Upgrade LLVM

This comes with a number of fixes to be compatible with upstream LLVM:

* Previously all monomorphizations of "mem::size_of()" would receive the same
  symbol. In the past LLVM would silently rename duplicated symbols, but it
  appears to now be dropping the duplicate symbols and functions now. The symbol
  names of monomorphized functions are now no longer solely based on the type of
  the function, but rather the type and the unique hash for the
  monomorphization.

* Split stacks are no longer a global feature controlled by a flag in LLVM.
  Instead, they are opt-in on a per-function basis through a function attribute.
  The rust #[no_split_stack] attribute will disable this, otherwise all
  functions have #[split_stack] attached to them.

* The compare and swap instruction now takes two atomic orderings, one for the
  successful case and one for the failure case. LLVM internally has an
  implementation of calculating the appropriate failure ordering given a
  particular success ordering (previously only a success ordering was
  specified), and I copied that into the intrinsic translation so the failure
  ordering isn't supplied on a source level for now.

* Minor tweaks to LLVM's API in terms of debuginfo, naming, c++11 conventions,
  etc.

src/librustc/lib/llvm.rs

@@ -1261,7 +1261,8 @@ pub mod llvm {
                                       LHS: ValueRef,
                                       CMP: ValueRef,
                                       RHS: ValueRef,
-                                      Order: AtomicOrdering)
+                                      Order: AtomicOrdering,
+                                      FailureOrder: AtomicOrdering)
                                       -> ValueRef;
         pub fn LLVMBuildAtomicRMW(B: BuilderRef,
                                   Op: AtomicBinOp,
@@ -1586,7 +1587,8 @@ pub mod llvm {
                                                Scope: DIDescriptor,
                                                File: DIFile,
                                                Line: c_uint,
-                                               Col: c_uint)
+                                               Col: c_uint,
+                                               Discriminator: c_uint)
                                                -> DILexicalBlock;
 
         pub fn LLVMDIBuilderCreateStaticVariable(Builder: DIBuilderRef,

src/librustc/middle/trans/base.rs

@@ -445,8 +445,8 @@ pub fn set_llvm_fn_attrs(attrs: &[ast::Attribute], llfn: ValueRef) {
     }
 
     // Add the no-split-stack attribute if requested
-    if contains_name(attrs, "no_split_stack") {
-        set_no_split_stack(llfn);
+    if !contains_name(attrs, "no_split_stack") {
+        set_split_stack(llfn);
     }
 
     if contains_name(attrs, "cold") {
@@ -458,8 +458,8 @@ pub fn set_always_inline(f: ValueRef) {
     lib::llvm::SetFunctionAttribute(f, lib::llvm::AlwaysInlineAttribute)
 }
 
-pub fn set_no_split_stack(f: ValueRef) {
-    "no-split-stack".with_c_str(|buf| {
+pub fn set_split_stack(f: ValueRef) {
+    "split-stack".with_c_str(|buf| {
         unsafe { llvm::LLVMAddFunctionAttrString(f, buf); }
     })
 }

src/librustc/middle/trans/build.rs

@@ -814,8 +814,9 @@ pub fn Resume(cx: &Block, exn: ValueRef) -> ValueRef {
 // Atomic Operations
 pub fn AtomicCmpXchg(cx: &Block, dst: ValueRef,
                      cmp: ValueRef, src: ValueRef,
-                     order: AtomicOrdering) -> ValueRef {
-    B(cx).atomic_cmpxchg(dst, cmp, src, order)
+                     order: AtomicOrdering,
+                     failure_order: AtomicOrdering) -> ValueRef {
+    B(cx).atomic_cmpxchg(dst, cmp, src, order, failure_order)
 }
 pub fn AtomicRMW(cx: &Block, op: AtomicBinOp,
                  dst: ValueRef, src: ValueRef,

src/librustc/middle/trans/builder.rs

@@ -949,9 +949,11 @@ impl<'a> Builder<'a> {
     // Atomic Operations
     pub fn atomic_cmpxchg(&self, dst: ValueRef,
                          cmp: ValueRef, src: ValueRef,
-                         order: AtomicOrdering) -> ValueRef {
+                         order: AtomicOrdering,
+                         failure_order: AtomicOrdering) -> ValueRef {
         unsafe {
-            llvm::LLVMBuildAtomicCmpXchg(self.llbuilder, dst, cmp, src, order)
+            llvm::LLVMBuildAtomicCmpXchg(self.llbuilder, dst, cmp, src,
+                                         order, failure_order)
         }
     }
     pub fn atomic_rmw(&self, op: AtomicBinOp,

src/librustc/middle/trans/debuginfo.rs

@@ -2422,7 +2422,8 @@ fn populate_scope_map(cx: &CrateContext,
                 parent_scope,
                 file_metadata,
                 loc.line as c_uint,
-                loc.col.to_uint() as c_uint)
+                loc.col.to_uint() as c_uint,
+                0)
         };
 
         scope_stack.push(ScopeStackEntry { scope_metadata: scope_metadata, ident: None });
@@ -2539,7 +2540,8 @@ fn populate_scope_map(cx: &CrateContext,
                                 parent_scope,
                                 file_metadata,
                                 loc.line as c_uint,
-                                loc.col.to_uint() as c_uint)
+                                loc.col.to_uint() as c_uint,
+                                0)
                         };
 
                         scope_stack.push(ScopeStackEntry {

src/librustc/middle/trans/intrinsic.rs

@@ -223,10 +223,23 @@ pub fn trans_intrinsic(ccx: &CrateContext,
 
         match *split.get(1) {
             "cxchg" => {
+                // See include/llvm/IR/Instructions.h for their implementation
+                // of this, I assume that it's good enough for us to use for
+                // now.
+                let strongest_failure_ordering = match order {
+                    lib::llvm::NotAtomic | lib::llvm::Unordered =>
+                        ccx.sess().fatal("cmpxchg must be atomic"),
+                    lib::llvm::Monotonic | lib::llvm::Release =>
+                        lib::llvm::Monotonic,
+                    lib::llvm::Acquire | lib::llvm::AcquireRelease =>
+                        lib::llvm::Acquire,
+                    lib::llvm::SequentiallyConsistent =>
+                        lib::llvm::SequentiallyConsistent,
+                };
                 let old = AtomicCmpXchg(bcx, get_param(decl, first_real_arg),
                                         get_param(decl, first_real_arg + 1u),
                                         get_param(decl, first_real_arg + 2u),
-                                        order);
+                                        order, strongest_failure_ordering);
                 Ret(bcx, old);
             }
             "load" => {

src/librustc/middle/trans/monomorphize.rs

@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-
-use back::link::mangle_exported_name;
+use back::link::exported_name;
 use driver::session;
 use lib::llvm::ValueRef;
 use middle::trans::base::{set_llvm_fn_attrs, set_inline_hint};
@@ -27,6 +26,7 @@ use syntax::abi;
 use syntax::ast;
 use syntax::ast_map;
 use syntax::ast_util::local_def;
+use std::hash::sip;
 
 pub fn monomorphic_fn(ccx: &CrateContext,
                       fn_id: ast::DefId,
@@ -178,7 +178,8 @@ pub fn monomorphic_fn(ccx: &CrateContext,
     }
 
     let s = ccx.tcx.map.with_path(fn_id.node, |path| {
-        mangle_exported_name(ccx, path, mono_ty, fn_id.node)
+        exported_name(path, format!("h{}", sip::hash(&(hash_id, mono_ty))),
+                      ccx.link_meta.crateid.version_or_default())
     });
     debug!("monomorphize_fn mangled to {}", s);