Hlsl asint16 intrinsic

[metkarpoonam]

Implemented the asint16 function and added test cases for codegen, Sema, and SPIR-V backend.
fixes #99184

[llvmbot]

@llvm/pr-subscribers-backend-x86
@llvm/pr-subscribers-clang

@llvm/pr-subscribers-backend-spir-v

Author: None (metkarpoonam)

Changes

Implemented the asint16 function and added test cases for codegen, Sema, and SPIR-V backend.

---

Full diff: https://github.com/llvm/llvm-project/pull/131900.diff

4 Files Affected:

• (modified) clang/lib/Headers/hlsl/hlsl_intrinsics.h (+18)
• (added) clang/test/CodeGenHLSL/builtins/asint16.hlsl (+48)
• (added) clang/test/SemaHLSL/BuiltIns/asint16-errors.hlsl (+29)
• (added) llvm/test/CodeGen/SPIRV/hlsl-intrinsics/asint16.ll (+55)

diff --git a/clang/lib/Headers/hlsl/hlsl_intrinsics.h b/clang/lib/Headers/hlsl/hlsl_intrinsics.h
index a48a8e998a015..e0366693deae0 100644
--- a/clang/lib/Headers/hlsl/hlsl_intrinsics.h
+++ b/clang/lib/Headers/hlsl/hlsl_intrinsics.h
@@ -80,6 +80,24 @@ void asuint(double3, out uint3, out uint3);
 _HLSL_BUILTIN_ALIAS(__builtin_hlsl_elementwise_splitdouble)
 void asuint(double4, out uint4, out uint4);
 
