Modify failure lang items to take less pointers.

Divide-by-zero before:

```
        leaq    "str\"str\"(1762)"(%rip), %rax
        movq    %rax, 16(%rsp)
        movq    $27, 24(%rsp)
        leaq    "str\"str\"(1542)"(%rip), %rax
        movq    %rax, (%rsp)
        movq    $19, 8(%rsp)
        leaq    16(%rsp), %rdi
        leaq    (%rsp), %rsi
        movl    $32, %edx
        callq   _ZN7failure5fail_20hc04408f955ce60aaqWjE@PLT
```

After:

```
        leaq    .Lconst(%rip), %rdi
        callq   _ZN7failure5fail_20haf918a97c8f7f2bfqWjE@PLT
```

Bounds check before:

```
        leaq    "str\"str\"(1542)"(%rip), %rax
        movq    %rax, 8(%rsp)
        movq    $19, 16(%rsp)
        leaq    8(%rsp), %rdi
        movl    $38, %esi
        movl    $1, %edx
        movl    $1, %ecx
        callq   _ZN7failure17fail_bounds_check20hf4bc3c69e96caf41RXjE@PLT
```

Bounds check after:

```
        leaq    .Lconst2(%rip), %rdi
        movl    $1, %esi
        movl    $1, %edx
        callq   _ZN7failure17fail_bounds_check20h5267276a537a7de22XjE@PLT
```

Size before:

21277995 librustc-4e7c5e5c.s

```
text       data
12554881   6089335
```

Size after:

21247617 librustc-4e7c5e5c.so

```
text       data
12518497   6095748
```

src/libcore/failure.rs

@@ -33,6 +33,7 @@
 use fmt;
 use intrinsics;
 
+#[cfg(stage0)]
 #[cold] #[inline(never)] // this is the slow path, always
 #[lang="fail_"]
 fn fail_(expr: &'static str, file: &'static str, line: uint) -> ! {
@@ -43,6 +44,7 @@ fn fail_(expr: &'static str, file: &'static str, line: uint) -> ! {
     unsafe { intrinsics::abort() }
 }
 
+#[cfg(stage0)]
 #[cold]
 #[lang="fail_bounds_check"]
 fn fail_bounds_check(file: &'static str, line: uint,
@@ -53,6 +55,30 @@ fn fail_bounds_check(file: &'static str, line: uint,
     unsafe { intrinsics::abort() }
 }
 
+#[cfg(not(stage0))]
+#[cold] #[inline(never)] // this is the slow path, always
+#[lang="fail_"]
+fn fail_(expr_file_line: &(&'static str, &'static str, uint)) -> ! {
+    let (expr, file, line) = *expr_file_line;
+    let ref file_line = (file, line);
+    format_args!(|args| -> () {
+        begin_unwind(args, file_line);
+    }, "{}", expr);
+
+    unsafe { intrinsics::abort() }
+}
+
+#[cfg(not(stage0))]
+#[cold]
+#[lang="fail_bounds_check"]
+fn fail_bounds_check(file_line: &(&'static str, uint),
+                     index: uint, len: uint) -> ! {
+    format_args!(|args| -> () {
+        begin_unwind(args, file_line);
+    }, "index out of bounds: the len is {} but the index is {}", len, index);
+    unsafe { intrinsics::abort() }
+}
+
 #[cold]
 pub fn begin_unwind(fmt: &fmt::Arguments, file_line: &(&'static str, uint)) -> ! {
     #[allow(ctypes)]

src/librustc/middle/trans/consts.rs

@@ -109,7 +109,7 @@ fn const_vec(cx: &CrateContext, e: &ast::Expr,
     (v, llunitty, inlineable.iter().fold(true, |a, &b| a && b))
 }
 
-fn const_addr_of(cx: &CrateContext, cv: ValueRef) -> ValueRef {
+pub fn const_addr_of(cx: &CrateContext, cv: ValueRef) -> ValueRef {
     unsafe {
         let gv = "const".with_c_str(|name| {
             llvm::LLVMAddGlobal(cx.llmod, val_ty(cv).to_ref(), name)

src/librustc/middle/trans/controlflow.rs

@@ -20,6 +20,7 @@ use middle::trans::callee;
 use middle::trans::cleanup::CleanupMethods;
 use middle::trans::cleanup;
 use middle::trans::common::*;
+use middle::trans::consts;
 use middle::trans::datum;
 use middle::trans::debuginfo;
 use middle::trans::expr;
@@ -477,14 +478,6 @@ pub fn trans_ret<'a>(bcx: &'a Block<'a>,
     return bcx;
 }
 
-fn str_slice_arg<'a>(bcx: &'a Block<'a>, s: InternedString) -> ValueRef {
-    let ccx = bcx.ccx();
-    let s = C_str_slice(ccx, s);
-    let slot = alloca(bcx, val_ty(s), "__temp");
-    Store(bcx, s, slot);
-    slot
-}
-
 pub fn trans_fail<'a>(
                   bcx: &'a Block<'a>,
                   sp: Span,
@@ -493,12 +486,14 @@ pub fn trans_fail<'a>(
     let ccx = bcx.ccx();
     let _icx = push_ctxt("trans_fail_value");
 
-    let v_str = str_slice_arg(bcx, fail_str);
+    let v_str = C_str_slice(ccx, fail_str);
     let loc = bcx.sess().codemap().lookup_char_pos(sp.lo);
     let filename = token::intern_and_get_ident(loc.file.name.as_slice());
-    let v_filename = str_slice_arg(bcx, filename);
-    let v_line = loc.line as int;
-    let args = vec!(v_str, v_filename, C_int(ccx, v_line));
+    let filename = C_str_slice(ccx, filename);
+    let line = C_int(ccx, loc.line as int);
+    let expr_file_line_const = C_struct(ccx, &[v_str, filename, line], false);
+    let expr_file_line = consts::const_addr_of(ccx, expr_file_line_const);
+    let args = vec!(expr_file_line);
     let did = langcall(bcx, Some(sp), "", FailFnLangItem);
     let bcx = callee::trans_lang_call(bcx,
                                       did,
@@ -514,6 +509,7 @@ pub fn trans_fail_bounds_check<'a>(
                                index: ValueRef,
                                len: ValueRef)
                                -> &'a Block<'a> {
+    let ccx = bcx.ccx();
     let _icx = push_ctxt("trans_fail_bounds_check");
 
     // Extract the file/line from the span
@@ -521,9 +517,11 @@ pub fn trans_fail_bounds_check<'a>(
     let filename = token::intern_and_get_ident(loc.file.name.as_slice());
 
     // Invoke the lang item
-    let filename = str_slice_arg(bcx, filename);
-    let line = C_int(bcx.ccx(), loc.line as int);
-    let args = vec!(filename, line, index, len);
+    let filename = C_str_slice(ccx,  filename);
+    let line = C_int(ccx, loc.line as int);
+    let file_line_const = C_struct(ccx, &[filename, line], false);
+    let file_line = consts::const_addr_of(ccx, file_line_const);
+    let args = vec!(file_line, index, len);
     let did = langcall(bcx, Some(sp), "", FailBoundsCheckFnLangItem);
     let bcx = callee::trans_lang_call(bcx,
                                       did,