Remove function_alignment from ObjectBuilder (#4888)

Removes the function_alignment field from ObjectBuilder and ObjectModule. Alignment information is now provided either by the Module trait for minimum function alignment requirements, or on FunctionInfo for fucntion specific alignment requirements.

cranelift/object/src/backend.rs

@@ -32,7 +32,6 @@ pub struct ObjectBuilder {
     endian: object::Endianness,
     name: Vec<u8>,
     libcall_names: Box<dyn Fn(ir::LibCall) -> String + Send + Sync>,
-    function_alignment: u64,
     per_function_section: bool,
 }
 
@@ -92,17 +91,10 @@ impl ObjectBuilder {
             endian,
             name: name.into(),
             libcall_names,
-            function_alignment: 1,
             per_function_section: false,
         })
     }
 
-    /// Set the alignment used for functions.
-    pub fn function_alignment(&mut self, alignment: u64) -> &mut Self {
-        self.function_alignment = alignment;
-        self
-    }
-
     /// Set if every function should end up in their own section.
     pub fn per_function_section(&mut self, per_function_section: bool) -> &mut Self {
         self.per_function_section = per_function_section;
@@ -123,7 +115,6 @@ pub struct ObjectModule {
     libcalls: HashMap<ir::LibCall, SymbolId>,
     libcall_names: Box<dyn Fn(ir::LibCall) -> String + Send + Sync>,
     known_symbols: HashMap<ir::KnownSymbol, SymbolId>,
-    function_alignment: u64,
     per_function_section: bool,
     anon_func_number: u64,
     anon_data_number: u64,
@@ -144,7 +135,6 @@ impl ObjectModule {
             libcalls: HashMap::new(),
             libcall_names: builder.libcall_names,
             known_symbols: HashMap::new(),
-            function_alignment: builder.function_alignment,
             per_function_section: builder.per_function_section,
             anon_func_number: 0,
             anon_data_number: 0,
@@ -351,10 +341,9 @@ impl Module for ObjectModule {
         }
         *defined = true;
 
-        let align = self
-            .function_alignment
-            .max(self.isa.symbol_alignment())
-            .max(alignment);
+        let align = alignment
+            .max(self.isa.function_alignment() as u64)
+            .max(self.isa.symbol_alignment());
         let (section, offset) = if self.per_function_section {
             let symbol_name = self.object.symbol(symbol).name.clone();
             let (section, offset) =