From a55ac1fea8fe4ca8d96d359a8f5b9538e5e9c351 Mon Sep 17 00:00:00 2001
From: Oliver Schneider <git-spam-no-reply9815368754983@oli-obk.de>
Date: Wed, 15 Jun 2016 12:55:04 +0200
Subject: [PATCH] pass arguments to `start`

---
 src/bin/miri.rs            | 11 +++++++++++
 src/interpreter/mod.rs     |  6 +++++-
 tests/compiletest.rs       |  3 +++
 tests/run-pass/start_fn.rs |  7 +++++--
 4 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/src/bin/miri.rs b/src/bin/miri.rs
index cdd6ee027d9..8cc52e39ca6 100644
--- a/src/bin/miri.rs
+++ b/src/bin/miri.rs
@@ -48,6 +48,17 @@ impl<'a> CompilerCalls<'a> for MiriCompilerCalls {
 
             ecx.push_stack_frame(def_id, mir.span, CachedMir::Ref(mir), substs, Some(return_ptr));
 
+            if mir.arg_decls.len() == 2 {
+                // start function
+                let ptr_size = ecx.memory().pointer_size;
+                let nargs = ecx.memory_mut().allocate(ptr_size);
+                ecx.memory_mut().write_usize(nargs, 0).unwrap();
+                let args = ecx.memory_mut().allocate(ptr_size);
+                ecx.memory_mut().write_usize(args, 0).unwrap();
+                ecx.frame_mut().locals[0] = nargs;
+                ecx.frame_mut().locals[1] = args;
+            }
+
             loop {
                 match step(&mut ecx) {
                     Ok(true) => {}
diff --git a/src/interpreter/mod.rs b/src/interpreter/mod.rs
index 1b0b416e0e1..89a3b2f593e 100644
--- a/src/interpreter/mod.rs
+++ b/src/interpreter/mod.rs
@@ -154,6 +154,10 @@ impl<'a, 'tcx> EvalContext<'a, 'tcx> {
         &self.memory
     }
 
+    pub fn memory_mut(&mut self) -> &mut Memory<'tcx> {
+        &mut self.memory
+    }
+
     pub fn stack(&self) -> &[Frame] {
         &self.stack
     }
@@ -1373,7 +1377,7 @@ impl<'a, 'tcx> EvalContext<'a, 'tcx> {
         self.stack.last().expect("no call frames exist")
     }
 
-    fn frame_mut(&mut self) -> &mut Frame<'a, 'tcx> {
+    pub fn frame_mut(&mut self) -> &mut Frame<'a, 'tcx> {
         self.stack.last_mut().expect("no call frames exist")
     }
 
diff --git a/tests/compiletest.rs b/tests/compiletest.rs
index 77cfc57db29..7ce9636fc05 100644
--- a/tests/compiletest.rs
+++ b/tests/compiletest.rs
@@ -21,6 +21,9 @@ fn run_mode(mode: &'static str) {
     let targets = &["x86_64-unknown-linux-gnu", "i686-unknown-linux-gnu"];
 
     for &target in targets {
+        use std::io::Write;
+        let stderr = std::io::stderr();
+        write!(stderr.lock(), "running tests for target {}", target).unwrap();
         let mut config = compiletest::default_config();
         config.host_rustcflags = Some(flags.clone());
         config.mode = mode.parse().expect("Invalid mode");
diff --git a/tests/run-pass/start_fn.rs b/tests/run-pass/start_fn.rs
index 600f6e49f68..8b884e22fed 100644
--- a/tests/run-pass/start_fn.rs
+++ b/tests/run-pass/start_fn.rs
@@ -1,6 +1,9 @@
 #![feature(start)]
 
 #[start]
-fn foo(_nargs: isize, _args: *const *const u8) -> isize {
-    return 0;
+fn foo(nargs: isize, args: *const *const u8) -> isize {
+    if nargs > 0 {
+        assert!(unsafe{*args} as usize != 0);
+    }
+    0
 }