[MLIR] Add function to create BFloat16 array attribute

This patch adds a new function `mlirDenseElementsAttrBFloat16Get()`,
which accepts the shaped type, the number of BFloat16 values, and a
pointer to an array of BFloat16 values, each of which is a `uint16_t`
value.

Reviewed By: stellaraccident

Differential Revision: https://reviews.llvm.org/D123981

Author: ashay

mlir/include/mlir-c/BuiltinAttributes.h

@@ -379,6 +379,8 @@ MLIR_CAPI_EXPORTED MlirAttribute mlirDenseElementsAttrFloatGet(
     MlirType shapedType, intptr_t numElements, const float *elements);
 MLIR_CAPI_EXPORTED MlirAttribute mlirDenseElementsAttrDoubleGet(
     MlirType shapedType, intptr_t numElements, const double *elements);
+MLIR_CAPI_EXPORTED MlirAttribute mlirDenseElementsAttrBFloat16Get(
+    MlirType shapedType, intptr_t numElements, const uint16_t *elements);
 
 /// Creates a dense elements attribute with the given shaped type from string
 /// elements.

mlir/lib/CAPI/IR/BuiltinAttributes.cpp

@@ -474,6 +474,13 @@ MlirAttribute mlirDenseElementsAttrDoubleGet(MlirType shapedType,
                                              const double *elements) {
   return getDenseAttribute(shapedType, numElements, elements);
 }
+MlirAttribute mlirDenseElementsAttrBFloat16Get(MlirType shapedType,
+                                               intptr_t numElements,
+                                               const uint16_t *elements) {
+  size_t bufferSize = numElements * 2;
+  const void *buffer = static_cast<const void *>(elements);
+  return mlirDenseElementsAttrRawBufferGet(shapedType, bufferSize, buffer);
+}
 
 MlirAttribute mlirDenseElementsAttrStringGet(MlirType shapedType,
                                              intptr_t numElements,

mlir/test/CAPI/ir.c

@@ -936,6 +936,7 @@ int printBuiltinAttributes(MlirContext ctx) {
   int64_t ints64[] = {0, 1};
   float floats[] = {0.0f, 1.0f};
   double doubles[] = {0.0, 1.0};
+  uint16_t bf16s[] = {0x0, 0x3f80};
   MlirAttribute encoding = mlirAttributeGetNull();
   MlirAttribute boolElements = mlirDenseElementsAttrBoolGet(
       mlirRankedTensorTypeGet(2, shape, mlirIntegerTypeGet(ctx, 1), encoding),
@@ -974,6 +975,9 @@ int printBuiltinAttributes(MlirContext ctx) {
   MlirAttribute doubleElements = mlirDenseElementsAttrDoubleGet(
       mlirRankedTensorTypeGet(2, shape, mlirF64TypeGet(ctx), encoding), 2,
       doubles);
+  MlirAttribute bf16Elements = mlirDenseElementsAttrBFloat16Get(
+      mlirRankedTensorTypeGet(2, shape, mlirBF16TypeGet(ctx), encoding), 2,
+      bf16s);
 
   if (!mlirAttributeIsADenseElements(boolElements) ||
       !mlirAttributeIsADenseElements(uint8Elements) ||
@@ -983,7 +987,8 @@ int printBuiltinAttributes(MlirContext ctx) {
       !mlirAttributeIsADenseElements(uint64Elements) ||
       !mlirAttributeIsADenseElements(int64Elements) ||
       !mlirAttributeIsADenseElements(floatElements) ||
-      !mlirAttributeIsADenseElements(doubleElements))
+      !mlirAttributeIsADenseElements(doubleElements) ||
+      !mlirAttributeIsADenseElements(bf16Elements))
     return 14;
 
   if (mlirDenseElementsAttrGetBoolValue(boolElements, 1) != 1 ||
@@ -1009,6 +1014,7 @@ int printBuiltinAttributes(MlirContext ctx) {
   mlirAttributeDump(int64Elements);
   mlirAttributeDump(floatElements);
   mlirAttributeDump(doubleElements);
+  mlirAttributeDump(bf16Elements);
   // CHECK: dense<{{\[}}[false, true]]> : tensor<1x2xi1>
   // CHECK: dense<{{\[}}[0, 1]]> : tensor<1x2xui8>
   // CHECK: dense<{{\[}}[0, 1]]> : tensor<1x2xi8>
@@ -1018,6 +1024,7 @@ int printBuiltinAttributes(MlirContext ctx) {
   // CHECK: dense<{{\[}}[0, 1]]> : tensor<1x2xi64>
   // CHECK: dense<{{\[}}[0.000000e+00, 1.000000e+00]]> : tensor<1x2xf32>
   // CHECK: dense<{{\[}}[0.000000e+00, 1.000000e+00]]> : tensor<1x2xf64>
+  // CHECK: dense<{{\[}}[0.000000e+00, 1.000000e+00]]> : tensor<1x2xbf16>
 
   MlirAttribute splatBool = mlirDenseElementsAttrBoolSplatGet(
       mlirRankedTensorTypeGet(2, shape, mlirIntegerTypeGet(ctx, 1), encoding),
@@ -1094,12 +1101,15 @@ int printBuiltinAttributes(MlirContext ctx) {
   float *floatRawData = (float *)mlirDenseElementsAttrGetRawData(floatElements);
   double *doubleRawData =
       (double *)mlirDenseElementsAttrGetRawData(doubleElements);
+  uint16_t *bf16RawData =
+      (uint16_t *)mlirDenseElementsAttrGetRawData(bf16Elements);
   if (uint8RawData[0] != 0u || uint8RawData[1] != 1u || int8RawData[0] != 0 ||
       int8RawData[1] != 1 || uint32RawData[0] != 0u || uint32RawData[1] != 1u ||
       int32RawData[0] != 0 || int32RawData[1] != 1 || uint64RawData[0] != 0u ||
       uint64RawData[1] != 1u || int64RawData[0] != 0 || int64RawData[1] != 1 ||
       floatRawData[0] != 0.0f || floatRawData[1] != 1.0f ||
-      doubleRawData[0] != 0.0 || doubleRawData[1] != 1.0)
+      doubleRawData[0] != 0.0 || doubleRawData[1] != 1.0 ||
+      bf16RawData[0] != 0 || bf16RawData[1] != 0x3f80)
     return 18;
 
   mlirAttributeDump(splatBool);
@@ -1123,8 +1133,10 @@ int printBuiltinAttributes(MlirContext ctx) {
 
   mlirAttributeDump(mlirElementsAttrGetValue(floatElements, 2, uints64));
   mlirAttributeDump(mlirElementsAttrGetValue(doubleElements, 2, uints64));
+  mlirAttributeDump(mlirElementsAttrGetValue(bf16Elements, 2, uints64));
   // CHECK: 1.000000e+00 : f32
   // CHECK: 1.000000e+00 : f64
+  // CHECK: 1.000000e+00 : bf16
 
   int64_t indices[] = {0, 1};
   int64_t one = 1;