[Mlir-commits] [mlir] [MLIR] Fixes arith.sub folder crash on dynamically shaped tensors (PR #118908)

[Mehdi Amini]

https://github.com/joker-eph created https://github.com/llvm/llvm-project/pull/118908

We can't create a constant for a value with dynamic shape.

Fixes #118772

>From 469ab15d029b63451346e9df476757a4e2ef3fa7 Mon Sep 17 00:00:00 2001
From: Mehdi Amini <joker.eph at gmail.com>
Date: Thu, 5 Dec 2024 16:52:35 -0800
Subject: [PATCH] [MLIR] Fixes arith.sub folder crash on dynamically shaped
 tensors

We can't create a constant for a value with dynamic shape.

Fixes #118772
---
 mlir/lib/Dialect/Arith/IR/ArithOps.cpp    |  8 ++++++--
 mlir/test/Dialect/Arith/canonicalize.mlir | 11 +++++++++++
 2 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/mlir/lib/Dialect/Arith/IR/ArithOps.cpp b/mlir/lib/Dialect/Arith/IR/ArithOps.cpp
index 5f445231b80fdf..5a79add16569f4 100644
--- a/mlir/lib/Dialect/Arith/IR/ArithOps.cpp
+++ b/mlir/lib/Dialect/Arith/IR/ArithOps.cpp
@@ -393,8 +393,12 @@ void arith::AddUIExtendedOp::getCanonicalizationPatterns(
 
 OpFoldResult arith::SubIOp::fold(FoldAdaptor adaptor) {
   // subi(x,x) -> 0
-  if (getOperand(0) == getOperand(1))
-    return Builder(getContext()).getZeroAttr(getType());
+  if (getOperand(0) == getOperand(1)) {
+    auto tensorType = dyn_cast<TensorType>(getType());
+    // We can't generate a constant with a dynamic shaped tensor.
+    if (!tensorType || tensorType.hasStaticShape())
+      return Builder(getContext()).getZeroAttr(getType());
+  }
   // subi(x,0) -> x
   if (matchPattern(adaptor.getRhs(), m_Zero()))
     return getLhs();
diff --git a/mlir/test/Dialect/Arith/canonicalize.mlir b/mlir/test/Dialect/Arith/canonicalize.mlir
index 69df83d42f543e..8c22506b9afcf1 100644
--- a/mlir/test/Dialect/Arith/canonicalize.mlir
+++ b/mlir/test/Dialect/Arith/canonicalize.mlir
@@ -869,6 +869,17 @@ func.func @tripleAddAddOvf2(%arg0: index) -> index {
   return %add2 : index
 }
 
+
+// CHECK-LABEL: @foldSubXX
+//       CHECK:   %[[c0:.+]] = arith.constant dense<0> : tensor<10xi32> 
+//       CHECK:   %[[sub:.+]] = arith.subi
+//       CHECK:   return %[[c0]], %[[sub]]
+func.func @foldSubXX(%dyn : tensor<?x?xi32>, %static : tensor<10xi32>) -> (tensor<10xi32>, tensor<?x?xi32>) {
+  %static_sub = arith.subi %static, %static : tensor<10xi32>
+  %dyn_sub = arith.subi %dyn, %dyn : tensor<?x?xi32>
+  return %static_sub, %dyn_sub : tensor<10xi32>, tensor<?x?xi32>
+}
+
 // CHECK-LABEL: @tripleAddSub0
 //       CHECK:   %[[cres:.+]] = arith.constant 59 : index
 //       CHECK:   %[[add:.+]] = arith.subi %[[cres]], %arg0 : index