freedreno/computerator: Add script for finding reg file size

This helps with finding the various parameters introduced in the last
commit.

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/9498>

src/freedreno/computerator/examples/test-regfile.sh

@@ -0,0 +1,53 @@
+#!/bin/bash
+
+# This tests for the size of the register file. We do this by launching a
+# lot of workgroups with only one invocation, which causes the GPU to be
+# saturated with in-flight waves. Each thread records its wave id using "getwid"
+# (only available in a6xx+!) and stores it in the buffer. We then vary the
+# register footprint by introducing uses of higher and higher registers. This
+# lets us determine:
+# 1. The total number of waves available (always 16 for known models)
+# 2. The wave granularity (how many waves are always launched together, always 2
+# for known models).
+# 3. The total size of the register file that is divvied up between the waves.
+
+set -e
+
+gen_shader() {
+	n=$1;
+	cat <<EOF
+@localsize 1, 1, 1
+@buf 128  ; g[0]
+@wgid(r48.x)
+getwid.u32 r1.x
+mov.u32u32 r0.x, r48.x
+
+; busy loop to make sure it actually uses all possible waves
+mov.u32u32 r0.y, 16
+(rpt2)nop
+loop:
+cmps.u.gt p0.x, r0.y, 0
+sub.u r0.y, r0.y, 1
+(rpt5)nop
+br p0.x, #loop
+add.f r1.y, r1.x, r$n.w
+
+(ss)(sy)(rpt5)nop
+stib.b.untyped.1d.u32.1.imm r1.x, r0.x, 0
+end
+nop
+EOF
+}
+
+# generate reference:
+gen_shader 1 | ./computerator -g 128,1,1 | tee reference.log
+
+for n in `seq 2 32`; do
+	echo "Trying max reg: r$n"
+	gen_shader $n | ./computerator -g 128,1,1 | tee new.log
+	diff reference.log new.log
+	if [ "$?" != "0" ]; then
+		echo "Changes at r$n"
+		break
+	fi
+done