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

[Farzon Lotfi via cfe-commits]

================
@@ -0,0 +1,21 @@
+; RUN: llc -verify-machineinstrs -O0 -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: OpMemoryModel Logical GLSL450
+
+define noundef i32 @countbits_i32(i32 noundef %a) {
+entry:
+; CHECK: %[[#]] = OpBitCount %[[#]] %[[#]]
+  %elt.bitreverse = call i32 @llvm.ctpop.i32(i32 %a)
+  ret i32 %elt.bitreverse
+}
+
+define noundef i16 @countbits_i16(i16 noundef %a) {
+entry:
+; CHECK: %[[#]] = OpBitCount %[[#]] %[[#]]
+  %elt.ctpop = call i16 @llvm.ctpop.i16(i16 %a)
+  ret i16 %elt.ctpop
+}
+
+declare i16 @llvm.ctpop.i16(i16)
+declare i32 @llvm.ctpop.i32(i32)
----------------
farzonl wrote:

add a vector test

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