Add intrinsics for va_list

Add the llvm intrinsics used to manipulate a va_list and add the va_list
method to Type that builds a va_list according to the targets
va_list_kind.

src/libcore/intrinsics.rs

@@ -1401,4 +1401,22 @@ extern "rust-intrinsic" {
     /// Emits a `!nontemporal` store according to LLVM (see their docs).
     /// Probably will never become stable.
     pub fn nontemporal_store<T>(ptr: *mut T, val: T);
+
+    /// Initialize the arglist `ap` for processing via `va_arg`.
+    #[cfg(not(stage0))]
+    pub fn va_start(ap: *mut i8);
+
+    /// Destroy the arglist `ap` after initialization with `va_start` or
+    /// `va_copy`.
+    #[cfg(not(stage0))]
+    pub fn va_end(ap: *mut i8);
+
+    /// Copy the current location of arglist `ap0` to the arglist `ap1`.
+    #[cfg(not(stage0))]
+    pub fn va_copy(ap0: *const i8, ap1: *mut i8);
+
+    /// Loads an argument of type `T` from the `va_list` `ap` and increment the
+    /// argument `ap` points to.
+    #[cfg(not(stage0))]
+    pub fn va_arg<T: Copy>(ap: *mut i8) -> T;
 }

src/librustc_trans/context.rs

@@ -658,6 +658,11 @@ fn declare_intrinsic(cx: &CodegenCx, key: &str) -> Option<ValueRef> {
     ifn!("llvm.assume", fn(i1) -> void);
     ifn!("llvm.prefetch", fn(i8p, t_i32, t_i32, t_i32) -> void);
 
+    // variadic intrinsics
+    ifn!("llvm.va_start", fn(i8p) -> void);
+    ifn!("llvm.va_end", fn(i8p) -> void);
+    ifn!("llvm.va_copy", fn(i8p, i8p) -> void);
+
     if cx.sess().opts.debuginfo != NoDebugInfo {
         ifn!("llvm.dbg.declare", fn(Type::metadata(cx), Type::metadata(cx)) -> void);
         ifn!("llvm.dbg.value", fn(Type::metadata(cx), t_i64, Type::metadata(cx)) -> void);

src/librustc_trans/intrinsic.rs

@@ -77,6 +77,9 @@ fn get_simple_intrinsic(cx: &CodegenCx, name: &str) -> Option<ValueRef> {
         "roundf64" => "llvm.round.f64",
         "assume" => "llvm.assume",
         "abort" => "llvm.trap",
+        "va_start" => "llvm.va_start",
+        "va_copy" => "llvm.va_copy",
+        "va_end" => "llvm.va_end",
         _ => return None
     };
     Some(cx.get_intrinsic(&llvm_name))
@@ -138,6 +141,9 @@ pub fn trans_intrinsic_call<'a, 'tcx>(bx: &Builder<'a, 'tcx>,
             let llfn = cx.get_intrinsic(&("llvm.debugtrap"));
             bx.call(llfn, &[], None)
         }
+        "va_arg" => {
+            bx.va_arg(args[0].immediate(), llret_ty)
+        }
         "size_of" => {
             let tp_ty = substs.type_at(0);
             C_usize(cx, cx.size_of(tp_ty).bytes())

src/librustc_trans/type_.rs

@@ -18,6 +18,7 @@ use context::CodegenCx;
 
 use syntax::ast;
 use rustc::ty::layout::{self, Align, Size};
+use rustc_target::spec::VaListKind;
 
 use std::ffi::CString;
 use std::fmt;
@@ -297,4 +298,34 @@ impl Type {
     pub fn x86_mmx(cx: &CodegenCx) -> Type {
         ty!(llvm::LLVMX86MMXTypeInContext(cx.llcx))
     }
+
+    pub fn va_list(cx: &CodegenCx, name: &str) -> Type {
+        let int_t = Type::c_int(cx);
+        let voidp_t = Type::i8p(cx);
+        match cx.tcx.sess.target.target.options.va_list_kind {
+            VaListKind::CharPtr => {
+                Type::i8p(cx)
+            },
+            VaListKind::VoidPtr => {
+                voidp_t
+            },
+            VaListKind::X86_64Abi => {
+                let mut va_list_t = Type::named_struct(cx, name);
+                va_list_t.set_struct_body(&[int_t, int_t, voidp_t, voidp_t], false);
+                va_list_t
+            },
+            VaListKind::AArch64Abi => {
+                let mut va_list_t = Type::named_struct(cx, name);
+                va_list_t.set_struct_body(&[voidp_t, voidp_t, voidp_t, int_t, int_t], false);
+                va_list_t
+            },
+            VaListKind::PowerPcAbi => {
+                let i8_t = Type::i8(cx);
+                let i16_t = Type::i16(cx);
+                let mut va_list_t = Type::named_struct(cx, name);
+                va_list_t.set_struct_body(&[i8_t, i8_t, i16_t, voidp_t, voidp_t], false);
+                va_list_t
+            },
+        }
+    }
 }

src/librustc_typeck/check/intrinsic.rs

@@ -319,6 +319,14 @@ pub fn check_intrinsic_type<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
                 (0, vec![ptr_ty, tcx.types.usize], tcx.types.usize)
             },
 
+            "va_start" | "va_end" => (0, vec![tcx.mk_mut_ptr(tcx.types.i8)], tcx.mk_nil()),
+
+            "va_copy" => {
+                (0, vec![tcx.mk_imm_ptr(tcx.types.i8), tcx.mk_mut_ptr(tcx.types.i8)], tcx.mk_nil())
+            }
+
+            "va_arg" => (1, vec![tcx.mk_mut_ptr(tcx.types.i8)], param(0)),
+
             "nontemporal_store" => {
                 (1, vec![ tcx.mk_mut_ptr(param(0)), param(0) ], tcx.mk_nil())
             }