From 966401a8e7e263a4cfbeefce3891177ce9231448 Mon Sep 17 00:00:00 2001
From: Dave Cheney <dave@cheney.net>
Date: Thu, 22 Oct 2026 12:08:03 +1100
Subject: [PATCH] builder: add size tests for startup work removed by interp

Recent changes that let interp move startup work to compile time did
not show up in TestBinarySize, so their savings went unmeasured and a
regression would go unnoticed. These samples cover the RP2 targets,
ESP32-C3, slice growth and os. Their sizes match on Go 1.25 to 1.27.

Run against the commits before and after each change, these rows show
(code/rodata bytes, opt=z):

- #5837 RP2 PLL: pico -1308/-548, pico2 -1128/-552 (opt=2 code -5 to
  -6 KB). Visible only with #5975.
- #5963 llvm.ctlz: pico -818/-142, pico2 -754/-142, size-slice -163/-5.
- #5973 os temp file seed: pico2 size-os -16 (opt=2 -32).
---
 builder/sizes_test.go               | 12 ++++++++++++
 builder/testdata/binary-size.txt    | 26 ++++++++++++++++++--------
 builder/testdata/size-os/main.go    |  7 +++++++
 builder/testdata/size-slice/main.go | 17 +++++++++++++++++
 4 files changed, 54 insertions(+), 8 deletions(-)
 create mode 100644 builder/testdata/size-os/main.go
 create mode 100644 builder/testdata/size-slice/main.go

diff --git a/builder/sizes_test.go b/builder/sizes_test.go
index 0f513cc27c..6a6f8d8fcf 100644
--- a/builder/sizes_test.go
+++ b/builder/sizes_test.go
@@ -75,6 +75,18 @@ func TestBinarySize(t *testing.T) {
 		{target: "microbit", path: "examples/serial", opt: "z"},
 		{target: "wioterminal", path: "examples/pininterrupt", opt: "z"},
 
+		{target: "pico", path: "examples/serial", opt: "z"},
+		{target: "pico", path: "examples/serial", opt: "2"},
+		{target: "pico2", path: "examples/serial", opt: "z"},
+		{target: "pico2", path: "examples/serial", opt: "2"},
+		{target: "esp32c3-generic", path: "examples/serial", opt: "z"},
+		{target: "esp32c3-generic", path: "examples/serial", opt: "2"},
+
+		{target: "cortex-m-qemu", path: "./testdata/size-slice", opt: "z"},
+		{target: "cortex-m-qemu", path: "./testdata/size-slice", opt: "2"},
+		{target: "pico2", path: "./testdata/size-os", opt: "z"},
+		{target: "pico2", path: "./testdata/size-os", opt: "2"},
+
 		{target: "cortex-m-qemu", path: "./testdata/size-corpus", opt: "z"},
 		{target: "cortex-m-qemu", path: "./testdata/size-corpus", opt: "2"},
 		{target: "riscv-qemu", path: "./testdata/size-corpus", opt: "z"},
diff --git a/builder/testdata/binary-size.txt b/builder/testdata/binary-size.txt
index ebf3394095..b5e1676839 100644
--- a/builder/testdata/binary-size.txt
+++ b/builder/testdata/binary-size.txt
@@ -1,8 +1,18 @@
-target        package                opt  code rodata data   bss
-hifive1b      examples/echo          z    4558    402    0  2276
-microbit      examples/serial        z    3001    439    8  2272
-wioterminal   examples/pininterrupt  z    7802   1686  136  7280
-cortex-m-qemu ./testdata/size-corpus z    9907   1301   80  4188
-cortex-m-qemu ./testdata/size-corpus 2   17482    862   72  4188
-riscv-qemu    ./testdata/size-corpus z   17540   1028   88 16660
-riscv-qemu    ./testdata/size-corpus 2   25160    744   80 16644
+target          package                opt  code rodata data   bss
+hifive1b        examples/echo          z    4558    402    0  2276
+microbit        examples/serial        z    3001    439    8  2272
+wioterminal     examples/pininterrupt  z    7802   1686  136  7280
+pico            examples/serial        z    7673   1071  112  5616
+pico            examples/serial        2   16298    862  108  5616
+pico2           examples/serial        z    6468   1172  112  5608
+pico2           examples/serial        2   15925    979  108  5608
+esp32c3-generic examples/serial        z    5864    768    0  8664
+esp32c3-generic examples/serial        2    9888    600    8  8672
+cortex-m-qemu   ./testdata/size-slice  z    3087    793    4  4168
+cortex-m-qemu   ./testdata/size-slice  2    7331    341    4  4168
+pico2           ./testdata/size-os     z    6153   1207  128  5592
+pico2           ./testdata/size-os     2   15240   1016  128  5592
+cortex-m-qemu   ./testdata/size-corpus z    9907   1301   80  4188
+cortex-m-qemu   ./testdata/size-corpus 2   17482    862   72  4188
+riscv-qemu      ./testdata/size-corpus z   17540   1028   88 16660
+riscv-qemu      ./testdata/size-corpus 2   25160    744   80 16644
diff --git a/builder/testdata/size-os/main.go b/builder/testdata/size-os/main.go
new file mode 100644
index 0000000000..f481dc0224
--- /dev/null
+++ b/builder/testdata/size-os/main.go
@@ -0,0 +1,7 @@
+package main
+
+import "os"
+
+func main() {
+	os.Stdout.WriteString("hello\n")
+}
diff --git a/builder/testdata/size-slice/main.go b/builder/testdata/size-slice/main.go
new file mode 100644
index 0000000000..0418348132
--- /dev/null
+++ b/builder/testdata/size-slice/main.go
@@ -0,0 +1,17 @@
+package main
+
+var values = makeValues()
+
+func makeValues() []byte {
+	var values []byte
+	for i := 0; i < 32; i++ {
+		values = append(values, byte(i))
+	}
+	return values
+}
+
+func main() {
+	for _, value := range values {
+		println(value)
+	}
+}