Implement memory.grow and memory.current (#9)

* Implement.

* Clean and doc

* Collect base addresses instead of leaking them

* Fix code for 1.25.

* Simplify $assert

* Use AbiParam::special.

* Use &mut self in base_addr

lib/environ/src/compilation.rs

@@ -46,16 +46,19 @@ impl binemit::RelocSink for RelocSink {
         name: &ExternalName,
         addend: binemit::Addend,
     ) {
-        // FIXME: Handle grow_memory/current_memory.
-        let func_index = if let ExternalName::User { namespace, index } = *name {
+        let reloc_target = if let ExternalName::User { namespace, index } = *name {
             debug_assert!(namespace == 0);
-            index
+            RelocationTarget::UserFunc(index as usize)
+        } else if *name == ExternalName::testcase("grow_memory") {
+            RelocationTarget::GrowMemory
+        } else if *name == ExternalName::testcase("current_memory") {
+            RelocationTarget::CurrentMemory
         } else {
             panic!("unrecognized external name")
-        } as usize;
+        };
         self.func_relocs.push(Relocation {
             reloc,
-            func_index,
+            reloc_target,
             offset,
             addend,
         });
@@ -83,14 +86,25 @@ impl RelocSink {
 pub struct Relocation {
     /// The relocation code.
     pub reloc: binemit::Reloc,
-    /// The function index.
-    pub func_index: FunctionIndex,
+    /// Relocation target.
+    pub reloc_target: RelocationTarget,
     /// The offset where to apply the relocation.
     pub offset: binemit::CodeOffset,
     /// The addend to add to the relocation value.
     pub addend: binemit::Addend,
 }
 
+/// Destination function. Can be either user function or some special one, like grow_memory.
+#[derive(Debug)]
+pub enum RelocationTarget {
+    /// The user function index.
+    UserFunc(FunctionIndex),
+    /// Function for growing the default memory by the specified amount of pages.
+    GrowMemory,
+    /// Function for query current size of the default linear memory.
+    CurrentMemory,
+}
+
 /// Relocations to apply to function bodies.
 pub type Relocations = Vec<Vec<Relocation>>;
 

lib/environ/src/environ.rs

@@ -3,8 +3,7 @@ use cranelift_codegen::ir;
 use cranelift_codegen::ir::immediates::Offset32;
 use cranelift_codegen::ir::types::*;
 use cranelift_codegen::ir::{
-    AbiParam, ArgumentExtension, ArgumentLoc, ArgumentPurpose, ExtFuncData, ExternalName, FuncRef,
-    Function, InstBuilder, Signature,
+    AbiParam, ArgumentPurpose, ExtFuncData, ExternalName, FuncRef, Function, InstBuilder, Signature,
 };
 use cranelift_codegen::isa;
 use cranelift_codegen::settings;
@@ -132,12 +131,10 @@ impl<'data, 'module> cranelift_wasm::ModuleEnvironment<'data>
 
     fn declare_signature(&mut self, sig: &ir::Signature) {
         let mut sig = sig.clone();
-        sig.params.push(AbiParam {
-            value_type: self.pointer_type(),
-            purpose: ArgumentPurpose::VMContext,
-            extension: ArgumentExtension::None,
-            location: ArgumentLoc::Unassigned,
-        });
+        sig.params.push(AbiParam::special(
+            self.pointer_type(),
+            ArgumentPurpose::VMContext,
+        ));
         // TODO: Deduplicate signatures.
         self.module.signatures.push(sig);
     }
@@ -377,7 +374,10 @@ impl<'module_environment> cranelift_wasm::FuncEnvironment for FuncEnvironment<'m
             let sig_ref = pos.func.import_signature(Signature {
                 call_conv: self.isa.flags().call_conv(),
                 argument_bytes: None,
-                params: vec![AbiParam::new(I32)],
+                params: vec![
+                    AbiParam::new(I32),
+                    AbiParam::special(self.pointer_type(), ArgumentPurpose::VMContext),
+                ],
                 returns: vec![AbiParam::new(I32)],
             });
             // We currently allocate all code segments independently, so nothing
@@ -391,7 +391,8 @@ impl<'module_environment> cranelift_wasm::FuncEnvironment for FuncEnvironment<'m
             })
         });
         self.grow_memory_extfunc = Some(grow_mem_func);
-        let call_inst = pos.ins().call(grow_mem_func, &[val]);
+        let vmctx = pos.func.special_param(ArgumentPurpose::VMContext).unwrap();
+        let call_inst = pos.ins().call(grow_mem_func, &[val, vmctx]);
         Ok(*pos.func.dfg.inst_results(call_inst).first().unwrap())
     }
 
@@ -406,7 +407,10 @@ impl<'module_environment> cranelift_wasm::FuncEnvironment for FuncEnvironment<'m
             let sig_ref = pos.func.import_signature(Signature {
                 call_conv: self.isa.flags().call_conv(),
                 argument_bytes: None,
-                params: Vec::new(),
+                params: vec![AbiParam::special(
+                    self.pointer_type(),
+                    ArgumentPurpose::VMContext,
+                )],
                 returns: vec![AbiParam::new(I32)],
             });
             // We currently allocate all code segments independently, so nothing
@@ -420,7 +424,8 @@ impl<'module_environment> cranelift_wasm::FuncEnvironment for FuncEnvironment<'m
             })
         });
         self.current_memory_extfunc = Some(cur_mem_func);
-        let call_inst = pos.ins().call(cur_mem_func, &[]);
+        let vmctx = pos.func.special_param(ArgumentPurpose::VMContext).unwrap();
+        let call_inst = pos.ins().call(cur_mem_func, &[vmctx]);
         Ok(*pos.func.dfg.inst_results(call_inst).first().unwrap())
     }
 }

lib/environ/src/lib.rs

@@ -23,6 +23,6 @@ mod compilation;
 mod environ;
 mod module;
 
-pub use compilation::{compile_module, Compilation, Relocation, Relocations};
+pub use compilation::{compile_module, Compilation, Relocation, RelocationTarget, Relocations};
 pub use environ::{ModuleEnvironment, ModuleTranslation};
 pub use module::{DataInitializer, Module, TableElements};