[clang] [HLSL] Implement support for HLSL intrinsic - select (PR #107129)

[Damyan Pepper via cfe-commits]

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+// RUN: %clang_cc1 -finclude-default-header -triple dxil-pc-shadermodel6.6-library %s -emit-llvm-only -disable-llvm-passes -verify -verify-ignore-unexpected
+
+int test_no_arg() {
+  return select();
+  // expected-error at -1 {{no matching function for call to 'select'}}
+  // expected-note at hlsl/hlsl_intrinsics.h:* {{candidate function template not viable: requires 3 arguments, but 0 were provided}}
+  // expected-note at hlsl/hlsl_intrinsics.h:* {{candidate function template not viable: requires 3 arguments, but 0 were provided}}
+}
+
+int test_too_few_args(bool p0) {
+  return select(p0);
+  // expected-error at -1 {{no matching function for call to 'select'}}
+  // expected-note at hlsl/hlsl_intrinsics.h:* {{candidate function template not viable: requires 3 arguments, but 1 was provided}}
+  // expected-note at hlsl/hlsl_intrinsics.h:* {{candidate function template not viable: requires 3 arguments, but 1 was provided}}
+}
+
+int test_too_many_args(bool p0, int t0, int f0, int g0) {
+  return select<int>(p0, t0, f0, g0);
+  // expected-error at -1 {{no matching function for call to 'select'}}
+  // expected-note at hlsl/hlsl_intrinsics.h:* {{candidate function template not viable: requires 3 arguments, but 4 were provided}}
+  // expected-note at hlsl/hlsl_intrinsics.h:* {{candidate function template not viable: requires 3 arguments, but 4 were provided}}
+}
+
+int test_select_first_arg_wrong_type(vector<int,1> p0, int t0, int f0) {
+  return select(p0, t0, f0);
+  // expected-error at -1 {{no matching function for call to 'select'}}
+  // expected-note at hlsl/hlsl_intrinsics.h:* {{candidate function template not viable: no known conversion from 'vector<int, 1>' (vector of 1 'int' value) to 'bool' for 1st argument}}
+  // expected-note at hlsl/hlsl_intrinsics.h:* {{candidate template ignored: could not match 'vector<T, Sz>' against 'int'}}
+}
+
+vector<int,1> test_select_bool_vals_diff_vecs(bool p0, vector<int,1> t0, vector<int,2> f0) {
+  return select<vector<int,1> >(p0, t0, f0);
+  // expected-warning at -1 {{implicit conversion truncates vector: 'vector<int, 2>' (vector of 2 'int' values) to 'vector<int, 1>' (vector of 1 'int' value)}}
+}
+
+vector<int,2> test_select_vector_vals_not_vecs(vector<bool,2> p0, int t0, int f0) {
+  return select(p0, t0, f0);
+  // expected-error at -1 {{no matching function for call to 'select'}}
+  // expected-note at hlsl/hlsl_intrinsics.h:* {{candidate template ignored: could not match 'vector<T, Sz>' against 'int'}}
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damyanp wrote:

I'm looking at some of these errors here and wondering if you've managed to actually exercise all of the diagnostics emitted from SemaHLSL?  I think that most of these diagnostics are actually caught by standard C++ rules for function lookup.

I wonder if some tests that directly call `__builtin_hlsl_select` with invalid parameters are really required here to have complete coverage?

https://github.com/llvm/llvm-project/pull/107129