nir: add shader_info::disable_input/output_offset_src_constant_folding

and set it where needed to prevent nir_opt_constant_folding from breaking
those drivers.

Acked-by: Alyssa Rosenzweig <alyssa.rosenzweig@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/38277>

src/broadcom/compiler/vir.c

@@ -1040,6 +1040,7 @@ v3d_nir_lower_vs_early(struct v3d_compile *c)
         NIR_PASS(_, c->s, nir_lower_io, nir_var_shader_in | nir_var_shader_out,
                  type_size_vec4,
                  (nir_lower_io_options)0);
+        c->s->info.disable_output_offset_src_constant_folding = true;
 
         /* For geometry stages using the same segment for inputs and outputs
          * we need to read all inputs before writing any output. If we switch
@@ -1082,6 +1083,8 @@ v3d_nir_lower_gs_early(struct v3d_compile *c)
         NIR_PASS(_, c->s, nir_lower_io, nir_var_shader_in | nir_var_shader_out,
                  type_size_vec4,
                  (nir_lower_io_options)0);
+        c->s->info.disable_output_offset_src_constant_folding = true;
+
         /* clean up nir_lower_io's deref_var remains and do a constant folding pass
          * on the code it generated.
          */

src/compiler/shader_info.h

@@ -244,6 +244,12 @@ typedef struct shader_info {
    /* Whether flrp has been lowered. */
    bool flrp_lowered:1;
 
+   /* Whether nir_opt_constant_folding should not fold offset srcs of
+    * IO intrinsics.
+    */
+   bool disable_input_offset_src_constant_folding:1;
+   bool disable_output_offset_src_constant_folding:1;
+
    /* Whether nir_lower_io has been called to lower derefs.
     * nir_variables for inputs and outputs might not be present in the IR.
     */

src/gallium/drivers/vc4/vc4_program.c

@@ -2514,6 +2514,7 @@ vc4_shader_state_create(struct pipe_context *pctx,
         NIR_PASS(_, s, nir_lower_io,
                  nir_var_shader_in | nir_var_shader_out | nir_var_uniform,
                  type_size, (nir_lower_io_options)0);
+        s->info.disable_output_offset_src_constant_folding = true;
 
         NIR_PASS(_, s, nir_normalize_cubemap_coords);
 

src/intel/compiler/brw/brw_nir.c

@@ -1165,6 +1165,7 @@ brw_nir_lower_fs_outputs(nir_shader *nir)
    }
 
    NIR_PASS(_, nir, nir_lower_io, nir_var_shader_out, type_size_vec4, 0);
+   nir->info.disable_output_offset_src_constant_folding = true;
 }
 
 static bool

src/microsoft/compiler/nir_to_dxil.c

@@ -6636,6 +6636,8 @@ nir_to_dxil(struct nir_shader *s, const struct nir_to_dxil_options *opts,
    NIR_PASS(_, s, nir_lower_frexp);
    NIR_PASS(_, s, nir_lower_flrp, 16 | 32 | 64, true);
    NIR_PASS(_, s, nir_lower_io, nir_var_shader_in | nir_var_shader_out, type_size_vec4, nir_lower_io_lower_64bit_to_32);
+   s->info.disable_input_offset_src_constant_folding = true;
+   s->info.disable_output_offset_src_constant_folding = true;
    NIR_PASS(_, s, dxil_nir_ensure_position_writes);
    NIR_PASS(_, s, dxil_nir_lower_system_values);
    NIR_PASS(_, s, nir_lower_io_to_scalar, nir_var_shader_in | nir_var_system_value | nir_var_shader_out, NULL, NULL);