[Mlir-commits] [mlir] 2d42476 - [mlir][IR][NFC] `DominanceInfo`: Share same impl for block/op dominance (#115587)
llvmlistbot at llvm.org
llvmlistbot at llvm.org
Sat Jan 4 00:12:07 PST 2025
Author: Matthias Springer
Date: 2025-01-04T09:12:03+01:00
New Revision: 2d424765f496410d6ab95a80c90d2eda933d66d4
URL: https://github.com/llvm/llvm-project/commit/2d424765f496410d6ab95a80c90d2eda933d66d4
DIFF: https://github.com/llvm/llvm-project/commit/2d424765f496410d6ab95a80c90d2eda933d66d4.diff
LOG: [mlir][IR][NFC] `DominanceInfo`: Share same impl for block/op dominance (#115587)
The `properlyDominates` implementations for blocks and ops are very
similar. This commit replaces them with a single implementation that
operates on block iterators. That implementation can be used to
implement both `properlyDominates` variants.
Before:
```c++
template <bool IsPostDom>
bool DominanceInfoBase<IsPostDom>::properlyDominatesImpl(Block *a,
Block *b) const;
template <bool IsPostDom>
bool DominanceInfoBase<IsPostDom>::properlyDominatesImpl(
Operation *a, Operation *b, bool enclosingOpOk) const;
```
After:
```c++
template <bool IsPostDom>
bool DominanceInfoBase<IsPostDom>::properlyDominatesImpl(
Block *aBlock, Block::iterator aIt, Block *bBlock, Block::iterator bIt,
bool enclosingOk) const;
```
Note: A subsequent commit will add a new public `properlyDominates`
overload that accepts block iterators. That functionality can then be
used to find a valid insertion point at which a range of values is
defined (by utilizing post dominance).
Added:
Modified:
mlir/include/mlir/IR/Dominance.h
mlir/lib/IR/Dominance.cpp
Removed:
################################################################################
diff --git a/mlir/include/mlir/IR/Dominance.h b/mlir/include/mlir/IR/Dominance.h
index 16d17b9c0f3d01..63504cad211a4d 100644
--- a/mlir/include/mlir/IR/Dominance.h
+++ b/mlir/include/mlir/IR/Dominance.h
@@ -113,12 +113,12 @@ class DominanceInfoBase {
llvm::PointerIntPair<DomTree *, 1, bool>
getDominanceInfo(Region *region, bool needsDomTree) const;
- /// Return "true" if the specified block A properly (post)dominates block B.
- bool properlyDominatesImpl(Block *a, Block *b) const;
-
- /// Return "true" if the specified op A properly (post)dominates op B.
- bool properlyDominatesImpl(Operation *a, Operation *b,
- bool enclosingOpOk = true) const;
+ /// Return "true" if block iterator A properly (post)dominates block iterator
+ /// B. If `enclosingOk` is set, A is considered to (post)dominate B if A
+ /// encloses B.
+ bool properlyDominatesImpl(Block *aBlock, Block::iterator aIt, Block *bBlock,
+ Block::iterator bIt,
+ bool enclosingOk = true) const;
/// A mapping of regions to their base dominator tree and a cached
/// "hasSSADominance" bit. This map does not contain dominator trees for
@@ -151,9 +151,7 @@ class DominanceInfo : public detail::DominanceInfoBase</*IsPostDom=*/false> {
/// The `enclosingOpOk` flag says whether we should return true if the B op
/// is enclosed by a region on A.
bool properlyDominates(Operation *a, Operation *b,
- bool enclosingOpOk = true) const {
- return super::properlyDominatesImpl(a, b, enclosingOpOk);
- }
+ bool enclosingOpOk = true) const;
/// Return true if operation A dominates operation B, i.e. if A and B are the
/// same operation or A properly dominates B.
@@ -188,9 +186,7 @@ class DominanceInfo : public detail::DominanceInfoBase</*IsPostDom=*/false> {
/// Graph regions have only a single block. To be consistent with "proper
/// dominance" of ops, the single block is considered to properly dominate
/// itself in a graph region.
- bool properlyDominates(Block *a, Block *b) const {
- return super::properlyDominatesImpl(a, b);
- }
+ bool properlyDominates(Block *a, Block *b) const;
};
/// A class for computing basic postdominance information.
