Add aarch64 library variants for no-unaligned-access (#572)

This introduces new library variants for aarch64 to support targets
where unaligned memory accesses are disabled.
To enable these changes a patch to picolibc was required, ensuring the
assembly implemenation that relies on unaligned accesses is not used
when __ARM_FEATURE_UNALIGNED is not defined.
Co-authored by: @pratlucas (

(#567)

---------

Co-authored-by: Lucas Prates <[email protected]>

Author: simpal01

arm-multilib/json/multilib.json

@@ -10,7 +10,7 @@
             "json": "aarch64a.json",
             "flags": "--target=aarch64-unknown-none-elf -fno-exceptions -fno-rtti"
         },
-        {
+        { 
             "variant": "aarch64a_be_exn_rtti",
             "json": "aarch64a_be_exn_rtti.json",
             "flags": "--target=aarch64_be-unknown-none-elf"
@@ -20,6 +20,16 @@
             "json": "aarch64a_be.json",
             "flags": "--target=aarch64_be-unknown-none-elf -fno-exceptions -fno-rtti"
         },
+        {
+            "variant": "aarch64a_strictalign_exn_rtti",
+            "json": "aarch64a_strictalign_exn_rtti.json",
+            "flags": "--target=aarch64-unknown-none-elf -mno-unaligned-access"
+        },
+        {
+            "variant": "aarch64a_strictalign",
+            "json": "aarch64a_strictalign.json",
+            "flags": "--target=aarch64-unknown-none-elf -mno-unaligned-access -fno-exceptions -fno-rtti"
+        },
         {
             "variant": "armv4t_exn_rtti",
             "json": "armv4t_exn_rtti.json",

arm-multilib/json/variants/aarch64a_strictalign.json

@@ -0,0 +1,40 @@
+{
+    "args": {
+        "common": {
+            "TARGET_ARCH": "aarch64a",
+            "VARIANT": "aarch64a_strictalign",
+            "COMPILE_FLAGS": "-march=armv8-a -mno-unaligned-access",
+            "ENABLE_EXCEPTIONS": "OFF",
+            "ENABLE_RTTI": "OFF",
+            "TEST_EXECUTOR": "fvp",
+            "FVP_MODEL": "aem-a",
+            "FVP_CONFIG": "v8a-aarch64",
+            "BOOT_FLASH_ADDRESS": "0x80000000",
+            "BOOT_FLASH_SIZE": "0x1000",
+            "FLASH_ADDRESS": "0x80001000",
+            "FLASH_SIZE": "0xfff000",
+            "RAM_ADDRESS": "0x81000000",
+            "RAM_SIZE": "0x1000000",
+            "STACK_SIZE": "8K"
+        },
+        "picolibc": {
+            "PICOLIBC_BUILD_TYPE": "release",
+            "ENABLE_CXX_LIBS": "ON",
+            "ENABLE_LIBC_TESTS": "ON",
+            "ENABLE_COMPILER_RT_TESTS": "OFF",
+            "ENABLE_LIBCXX_TESTS": "OFF"
+        },
+        "newlib": {
+            "ENABLE_CXX_LIBS": "ON",
+            "ENABLE_LIBC_TESTS": "OFF",
+            "ENABLE_COMPILER_RT_TESTS": "OFF",
+            "ENABLE_LIBCXX_TESTS": "OFF"
+        },
+        "llvmlibc": {
+            "ENABLE_CXX_LIBS": "OFF",
+            "ENABLE_LIBC_TESTS": "OFF",
+            "ENABLE_COMPILER_RT_TESTS": "OFF",
+            "ENABLE_LIBCXX_TESTS": "OFF"
+        }
+    }
+}

arm-multilib/json/variants/aarch64a_strictalign_exn_rtti.json

@@ -0,0 +1,40 @@
+{
+    "args": {
+        "common": {
+            "TARGET_ARCH": "aarch64a",
+            "VARIANT": "aarch64a_strictalign_exn_rtti",
+            "COMPILE_FLAGS": "-march=armv8-a -mno-unaligned-access",
+            "ENABLE_EXCEPTIONS": "ON",
+            "ENABLE_RTTI": "ON",
+            "TEST_EXECUTOR": "fvp",
+            "FVP_MODEL": "aem-a",
+            "FVP_CONFIG": "v8a-aarch64",
+            "BOOT_FLASH_ADDRESS": "0x80000000",
+            "BOOT_FLASH_SIZE": "0x1000",
+            "FLASH_ADDRESS": "0x80001000",
+            "FLASH_SIZE": "0xfff000",
+            "RAM_ADDRESS": "0x81000000",
+            "RAM_SIZE": "0x1000000",
+            "STACK_SIZE": "8K"
+        },
+        "picolibc": {
+            "PICOLIBC_BUILD_TYPE": "release",
+            "ENABLE_CXX_LIBS": "ON",
+            "ENABLE_LIBC_TESTS": "ON",
+            "ENABLE_COMPILER_RT_TESTS": "OFF",
+            "ENABLE_LIBCXX_TESTS": "OFF"
+        },
+        "newlib": {
+            "ENABLE_CXX_LIBS": "ON",
+            "ENABLE_LIBC_TESTS": "OFF",
+            "ENABLE_COMPILER_RT_TESTS": "OFF",
+            "ENABLE_LIBCXX_TESTS": "OFF"
+        },
+        "llvmlibc": {
+            "ENABLE_CXX_LIBS": "OFF",
+            "ENABLE_LIBC_TESTS": "OFF",
+            "ENABLE_COMPILER_RT_TESTS": "OFF",
+            "ENABLE_LIBCXX_TESTS": "OFF"
+        }
+    }
+}

patches/picolibc/0001-Enable-libcxx-builds.patch

@@ -1,7 +1,7 @@
-From 42f07bef7775a1387f9707e959f8b6782f9d6808 Mon Sep 17 00:00:00 2001
+From 028fe75e045951a9d091008a85971523358160db Mon Sep 17 00:00:00 2001
 From: Simi Pallipurath <[email protected]>
 Date: Thu, 14 Nov 2024 10:07:08 +0000
-Subject: [PATCH 1/2] [PATCH 1/2] Enable libcxx builds
+Subject: Enable libcxx builds
 
 Modifications to build config and linker script required to enable
 libc++ builds.
@@ -47,3 +47,6 @@ index 7b63ba172..cda5e1e7e 100644
  		*(.gnu.linkonce.t.*)
  		KEEP (*(.fini .fini.*))
  		@PREFIX@__text_end = .;
+-- 
+2.39.5 (Apple Git-154)
+

patches/picolibc/0002-Add-bootcode-for-AArch64-FVPs.patch

@@ -1,7 +1,7 @@
-From 3b0b62ce6d81211a71eebe63b4b4ef0732da93ef Mon Sep 17 00:00:00 2001
+From 58451642e678817d8822b04b8ff07ee4758a8f10 Mon Sep 17 00:00:00 2001
 From: Simi Pallipurath <[email protected]>
-Date: Mon, 25 Nov 2024 11:13:50 +0000
-Subject: [PATCH 2/2] [PATCH 2/2] Add bootcode for AArch64 FVPs
+Date: Thu, 14 Nov 2024 10:12:33 +0000
+Subject: Add bootcode for AArch64 FVPs
 
 The AArch64 FVP (Fixed Virtual Platform) models differ from QEMU in a
 few ways which affect the crt0 code:
@@ -886,4 +886,3 @@ index 76965990f..be8f875be 100644
  endforeach
 -- 
 2.34.1
-