[Mlir-commits] [mlir] [mlir][bufferization][NFC] Simplify helper `potentiallyAliasesMemref` (PR #78690)

[Matthias Springer]

https://github.com/matthias-springer created https://github.com/llvm/llvm-project/pull/78690

This commit simplifies a helper function in the ownership-based buffer deallocation pass.

>From 59a0a93acf1bc62a758bf82892778a6bce2a48ca Mon Sep 17 00:00:00 2001
From: Matthias Springer <springerm at google.com>
Date: Fri, 19 Jan 2024 10:36:30 +0000
Subject: [PATCH] [mlir][bufferization][NFC] Simplify helper
 `potentiallyAliasesMemref`

This commit simplifies a helper function in the ownership-based buffer deallocation pass.
---
 .../BufferDeallocationSimplification.cpp      | 26 ++++++++-----------
 1 file changed, 11 insertions(+), 15 deletions(-)

diff --git a/mlir/lib/Dialect/Bufferization/Transforms/BufferDeallocationSimplification.cpp b/mlir/lib/Dialect/Bufferization/Transforms/BufferDeallocationSimplification.cpp
index 4d1e21c2e406cd3..e30779868b47539 100644
--- a/mlir/lib/Dialect/Bufferization/Transforms/BufferDeallocationSimplification.cpp
+++ b/mlir/lib/Dialect/Bufferization/Transforms/BufferDeallocationSimplification.cpp
@@ -77,18 +77,12 @@ static bool distinctAllocAndBlockArgument(Value v1, Value v2) {
   return areDistinct(v1Base, v2Base) || areDistinct(v2Base, v1Base);
 }
 
-/// Checks if `memref` may or must alias a MemRef in `otherList`. It is often a
-/// requirement of optimization patterns that there cannot be any aliasing
-/// memref in order to perform the desired simplification. The `allowSelfAlias`
-/// argument indicates whether `memref` may be present in `otherList` which
-/// makes this helper function applicable to situations where we already know
-/// that `memref` is in the list but also when we don't want it in the list.
+/// Checks if `memref` may potentially alias a MemRef in `otherList`. It is
+/// often a requirement of optimization patterns that there cannot be any
+/// aliasing memref in order to perform the desired simplification.
 static bool potentiallyAliasesMemref(AliasAnalysis &analysis,
-                                     ValueRange otherList, Value memref,
-                                     bool allowSelfAlias) {
+                                     ValueRange otherList, Value memref) {
   for (auto other : otherList) {
-    if (allowSelfAlias && other == memref)
-      continue;
     if (distinctAllocAndBlockArgument(other, memref))
       continue;
     if (!analysis.alias(other, memref).isNo())
@@ -243,7 +237,7 @@ struct RemoveRetainedMemrefsGuaranteedToNotAlias
 
     for (auto retainedMemref : deallocOp.getRetained()) {
       if (potentiallyAliasesMemref(aliasAnalysis, deallocOp.getMemrefs(),
-                                   retainedMemref, false)) {
+                                   retainedMemref)) {
         newRetainedMemrefs.push_back(retainedMemref);
         replacements.push_back({});
         continue;
@@ -314,11 +308,13 @@ struct SplitDeallocWhenNotAliasingAnyOther
 
     SmallVector<Value> remainingMemrefs, remainingConditions;
     SmallVector<SmallVector<Value>> updatedConditions;
-    for (auto [memref, cond] :
-         llvm::zip(deallocOp.getMemrefs(), deallocOp.getConditions())) {
+    for (int64_t i = 0, e = deallocOp.getMemrefs().size(); i < e; ++i) {
+      Value memref = deallocOp.getMemrefs()[i];
+      Value cond = deallocOp.getConditions()[i];
+      SmallVector<Value> otherMemrefs(deallocOp.getMemrefs());
+      otherMemrefs.erase(otherMemrefs.begin() + i);
       // Check if `memref` can split off into a separate bufferization.dealloc.
-      if (potentiallyAliasesMemref(aliasAnalysis, deallocOp.getMemrefs(),
-                                   memref, true)) {
+      if (potentiallyAliasesMemref(aliasAnalysis, otherMemrefs, memref)) {
         // `memref` alias with other memrefs, do not split off.
         remainingMemrefs.push_back(memref);
         remainingConditions.push_back(cond);