@@ -200,9 +196,7 @@ class PostDominanceInfo : public detail::DominanceInfoBase</*IsPostDom=*/true> {
/// Return true if operation A properly postdominates operation B.
bool properlyPostDominates(Operation *a, Operation *b,
- bool enclosingOpOk = true) const {
- return super::properlyDominatesImpl(a, b, enclosingOpOk);
- }
+ bool enclosingOpOk = true) const;
/// Return true if operation A postdominates operation B.
bool postDominates(Operation *a, Operation *b) const {
@@ -210,9 +204,7 @@ class PostDominanceInfo : public detail::DominanceInfoBase</*IsPostDom=*/true> {
}
/// Return true if the specified block A properly postdominates block B.
- bool properlyPostDominates(Block *a, Block *b) const {
- return super::properlyDominatesImpl(a, b);
- }
+ bool properlyPostDominates(Block *a, Block *b) const;
/// Return true if the specified block A postdominates block B.
bool postDominates(Block *a, Block *b) const {
diff --git a/mlir/lib/IR/Dominance.cpp b/mlir/lib/IR/Dominance.cpp
index 406e0f2d62d640..1c54e09d29b9b5 100644
--- a/mlir/lib/IR/Dominance.cpp
+++ b/mlir/lib/IR/Dominance.cpp
@@ -213,61 +213,73 @@ DominanceInfoBase<IsPostDom>::findNearestCommonDominator(Block *a,
return getDomTree(a->getParent()).findNearestCommonDominator(a, b);
}
-/// Return true if the specified block A properly dominates block B.
-template <bool IsPostDom>
-bool DominanceInfoBase<IsPostDom>::properlyDominatesImpl(Block *a,
- Block *b) const {
- assert(a && b && "null blocks not allowed");
+/// Returns the given block iterator if it lies within the region region.
+/// Otherwise, otherwise finds the ancestor of the given block iterator that
+/// lies within the given region. Returns and "empty" iterator if the latter
+/// fails.
+///
+/// Note: This is a variant of Region::findAncestorOpInRegion that operates on
+/// block iterators instead of ops.
+static std::pair<Block *, Block::iterator>
+findAncestorIteratorInRegion(Region *r, Block *b, Block::iterator it) {
+ // Case 1: The iterator lies within the region region.
+ if (b->getParent() == r)
+ return std::make_pair(b, it);
+
+ // Otherwise: Find ancestor iterator. Bail if we run out of parent ops.
+ Operation *parentOp = b->getParentOp();
+ if (!parentOp)
+ return std::make_pair(static_cast<Block *>(nullptr), Block::iterator());
+ Operation *op = r->findAncestorOpInRegion(*parentOp);
+ if (!op)
+ return std::make_pair(static_cast<Block *>(nullptr), Block::iterator());
+ return std::make_pair(op->getBlock(), op->getIterator());
+}
- // A block dominates, but does not properly dominate, itself unless this
- // is a graph region.
+/// Given two iterators into the same block, return "true" if `a` is before `b.
+/// Note: This is a variant of Operation::isBeforeInBlock that operates on
+/// block iterators instead of ops.
+static bool isBeforeInBlock(Block *block, Block::iterator a,
+ Block::iterator b) {
if (a == b)
- return !hasSSADominance(a);
-
- // If both blocks are not in the same region, `a` properly dominates `b` if
- // `b` is defined in an operation region that (recursively) ends up being
- // dominated by `a`. Walk up the list of containers enclosing B.
- Region *regionA = a->getParent();
- if (regionA != b->getParent()) {
- b = regionA ? regionA->findAncestorBlockInRegion(*b) : nullptr;
- // If we could not find a valid block b then it is a not a dominator.
- if (!b)
- return false;
-
- // Check to see if the ancestor of `b` is the same block as `a`. A properly
- // dominates B if it contains an op that contains the B block.
- if (a == b)
- return true;
- }
-
- // Otherwise, they are two
diff erent blocks in the same region, use DomTree.
