[clang] [llvm] [HLSL] Implement elementwise popcount (PR #108121)

[Simon Pilgrim via cfe-commits]

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@@ -505,6 +505,27 @@ void test_builtin_elementwise_log2(int i, float f, double d, float4 v, int3 iv,
   // expected-error at -1 {{1st argument must be a floating point type (was 'unsigned4' (vector of 4 'unsigned int' values))}}
 }
 
+void test_builtin_elementwise_popcount(int i, float f, double d, float4 v, int3 iv, unsigned u, unsigned4 uv) {
+
+  struct Foo s = __builtin_elementwise_popcount(i);
+  // expected-error at -1 {{initializing 'struct Foo' with an expression of incompatible type 'int'}}
+
+  i = __builtin_elementwise_popcount();
+  // expected-error at -1 {{too few arguments to function call, expected 1, have 0}}
+
+  i = __builtin_elementwise_popcount(f);
+  // expected-error at -1 {{1st argument must be a vector of integers (was 'float')}}
+
+  i = __builtin_elementwise_popcount(f, f);
+  // expected-error at -1 {{too many arguments to function call, expected 1, have 2}}
+
+  u = __builtin_elementwise_popcount(d);
+  // expected-error at -1 {{1st argument must be a vector of integers (was 'double')}}
+
+  v = __builtin_elementwise_popcount(v);
+  // expected-error at -1 {{1st argument must be a vector of integers (was 'float4' (vector of 4 'float' values))}}
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RKSimon wrote:

please can you add tests for vector element count mismatches and implicit arg vs result vector extension/truncation/sign changes

https://github.com/llvm/llvm-project/pull/108121