virgL: lower fneg and fabs

The host doesn't currently handle source mods on immediate values
correctly, so lower the ops that would create these source mods.

v2: update trace checksum

Fixes:  c5cc9ed29b
    virgl: Switch to nir-to-tgsi by default.

Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/6929

Signed-off-by: Gert Wollny <gert.wollny@collabora.com>
Reviewed-by: Italo Nicola <italonicola@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/17765>

src/gallium/drivers/virgl/ci/traces-virgl.yml

@@ -207,7 +207,7 @@ traces:
   - path: itoral-gl-terrain-demo/demo-v2.trace
     expectations:
       - device: gl-virgl
-        checksum: 716d4fe36a6212b161285fed8a423ee8
+        checksum: 37780a6eaa38a55700e8207e89009f56
   - path: neverball/neverball-v2.trace
     expectations:
       - device: gl-virgl

src/gallium/drivers/virgl/virgl_context.c

@@ -686,7 +686,8 @@ static void *virgl_shader_encoder(struct pipe_context *ctx,
 
    if (shader->type == PIPE_SHADER_IR_NIR) {
       struct nir_to_tgsi_options options = {
-         .unoptimized_ra = true
+         .unoptimized_ra = true,
+         .lower_fabs = true
       };
       nir_shader *s = nir_shader_clone(NULL, shader->ir.nir);
 
@@ -1375,7 +1376,8 @@ static void *virgl_create_compute_state(struct pipe_context *ctx,
 
    if (state->ir_type == PIPE_SHADER_IR_NIR) {
       struct nir_to_tgsi_options options = {
-         .unoptimized_ra = true
+         .unoptimized_ra = true,
+         .lower_fabs = true
       };
       nir_shader *s = nir_shader_clone(NULL, state->prog);
       ntt_tokens = tokens = nir_to_tgsi_options(s, vctx->base.screen, &options); /* takes ownership */

src/gallium/drivers/virgl/virgl_screen.c

@@ -1088,6 +1088,7 @@ virgl_create_screen(struct virgl_winsys *vws, const struct pipe_screen_config *c
        * ffract+fsub back into ffloor.
        */
       screen->compiler_options.lower_ffloor = true;
+      screen->compiler_options.lower_fneg = true;
    }
 
    slab_create_parent(&screen->transfer_pool, sizeof(struct virgl_transfer), 16);