+//===----------------------------------------------------------------------===//
+// asint16 builtins
+//===----------------------------------------------------------------------===//
+
+/// \fn int16_t asint16(T Val)
+/// \brief Interprets the bit pattern of x as an 16-bit integer.
+/// \param Val The input value.
+#ifdef __HLSL_ENABLE_16_BIT
+
+template <typename T, int N> constexpr vector<int16_t, N> asint16(vector<T, N> V) {
+  return __detail::bit_cast<int16_t, T, N>(V);
+}
+
+template <typename T> constexpr int16_t asint16(T F) {
+  return __detail::bit_cast<int16_t, T>(F);
+}
+#endif
+
 //===----------------------------------------------------------------------===//
 // distance builtins
 //===----------------------------------------------------------------------===//
diff --git a/clang/test/CodeGenHLSL/builtins/asint16.hlsl b/clang/test/CodeGenHLSL/builtins/asint16.hlsl
new file mode 100644
index 0000000000000..0cd6ee63fa078
--- /dev/null
+++ b/clang/test/CodeGenHLSL/builtins/asint16.hlsl
@@ -0,0 +1,48 @@
+// RUN: %clang_cc1 -finclude-default-header -x hlsl -triple dxil-pc-shadermodel6.2-library %s -fnative-half-type -emit-llvm -O1 -o - | FileCheck %s
+// CHECK: define {{.*}}test_ints{{.*}}(i16 {{.*}} [[VAL:%.*]]){{.*}}
+// CHECK-NOT: bitcast
+// CHECK: ret i16 [[VAL]]
+int16_t test_int(int16_t p0)
+{
+    return asint16(p0);
+}
+
+//CHECK: define {{.*}}test_uint{{.*}}(i16 {{.*}} [[VAL:%.*]]){{.*}}
+//CHECK-NOT: bitcast
+//CHECK: ret i16 [[VAL]]
+int16_t test_uint(uint16_t p0)
+{
+    return asint16(p0);
+}
+
+//CHECK: define {{.*}}test_half{{.*}}(half {{.*}} [[VAL:%.*]]){{.*}}
+//CHECK: [[RES:%.*]] = bitcast half [[VAL]] to i16
+//CHECK : ret i16 [[RES]]
+int16_t test_half(half p0)
+{
+    return asint16(p0);
+}
+
+//CHECK: define {{.*}}test_vector_int{{.*}}(<4 x i16> {{.*}} [[VAL:%.*]]){{.*}}
+//CHECK-NOT: bitcast
+//CHECK: ret <4 x i16> [[VAL]]
+int16_t4 test_vector_int(int16_t4 p0)
+{
+    return asint16(p0);
+}
+
+//CHECK: define {{.*}}test_vector_uint{{.*}}(<4 x i16> {{.*}} [[VAL:%.*]]){{.*}}
+//CHECK-NOT: bitcast
+//CHECK: ret <4 x i16> [[VAL]]
+int16_t4 test_vector_uint(uint16_t4 p0)
+{
+    return asint16(p0);
+}
+
+//CHECK: define {{.*}}fn{{.*}}(<4 x half> {{.*}} [[VAL:%.*]]){{.*}}
+//CHECK: [[RES:%.*]] = bitcast <4 x half> [[VAL]] to <4 x i16>
+//CHECK: ret <4 x i16> [[RES]]
+int16_t4 fn(half4 p1)
+{
+    return asint16(p1);
+}
\ No newline at end of file
diff --git a/clang/test/SemaHLSL/BuiltIns/asint16-errors.hlsl b/clang/test/SemaHLSL/BuiltIns/asint16-errors.hlsl
new file mode 100644
index 0000000000000..03a3e46bd1d46
--- /dev/null
+++ b/clang/test/SemaHLSL/BuiltIns/asint16-errors.hlsl
@@ -0,0 +1,29 @@
+// RUN: %clang_cc1 -finclude-default-header -triple dxil-pc-shadermodel6.2-library %s -fnative-half-type -verify
+
+
+int16_t4 test_asint_too_many_arg(uint16_t p0, uint16_t p1)
+{
+    return asint16(p0, p1);
+  // expected-error@-1 {{no matching function for call to 'asint16'}}
+  // expected-note@hlsl/hlsl_intrinsics.h:* {{candidate function template not viable: requires single argument 'V', but 2 arguments were provided}}
+  // expected-note@hlsl/hlsl_intrinsics.h:* {{candidate function template not viable: requires single argument 'F', but 2 arguments were provided}}
+}
+
+
+int16_t test_asint_int(int p1)
+{
+    return asint16(p1);
+    // expected-error@hlsl/hlsl_intrinsics.h:* {{no matching function for call to 'bit_cast'}}
+    // expected-note@-2 {{in instantiation of function template specialization 'hlsl::asint16<int>'}}
+    // expected-note@hlsl/hlsl_detail.h:* {{candidate template ignored: could not match 'vector<int, N>' against 'int'}}
+    // expected-note@hlsl/hlsl_detail.h:* {{candidate template ignored: substitution failure [with U = int16_t, T = int]: no type named 'Type'}}
+}
+
+int16_t test_asint_float(float p1)
+{
+    return asint16(p1);
