nir: Add more tex_src helpers

This adds a variant of nir_steal_tex_src() which is for derefs as well
as versions that just return the source without removing it.

Reviewed-by: Christian Gmeiner <cgmeiner@igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/35623>

src/compiler/nir/nir.h

@@ -2563,6 +2563,26 @@ void nir_tex_instr_add_src(nir_tex_instr *tex,
 /** Removes a source from a texture instruction */
 void nir_tex_instr_remove_src(nir_tex_instr *tex, unsigned src_idx);
 
+static inline nir_def *
+nir_get_tex_src(nir_tex_instr *tex, nir_tex_src_type type_)
+{
+   int idx = nir_tex_instr_src_index(tex, type_);
+   if (idx < 0)
+      return NULL;
+
+   return tex->src[idx].src.ssa;
+}
+
+static inline nir_deref_instr *
+nir_get_tex_deref(nir_tex_instr *tex, nir_tex_src_type type_)
+{
+   int idx = nir_tex_instr_src_index(tex, type_);
+   if (idx < 0)
+      return NULL;
+
+   return nir_src_as_deref(tex->src[idx].src);
+}
+
 /*
  * Find a texture source, remove it, and return its nir_def. If the texture
  * source does not exist, return NULL. This is useful for texture lowering pass
@@ -2580,6 +2600,18 @@ nir_steal_tex_src(nir_tex_instr *tex, nir_tex_src_type type_)
    return ssa;
 }
 
+static inline nir_deref_instr *
+nir_steal_tex_deref(nir_tex_instr *tex, nir_tex_src_type type_)
+{
+   int idx = nir_tex_instr_src_index(tex, type_);
+   if (idx < 0)
+      return NULL;
+
+   nir_deref_instr *deref = nir_src_as_deref(tex->src[idx].src);
+   nir_tex_instr_remove_src(tex, idx);
+   return deref;
+}
+
 bool nir_tex_instr_has_explicit_tg4_offsets(nir_tex_instr *tex);
 
 typedef struct nir_load_const_instr {