rename to thumbv8m.base-none-eabi, fix strict alignment

src/librustc_target/spec/mod.rs

@@ -397,7 +397,7 @@ supported_targets! {
     ("thumbv7m-none-eabi", thumbv7m_none_eabi),
     ("thumbv7em-none-eabi", thumbv7em_none_eabi),
     ("thumbv7em-none-eabihf", thumbv7em_none_eabihf),
-    ("thumbv8m-none-eabi", thumbv8m_none_eabi),
+    ("thumbv8m.base-none-eabi", thumbv8m_base_none_eabi),
 
     ("msp430-none-elf", msp430_none_elf),
 

src/librustc_target/spec/thumbv8m_base_none_eabi.rs

@@ -26,6 +26,9 @@ pub fn target() -> TargetResult {
         linker_flavor: LinkerFlavor::Lld(LldFlavor::Ld),
 
         options: TargetOptions {
+            // ARMv8-M baseline doesn't support unaligned loads/stores so we disable them
+            // with +strict-align.
+            features: "+strict-align".to_string(),
             max_atomic_width: Some(32),
             .. super::thumb_base::opts()
         },