From d61a8bb6d2a95a4ec45f996e222e0c86cde56cf0 Mon Sep 17 00:00:00 2001
From: losfair <zhy20000919@hotmail.com>
Date: Sat, 10 Aug 2019 03:10:12 +0800
Subject: [PATCH] Prevent continueing execution on unreliable stack. (LLVM
 register save area information is missing)

---
 lib/runtime-core/src/tiering.rs |  4 ++--
 src/bin/wasmer.rs               | 36 +++++++++------------------------
 2 files changed, 12 insertions(+), 28 deletions(-)

diff --git a/lib/runtime-core/src/tiering.rs b/lib/runtime-core/src/tiering.rs
index 75688bab4..36ec19a1a 100644
--- a/lib/runtime-core/src/tiering.rs
+++ b/lib/runtime-core/src/tiering.rs
@@ -28,6 +28,7 @@ pub enum ShellExitOperation {
 
 pub struct InteractiveShellContext {
     pub image: Option<InstanceImage>,
+    pub patched: bool,
 }
 
 struct OptimizationState {
@@ -178,8 +179,6 @@ pub fn run_tiering<F: Fn(InteractiveShellContext) -> ShellExitOperation>(
                         .as_ptr() as usize,
                 });
                 n_versions.set(n_versions.get() + 1);
-
-                eprintln!("Patched");
             }
             // TODO: Fix this for optimized version.
             let breakpoints = baseline.module.runnable_module.get_breakpoints();
@@ -215,6 +214,7 @@ pub fn run_tiering<F: Fn(InteractiveShellContext) -> ShellExitOperation>(
                     }
                     let op = interactive_shell(InteractiveShellContext {
                         image: Some(new_image.clone()),
+                        patched: n_versions.get() > 1,
                     });
                     match op {
                         ShellExitOperation::ContinueWith(new_image) => {
diff --git a/src/bin/wasmer.rs b/src/bin/wasmer.rs
index 07bf68d5c..a68ef2190 100644
--- a/src/bin/wasmer.rs
+++ b/src/bin/wasmer.rs
@@ -635,37 +635,21 @@ fn interactive_shell(mut ctx: InteractiveShellContext) -> ShellExitOperation {
                 }
             }
             "continue" | "c" => {
-                if let Some(image) = ctx.image.take() {
-                    return ShellExitOperation::ContinueWith(image);
+                if ctx.patched {
+                    println!("Error: Continueing execution is not yet supported on patched code.");
                 } else {
-                    println!("Program state not available, cannot continue execution");
-                }
-            }
-            // Disabled due to unsafety.
-            /*
-            "switch_backend" => {
-                let backend_name = parts.next();
-                if backend_name.is_none() {
-                    println!("Usage: switch_backend [backend_name]");
-                    continue;
-                }
-                let backend_name = backend_name.unwrap();
-                let backend = match backend_name {
-                    "singlepass" => Backend::Singlepass,
-                    "llvm" => Backend::LLVM,
-                    _ => {
-                        println!("unknown backend");
-                        continue;
+                    if let Some(image) = ctx.image.take() {
+                        return ShellExitOperation::ContinueWith(image);
+                    } else {
+                        println!("Program state not available, cannot continue execution");
                     }
-                };
-                if let Some(image) = ctx.image.take() {
-                    return ShellExitOperation::ContinueWith(image, Some(backend));
-                } else {
-                    println!("Program state not available, cannot continue execution");
                 }
             }
-            */
             "backtrace" | "bt" => {
+                if ctx.patched {
+                    println!("Warning: Backtrace on patched code might be inaccurate.");
+                }
+
                 if let Some(ref image) = ctx.image {
                     println!("{}", image.execution_state.colored_output());
                 } else {