avr: use compiler-rt

targets/arduino.json

@@ -2,8 +2,8 @@
 	"inherits": ["atmega328p"],
 	"build-tags": ["arduino"],
 	"ldflags": [
-		"-Wl,--defsym=_bootloader_size=512",
-		"-Wl,--defsym=_stack_size=512"
+		"--defsym=_bootloader_size=512",
+		"--defsym=_stack_size=512"
 	],
 	"flash-command": "avrdude -c arduino -p atmega328p -P {port} -U flash:w:{hex}:i"
 }

targets/atmega1284p.json

@@ -7,9 +7,8 @@
         "-mmcu=atmega1284p"
     ],
     "ldflags": [
-        "-mmcu=avr51",
-        "-Wl,--defsym=_bootloader_size=0",
-        "-Wl,--defsym=_stack_size=512"
+        "--defsym=_bootloader_size=0",
+        "--defsym=_stack_size=512"
     ],
     "linkerscript": "src/device/avr/atmega1284p.ld",
     "extra-files": [

targets/atmega328p.json

@@ -7,7 +7,7 @@
 		"-mmcu=atmega328p"
 	],
 	"ldflags": [
-		"-mmcu=avr5"
+		"-mavr5"
 	],
 	"linkerscript": "src/device/avr/atmega328p.ld",
 	"extra-files": [

targets/avr.S

@@ -2,6 +2,30 @@
 ; in Go.
 ; The reset vector is device-specific and is generated by tools/gen-device-avr.py.
 
+#ifndef xl
+#define xl r26
+#endif
+
+#ifndef xh
+#define xh r27
+#endif
+
+#ifndef yl
+#define yl r28
+#endif
+
+#ifndef yh
+#define yh r29
+#endif
+
+#ifndef zl
+#define zl r30
+#endif
+
+#ifndef zh
+#define zh r31
+#endif
+
 ; Startup code
 .section .text.__vector_RESET
 .global  __vector_RESET

targets/avr.json

@@ -2,16 +2,21 @@
 	"build-tags": ["avr", "baremetal", "linux", "arm"],
 	"goos": "linux",
 	"goarch": "arm",
-	"compiler": "avr-gcc",
+	"compiler": "clang",
 	"gc": "conservative",
-	"linker": "avr-gcc",
+	"linker": "llvm-build.master/bin/ld.lld",
 	"scheduler": "none",
+	"rtlib": "compiler-rt",
+	"libc": "picolibc",
 	"cflags": [
-		"-gdwarf-4"
+		"--target=avr-atmel-none",
+		"-g",
+		"-Werror",
+		"-Qunused-arguments"
 	],
 	"ldflags": [
 		"-T", "targets/avr.ld",
-		"-Wl,--gc-sections"
+		"--gc-sections"
 	],
 	"extra-files": [
 		"src/runtime/scheduler_avr.S"

targets/avr.ld

@@ -5,17 +5,22 @@ MEMORY
     RAM (xrw)       : ORIGIN = 0x800000 + __ram_start, LENGTH = __ram_size
 }
 
+ENTRY(main)
+
 SECTIONS
 {
-    .text :
+    .text : ALIGN(2)
     {
         KEEP(*(.vectors))
         KEEP(*(.text.__vector_RESET))
         KEEP(*(.text.main)) /* main must follow the reset handler */
+        *(.text)
         *(.text.*)
         *(.rodata)
         *(.rodata.*)
-    }
+        *(.progmem.data)
+        . = ALIGN(16); /* required because of lld (not sure why) */
+    } > FLASH_TEXT
 
     .stack (NOLOAD) :
     {
@@ -29,7 +34,7 @@ SECTIONS
     {
         _sdata = .;        /* used by startup code */
         *(.data)
-        *(.data*)
+        *(.data.*)
         _edata = .;        /* used by startup code */
     } >RAM AT>FLASH_TEXT
 
@@ -37,7 +42,7 @@ SECTIONS
     {
         _sbss = .;         /* used by startup code */
         *(.bss)
-        *(.bss*)
+        *(.bss.*)
         *(COMMON)
         _ebss = .;         /* used by startup code */
     } >RAM