[Mlir-commits] [mlir] [MLIR][Python] add ctype python binding support for bf16 (PR #92489)

[llvmlistbot at llvm.org]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-mlir

Author: Bimo (xurui1995)

<details>
<summary>Changes</summary>

Since bf16 is supported by mlir, similar to complex128/complex64/float16, we need an implementation of bf16 ctype in Python binding. Furthermore, to resolve the absence of bf16 support in NumPy, a third-party package [ml_dtypes ](https://github.com/jax-ml/ml_dtypes) is introduced to add bf16 extension, and the same approach was used in `torch-mlir` project.

See motivation and discussion in: https://discourse.llvm.org/t/how-to-run-executionengine-with-bf16-dtype-in-mlir-python-bindings/79025

---
Full diff: https://github.com/llvm/llvm-project/pull/92489.diff


3 Files Affected:

- (modified) mlir/python/mlir/runtime/np_to_memref.py (+10) 
- (modified) mlir/python/requirements.txt (+2-1) 
- (modified) mlir/test/python/execution_engine.py (+51) 


``````````diff
diff --git a/mlir/python/mlir/runtime/np_to_memref.py b/mlir/python/mlir/runtime/np_to_memref.py
index f6b706f9bc8ae..55e6a6cc5ab3e 100644
--- a/mlir/python/mlir/runtime/np_to_memref.py
+++ b/mlir/python/mlir/runtime/np_to_memref.py
@@ -6,6 +6,7 @@
 
 import numpy as np
 import ctypes
+import ml_dtypes
 
 
 class C128(ctypes.Structure):
@@ -25,6 +26,11 @@ class F16(ctypes.Structure):
 
     _fields_ = [("f16", ctypes.c_int16)]
 
+class BF16(ctypes.Structure):
+    """A ctype representation for MLIR's BFloat16."""
+
+    _fields_ = [("bf16", ctypes.c_int16)]
+
 
 # https://stackoverflow.com/questions/26921836/correct-way-to-test-for-numpy-dtype
 def as_ctype(dtp):
@@ -35,6 +41,8 @@ def as_ctype(dtp):
         return C64
     if dtp == np.dtype(np.float16):
         return F16
+    if dtp == ml_dtypes.bfloat16:
+        return BF16
     return np.ctypeslib.as_ctypes_type(dtp)
 
 
@@ -46,6 +54,8 @@ def to_numpy(array):
         return array.view("complex64")
     if array.dtype == F16:
         return array.view("float16")
+    if array.dtype == BF16:
+        return array.view("bfloat16")
     return array
 
 
diff --git a/mlir/python/requirements.txt b/mlir/python/requirements.txt
index acd6dbb25edaf..90acba8d65f09 100644
--- a/mlir/python/requirements.txt
+++ b/mlir/python/requirements.txt
@@ -1,3 +1,4 @@
 numpy>=1.19.5, <=1.26
 pybind11>=2.9.0, <=2.10.3
-PyYAML>=5.3.1, <=6.0.1
\ No newline at end of file
+PyYAML>=5.3.1, <=6.0.1
+ml_dtypes
\ No newline at end of file
diff --git a/mlir/test/python/execution_engine.py b/mlir/test/python/execution_engine.py
index e8b47007a8907..61d145ef24d95 100644
--- a/mlir/test/python/execution_engine.py
+++ b/mlir/test/python/execution_engine.py
@@ -5,6 +5,7 @@
 from mlir.passmanager import *
 from mlir.execution_engine import *
 from mlir.runtime import *
+from ml_dtypes import bfloat16
 
 
 # Log everything to stderr and flush so that we have a unified stream to match
@@ -521,6 +522,56 @@ def testComplexUnrankedMemrefAdd():
 run(testComplexUnrankedMemrefAdd)
 
 
+# Test addition of two bf16 memrefs
+# CHECK-LABEL: TEST: testBF16MemrefAdd
+def testBF16MemrefAdd():
+    with Context():
+        module = Module.parse(
+            """
+    module  {
+      func.func @main(%arg0: memref<1xcomplex<bf16>>,
+                      %arg1: memref<1xcomplex<bf16>>,
+                      %arg2: memref<1xcomplex<bf16>>) attributes { llvm.emit_c_interface } {
+        %0 = arith.constant 0 : index
+        %1 = memref.load %arg0[%0] : memref<1xcomplex<bf16>>
+        %2 = memref.load %arg1[%0] : memref<1xcomplex<bf16>>
+        %3 = complex.add %1, %2 : complex<bf16>
+        memref.store %3, %arg2[%0] : memref<1xcomplex<bf16>>
+        return
+      }
+    } """
+        )
+
+        arg1 = np.array([11.0]).astype(bfloat16)
+        arg2 = np.array([12.0]).astype(bfloat16)
+        arg3 = np.array([0.0]).astype(bfloat16)
+
+        arg1_memref_ptr = ctypes.pointer(
+            ctypes.pointer(get_ranked_memref_descriptor(arg1))
+        )
+        arg2_memref_ptr = ctypes.pointer(
+            ctypes.pointer(get_ranked_memref_descriptor(arg2))
+        )
+        arg3_memref_ptr = ctypes.pointer(
+            ctypes.pointer(get_ranked_memref_descriptor(arg3))
+        )
+
+        execution_engine = ExecutionEngine(lowerToLLVM(module))
+        execution_engine.invoke(
+            "main", arg1_memref_ptr, arg2_memref_ptr, arg3_memref_ptr
+        )
+        # CHECK: [11.] + [22.] = [33.]
+        log("{0} + {1} = {2}".format(arg1, arg2, arg3))
+
+        # test to-numpy utility
+        # CHECK: [33.]
+        npout = ranked_memref_to_numpy(arg3_memref_ptr[0])
+        log(npout)
+
+
+run(testBF16MemrefAdd)
+
+
 #  Test addition of two 2d_memref
 # CHECK-LABEL: TEST: testDynamicMemrefAdd2D
 def testDynamicMemrefAdd2D():

``````````

</details>


https://github.com/llvm/llvm-project/pull/92489