platforms: Add cortex-m33 platforms and device configs

Map from @platforms cpu flag to what gcc expects.

constraints/cpu/BUILD

@@ -15,3 +15,4 @@ constraint_value(
     constraint_setting = "@platforms//cpu:cpu",
     visibility = ["//visibility:public"],
 )
+

devices/arm/cortex_m.bzl

@@ -61,4 +61,18 @@ CORTEX_M7_FPU_DEVICE_CONFIG = device_config(
     fpu = "fpv5-d16",
 )
 
-CORTEX_M_DEVICE_CONFIGS = [CORTEX_M0_DEVICE_CONFIG, CORTEX_M3_DEVICE_CONFIG, CORTEX_M4_FPU_DEVICE_CONFIG, CORTEX_M4_DEVICE_CONFIG, CORTEX_M7_FPU_DEVICE_CONFIG]
+CORTEX_M33_DEVICE_CONFIG = device_config(
+    cpu = "armv8-m",
+    endian = "little",
+    float_abi = "soft",
+    fpu = "none",
+)
+
+CORTEX_M33_FPU_DEVICE_CONFIG = device_config(
+    cpu = "armv8-m",
+    endian = "little",
+    float_abi = "hard",
+    fpu = "fpv5-d16",
+)
+
+CORTEX_M_DEVICE_CONFIGS = [CORTEX_M0_DEVICE_CONFIG, CORTEX_M3_DEVICE_CONFIG, CORTEX_M4_FPU_DEVICE_CONFIG, CORTEX_M4_DEVICE_CONFIG, CORTEX_M7_FPU_DEVICE_CONFIG, CORTEX_M33_DEVICE_CONFIG, CORTEX_M33_FPU_DEVICE_CONFIG]

platforms/BUILD

@@ -77,6 +77,29 @@ platform(
     parents = [":cortex_m"],
 )
 
+platform(
+    name = "cortex_m33",
+    constraint_values = [
+        "@platforms//cpu:armv8-m",
+    ],
+    exec_properties = {
+        "EXECUTOR": "cortex_m33"
+    },
+    parents = [":cortex_m3"]
+)
+
+platform(
+    name = "cortex_m33_fpu",
+    constraint_values = [
+        "@platforms//cpu:armv8-m",
+        "@bazel_embedded//constraints/fpu:fpv5-d16",
+    ],
+    exec_properties = {
+        "EXECUTOR": "cortex_m33_fpu"
+    },
+    parents = [":cortex_m3"]
+)
+
 platform(
     name = "stm32f2xx",
     parents = [":cortex_m3"],

toolchains/features/common/impl/gcc.bzl

@@ -49,6 +49,12 @@ def GccIncludeFeature(include_paths):
 def GccAchitectureFeature(architecture, float_abi, endian, fpu):
     if fpu == "none":
         fpu = "auto"
+
+    # @platforms//cpu has armv8-m entry intended to match cortex m23, m33, m35p
+    # processors which all have the main instruction set. GCC needs this
+    # explicitly set when using cpu flag.
+    if architecture == "armv8-m":
+        architecture = "armv8-m.main"
     _ARCHITECTURE_FEATURE = feature(
         name = "architecture",
         enabled = True,

toolchains/gcc_arm_none_eabi/gcc_arm_none_toolchain.bzl

@@ -200,6 +200,7 @@ gcc_arm_none_toolchain_config = rule(
                 "armv6s-m",
                 "armv7-m",
                 "armv7e-m",
+                "armv8-m",
                 "armv8-m.base",
                 "armv8-m.main",
                 "iwmmxt",