ac/nir: handle more special cases in ac_nir_unpack_arg

Foz-DB Navi21:
Totals from 60972 (45.96% of 132657) affected shaders:
CodeSize: 158371336 -> 158127376 (-0.15%)

Reviewed-by: Rhys Perry <pendingchaos02@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/24534>

diff --git a/src/amd/common/ac_nir.c b/src/amd/common/ac_nir.c
index bf58a79..63e73c5 100644 (file)
--- a/src/amd/common/ac_nir.c
+++ b/src/amd/common/ac_nir.c
@@ -40,10 +40,14 @@ ac_nir_unpack_arg(nir_builder *b, const struct ac_shader_args *ac_args, struct a
                   unsigned rshift, unsigned bitwidth)
 {
    nir_ssa_def *value = ac_nir_load_arg(b, ac_args, arg);
-   if (rshift)
-      return nir_ubfe_imm(b, value, rshift, bitwidth);
-   else
+   if (rshift == 0 && bitwidth == 32)
+      return value;
+   else if (rshift == 0)
       return nir_iand_imm(b, value, BITFIELD_MASK(bitwidth));
+   else if ((32 - rshift) <= bitwidth)
+      return nir_ushr_imm(b, value, rshift);
+   else
+      return nir_ubfe_imm(b, value, rshift, bitwidth);
 }
 
 static bool