From 6b6ace5199c2ed5dfd851435450f0c5ca353ffb5 Mon Sep 17 00:00:00 2001
From: Alyssa Rosenzweig <alyssa@collabora.com>
Date: Tue, 3 May 2022 17:05:57 -0400
Subject: [PATCH] pan/bi: Add option to test spilling

BIFROST_MESA_DEBUG=spill now restricts the register file to 1/4 its usual size,
useful for testing register spilling (e.g. running CTS) as well as debugging
spilling on small shaders.

Note blend shaders are exempt, as we don't allow blend shaders to spill.

Signed-off-by: Alyssa Rosenzweig <alyssa@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/16314>
---
 src/panfrost/bifrost/bi_ra.c           | 4 ++++
 src/panfrost/bifrost/bifrost.h         | 1 +
 src/panfrost/bifrost/bifrost_compile.c | 1 +
 3 files changed, 6 insertions(+)

diff --git a/src/panfrost/bifrost/bi_ra.c b/src/panfrost/bifrost/bi_ra.c
index 8a7fa6309d9..4a15b560abf 100644
--- a/src/panfrost/bifrost/bi_ra.c
+++ b/src/panfrost/bifrost/bi_ra.c
@@ -314,6 +314,10 @@ bi_allocate_registers(bi_context *ctx, bool *success, bool full_regs)
                 full_regs ? BITFIELD64_MASK(64) :
                 (BITFIELD64_MASK(16) | (BITFIELD64_MASK(16) << 48));
 
+        /* To test spilling, mimic a small register file */
+        if (bifrost_debug & BIFROST_DBG_SPILL && !ctx->inputs->is_blend)
+                default_affinity &= BITFIELD64_MASK(48) << 8;
+
         bi_foreach_instr_global(ctx, ins) {
                 bi_foreach_dest(ins, d) {
                         unsigned dest = bi_get_node(ins->dest[d]);
diff --git a/src/panfrost/bifrost/bifrost.h b/src/panfrost/bifrost/bifrost.h
index 6dce0c53b38..d80844e012f 100644
--- a/src/panfrost/bifrost/bifrost.h
+++ b/src/panfrost/bifrost/bifrost.h
@@ -47,6 +47,7 @@ extern "C" {
 #define BIFROST_DBG_NOIDVS      0x0200
 #define BIFROST_DBG_NOSB        0x0400
 #define BIFROST_DBG_NOPRELOAD   0x0800
+#define BIFROST_DBG_SPILL       0x1000
 
 extern int bifrost_debug;
 
diff --git a/src/panfrost/bifrost/bifrost_compile.c b/src/panfrost/bifrost/bifrost_compile.c
index 5464e581024..12c09a68282 100644
--- a/src/panfrost/bifrost/bifrost_compile.c
+++ b/src/panfrost/bifrost/bifrost_compile.c
@@ -52,6 +52,7 @@ static const struct debug_named_value bifrost_debug_options[] = {
         {"noidvs",    BIFROST_DBG_NOIDVS,       "Disable IDVS"},
         {"nosb",      BIFROST_DBG_NOSB,         "Disable scoreboarding"},
         {"nopreload", BIFROST_DBG_NOPRELOAD,    "Disable message preloading"},
+        {"spill",     BIFROST_DBG_SPILL,        "Test register spilling"},
         DEBUG_NAMED_VALUE_END
 };