+    // expected-error@hlsl/hlsl_intrinsics.h:* {{no matching function for call to 'bit_cast'}}
+    // expected-note@-2 {{in instantiation of function template specialization 'hlsl::asint16<float>'}}
+    // expected-note@hlsl/hlsl_detail.h:* {{candidate template ignored: could not match 'vector<float, N>' against 'float'}}
+    // expected-note@hlsl/hlsl_detail.h:* {{candidate template ignored: substitution failure [with U = int16_t, T = float]: no type named 'Type'}}
+}
\ No newline at end of file
diff --git a/llvm/test/CodeGen/SPIRV/hlsl-intrinsics/asint16.ll b/llvm/test/CodeGen/SPIRV/hlsl-intrinsics/asint16.ll
new file mode 100644
index 0000000000000..4c3c4337bc62a
--- /dev/null
+++ b/llvm/test/CodeGen/SPIRV/hlsl-intrinsics/asint16.ll
@@ -0,0 +1,55 @@
+; RUN: llc -O0 -verify-machineinstrs -mtriple=spirv-unknown-unknown %s -o - | FileCheck %s
+; RUN: %if spirv-tools %{ llc -O0 -mtriple=spirv-unknown-unknown %s -o - -filetype=obj | spirv-val %}
+
+; CHECK: OpCapability Int16
+; CHECK: OpCapability Float16
+; CHECK-DAG: %[[#int_16:]] = OpTypeInt 16 0
+; CHECK-DAG: %[[#float_16:]] = OpTypeFloat 16
+; CHECK-DAG: %[[#vec4_int_16:]] = OpTypeVector %[[#int_16]] 4
+; CHECK-DAG: %[[#vec4_float_16:]] = OpTypeVector %[[#float_16]] 4
+
+
+define i16 @test_int16(i16 returned %p0) {
+entry:
+  ; CHECK: %[[#arg0:]] = OpFunctionParameter %[[#int_16]]
+  ; CHECK: OpReturnValue %[[#arg0]]
+  ret i16 %p0
+}
+
+define i16 @test_half(half nofpclass(nan inf) %p0) {
+entry:
+  ; CHECK: %[[#arg0:]] = OpFunctionParameter %[[#float_16:]]
+  ; CHECK: %[[#]] = OpBitcast %[[#int_16]] %[[#arg0]]
+  %0 = bitcast half %p0 to i16
+  ;CHECK: OpReturnValue %[[#]]
+  ret i16 %0
+
+}
+
+; Function Attrs: alwaysinline mustprogress nofree norecurse nosync nounwind willreturn memory(none)
+define <4 x i16> @test_vector_int4(<4 x i16> returned %p0) {
+entry:
+  ; CHECK: %[[#arg0:]] = OpFunctionParameter %[[#vec4_int_16]]
+  ; CHECK: OpReturnValue %[[#arg0]]
+  ret <4 x i16> %p0
+}
+
+; Function Attrs: alwaysinline mustprogress nofree norecurse nosync nounwind willreturn memory(none)
+define <4 x i16> @test_vector_half4(<4 x half> nofpclass(nan inf) %p1) {
+entry:
+  ; CHECK: %[[#arg0:]] = OpFunctionParameter %[[#vec4_float_16]]
+  ; CHECK: %[[#]] = OpBitcast %[[#vec4_int_16]] %[[#arg0]]
+  %0 = bitcast <4 x half> %p1 to <4 x i16>
+  ;CHECK: OpReturnValue %[[#]]
+  ret <4 x i16> %0
+}
+
+attributes #0 = { alwaysinline mustprogress nofree norecurse nosync nounwind willreturn memory(none) "approx-func-fp-math"="true" "no-infs-fp-math"="true" "no-nans-fp-math"="true" "no-signed-zeros-fp-math"="true" "no-trapping-math"="true" "stack-protector-buffer-size"="8" }
+
+!llvm.module.flags = !{!0}
+!dx.valver = !{!1}
+!llvm.ident = !{!2}
+
+!0 = !{i32 1, !"wchar_size", i32 4}
+!1 = !{i32 1, i32 8}
+!2 = !{!"clang version 21.0.0git (https://github.com/llvm/llvm-project.git 5929de8c7731748bf58ad9b1fedfed75e7aae455)"}
\ No newline at end of file

[github-actions]

✅ With the latest revision this PR passed the C/C++ code formatter.

[V-FEXrt]

I'm assuming this PR resolves an issue right? We typically add Fixes #1234 (without the `) as part of the description so it will close the issue when the PR is merged

[farzonl]

Test changes needed aswell as some type constraints to template type T.

[farzonl]

LGTM don't forget to add the newline to the end of clang/test/SemaHLSL/BuiltIns/asint16-errors.hlsl

[farzonl]

There seems to be something odd with this PR. Looks like a ton of people just got added to it... Will need to investigate in the morning.

[farzonl]

There seems to be something odd with this PR. Looks like a ton of people just got added to it... Will need to investigate in the morning.

I removed all the extra reviewers. Don't see any artifacts of what could have caused it. Will confer with the team if this is safe to merge in the morning.

[farzonl]

LGTM