[Mlir-commits] [mlir] [mlir][inline] avoid inline self-recursive function (PR #82997)

[Congcong Cai]

https://github.com/HerrCai0907 created https://github.com/llvm/llvm-project/pull/82997

We cannot get any benifit from inlining self-recursive function.
This patch want to detect this cases and ignore it.

>From 67a932e98ed051834f72cbf969d5ae273fc26ff8 Mon Sep 17 00:00:00 2001
From: Congcong Cai <congcongcai0907 at 163.com>
Date: Mon, 26 Feb 2024 16:34:09 +0800
Subject: [PATCH 1/2] [mlir][inline] avoid inline self-recursive function

We cannot get any benifit from inlining self-recursive function.
This patch want to detect this cases and ignore it.
---
 mlir/lib/Transforms/Inliner.cpp               | 12 ++++++++++
 .../Transforms/inlining-recursive-self.mlir   | 22 +++++++++++++++++++
 2 files changed, 34 insertions(+)
 create mode 100644 mlir/test/Transforms/inlining-recursive-self.mlir

diff --git a/mlir/lib/Transforms/Inliner.cpp b/mlir/lib/Transforms/Inliner.cpp
index b32b0fc28c78b0..3da6e9cff81cbb 100644
--- a/mlir/lib/Transforms/Inliner.cpp
+++ b/mlir/lib/Transforms/Inliner.cpp
@@ -273,6 +273,10 @@ class CallGraphSCC {
   /// Reset the nodes of this SCC with those provided.
   void reset(const std::vector<CallGraphNode *> &newNodes) { nodes = newNodes; }
 
+  bool has(CallGraphNode *node) {
+    return std::count(nodes.begin(), nodes.end(), node) > 0;
+  }
+
   /// Remove the given node from this SCC.
   void remove(CallGraphNode *node) {
     auto it = llvm::find(nodes, node);
@@ -455,6 +459,14 @@ static bool shouldInline(ResolvedCall &resolvedCall) {
   if (callableRegion->isAncestor(resolvedCall.call->getParentRegion()))
     return false;
 
+  // Don't allow inlining if the target is a self-recursive function.
+  if (std::count_if(resolvedCall.targetNode->begin(),
+                    resolvedCall.targetNode->end(),
+                    [&](CallGraphNode::Edge const &edge) -> bool {
+                      return edge.getTarget() == resolvedCall.targetNode;
+                    }) > 0)
+    return false;
+
   // Don't allow inlining if the callee has multiple blocks (unstructured
   // control flow) but we cannot be sure that the caller region supports that.
   bool calleeHasMultipleBlocks =
diff --git a/mlir/test/Transforms/inlining-recursive-self.mlir b/mlir/test/Transforms/inlining-recursive-self.mlir
new file mode 100644
index 00000000000000..5cc922db8e9786
--- /dev/null
+++ b/mlir/test/Transforms/inlining-recursive-self.mlir
@@ -0,0 +1,22 @@
+// RUN: mlir-opt %s -inline='default-pipeline=''' | FileCheck %s
+// RUN: mlir-opt %s --mlir-disable-threading -inline='default-pipeline=''' | FileCheck %s
+
+// CHECK-LABEL: func.func @b0
+func.func @b0() {
+  // CHECK:         call @b0
+  // CHECK-NEXT:    call @b1
+  // CHECK-NEXT:    call @b0
+  // CHECK-NEXT:    call @b1
+  // CHECK-NEXT:    call @b0
+  func.call @b0() : () -> ()
+  func.call @b1() : () -> ()
+  func.call @b0() : () -> ()
+  func.call @b1() : () -> ()
+  func.call @b0() : () -> ()
+  return
+}
+func.func @b1() {
+  func.call @b1() : () -> ()
+  func.call @b1() : () -> ()
+  return
+}

>From cb00df68eb750575ef5b2f24cf409d589993a6c9 Mon Sep 17 00:00:00 2001
From: Congcong Cai <congcongcai0907 at 163.com>
Date: Mon, 26 Feb 2024 20:58:06 +0800
Subject: [PATCH 2/2] fix

---
 mlir/lib/Transforms/Inliner.cpp | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/mlir/lib/Transforms/Inliner.cpp b/mlir/lib/Transforms/Inliner.cpp
index 3da6e9cff81cbb..b92ee49403c74c 100644
--- a/mlir/lib/Transforms/Inliner.cpp
+++ b/mlir/lib/Transforms/Inliner.cpp
@@ -273,10 +273,6 @@ class CallGraphSCC {
   /// Reset the nodes of this SCC with those provided.
   void reset(const std::vector<CallGraphNode *> &newNodes) { nodes = newNodes; }
 
-  bool has(CallGraphNode *node) {
-    return std::count(nodes.begin(), nodes.end(), node) > 0;
-  }
-
   /// Remove the given node from this SCC.
   void remove(CallGraphNode *node) {
     auto it = llvm::find(nodes, node);