[clang] [llvm] [HLSL] Implement dot2add intrinsic (PR #131237)

[Farzon Lotfi via llvm-commits]

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+// RUN: %clang_cc1 -finclude-default-header -triple dxil-pc-shadermodel6.6-library %s -fnative-half-type -emit-llvm-only -disable-llvm-passes -verify
+
+float test_too_few_arg() {
+  return __builtin_hlsl_dot2add();
+  // expected-error at -1 {{too few arguments to function call, expected 3, have 0}}
+}
+
+float test_too_many_arg(half2 p1, half2 p2, float p3) {
+  return __builtin_hlsl_dot2add(p1, p2, p3, p1);
+  // expected-error at -1 {{too many arguments to function call, expected 3, have 4}}
+}
+
+float test_float_arg2_type(half2 p1, float2 p2, float p3) {
+  return __builtin_hlsl_dot2add(p1, p2, p3);
+  // expected-error at -1 {{passing 'float2' (aka 'vector<float, 2>') to parameter of incompatible type '__attribute__((__vector_size__(2 * sizeof(half)))) half' (vector of 2 'half' values)}}
+}
+
+float test_float_arg1_type(float2 p1, half2 p2, float p3) {
+  return __builtin_hlsl_dot2add(p1, p2, p3);
+  // expected-error at -1 {{passing 'float2' (aka 'vector<float, 2>') to parameter of incompatible type '__attribute__((__vector_size__(2 * sizeof(half)))) half' (vector of 2 'half' values)}}
+}
+
+float test_double_arg3_type(half2 p1, half2 p2, double p3) {
+  return __builtin_hlsl_dot2add(p1, p2, p3);
+  // expected-error at -1 {{passing 'double' to parameter of incompatible type 'float'}}
+}
+
+float test_float_arg1_arg2_type(float2 p1, float2 p2, float p3) {
+  return __builtin_hlsl_dot2add(p1, p2, p3);
+  // expected-error at -1 {{passing 'float2' (aka 'vector<float, 2>') to parameter of incompatible type '__attribute__((__vector_size__(2 * sizeof(half)))) half' (vector of 2 'half' values)}}
+}
+
+float test_int16_arg1_arg2_type(int16_t2 p1, int16_t2 p2, float p3) {
+  return __builtin_hlsl_dot2add(p1, p2, p3);
+  // expected-error at -1 {{passing 'int16_t2' (aka 'vector<int16_t, 2>') to parameter of incompatible type '__attribute__((__vector_size__(2 * sizeof(half)))) half' (vector of 2 'half' values)}}
+}
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farzonl wrote:

Now that the builtin defines the vector size we should test that we get errors for different vector sizes. We also need tests for `dot2add` test aswell without using the builtin since the builtin is just for the directX resolutions while the `dot2add` covers all targets.

https://github.com/llvm/llvm-project/pull/131237