pan/bi: Add helper to measure clause size
Useful for branching.
Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5260>
diff --git a/src/panfrost/bifrost/bi_layout.c b/src/panfrost/bifrost/bi_layout.c
index cc40d03..1c700b1 100644
--- a/src/panfrost/bifrost/bi_layout.c
+++ b/src/panfrost/bifrost/bi_layout.c
@@ -49,3 +49,43 @@
return (constant_count + bundle_count) <= 13;
}
+
+/* Helper to calculate the number of quadwords in a clause. This is a function
+ * of the number of instructions and constants; it doesn't require actually
+ * packing, which is useful for branch offsets.
+ *
+ * Table of instruction count to instruction quadwords, per the packing
+ * algorithm, where * indicates a constant is packed for free:
+ *
+ * X | Y
+ * ---|---
+ * 1 | 1
+ * 2 | 2
+ * 3 | 3*
+ * 4 | 3
+ * 5 | 4*
+ * 6 | 5*
+ * 7 | 5
+ * 8 | 6*
+ *
+ * Y = { X if X <= 3
+ * { X - 1 if 4 <= X <= 6
+ * { X - 2 if 7 <= X <= 8
+ *
+ * and there is a constant for free if X is in {3, 5, 6, 8}. The remaining
+ * constants are packed two-by-two as constant quadwords.
+ */
+
+unsigned
+bi_clause_quadwords(bi_clause *clause)
+{
+ unsigned X = clause->bundle_count;
+ unsigned Y = X - ((X >= 7) ? 2 : (X >= 4) ? 1 : 0);
+
+ unsigned constants = clause->constant_count;
+
+ if ((X != 4) && (X != 7) && (X >= 3) && constants)
+ constants--;
+
+ return Y + DIV_ROUND_UP(constants, 2);
+}
diff --git a/src/panfrost/bifrost/compiler.h b/src/panfrost/bifrost/compiler.h
index eda8694..b1f7887 100644
--- a/src/panfrost/bifrost/compiler.h
+++ b/src/panfrost/bifrost/compiler.h
@@ -584,6 +584,7 @@
/* Layout */
bool bi_can_insert_bundle(bi_clause *clause, bool constant);
+unsigned bi_clause_quadwords(bi_clause *clause);
/* Code emit */