store target.min_global_align as an Align

compiler/rustc_target/src/spec/json.rs

@@ -2,7 +2,7 @@ use std::borrow::Cow;
 use std::collections::BTreeMap;
 use std::str::FromStr;
 
-use rustc_abi::ExternAbi;
+use rustc_abi::{Align, AlignFromBytesError, ExternAbi};
 use serde_json::Value;
 
 use super::{Target, TargetKind, TargetOptions, TargetWarnings};
@@ -57,6 +57,14 @@ impl Target {
             base.metadata.std = metadata.remove("std").and_then(|host| host.as_bool());
         }
 
+        let alignment_error = |field_name: &str, error: AlignFromBytesError| -> String {
+            let msg = match error {
+                AlignFromBytesError::NotPowerOfTwo(_) => "not a power of 2 number of bytes",
+                AlignFromBytesError::TooLarge(_) => "too large",
+            };
+            format!("`{}` bits is not a valid value for {field_name}: {msg}", error.align() * 8)
+        };
+
         let mut incorrect_type = vec![];
 
         macro_rules! key {
@@ -111,6 +119,15 @@ impl Target {
                     base.$key_name = Some(s.into());
                 }
             } );
+            ($key_name:ident, Option<Align>) => ( {
+                let name = (stringify!($key_name)).replace("_", "-");
+                if let Some(b) = obj.remove(&name).and_then(|b| b.as_u64()) {
+                    match Align::from_bits(b) {
+                        Ok(align) => base.$key_name = Some(align),
+                        Err(e) => return Err(alignment_error(&name, e)),
+                    }
+                }
+            } );
             ($key_name:ident, BinaryFormat) => ( {
                 let name = (stringify!($key_name)).replace("_", "-");
                 obj.remove(&name).and_then(|f| f.as_str().and_then(|s| {
@@ -617,7 +634,7 @@ impl Target {
         key!(crt_static_default, bool);
         key!(crt_static_respected, bool);
         key!(stack_probes, StackProbeType)?;
-        key!(min_global_align, Option<u64>);
+        key!(min_global_align, Option<Align>);
         key!(default_codegen_units, Option<u64>);
         key!(default_codegen_backend, Option<StaticCow<str>>);
         key!(trap_unreachable, bool);

compiler/rustc_target/src/spec/mod.rs

@@ -1697,6 +1697,12 @@ impl ToJson for BinaryFormat {
     }
 }
 
+impl ToJson for Align {
+    fn to_json(&self) -> Json {
+        self.bits().to_json()
+    }
+}
+
 macro_rules! supported_targets {
     ( $(($tuple:literal, $module:ident),)+ ) => {
         mod targets {
@@ -2513,7 +2519,7 @@ pub struct TargetOptions {
     pub stack_probes: StackProbeType,
 
     /// The minimum alignment for global symbols.
-    pub min_global_align: Option<u64>,
+    pub min_global_align: Option<Align>,
 
     /// Default number of codegen units to use in debug mode
     pub default_codegen_units: Option<u64>,

compiler/rustc_target/src/spec/targets/s390x_unknown_linux_gnu.rs

@@ -1,4 +1,4 @@
-use rustc_abi::Endian;
+use rustc_abi::{Align, Endian};
 
 use crate::spec::{SanitizerSet, StackProbeType, Target, TargetMetadata, base};
 
@@ -8,7 +8,7 @@ pub(crate) fn target() -> Target {
     // z10 is the oldest CPU supported by LLVM
     base.cpu = "z10".into();
     base.max_atomic_width = Some(128);
-    base.min_global_align = Some(16);
+    base.min_global_align = Some(Align::from_bits(16).unwrap());
     base.stack_probes = StackProbeType::Inline;
     base.supported_sanitizers =
         SanitizerSet::ADDRESS | SanitizerSet::LEAK | SanitizerSet::MEMORY | SanitizerSet::THREAD;

compiler/rustc_target/src/spec/targets/s390x_unknown_linux_musl.rs

@@ -1,4 +1,4 @@
-use rustc_abi::Endian;
+use rustc_abi::{Align, Endian};
 
 use crate::spec::{SanitizerSet, StackProbeType, Target, TargetMetadata, base};
 
@@ -8,7 +8,7 @@ pub(crate) fn target() -> Target {
     // z10 is the oldest CPU supported by LLVM
     base.cpu = "z10".into();
     base.max_atomic_width = Some(128);
-    base.min_global_align = Some(16);
+    base.min_global_align = Some(Align::from_bits(16).unwrap());
     base.static_position_independent_executables = true;
     base.stack_probes = StackProbeType::Inline;
     base.supported_sanitizers =