Add text_section_builder method to TargetIsa

cranelift/codegen/src/isa/mod.rs

@@ -49,7 +49,7 @@ use crate::flowgraph;
 use crate::ir::{self, Function};
 #[cfg(feature = "unwind")]
 use crate::isa::unwind::systemv::RegisterMappingError;
-use crate::machinst::{MachBackend, MachCompileResult, UnwindInfoKind};
+use crate::machinst::{MachBackend, MachCompileResult, TextSectionBuilder, UnwindInfoKind};
 use crate::settings;
 use crate::settings::SetResult;
 use crate::CodegenResult;
@@ -263,6 +263,17 @@ pub trait TargetIsa: fmt::Display + Send + Sync {
         None
     }
 
+    /// Returns an object that can be used to build the text section of an
+    /// executable.
+    ///
+    /// This object will internally attempt to handle as many relocations as
+    /// possible using relative calls/jumps/etc between functions.
+    ///
+    /// The `num_labeled_funcs` argument here is the number of functions which
+    /// will be "labeled" or might have calls between them, typically the number
+    /// of defined functions in the object file.
+    fn text_section_builder(&self, num_labeled_funcs: u32) -> Box<dyn TextSectionBuilder>;
+
     /// Get the new-style MachBackend.
     fn get_mach_backend(&self) -> &dyn MachBackend;
 }

cranelift/codegen/src/machinst/adapter.rs

@@ -86,4 +86,8 @@ impl TargetIsa for TargetIsaAdapter {
     fn map_regalloc_reg_to_dwarf(&self, r: Reg) -> Result<u16, RegisterMappingError> {
         self.backend.map_reg_to_dwarf(r)
     }
+
+    fn text_section_builder(&self, num_labeled_funcs: u32) -> Box<dyn TextSectionBuilder> {
+        self.backend.text_section_builder(num_labeled_funcs)
+    }
 }

crates/cranelift/src/obj.rs

@@ -205,7 +205,6 @@ impl<'a> ObjectBuilder<'a> {
             systemv_unwind_info: Vec::new(),
             relocations: Vec::new(),
             text: isa
-                .get_mach_backend()
                 .text_section_builder((module.functions.len() - module.num_imported_funcs) as u32),
             added_unwind_info: false,
         }