the `slicetripCountMap` provided.
uint64_t getSliceIterationCount(
diff --git a/mlir/lib/Analysis/FlatLinearValueConstraints.cpp b/mlir/lib/Analysis/FlatLinearValueConstraints.cpp
index 0d6ff2fd908db..abf440ee699ae 100644
--- a/mlir/lib/Analysis/FlatLinearValueConstraints.cpp
+++ b/mlir/lib/Analysis/FlatLinearValueConstraints.cpp
@@ -445,6 +445,58 @@ static bool detectAsFloorDiv(const FlatLinearConstraints &cst, unsigned pos,
return true;
}
+void FlatLinearConstraints::dumpRow(ArrayRef<int64_t> row,
+ bool fixedColWidth) const {
+ unsigned ncols = getNumCols();
+ bool firstNonZero = true;
+ for (unsigned j = 0; j < ncols; j++) {
+ if (j == ncols - 1) {
+ // Constant.
+ if (row[j] == 0 && !firstNonZero) {
+ if (fixedColWidth)
+ llvm::errs().indent(7);
+ } else {
+ llvm::errs() << ((row[j] >= 0) ? "+ " : "") << row[j] << ' ';
+ }
+ } else {
+ std::string var = std::string("c_") + std::to_string(j);
+ if (row[j] == 1)
+ llvm::errs() << "+ " << var << ' ';
+ else if (row[j] == -1)
+ llvm::errs() << "- " << var << ' ';
+ else if (row[j] >= 2)
+ llvm::errs() << "+ " << row[j] << '*' << var << ' ';
+ else if (row[j] <= -2)
+ llvm::errs() << "- " << -row[j] << '*' << var << ' ';
+ else if (fixedColWidth)
+ // Zero coeff.
+ llvm::errs().indent(7);
+ if (row[j] != 0)
+ firstNonZero = false;
+ }
+ }
+}
+
+void FlatLinearConstraints::dumpPretty() const {
+ assert(hasConsistentState());
+ llvm::errs() << "Constraints (" << getNumDimVars() << " dims, "
+ << getNumSymbolVars() << " symbols, " << getNumLocalVars()
+ << " locals), (" << getNumConstraints() << " constraints)\n";
+ auto dumpConstraint = [&](unsigned rowPos, bool isEq) {
+ // Is it the first non-zero entry?
+ SmallVector<int64_t> row =
+ isEq ? getEquality64(rowPos) : getInequality64(rowPos);
+ dumpRow(row);
+ llvm::errs() << (isEq ? "=" : ">=") << " 0\n";
+ };
+
+ for (unsigned i = 0, e = getNumInequalities(); i < e; i++)
+ dumpConstraint(i, /*isEq=*/false);
+ for (unsigned i = 0, e = getNumEqualities(); i < e; i++)
+ dumpConstraint(i, /*isEq=*/true);
+ llvm::errs() << '\n';
+}
+
std::pair<AffineMap, AffineMap> FlatLinearConstraints::getLowerAndUpperBound(
unsigned pos, unsigned offset, unsigned num, unsigned symStartPos,
ArrayRef<AffineExpr> localExprs, MLIRContext *context,
@@ -544,9 +596,9 @@ void FlatLinearConstraints::getSliceBounds(unsigned offset, unsigned num,
// Basic simplification.
normalizeConstraintsByGCD();
- LLVM_DEBUG(llvm::dbgs() << "getSliceBounds for first " << num
- << " variables\n");
- LLVM_DEBUG(dump());
+ LLVM_DEBUG(llvm::dbgs() << "getSliceBounds for variables at positions ["
+ << offset << ", " << offset + num << ")\n");
+ LLVM_DEBUG(dumpPretty());
// Record computed/detected variables.
