pan/bi: Add branch constant field to IR

The offsets used for branches need some extra bits twiddled, so add a
field to the clause to indicate this is happening. This is not ambiguous
since a clause can only have a single branch.

Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5260>

src/panfrost/bifrost/bi_print.c

@@ -479,6 +479,9 @@ bi_print_clause(bi_clause *clause, FILE *fp)
                 for (unsigned i = 0; i < clause->constant_count; ++i)
                         fprintf(fp, "%" PRIx64 " ", clause->constants[i]);
 
+                if (clause->branch_constant)
+                        fprintf(fp, "*");
+
                 fprintf(fp, "\n");
         }
 }

src/panfrost/bifrost/compiler.h

@@ -376,6 +376,12 @@ typedef struct {
         uint64_t constants[8];
         unsigned constant_count;
 
+        /* Branches encode a constant offset relative to the program counter
+         * with some magic flags. By convention, if there is a branch, its
+         * constant will be last. Set this flag to indicate this is required.
+         */
+        bool branch_constant;
+
         /* What type of high latency instruction is here, basically */
         unsigned clause_type;
 } bi_clause;