[Mlir-commits] [mlir] [mlir][arith] fix wrong floordivsi fold (#83079) (PR #83248)

[llvmlistbot at llvm.org]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-mlir-arith

Author: long.chen (lipracer)

<details>
<summary>Changes</summary>

Fixs https://github.com/llvm/llvm-project/issues/83079

---
Full diff: https://github.com/llvm/llvm-project/pull/83248.diff


2 Files Affected:

- (modified) mlir/lib/Dialect/Arith/IR/ArithOps.cpp (+9-3) 
- (modified) mlir/test/Transforms/canonicalize.mlir (+9) 


``````````diff
diff --git a/mlir/lib/Dialect/Arith/IR/ArithOps.cpp b/mlir/lib/Dialect/Arith/IR/ArithOps.cpp
index 0f71c19c23b654..d370b7d04dea7e 100644
--- a/mlir/lib/Dialect/Arith/IR/ArithOps.cpp
+++ b/mlir/lib/Dialect/Arith/IR/ArithOps.cpp
@@ -709,19 +709,25 @@ OpFoldResult arith::FloorDivSIOp::fold(FoldAdaptor adaptor) {
         }
         if (!aGtZero && !bGtZero) {
           // Both negative, return -a / -b.
-          APInt posA = zero.ssub_ov(a, overflowOrDiv0);
-          APInt posB = zero.ssub_ov(b, overflowOrDiv0);
-          return posA.sdiv_ov(posB, overflowOrDiv0);
+          return a.sdiv_ov(b, overflowOrDiv0);
         }
         if (!aGtZero && bGtZero) {
           // A is negative, b is positive, return - ceil(-a, b).
           APInt posA = zero.ssub_ov(a, overflowOrDiv0);
+          if (overflowOrDiv0)
+            return a;
           APInt ceil = signedCeilNonnegInputs(posA, b, overflowOrDiv0);
+          if (overflowOrDiv0)
+            return a;
           return zero.ssub_ov(ceil, overflowOrDiv0);
         }
         // A is positive, b is negative, return - ceil(a, -b).
         APInt posB = zero.ssub_ov(b, overflowOrDiv0);
+        if (overflowOrDiv0)
+          return a;
         APInt ceil = signedCeilNonnegInputs(a, posB, overflowOrDiv0);
+        if (overflowOrDiv0)
+          return a;
         return zero.ssub_ov(ceil, overflowOrDiv0);
       });
 
diff --git a/mlir/test/Transforms/canonicalize.mlir b/mlir/test/Transforms/canonicalize.mlir
index 2cf86b50d432f6..d2c2c12d323892 100644
--- a/mlir/test/Transforms/canonicalize.mlir
+++ b/mlir/test/Transforms/canonicalize.mlir
@@ -989,6 +989,15 @@ func.func @tensor_arith.floordivsi_by_one(%arg0: tensor<4x5xi32>) -> tensor<4x5x
   return %res : tensor<4x5xi32>
 }
 
+// CHECK-LABEL: func @arith.floordivsi_by_one_overflow
+func.func @arith.floordivsi_by_one_overflow() -> i64 {
+  %neg_one = arith.constant -1 : i64
+  %min_int = arith.constant -9223372036854775808 : i64
+  // CHECK: arith.floordivsi
+  %poision = arith.floordivsi %min_int, %neg_one : i64
+  return %poision : i64
+}
+
 // -----
 
 // CHECK-LABEL: func @arith.ceildivsi_by_one

``````````

</details>


https://github.com/llvm/llvm-project/pull/83248