SmallVector<AffineExpr, 8> memo(getNumVars());
@@ -699,12 +751,12 @@ void FlatLinearConstraints::getSliceBounds(unsigned offset, unsigned num,
}
}
}
- LLVM_DEBUG(llvm::dbgs()
- << "lb map for pos = " << Twine(pos + offset) << ", expr: ");
- LLVM_DEBUG(lbMap.dump(););
- LLVM_DEBUG(llvm::dbgs()
- << "ub map for pos = " << Twine(pos + offset) << ", expr: ");
- LLVM_DEBUG(ubMap.dump(););
+
+ LLVM_DEBUG(llvm::dbgs() << "Slice bounds:\n");
+ LLVM_DEBUG(llvm::dbgs() << "lb map for pos = " << Twine(pos + offset)
+ << ", expr: " << lbMap << '\n');
+ LLVM_DEBUG(llvm::dbgs() << "ub map for pos = " << Twine(pos + offset)
+ << ", expr: " << ubMap << '\n');
}
}
diff --git a/mlir/lib/Dialect/Affine/Analysis/LoopAnalysis.cpp b/mlir/lib/Dialect/Affine/Analysis/LoopAnalysis.cpp
index 411b5efb36cab..0d4b0ea1668e0 100644
--- a/mlir/lib/Dialect/Affine/Analysis/LoopAnalysis.cpp
+++ b/mlir/lib/Dialect/Affine/Analysis/LoopAnalysis.cpp
@@ -182,10 +182,9 @@ template bool mlir::affine::isInvariantAccess(AffineStoreOp, AffineForOp);
DenseSet<Value> mlir::affine::getInvariantAccesses(Value iv,
ArrayRef<Value> indices) {
DenseSet<Value> res;
- for (auto val : indices) {
- if (isAccessIndexInvariant(iv, val)) {
- res.insert(val);
- }
+ for (Value index : indices) {
+ if (isAccessIndexInvariant(iv, index))
+ res.insert(index);
}
return res;
}
diff --git a/mlir/lib/Dialect/Affine/Analysis/Utils.cpp b/mlir/lib/Dialect/Affine/Analysis/Utils.cpp
index b829633252fdd..646bb54830762 100644
--- a/mlir/lib/Dialect/Affine/Analysis/Utils.cpp
+++ b/mlir/lib/Dialect/Affine/Analysis/Utils.cpp
@@ -249,6 +249,7 @@ bool MemRefDependenceGraph::init() {
// the memref.
DenseMap<Value, SetVector<unsigned>> memrefAccesses;
+ // Create graph nodes.
DenseMap<Operation *, unsigned> forToNodeMap;
for (Operation &op : block) {
if (auto forOp = dyn_cast<AffineForOp>(op)) {
@@ -300,11 +301,7 @@ bool MemRefDependenceGraph::init() {
// interface.
}
- for (auto &idAndNode : nodes) {
- LLVM_DEBUG(llvm::dbgs() << "Create node " << idAndNode.first << " for:\n"
- << *(idAndNode.second.op) << "\n");
- (void)idAndNode;
- }
+ LLVM_DEBUG(llvm::dbgs() << "Created " << nodes.size() << " nodes\n");
// Add dependence edges between nodes which produce SSA values and their
// users. Load ops can be considered as the ones producing SSA values.
@@ -1556,9 +1553,9 @@ mlir::affine::computeSliceUnion(ArrayRef<Operation *> opsA,
FlatAffineValueConstraints sliceUnionCst;
assert(sliceUnionCst.getNumDimAndSymbolVars() == 0);
std::vector<std::pair<Operation *, Operation *>> dependentOpPairs;
- for (auto *i : opsA) {
+ for (Operation *i : opsA) {
MemRefAccess srcAccess(i);
- for (auto *j : opsB) {
+ for (Operation *j : opsB) {
MemRefAccess dstAccess(j);
if (srcAccess.memref != dstAccess.memref)
continue;
@@ -1587,7 +1584,7 @@ mlir::affine::computeSliceUnion(ArrayRef<Operation *> opsA,
// Compute slice bounds for 'srcAccess' and 'dstAccess'.
ComputationSliceState tmpSliceState;
- mlir::affine::getComputationSliceState(i, j, &dependenceConstraints,
+ mlir::affine::getComputationSliceState(i, j, dependenceConstraints,
loopDepth, isBackwardSlice,
&tmpSliceState);
@@ -1646,8 +1643,10 @@ mlir::affine::computeSliceUnion(ArrayRef<Operation *> opsA,
}
// Empty union.
