Mesa (master): ilo: simplify shader variant handling

[Chia-I Wu]

Module: Mesa
Branch: master
Commit: 8b1c9de166129086ff73a3ed0378e3feb06dda15
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=8b1c9de166129086ff73a3ed0378e3feb06dda15

Author: Courtney Goeltzenleuchter <courtney at lunarg.com>
Date:   Tue May 28 09:54:43 2013 -0600

ilo: simplify shader variant handling

Remove hash function on shader variants. Nature of variants limits them to a
small number and thus its more efficient to just do a memory compare of the
actual shader structures rather than compute and compare hashes.

---

 src/gallium/drivers/ilo/ilo_shader.c |   25 ++-----------------------
 src/gallium/drivers/ilo/ilo_shader.h |    2 --
 2 files changed, 2 insertions(+), 25 deletions(-)

diff --git a/src/gallium/drivers/ilo/ilo_shader.c b/src/gallium/drivers/ilo/ilo_shader.c
index 9a36721..67e1a80 100644
--- a/src/gallium/drivers/ilo/ilo_shader.c
+++ b/src/gallium/drivers/ilo/ilo_shader.c
@@ -160,23 +160,6 @@ ilo_shader_variant_guess(struct ilo_shader_variant *variant,
    }
 }
 
-/**
- * Hash a shader variant.
- */
-static unsigned int
-ilo_shader_variant_hash(const struct ilo_shader_variant *variant)
-{
-   const int num_bytes = sizeof(*variant);
-   const unsigned char *bytes = (const unsigned char *) variant;
-   const unsigned int seed = 131;
-   unsigned int hash = 0;
-   int i;
-
-   for (i = 0; i < num_bytes; i++)
-      hash = hash * seed + bytes[i];
-
-   return hash;
-}
 
 /**
  * Parse a TGSI instruction for the shader info.
@@ -428,14 +411,12 @@ ilo_shader_state_gc(struct ilo_shader_state *state)
  */
 static struct ilo_shader *
 ilo_shader_state_search_variant(struct ilo_shader_state *state,
-                                unsigned int hash,
                                 const struct ilo_shader_variant *variant)
 {
    struct ilo_shader *sh = NULL, *tmp;
 
    LIST_FOR_EACH_ENTRY(tmp, &state->variants, list) {
-      if (tmp->hash == hash &&
-          memcmp(&tmp->variant, variant, sizeof(*variant)) == 0) {
+      if (memcmp(&tmp->variant, variant, sizeof(*variant)) == 0) {
          sh = tmp;
          break;
       }
@@ -451,10 +432,9 @@ struct ilo_shader *
 ilo_shader_state_add_variant(struct ilo_shader_state *state,
                              const struct ilo_shader_variant *variant)
 {
-   const unsigned int hash = ilo_shader_variant_hash(variant);
    struct ilo_shader *sh;
 
-   sh = ilo_shader_state_search_variant(state, hash, variant);
+   sh = ilo_shader_state_search_variant(state, variant);
    if (sh)
       return sh;
 
@@ -483,7 +463,6 @@ ilo_shader_state_add_variant(struct ilo_shader_state *state,
    }
 
    sh->variant = *variant;
-   sh->hash = hash;
 
    ilo_shader_state_add_shader(state, sh);
 
diff --git a/src/gallium/drivers/ilo/ilo_shader.h b/src/gallium/drivers/ilo/ilo_shader.h
index 66adaba..1ea0b4a 100644
--- a/src/gallium/drivers/ilo/ilo_shader.h
+++ b/src/gallium/drivers/ilo/ilo_shader.h
@@ -74,8 +74,6 @@ struct ilo_shader_variant {
  */
 struct ilo_shader {
    struct ilo_shader_variant variant;
-   /* hash of the shader variant for quicker lookup */
-   unsigned hash;
 
    struct {
       int semantic_names[PIPE_MAX_SHADER_INPUTS];