Mesa (staging/22.1): nir/deref: Make compare_deref_paths take a stop callback

[GitLab Mirror]

Module: Mesa
Branch: staging/22.1
Commit: 9da59bdc7ff3fa2acc806953bede8940397d99d0
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=9da59bdc7ff3fa2acc806953bede8940397d99d0

Author: Jason Ekstrand <jason.ekstrand at collabora.com>
Date:   Fri Jun  3 16:06:33 2022 -0500

nir/deref: Make compare_deref_paths take a stop callback

This will let us use it to compare only the first part of a pair of
deref paths and continue the comparison later.

Tested-by: Mike Blumenkrantz <michael.blumenkrantz at gmail.com>
Reviewed-by: M Henning <drawoc at darkrefraction.com>
Reviewed-by: Rhys Perry <pendingchaos02 at gmail.com>
Cc: mesa-stable at lists.freedesktop.org
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/16894>
(cherry picked from commit 130d9d80dbbe4a2e64c8c2b5882f94176ea1e12d)

---

 .pick_status.json            |  2 +-
 src/compiler/nir/nir_deref.c | 23 ++++++++++++++++++-----
 2 files changed, 19 insertions(+), 6 deletions(-)

diff --git a/.pick_status.json b/.pick_status.json
index efbf00a7991..e463de3866b 100644
--- a/.pick_status.json
+++ b/.pick_status.json
@@ -4018,7 +4018,7 @@
         "description": "nir/deref: Make compare_deref_paths take a stop callback",
         "nominated": true,
         "nomination_type": 0,
-        "resolution": 0,
+        "resolution": 1,
         "main_sha": null,
         "because_sha": null
     },
diff --git a/src/compiler/nir/nir_deref.c b/src/compiler/nir/nir_deref.c
index 908c8215ee2..95bb5c9a474 100644
--- a/src/compiler/nir/nir_deref.c
+++ b/src/compiler/nir/nir_deref.c
@@ -444,7 +444,7 @@ modes_may_alias(nir_variable_mode a, nir_variable_mode b)
 
 ALWAYS_INLINE static nir_deref_compare_result
 compare_deref_paths(nir_deref_path *a_path, nir_deref_path *b_path,
-                    unsigned *i)
+                    unsigned *i, bool (*stop_fn)(const nir_deref_instr *))
 {
    /* Start off assuming they fully compare.  We ignore equality for now.  In
     * the end, we'll determine that by containment.
@@ -459,6 +459,9 @@ compare_deref_paths(nir_deref_path *a_path, nir_deref_path *b_path,
    for (; a[*i] != NULL; (*i)++) {
       if (a[*i] != b[*i])
          break;
+
+      if (stop_fn && stop_fn(a[*i]))
+         break;
    }
 
    /* We're at either the tail or the divergence point between the two deref
@@ -473,17 +476,26 @@ compare_deref_paths(nir_deref_path *a_path, nir_deref_path *b_path,
     * different constant indices.
     */
    for (unsigned j = *i; a[j] != NULL; j++) {
+      if (stop_fn && stop_fn(a[j]))
+         break;
+
       if (a[j]->deref_type == nir_deref_type_cast ||
           a[j]->deref_type == nir_deref_type_ptr_as_array)
          return nir_derefs_may_alias_bit;
    }
    for (unsigned j = *i; b[j] != NULL; j++) {
+      if (stop_fn && stop_fn(b[j]))
+         break;
+
       if (b[j]->deref_type == nir_deref_type_cast ||
           b[j]->deref_type == nir_deref_type_ptr_as_array)
          return nir_derefs_may_alias_bit;
    }
 
    for (; a[*i] != NULL && b[*i] != NULL; (*i)++) {
+      if (stop_fn && (stop_fn(a[*i]) || stop_fn(b[*i])))
+         break;
+
       switch (a[*i]->deref_type) {
       case nir_deref_type_array:
       case nir_deref_type_array_wildcard: {
@@ -533,9 +545,10 @@ compare_deref_paths(nir_deref_path *a_path, nir_deref_path *b_path,
       }
    }
 
-   assert(a[*i] == NULL || b[*i] == NULL);
-
-   /* If a is longer than b, then it can't contain b */
+   /* If a is longer than b, then it can't contain b.  If neither a[i] nor
+    * b[i] are NULL then we aren't at the end of the chain and we know nothing
+    * about containment.
+    */
    if (a[*i] != NULL)
       result &= ~nir_derefs_a_contains_b_bit;
    if (b[*i] != NULL)
@@ -606,7 +619,7 @@ nir_compare_deref_paths(nir_deref_path *a_path,
    }
 
    unsigned path_idx = 1;
-   return compare_deref_paths(a_path, b_path, &path_idx);
+   return compare_deref_paths(a_path, b_path, &path_idx, NULL);
 }
 
 nir_deref_compare_result