Add ability to relocate constants using RelocSink

cranelift/codegen/src/binemit/memorysink.rs

@@ -16,7 +16,7 @@
 use super::{Addend, CodeInfo, CodeOffset, CodeSink, Reloc};
 use crate::binemit::stackmap::Stackmap;
 use crate::ir::entities::Value;
-use crate::ir::{ExternalName, Function, JumpTable, SourceLoc, TrapCode};
+use crate::ir::{ConstantOffset, ExternalName, Function, JumpTable, SourceLoc, TrapCode};
 use crate::isa::TargetIsa;
 use core::ptr::write_unaligned;
 
@@ -78,6 +78,9 @@ pub trait RelocSink {
     /// Add a relocation referencing an external symbol at the current offset.
     fn reloc_external(&mut self, _: CodeOffset, _: Reloc, _: &ExternalName, _: Addend);
 
+    /// Add a relocation referencing a constant.
+    fn reloc_constant(&mut self, _: CodeOffset, _: Reloc, _: ConstantOffset);
+
     /// Add a relocation referencing a jump table.
     fn reloc_jt(&mut self, _: CodeOffset, _: Reloc, _: JumpTable);
 }
@@ -132,6 +135,11 @@ impl<'a> CodeSink for MemoryCodeSink<'a> {
         self.relocs.reloc_external(ofs, rel, name, addend);
     }
 
+    fn reloc_constant(&mut self, rel: Reloc, constant_offset: ConstantOffset) {
+        let ofs = self.offset();
+        self.relocs.reloc_constant(ofs, rel, constant_offset);
+    }
+
     fn reloc_jt(&mut self, rel: Reloc, jt: JumpTable) {
         let ofs = self.offset();
         self.relocs.reloc_jt(ofs, rel, jt);
@@ -169,6 +177,7 @@ pub struct NullRelocSink {}
 impl RelocSink for NullRelocSink {
     fn reloc_ebb(&mut self, _: u32, _: Reloc, _: u32) {}
     fn reloc_external(&mut self, _: u32, _: Reloc, _: &ExternalName, _: i64) {}
+    fn reloc_constant(&mut self, _: CodeOffset, _: Reloc, _: ConstantOffset) {}
     fn reloc_jt(&mut self, _: u32, _: Reloc, _: JumpTable) {}
 }
 

cranelift/codegen/src/binemit/mod.rs

@@ -16,7 +16,7 @@ pub use self::relaxation::relax_branches;
 pub use self::shrink::shrink_instructions;
 pub use self::stackmap::Stackmap;
 use crate::ir::entities::Value;
-use crate::ir::{ExternalName, Function, Inst, JumpTable, SourceLoc, TrapCode};
+use crate::ir::{ConstantOffset, ExternalName, Function, Inst, JumpTable, SourceLoc, TrapCode};
 use crate::isa::TargetIsa;
 pub use crate::regalloc::RegDiversions;
 use core::fmt;
@@ -133,6 +133,9 @@ pub trait CodeSink {
     /// Add a relocation referencing an external symbol plus the addend at the current offset.
     fn reloc_external(&mut self, _: Reloc, _: &ExternalName, _: Addend);
 
+    /// Add a relocation referencing a jump table.
+    fn reloc_constant(&mut self, _: Reloc, _: ConstantOffset);
+
     /// Add a relocation referencing a jump table.
     fn reloc_jt(&mut self, _: Reloc, _: JumpTable);
 
@@ -192,7 +195,13 @@ where
     }
 
     sink.begin_rodata();
-    // TODO: No read-only data (constant pools) at this time.
+
+    // output constants
+    for (_, constant_data) in func.dfg.constants.iter() {
+        for byte in constant_data.iter() {
+            sink.put1(*byte)
+        }
+    }
 
     sink.end_codegen();
 }

cranelift/codegen/src/binemit/relaxation.rs

@@ -37,6 +37,7 @@ use crate::iterators::IteratorExtras;
 use crate::regalloc::RegDiversions;
 use crate::timing;
 use crate::CodegenResult;
+use core::convert::TryFrom;
 use log::debug;
 
 #[cfg(feature = "basic-blocks")]
@@ -135,7 +136,11 @@ pub fn relax_branches(
     let jumptables_size = offset - jumptables;
     let rodata = offset;
 
-    // TODO: Once we have constant pools we'll do some processing here to update offset.
+    for constant in func.dfg.constants.entries_mut() {
+        constant.set_offset(offset);
+        offset +=
+            u32::try_from(constant.len()).expect("Constants must have a length that fits in a u32")
+    }
 
     let rodata_size = offset - rodata;