tgsi/scan: use wrap-around shift behavior explicitly for file_mask

The comment said it will only represent the lowest 32 regs. This was
not entirely true in practice, since at least on x86 you'll get
masked shifts (unless the compiler could recognize it already and toss
it out). It turns out this actually works out alright (presumably
noone uses it for temp regs) when increasing max sampler views, so
make that behavior explicit.
Albeit it feels a bit hacky (but in any case, explicit behavior there
is better than undefined behavior).

Reviewed-by: Jose Fonseca <[email protected]>
Reviewed-by: Brian Paul <[email protected]>

2 files changed, 7 insertions, 2 deletions

diff --git a/src/gallium/drivers/llvmpipe/lp_state_fs.c b/src/gallium/drivers/llvmpipe/lp_state_fs.c
index 603fd84f6b1..66645b07ac7 100644
--- a/src/gallium/drivers/llvmpipe/lp_state_fs.c
+++ b/src/gallium/drivers/llvmpipe/lp_state_fs.c
@@ -3323,7 +3323,12 @@ make_variant_key(struct llvmpipe_context *lp,
    if (shader->info.base.file_max[TGSI_FILE_SAMPLER_VIEW] != -1) {
       key->nr_sampler_views = shader->info.base.file_max[TGSI_FILE_SAMPLER_VIEW] + 1;
       for(i = 0; i < key->nr_sampler_views; ++i) {
-         if(shader->info.base.file_mask[TGSI_FILE_SAMPLER_VIEW] & (1 << i)) {
+         /*
+          * Note sview may exceed what's representable by file_mask.
+          * This will still work, the only downside is that not actually
+          * used views may be included in the shader key.
+          */
+         if(shader->info.base.file_mask[TGSI_FILE_SAMPLER_VIEW] & (1u << (i & 31))) {
             lp_sampler_static_texture_state(&key->state[i].texture_state,
                                             lp->sampler_views[PIPE_SHADER_FRAGMENT][i]);
          }
diff --git a/src/gallium/drivers/swr/swr_shader.cpp b/src/gallium/drivers/swr/swr_shader.cpp
index e5fb679f8b3..477fa7f2db4 100644
--- a/src/gallium/drivers/swr/swr_shader.cpp
+++ b/src/gallium/drivers/swr/swr_shader.cpp
@@ -98,7 +98,7 @@ swr_generate_sampler_key(const struct lp_tgsi_info &info,
       key.nr_sampler_views =
          info.base.file_max[TGSI_FILE_SAMPLER_VIEW] + 1;
       for (unsigned i = 0; i < key.nr_sampler_views; i++) {
-         if (info.base.file_mask[TGSI_FILE_SAMPLER_VIEW] & (1 << i)) {
+         if (info.base.file_mask[TGSI_FILE_SAMPLER_VIEW] & (1u << (i & 31))) {
             const struct pipe_sampler_view *view =
                ctx->sampler_views[shader_type][i];
             lp_sampler_static_texture_state(