[clang] [AMDGPU] Add missing `__builtin_amdgcn_wavefrontsize` builtin (PR #80741)

[Stanislav Mekhanoshin via cfe-commits]

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@@ -832,6 +832,13 @@ void test_atomic_inc_dec(local uint *lptr, global uint *gptr, uint val) {
   res = __builtin_amdgcn_atomic_dec32((volatile global uint*)gptr, val, __ATOMIC_SEQ_CST, "");
 }
 
+// CHECK-LABEL test_wavefrontsize(
+unsigned test_wavefrontsize() {
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rampitec wrote:

Ugh, it's inside the body. Unusual, but test above is he same.

https://github.com/llvm/llvm-project/pull/80741