targets: add CPU property everywhere

This is for consistency with Clang, which always adds a CPU flag even if
it's not specified in CFLAGS.

This commit also adds some tests to make sure the Clang target-cpu
matches the CPU property in the JSON files.

This does have an effect on the generated binaries. The effect is very
small though: on average just 0.2% increase in binary size, apparently
because Cortex-M3 and Cortex-M4 are compiled a bit differently. However,
when rebased on top of https://github.com/tinygo-org/tinygo/pull/2218
(minsize), the difference drops to -0.1% (a slight decrease on average).

targets/atmega1280.json

@@ -3,9 +3,6 @@
     "cpu": "atmega1280",
     "build-tags": ["atmega1280", "atmega"],
     "serial": "uart",
-    "cflags": [
-        "-mmcu=atmega1280"
-    ],
     "ldflags": [
         "-mmcu=avr51",
         "-Wl,--defsym=_stack_size=512"

targets/atmega1284p.json

@@ -3,9 +3,6 @@
     "cpu": "atmega1284p",
     "build-tags": ["atmega1284p", "atmega"],
     "serial": "uart",
-    "cflags": [
-        "-mmcu=atmega1284p"
-    ],
     "ldflags": [
         "-mmcu=avr51",
         "-Wl,--defsym=_bootloader_size=0",

targets/atmega2560.json

@@ -3,9 +3,6 @@
     "cpu": "atmega2560",
     "build-tags": ["atmega2560", "atmega"],
     "serial": "uart",
-    "cflags": [
-        "-mmcu=atmega2560"
-    ],
     "ldflags": [
         "-mmcu=avr6",
         "-Wl,--defsym=_stack_size=512"

targets/atmega328p.json

@@ -3,9 +3,6 @@
 	"cpu": "atmega328p",
 	"build-tags": ["atmega328p", "atmega", "avr5"],
 	"serial": "uart",
-	"cflags": [
-		"-mmcu=atmega328p"
-	],
 	"ldflags": [
 		"-mmcu=avr5"
 	],

targets/attiny85.json

@@ -3,7 +3,6 @@
 	"cpu": "attiny85",
 	"build-tags": ["attiny85", "attiny", "avr2", "avr25"],
 	"cflags": [
-		"-mmcu=attiny85",
 		"-D__AVR_ARCH__=25"
 	],
 	"ldflags": [

targets/cortex-m0.json

@@ -1,4 +1,5 @@
 {
 	"inherits": ["cortex-m"],
-	"llvm-target": "armv6m-unknown-unknown-eabi"
+	"llvm-target": "armv6m-unknown-unknown-eabi",
+	"cpu": "cortex-m0"
 }

targets/cortex-m0plus.json

@@ -1,4 +1,5 @@
 {
 	"inherits": ["cortex-m"],
-	"llvm-target": "armv6m-unknown-unknown-eabi"
+	"llvm-target": "armv6m-unknown-unknown-eabi",
+	"cpu": "cortex-m0plus"
 }

targets/cortex-m3.json

@@ -1,4 +1,5 @@
 {
 	"inherits": ["cortex-m"],
-	"llvm-target": "armv7m-unknown-unknown-eabi"
+	"llvm-target": "armv7m-unknown-unknown-eabi",
+	"cpu": "cortex-m3"
 }

targets/cortex-m4.json

@@ -1,6 +1,7 @@
 {
 	"inherits": ["cortex-m"],
 	"llvm-target": "armv7em-unknown-unknown-eabi",
+	"cpu": "cortex-m4",
 	"cflags": [
 		"-mfloat-abi=soft"
 	]

targets/cortex-m7.json

@@ -3,7 +3,6 @@
 	"llvm-target": "armv7em-unknown-unknown-eabi",
 	"cpu": "cortex-m7",
 	"cflags": [
-		"-mcpu=cortex-m7",
 		"-mfloat-abi=soft"
 	]
 }

targets/esp32.json

@@ -6,9 +6,6 @@
 	"serial": "uart",
 	"linker": "xtensa-esp32-elf-ld",
 	"default-stack-size": 2048,
-	"cflags": [
-		"-mcpu=esp32"
-	],
 	"rtlib": "compiler-rt",
 	"libc": "picolibc",
 	"linkerscript": "targets/esp32.ld",

targets/esp8266.json

@@ -5,9 +5,6 @@
 	"scheduler": "tasks",
 	"linker": "xtensa-esp32-elf-ld",
 	"default-stack-size": 2048,
-	"cflags": [
-		"-mcpu=esp8266"
-	],
 	"rtlib": "compiler-rt",
 	"libc": "picolibc",
 	"linkerscript": "targets/esp8266.ld",

targets/fe310.json

@@ -1,5 +1,6 @@
 {
 	"inherits": ["riscv32"],
+	"cpu": "sifive-e31",
 	"features": ["+a", "+c", "+m"],
 	"build-tags": ["fe310", "sifive"]
 }

targets/gameboy-advance.json

@@ -8,7 +8,6 @@
 	"rtlib": "compiler-rt",
 	"libc": "picolibc",
 	"cflags": [
-		"-mcpu=arm7tdmi",
 		"-Werror",
 		"-fshort-enums",
 		"-fomit-frame-pointer",

targets/nintendoswitch.json

@@ -1,5 +1,6 @@
 {
   "llvm-target": "aarch64",
+  "cpu": "cortex-a57",
   "build-tags": ["nintendoswitch", "arm64"],
   "scheduler": "tasks",
   "goos": "linux",
@@ -9,11 +10,9 @@
   "libc": "picolibc",
   "gc": "conservative",
   "relocation-model": "pic",
-  "cpu": "cortex-a57",
   "default-stack-size": 2048,
   "cflags": [
     "-target", "aarch64-unknown-none",
-    "-mcpu=cortex-a57",
     "-fPIE",
     "-Werror",
     "-fshort-enums",

targets/wasi.json

@@ -1,5 +1,6 @@
 {
 	"llvm-target":   "wasm32-unknown-wasi",
+	"cpu":           "generic",
 	"build-tags":    ["tinygo.wasm", "wasi"],
 	"goos":          "linux",
 	"goarch":        "arm",

targets/wasm.json

@@ -1,5 +1,6 @@
 {
 	"llvm-target":   "wasm32-unknown-wasi",
+	"cpu":           "generic",
 	"build-tags":    ["tinygo.wasm"],
 	"goos":          "js",
 	"goarch":        "wasm",