From e753bc87458eb950e2a51200bb4dcc16cc775d82 Mon Sep 17 00:00:00 2001
From: Maksim Levental <maksim.levental@gmail.com>
Date: Thu, 29 Sep 2022 11:08:36 -0500
Subject: [PATCH] [mlir][Affine] Move/expose hasNoInterveningEffect

Expose [[ https://github.com/llvm/llvm-project/blob/main/mlir/lib/Dialect/Affine/Utils/Utils.cpp#L661 | Dialect/Affine/Utils/Utils.cpp#hasNoInterveningEffect ]] for downstream use (particular use case is a lazy implementation of [[ https://github.com/llvm/llvm-project/blob/main/mlir/lib/Dialect/Affine/Utils/Utils.cpp#L845 | forwardStoreToLoad ]] in CIRCT). This exposes hasNoInterveningEffect and instantiates for the necessary types.

Reviewed By: bondhugula

Differential Revision: https://reviews.llvm.org/D134374
---
 mlir/include/mlir/Dialect/Affine/Utils.h |  9 +++++++++
 mlir/lib/Dialect/Affine/Utils/Utils.cpp  | 21 +++++++++------------
 2 files changed, 18 insertions(+), 12 deletions(-)

diff --git a/mlir/include/mlir/Dialect/Affine/Utils.h b/mlir/include/mlir/Dialect/Affine/Utils.h
index 006c61c..4381d1f 100644
--- a/mlir/include/mlir/Dialect/Affine/Utils.h
+++ b/mlir/include/mlir/Dialect/Affine/Utils.h
@@ -319,6 +319,15 @@ FailureOr<SmallVector<Value>> delinearizeIndex(OpBuilder &b, Location loc,
                                                Value linearIndex,
                                                ArrayRef<Value> basis);
 
+/// Ensure that all operations that could be executed after `start`
+/// (noninclusive) and prior to `memOp` (e.g. on a control flow/op path
+/// between the operations) do not have the potential memory effect
+/// `EffectType` on `memOp`. `memOp`  is an operation that reads or writes to
+/// a memref. For example, if `EffectType` is MemoryEffects::Write, this method
+/// will check if there is no write to the memory between `start` and `memOp`
+/// that would change the read within `memOp`.
+template <typename EffectType, typename T>
+bool hasNoInterveningEffect(Operation *start, T memOp);
 } // namespace mlir
 
 #endif // MLIR_DIALECT_AFFINE_UTILS_H
diff --git a/mlir/lib/Dialect/Affine/Utils/Utils.cpp b/mlir/lib/Dialect/Affine/Utils/Utils.cpp
index 0161325..c26a6b0 100644
--- a/mlir/lib/Dialect/Affine/Utils/Utils.cpp
+++ b/mlir/lib/Dialect/Affine/Utils/Utils.cpp
@@ -650,15 +650,8 @@ LogicalResult mlir::normalizeAffineFor(AffineForOp op) {
   return success();
 }
 
-/// Ensure that all operations that could be executed after `start`
-/// (noninclusive) and prior to `memOp` (e.g. on a control flow/op path
-/// between the operations) do not have the potential memory effect
-/// `EffectType` on `memOp`. `memOp`  is an operation that reads or writes to
-/// a memref. For example, if `EffectType` is MemoryEffects::Write, this method
-/// will check if there is no write to the memory between `start` and `memOp`
-/// that would change the read within `memOp`.
 template <typename EffectType, typename T>
-static bool hasNoInterveningEffect(Operation *start, T memOp) {
+bool mlir::hasNoInterveningEffect(Operation *start, T memOp) {
   auto isLocallyAllocated = [](Value memref) {
     auto *defOp = memref.getDefiningOp();
     return defOp && hasSingleEffect<MemoryEffects::Allocate>(defOp, memref);
@@ -874,7 +867,7 @@ static LogicalResult forwardStoreToLoad(
 
     // 3. Ensure there is no intermediate operation which could replace the
     // value in memory.
-    if (!hasNoInterveningEffect<MemoryEffects::Write>(storeOp, loadOp))
+    if (!mlir::hasNoInterveningEffect<MemoryEffects::Write>(storeOp, loadOp))
       continue;
 
     // We now have a candidate for forwarding.
@@ -901,6 +894,10 @@ static LogicalResult forwardStoreToLoad(
   return success();
 }
 
+template bool mlir::hasNoInterveningEffect<mlir::MemoryEffects::Read,
+                                           mlir::AffineReadOpInterface>(
+    mlir::Operation *, mlir::AffineReadOpInterface);
+
 // This attempts to find stores which have no impact on the final result.
 // A writing op writeA will be eliminated if there exists an op writeB if
 // 1) writeA and writeB have mathematically equivalent affine access functions.
@@ -937,7 +934,7 @@ static void findUnusedStore(AffineWriteOpInterface writeA,
 
     // There cannot be an operation which reads from memory between
     // the two writes.
-    if (!hasNoInterveningEffect<MemoryEffects::Read>(writeA, writeB))
+    if (!mlir::hasNoInterveningEffect<MemoryEffects::Read>(writeA, writeB))
       continue;
 
     opsToErase.push_back(writeA);
@@ -973,8 +970,8 @@ static void loadCSE(AffineReadOpInterface loadA,
       continue;
 
     // 3. There is no write between loadA and loadB.
-    if (!hasNoInterveningEffect<MemoryEffects::Write>(loadB.getOperation(),
-                                                      loadA))
+    if (!mlir::hasNoInterveningEffect<MemoryEffects::Write>(
+            loadB.getOperation(), loadA))
       continue;
 
     // Check if two values have the same shape. This is needed for affine vector
-- 
2.7.4