ac/llvm: fix wave32 ac_build_mbcnt_add with 64-bit mask

Signed-off-by: Rhys Perry <pendingchaos02@gmail.com>
Reviewed-by: Timur Kristóf <timur.kristof@gmail.com>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Cc: mesa-stable
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/24140>

src/amd/llvm/ac_llvm_build.c

@@ -2752,6 +2752,9 @@ LLVMValueRef ac_build_mbcnt_add(struct ac_llvm_context *ctx, LLVMValueRef mask,
    LLVMValueRef val;
 
    if (ctx->wave_size == 32) {
+      if (LLVMTypeOf(mask) == ctx->i64)
+         mask = LLVMBuildTrunc(ctx->builder, mask, ctx->i32, "");
+
       val = ac_build_intrinsic(ctx, "llvm.amdgcn.mbcnt.lo", ctx->i32,
                                (LLVMValueRef[]){mask, add}, 2, 0);
    } else {