- return getDomTree(regionA).properlyDominates(a, b);
+ return false;
+ if (a == block->end())
+ return false;
+ if (b == block->end())
+ return true;
+ return a->isBeforeInBlock(&*b);
}
template <bool IsPostDom>
bool DominanceInfoBase<IsPostDom>::properlyDominatesImpl(
- Operation *a, Operation *b, bool enclosingOpOk) const {
- Block *aBlock = a->getBlock(), *bBlock = b->getBlock();
- assert(aBlock && bBlock && "operations must be in a block");
+ Block *aBlock, Block::iterator aIt, Block *bBlock, Block::iterator bIt,
+ bool enclosingOk) const {
+ assert(aBlock && bBlock && "expected non-null blocks");
- // An operation (pos)dominates, but does not properly (pos)dominate, itself
- // unless this is a graph region.
- if (a == b)
+ // A block iterator (post)dominates, but does not properly (post)dominate,
+ // itself unless this is a graph region.
+ if (aBlock == bBlock && aIt == bIt)
return !hasSSADominance(aBlock);
- // If these ops are in
diff erent regions, then normalize one into the other.
+ // If the iterators are in
diff erent regions, then normalize one into the
+ // other.
Region *aRegion = aBlock->getParent();
if (aRegion != bBlock->getParent()) {
- // Scoot up b's region tree until we find an operation in A's region that
+ // Scoot up b's region tree until we find a location in A's region that
// encloses it. If this fails, then we know there is no (post)dom relation.
- b = aRegion ? aRegion->findAncestorOpInRegion(*b) : nullptr;
- if (!b)
+ if (!aRegion) {
+ bBlock = nullptr;
+ bIt = Block::iterator();
+ } else {
+ std::tie(bBlock, bIt) =
+ findAncestorIteratorInRegion(aRegion, bBlock, bIt);
+ }
+ if (!bBlock)
return false;
- bBlock = b->getBlock();
- assert(bBlock->getParent() == aRegion);
+ assert(bBlock->getParent() == aRegion && "expected block in regionA");
// If 'a' encloses 'b', then we consider it to (post)dominate.
- if (a == b && enclosingOpOk)
+ if (aBlock == bBlock && aIt == bIt && enclosingOk)
return true;
}
@@ -279,9 +291,9 @@ bool DominanceInfoBase<IsPostDom>::properlyDominatesImpl(
if (!hasSSADominance(aBlock))
return true;
if constexpr (IsPostDom) {
- return b->isBeforeInBlock(a);
+ return isBeforeInBlock(aBlock, bIt, aIt);
} else {
- return a->isBeforeInBlock(b);
+ return isBeforeInBlock(aBlock, aIt, bIt);
}
}
@@ -309,6 +321,18 @@ template class detail::DominanceInfoBase</*IsPostDom=*/false>;
// DominanceInfo
//===----------------------------------------------------------------------===//
+bool DominanceInfo::properlyDominates(Operation *a, Operation *b,
+ bool enclosingOpOk) const {
+ return super::properlyDominatesImpl(a->getBlock(), a->getIterator(),
+ b->getBlock(), b->getIterator(),
+ enclosingOpOk);
+}
+
+bool DominanceInfo::properlyDominates(Block *a, Block *b) const {
+ return super::properlyDominatesImpl(a, a->begin(), b, b->begin(),
+ /*enclosingOk=*/true);
+}
+
/// Return true if the `a` value properly dominates operation `b`, i.e if the
/// operation that defines `a` properlyDominates `b` and the operation that
/// defines `a` does not contain `b`.
@@ -322,3 +346,19 @@ bool DominanceInfo::properlyDominates(Value a, Operation *b) const {
// `b`, but `a` does not itself enclose `b` in one of its regions.
return properlyDominates(a.getDefiningOp(), b, /*enclosingOpOk=*/false);
}
+
+//===----------------------------------------------------------------------===//
+// PostDominanceInfo
+//===----------------------------------------------------------------------===//
+
+bool PostDominanceInfo::properlyPostDominates(Operation *a, Operation *b,
+ bool enclosingOpOk) const {
+ return super::properlyDominatesImpl(a->getBlock(), a->getIterator(),
+ b->getBlock(), b->getIterator(),
+ enclosingOpOk);
+}
+
+bool PostDominanceInfo::properlyPostDominates(Block *a, Block *b) const {
+ return super::properlyDominatesImpl(a, a->end(), b, b->end(),
+ /*enclosingOk=*/true);
+}
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