From 7b51195f496fbea4be29a3d7e306aa5e23440be1 Mon Sep 17 00:00:00 2001
From: Dan Gohman <sunfish@mozilla.com>
Date: Thu, 6 Dec 2018 17:54:10 -0500
Subject: [PATCH] Add an offset to cranelift-wasm's `GlobalVariable`.

---
 lib/wasm/Cargo.toml             |  1 +
 lib/wasm/src/code_translator.rs |  9 +++++----
 lib/wasm/src/environ/dummy.rs   | 11 ++++-------
 lib/wasm/src/environ/spec.rs    |  3 +++
 lib/wasm/src/lib.rs             |  1 +
 5 files changed, 14 insertions(+), 11 deletions(-)

diff --git a/lib/wasm/Cargo.toml b/lib/wasm/Cargo.toml
index 6a768c87ba..a88550d1e1 100644
--- a/lib/wasm/Cargo.toml
+++ b/lib/wasm/Cargo.toml
@@ -18,6 +18,7 @@ hashmap_core = { version = "0.1.9", optional = true }
 failure = { version = "0.1.1", default-features = false, features = ["derive"] }
 failure_derive = { version = "0.1.1", default-features = false }
 log = { version = "0.4.4", default-features = false }
+cast = { version = "0.2.2" }
 
 [dev-dependencies]
 wabt = "0.7.0"
diff --git a/lib/wasm/src/code_translator.rs b/lib/wasm/src/code_translator.rs
index 8866eeef36..f62ac89f77 100644
--- a/lib/wasm/src/code_translator.rs
+++ b/lib/wasm/src/code_translator.rs
@@ -75,12 +75,12 @@ pub fn translate_operator<FE: FuncEnvironment + ?Sized>(
         Operator::GetGlobal { global_index } => {
             let val = match state.get_global(builder.func, global_index, environ) {
                 GlobalVariable::Const(val) => val,
-                GlobalVariable::Memory { gv, ty } => {
+                GlobalVariable::Memory { gv, offset, ty } => {
                     let addr = builder.ins().global_value(environ.pointer_type(), gv);
                     let mut flags = ir::MemFlags::new();
                     flags.set_notrap();
                     flags.set_aligned();
-                    builder.ins().load(ty, flags, addr, 0)
+                    builder.ins().load(ty, flags, addr, offset)
                 }
             };
             state.push1(val);
@@ -88,13 +88,14 @@ pub fn translate_operator<FE: FuncEnvironment + ?Sized>(
         Operator::SetGlobal { global_index } => {
             match state.get_global(builder.func, global_index, environ) {
                 GlobalVariable::Const(_) => panic!("global #{} is a constant", global_index),
-                GlobalVariable::Memory { gv, .. } => {
+                GlobalVariable::Memory { gv, offset, ty } => {
                     let addr = builder.ins().global_value(environ.pointer_type(), gv);
                     let mut flags = ir::MemFlags::new();
                     flags.set_notrap();
                     flags.set_aligned();
                     let val = state.pop1();
-                    builder.ins().store(flags, val, addr, 0);
+                    debug_assert_eq!(ty, builder.func.dfg.value_type(val));
+                    builder.ins().store(flags, val, addr, offset);
                 }
             }
         }
diff --git a/lib/wasm/src/environ/dummy.rs b/lib/wasm/src/environ/dummy.rs
index 70c13fd0e6..0a31b17b6a 100644
--- a/lib/wasm/src/environ/dummy.rs
+++ b/lib/wasm/src/environ/dummy.rs
@@ -1,6 +1,7 @@
 //! "Dummy" implementations of `ModuleEnvironment` and `FuncEnvironment` for testing
 //! wasm translation.
 
+use cast;
 use cranelift_codegen::cursor::FuncCursor;
 use cranelift_codegen::ir::immediates::{Offset32, Uimm64};
 use cranelift_codegen::ir::types::*;
@@ -169,15 +170,11 @@ impl<'dummy_environment> FuncEnvironment for DummyFuncEnvironment<'dummy_environ
 
     fn make_global(&mut self, func: &mut ir::Function, index: GlobalIndex) -> GlobalVariable {
         // Just create a dummy `vmctx` global.
-        let offset = ((index.index() * 8) as i64 + 8).into();
+        let offset = cast::i32((index.index() * 8) + 8).unwrap().into();
         let vmctx = func.create_global_value(ir::GlobalValueData::VMContext {});
-        let iadd = func.create_global_value(ir::GlobalValueData::IAddImm {
-            base: vmctx,
-            offset,
-            global_type: self.pointer_type(),
-        });
         GlobalVariable::Memory {
-            gv: iadd,
+            gv: vmctx,
+            offset: offset,
             ty: self.mod_info.globals[index].entity.ty,
         }
     }
diff --git a/lib/wasm/src/environ/spec.rs b/lib/wasm/src/environ/spec.rs
index ab2bc62a9f..7aeeb43c92 100644
--- a/lib/wasm/src/environ/spec.rs
+++ b/lib/wasm/src/environ/spec.rs
@@ -1,6 +1,7 @@
 //! All the runtime support necessary for the wasm to cranelift translation is formalized by the
 //! traits `FunctionEnvironment` and `ModuleEnvironment`.
 use cranelift_codegen::cursor::FuncCursor;
+use cranelift_codegen::ir::immediates::Offset32;
 use cranelift_codegen::ir::{self, InstBuilder};
 use cranelift_codegen::isa::TargetFrontendConfig;
 use std::convert::From;
@@ -20,6 +21,8 @@ pub enum GlobalVariable {
     Memory {
         /// The address of the global variable storage.
         gv: ir::GlobalValue,
+        /// An offset to add to the address.
+        offset: Offset32,
         /// The global variable's type.
         ty: ir::Type,
     },
diff --git a/lib/wasm/src/lib.rs b/lib/wasm/src/lib.rs
index 354a62f9e8..acd63bedb4 100644
--- a/lib/wasm/src/lib.rs
+++ b/lib/wasm/src/lib.rs
@@ -36,6 +36,7 @@
 extern crate cranelift_codegen;
 #[macro_use]
 extern crate cranelift_entity;
+extern crate cast;
 extern crate cranelift_frontend;
 #[cfg(test)]
 extern crate target_lexicon;