浮動小数点数を扱うRP2350コードを出力

ひとまず以下のコードを動くようにしたい。

code:sample/pi.ml

let pi = 3.1415 in

print_int (int_of_float pi);

print_newline()

ビルドコマンド

code:sh

touch sample/pi.ml && make min-caml min-caml.top sample/pi.res

以下のようなエラーが出力される。

code:sh

arm-none-eabi-gcc -mcpu=cortex-m33 -mthumb -mfpu=fpv5-sp-d16 -mfloat-abi=hard -ffreestanding -nostdlib -Wall -Wextra -O2 -T linker.ld -nostdlib -Wl,-Map=main.map -o sample/pi.elf sample/pi.s startup.c stub.c libmincaml.S

sample/pi.s: Assembler messages:

sample/pi.s:2: Error: unknown pseudo-op: `.literal8'

sample/pi.s:16: Error: bad instruction `lis r12,ha16(l.8)'

sample/pi.s:17: Error: bad instruction `addi r12,r12,lo16(l.8)'

sample/pi.s:18: Error: bad instruction `lfd f0,0(r12)'

浮動小数点数のコードの書き方の参考に、以下のCのコードからアセンブリコードを出力

code:c

void main() {

const float pi = 3.14;

printf("%d\n", (int)pi);

return;

}

Cのソースからアセンブリコードを出力

code:sh

$ arm-none-eabi-gcc -mcpu=cortex-m33 -mthumb -mfpu=fpv5-sp-d16 -mfloat-abi=hard -O0 -S test.c -o test.s

code:asm

.cpu cortex-m33

.eabi_attribute 27, 1

.eabi_attribute 28, 1

.eabi_attribute 20, 1

.eabi_attribute 21, 1

.eabi_attribute 23, 3

.eabi_attribute 24, 1

.eabi_attribute 25, 1

.eabi_attribute 26, 1

.eabi_attribute 30, 6

.eabi_attribute 34, 1

.eabi_attribute 18, 4

.file "test.c"

.text

.section .rodata

.align 2

.LC0:

.ascii "%d\012\000"

.text

.align 1

.global main

.arch armv8-m.main

.arch_extension dsp

.syntax unified

.thumb

.thumb_func

.fpu fpv5-sp-d16

.type main, %function

main:

@ args = 0, pretend = 0, frame = 8

@ frame_needed = 1, uses_anonymous_args = 0

push {r7, lr}

ldr r3, .L3

vcvt.s32.f32 s15, s15

vmov r1, s15 @ int

ldr r0, .L3+4

bl printf

nop

mov sp, r7

@ sp needed

pop {r7, pc}

.L4:

.align 2

.L3:

.word 1078523331

.word .LC0

.size main, .-main

.ident "GCC: (GNU Arm Embedded Toolchain 10.3-2021.07) 10.3.1 20210621 (release)"

対応した

code:diff

diff --git a/RP2350/asm.ml b/RP2350/asm.ml

index b7672ad..0b78ae3 100644

--- a/RP2350/asm.ml

+++ b/RP2350/asm.ml

@@ -46,7 +46,7 @@ let seq(e1, e2) = Let((Id.gentmp Type.Unit, Type.Unit), e1, e2)

(* 汎用レジスタのうちのR0からR9を使用（R10はMinCamlスタック、R11はMinCamlヒープに用いる） *)

let regs =

"%r0"; "%r1"; "%r3"; "%r4"; "%r5"; "%r6"; "%r7"; "%r8"; "%r9" |

-let fregs = Array.init 32 (fun i -> Printf.sprintf "%%f%d" i)

+let fregs = Array.init 32 (fun i -> Printf.sprintf "%%s%d" i)

let allregs = Array.to_list regs

let allfregs = Array.to_list fregs

let reg_cl = regs.(Array.length regs - 1) (* closure address (caml2html: sparcasm_regcl) *)

diff --git a/RP2350/emit.ml b/RP2350/emit.ml

index 4f313e8..b100b66 100644

--- a/RP2350/emit.ml

+++ b/RP2350/emit.ml

@@ -2,6 +2,7 @@ open Asm

external gethi : float -> int32 = "gethi"

external getlo : float -> int32 = "getlo"