- if (sliceUnionCst.getNumDimAndSymbolVars() == 0)
+ if (sliceUnionCst.getNumDimAndSymbolVars() == 0) {
+ LLVM_DEBUG(llvm::dbgs() << "empty slice union - unexpected\n");
return SliceComputationResult::GenericFailure;
+ }
// Gather loops surrounding ops from loop nest where slice will be inserted.
SmallVector<Operation *, 4> ops;
@@ -1686,7 +1685,8 @@ mlir::affine::computeSliceUnion(ArrayRef<Operation *> opsA,
sliceUnion->ivs.clear();
sliceUnionCst.getValues(0, numSliceLoopIVs, &sliceUnion->ivs);
- // Set loop nest insertion point to block start at 'loopDepth'.
+ // Set loop nest insertion point to block start at 'loopDepth' for forward
+ // slices, while at the end for backward slices.
sliceUnion->insertPoint =
isBackwardSlice
? surroundingLoops[loopDepth - 1].getBody()->begin()
@@ -1785,7 +1785,7 @@ const char *const kSliceFusionBarrierAttrName = "slice_fusion_barrier";
// the other loop nest's IVs, symbols and constants (using 'isBackwardsSlice').
void mlir::affine::getComputationSliceState(
Operation *depSourceOp, Operation *depSinkOp,
- FlatAffineValueConstraints *dependenceConstraints, unsigned loopDepth,
+ const FlatAffineValueConstraints &dependenceConstraints, unsigned loopDepth,
bool isBackwardSlice, ComputationSliceState *sliceState) {
// Get loop nest surrounding src operation.
SmallVector<AffineForOp, 4> srcLoopIVs;
@@ -1804,30 +1804,28 @@ void mlir::affine::getComputationSliceState(
unsigned pos = isBackwardSlice ? numSrcLoopIVs + loopDepth : loopDepth;
unsigned num =
isBackwardSlice ? numDstLoopIVs - loopDepth : numSrcLoopIVs - loopDepth;
- dependenceConstraints->projectOut(pos, num);
+ FlatAffineValueConstraints sliceCst(dependenceConstraints);
+ sliceCst.projectOut(pos, num);
// Add slice loop IV values to 'sliceState'.
unsigned offset = isBackwardSlice ? 0 : loopDepth;
unsigned numSliceLoopIVs = isBackwardSlice ? numSrcLoopIVs : numDstLoopIVs;
- dependenceConstraints->getValues(offset, offset + numSliceLoopIVs,
- &sliceState->ivs);
+ sliceCst.getValues(offset, offset + numSliceLoopIVs, &sliceState->ivs);
// Set up lower/upper bound affine maps for the slice.
sliceState->lbs.resize(numSliceLoopIVs, AffineMap());
sliceState->ubs.resize(numSliceLoopIVs, AffineMap());
// Get bounds for slice IVs in terms of other IVs, symbols, and constants.
- dependenceConstraints->getSliceBounds(offset, numSliceLoopIVs,
- depSourceOp->getContext(),
- &sliceState->lbs, &sliceState->ubs);
+ sliceCst.getSliceBounds(offset, numSliceLoopIVs, depSourceOp->getContext(),
+ &sliceState->lbs, &sliceState->ubs);
// Set up bound operands for the slice's lower and upper bounds.
