Mesa (master): panfrost: Add routines to calculate stack size/shift

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Module: Mesa
Branch: master
Commit: eac9247b2dfebdb22a3446f588b00ec773b9e3fa
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=eac9247b2dfebdb22a3446f588b00ec773b9e3fa

Author: Alyssa Rosenzweig <alyssa.rosenzweig at collabora.com>
Date:   Mon Dec  9 09:00:24 2019 -0500

panfrost: Add routines to calculate stack size/shift

These implement the aforementioned formulas.

Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig at collabora.com>

---

 src/panfrost/encoder/pan_encoder.h | 11 +++++++++++
 src/panfrost/encoder/pan_scratch.c | 20 ++++++++++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/src/panfrost/encoder/pan_encoder.h b/src/panfrost/encoder/pan_encoder.h
index ceff2e949de..d90dba8b2e8 100644
--- a/src/panfrost/encoder/pan_encoder.h
+++ b/src/panfrost/encoder/pan_encoder.h
@@ -66,4 +66,15 @@ panfrost_choose_hierarchy_mask(
         unsigned width, unsigned height,
         unsigned vertex_count, bool hierarchy);
 
+/* Stack sizes */
+
+unsigned
+panfrost_get_stack_shift(unsigned stack_size);
+
+unsigned
+panfrost_get_total_stack_size(
+                unsigned stack_shift,
+                unsigned threads_per_core,
+                unsigned core_count);
+
 #endif
diff --git a/src/panfrost/encoder/pan_scratch.c b/src/panfrost/encoder/pan_scratch.c
index 4a0561c7383..780dd539be6 100644
--- a/src/panfrost/encoder/pan_scratch.c
+++ b/src/panfrost/encoder/pan_scratch.c
@@ -77,3 +77,23 @@
  * There are other valid characterisations of this formula, of course, but this
  * is computationally simple, so good enough for our purposes.
  */
+
+/* Computes log_stack_size = ceil(log2(max(s, 256))) - 4 */
+
+unsigned
+panfrost_get_stack_shift(unsigned stack_size)
+{
+        return util_logbase2_ceil(MAX2(stack_size, 256)) - 4;
+}
+
+/* Computes the aligned stack size given the shift and thread count */
+
+unsigned
+panfrost_get_total_stack_size(
+                unsigned stack_shift,
+                unsigned threads_per_core,
+                unsigned core_count)
+{
+        unsigned stack_size = 1 << (stack_shift + 4);
+        return stack_size * threads_per_core * core_count;
+}