+external getf : float -> int32 = "getf"

let stackset = ref S.empty (* すでにSaveされた変数の集合 (caml2html: emit_stackset) *)

let stackmap = ref [] (* Saveされた変数の、スタックにおける位置 (caml2html: emit_stackmap) *)

@@ -32,8 +33,8 @@ let reg r =

let load_label r label =

let r' = reg r in

Printf.sprintf

- "\tlis\t%s, ha16(%s)\n\taddi\t%s, %s, lo16(%s)\n"

- r' label r' r' label

+ "\tldr %s, =%s\n"

+ r' label

(* 関数呼び出しのために引数を並べ替える(register shuffling) (caml2html: emit_shuffle) *)

let rec shuffle sw xys =

@@ -62,7 +63,8 @@ and g' oc = function (* 各命令のアセンブリ生成 (caml2html: emit_gprim

| NonTail(x), Li(i) -> Printf.fprintf oc "\tldr %s, =%d\n" (reg x) i

| NonTail(x), FLi(Id.L(l)) ->

let s = load_label (reg reg_tmp) l in

- Printf.fprintf oc "%s\tlfd\t%s, 0(%s)\n" s (reg x) (reg reg_tmp)

+ Printf.fprintf oc "%s" s;

| NonTail(x), SetL(Id.L(y)) ->

let s = load_label x y in

Printf.fprintf oc "%s" s

@@ -256,17 +258,18 @@ let h oc { name = Id.L(x); args = _; fargs = _; body = e; ret = _ } =

let f oc (Prog(data, fundefs, e)) =

Format.eprintf "generating assembly...@.";

if data <> [] then

- (Printf.fprintf oc "\t.data\n\t.literal8\n";

+ (Printf.fprintf oc "\t.data\n";

List.iter

(fun (Id.L(x), d) ->

- Printf.fprintf oc "\t.align 3\n";

+ Printf.fprintf oc "\t.align 2\n";

Printf.fprintf oc "%s:\t # %f\n" x d;

- Printf.fprintf oc "\t.long\t%ld\n" (gethi d);

- Printf.fprintf oc "\t.long\t%ld\n" (getlo d))

+ Printf.fprintf oc "\t.long\t%ld\n" (getf d))

data);

Printf.fprintf oc "\t.text\n";

Printf.fprintf oc "\t.syntax unified\n";

Printf.fprintf oc "\t.thumb\n";

+ Printf.fprintf oc "\t.fpu fpv5-sp-d16\n";

+ Printf.fprintf oc "\t.align 2\n";

Printf.fprintf oc "\t.globl min_caml_start\n";

List.iter (fun fundef -> h oc fundef) fundefs;

Printf.fprintf oc "min_caml_start: # main entry point\n";

diff --git a/float.c b/float.c

index 1165150..f260f0e 100644

--- a/float.c

+++ b/float.c

@@ -19,3 +19,14 @@ value getlo(value v) {

d.d = Double_val(v);

}

+

+ typedef union {

+ float f;

+ } flt;

+

+ value getf(value v) {

+ flt f;

+ f.f = Double_val(v);

+ }

diff --git a/sample/pi.ml b/sample/pi.ml

new file mode 100644

index 0000000..bf9c551

--- /dev/null

+++ b/sample/pi.ml

@@ -0,0 +1,3 @@

+let pi = 3.1415 in

+print_int (int_of_float pi);

+print_newline()

diff --git a/stub.c b/stub.c

index 32a89ff..1388380 100644

--- a/stub.c

+++ b/stub.c

@@ -87,6 +87,10 @@ void min_caml_print_newline(void) {

uart_putc('\n');

}

+int min_caml_int_of_float(float f) {

+ return (int)f;

+}

+

int main(void) {

uart_init();

実行してみる。

code:sh

$ touch sample/pi.ml && make clean min-caml min-caml.top sample/pi.res

...

qemu-system-arm \

-machine mps2-an505 \

-cpu cortex-m33 \

-m 16M \

-nographic \

-monitor none \

-kernel sample/pi.elf

Hello from QEMU mps2-an505 Cortex-M33!

3

参考

test/float.ml をワンパス通した

Add test/pi

浮動小数点の比較命令を実装中

浮動小数点数の比較命令のつづき

test/float.mlを動くようにした