[Mesa-dev] [PATCH v3] glsl: fix variable ordering in the output_read_remover

[Vadim Girlin]

Use the hash of the variable name instead of the pointer value.

Signed-off-by: Vadim Girlin <vadimgirlin at gmail.com>
Reviewed-by: Ian Romanick <ian.d.romanick at intel.com>
---

v3: Added the note about the non-uniqueness of the names as suggested by
    Ian Romanick

 src/glsl/lower_output_reads.cpp |   18 +++++++++++++++++-
 1 files changed, 17 insertions(+), 1 deletions(-)

diff --git a/src/glsl/lower_output_reads.cpp b/src/glsl/lower_output_reads.cpp
index 415b541..90d71b0 100644
--- a/src/glsl/lower_output_reads.cpp
+++ b/src/glsl/lower_output_reads.cpp
@@ -54,11 +54,27 @@ public:
    virtual ir_visitor_status visit_leave(class ir_function_signature *);
 };
 
+/**
+ * Hash function for the output variables - computes the hash of the name.
+ * NOTE: We're using the name string to ensure that the hash doesn't depend
+ * on any random factors, otherwise the output_read_remover could produce
+ * the random order of the assignments.
+ *
+ * NOTE: If you want to reuse this function please take into account that
+ * generally the names of the variables are non-unique.
+ */
+static unsigned
+hash_table_var_hash(const void *key)
+{
+   const ir_variable * var = static_cast<const ir_variable *>(key);
+   return hash_table_string_hash(var->name);
+}
+
 output_read_remover::output_read_remover()
 {
    mem_ctx = ralloc_context(NULL);
    replacements =
-      hash_table_ctor(0, hash_table_pointer_hash, hash_table_pointer_compare);
+      hash_table_ctor(0, hash_table_var_hash, hash_table_pointer_compare);
 }
 
 output_read_remover::~output_read_remover()
-- 
1.7.7.6