SmallVector<Value, 4> sliceBoundOperands;
- unsigned numDimsAndSymbols = dependenceConstraints->getNumDimAndSymbolVars();
+ unsigned numDimsAndSymbols = sliceCst.getNumDimAndSymbolVars();
for (unsigned i = 0; i < numDimsAndSymbols; ++i) {
- if (i < offset || i >= offset + numSliceLoopIVs) {
- sliceBoundOperands.push_back(dependenceConstraints->getValue(i));
- }
+ if (i < offset || i >= offset + numSliceLoopIVs)
+ sliceBoundOperands.push_back(sliceCst.getValue(i));
}
// Give each bound its own copy of 'sliceBoundOperands' for subsequent
@@ -2057,16 +2055,18 @@ static std::optional<int64_t> getMemoryFootprintBytes(Block &block,
if (failed(
region->compute(opInst,
/*loopDepth=*/getNestingDepth(&*block.begin())))) {
- return opInst->emitError("error obtaining memory region\n");
+ LLVM_DEBUG(opInst->emitError("error obtaining memory region"));
+ return failure();
}
auto [it, inserted] = regions.try_emplace(region->memref);
if (inserted) {
it->second = std::move(region);
} else if (failed(it->second->unionBoundingBox(*region))) {
- return opInst->emitWarning(
+ LLVM_DEBUG(opInst->emitWarning(
"getMemoryFootprintBytes: unable to perform a union on a memory "
- "region");
+ "region"));
+ return failure();
}
return WalkResult::advance();
});
diff --git a/mlir/lib/Dialect/Affine/Transforms/LoopFusion.cpp b/mlir/lib/Dialect/Affine/Transforms/LoopFusion.cpp
index 30019447d94e8..9e67e63f5040c 100644
--- a/mlir/lib/Dialect/Affine/Transforms/LoopFusion.cpp
+++ b/mlir/lib/Dialect/Affine/Transforms/LoopFusion.cpp
@@ -836,6 +836,15 @@ struct GreedyFusion {
// Get 'srcNode' from which to attempt fusion into 'dstNode'.
auto *srcNode = mdg->getNode(srcId);
auto srcAffineForOp = cast<AffineForOp>(srcNode->op);
+
+ LLVM_DEBUG(llvm::dbgs()
+ << "Trying to fuse producer loop nest " << srcId
+ << " with consumer loop nest " << dstId << "\n");
+ LLVM_DEBUG(llvm::dbgs()
+ << "Producer loop nest:\n"
+ << *srcNode->op << "\n and consumer loop nest:\n"
+ << *dstNode->op << '\n');
+
LLVM_DEBUG(llvm::dbgs() << "Evaluating src loop " << srcId
<< " for dst loop " << dstId << "\n");
@@ -904,9 +913,11 @@ struct GreedyFusion {
affine::canFuseLoops(srcAffineForOp, dstAffineForOp,
/*dstLoopDepth=*/i + numSurroundingLoops,
&depthSliceUnions[i - 1], strategy);
-
- if (result.value == FusionResult::Success)
+ if (result.value == FusionResult::Success) {
maxLegalFusionDepth = i;
+ LLVM_DEBUG(llvm::dbgs()
+ << "Found valid slice for depth: " << i << '\n');
+ }
}
if (maxLegalFusionDepth == 0) {
diff --git a/mlir/lib/Dialect/Affine/Utils/LoopFusionUtils.cpp b/mlir/lib/Dialect/Affine/Utils/LoopFusionUtils.cpp
index 7f3e43d0b4cd3..54bcc48ad8812 100644
--- a/mlir/lib/Dialect/Affine/Utils/LoopFusionUtils.cpp
+++ b/mlir/lib/Dialect/Affine/Utils/LoopFusionUtils.cpp
@@ -25,7 +25,7 @@
#include "llvm/Support/raw_ostream.h"
#include <optional>
-#define DEBUG_TYPE "loop-fusion-utils"
+#define DEBUG_TYPE "affine-fusion-utils"
using namespace mlir;
using namespace mlir::affine;
@@ -49,12 +49,10 @@ static void getLoadAndStoreMemRefAccesses(Operation *opA,
/// Returns false otherwise.
static bool isDependentLoadOrStoreOp(Operation *op,
DenseMap<Value, bool> &values) {
- if (auto loadOp = dyn_cast<AffineReadOpInterface>(op)) {
+ if (auto loadOp = dyn_cast<AffineReadOpInterface>(op))
return values.count(loadOp.getMemRef()) > 0 && values[loadOp.getMemRef()];
- }
- if (auto storeOp = dyn_cast<AffineWriteOpInterface>(op)) {
+ if (auto storeOp = dyn_cast<AffineWriteOpInterface>(op))
return values.count(storeOp.getMemRef()) > 0;
- }
return false;
}
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