trans: Upgrade LLVM

This brings some routine upgrades to the bundled LLVM that we're using, the most
notable of which is a bug fix to the way we handle range asserts when loading
the discriminant of an enum. This fix ended up being very similar to f9d4149
where we basically can't have a range assert when loading a discriminant due to
filling drop, and appropriate flags were added to communicate this to
`trans::adt`.

Author: alexcrichton

src/librustc_llvm/archive_ro.rs

@@ -79,14 +79,14 @@ impl Drop for ArchiveRO {
 }
 
 impl<'a> Iterator for Iter<'a> {
-    type Item = Child<'a>;
+    type Item = Result<Child<'a>, String>;
 
-    fn next(&mut self) -> Option<Child<'a>> {
+    fn next(&mut self) -> Option<Result<Child<'a>, String>> {
         let ptr = unsafe { ::LLVMRustArchiveIteratorNext(self.ptr) };
         if ptr.is_null() {
-            None
+            ::last_error().map(Err)
         } else {
-            Some(Child { ptr: ptr, _data: marker::PhantomData })
+            Some(Ok(Child { ptr: ptr, _data: marker::PhantomData }))
         }
     }
 }

src/librustc_llvm/lib.rs

@@ -56,7 +56,7 @@ pub use self::DiagnosticSeverity::*;
 pub use self::Linkage::*;
 pub use self::DLLStorageClassTypes::*;
 
-use std::ffi::CString;
+use std::ffi::{CString, CStr};
 use std::cell::RefCell;
 use std::slice;
 use libc::{c_uint, c_ushort, uint64_t, c_int, size_t, c_char};
@@ -2404,6 +2404,20 @@ pub fn initialize_available_targets() {
     init_pnacl();
 }
 
+pub fn last_error() -> Option<String> {
+    unsafe {
+        let cstr = LLVMRustGetLastError();
+        if cstr.is_null() {
+            None
+        } else {
+            let err = CStr::from_ptr(cstr).to_bytes();
+            let err = String::from_utf8_lossy(err).to_string();
+            libc::free(cstr as *mut _);
+            Some(err)
+        }
+    }
+}
+
 // The module containing the native LLVM dependencies, generated by the build system
 // Note that this must come after the rustllvm extern declaration so that
 // parts of LLVM that rustllvm depends on aren't thrown away by the linker.

src/librustc_metadata/loader.rs

@@ -729,7 +729,7 @@ pub fn note_crate_name(err: &mut DiagnosticBuilder, name: &str) {
 impl ArchiveMetadata {
     fn new(ar: ArchiveRO) -> Option<ArchiveMetadata> {
         let data = {
-            let section = ar.iter().find(|sect| {
+            let section = ar.iter().filter_map(|s| s.ok()).find(|sect| {
                 sect.name() == Some(METADATA_FILENAME)
             });
             match section {

src/librustc_trans/back/archive.rs

@@ -124,6 +124,7 @@ impl<'a> ArchiveBuilder<'a> {
         }
         let archive = self.src_archive.as_ref().unwrap().as_ref().unwrap();
         let ret = archive.iter()
+                         .filter_map(|child| child.ok())
                          .filter(is_relevant_child)
                          .filter_map(|child| child.name())
                          .filter(|name| !self.removals.iter().any(|x| x == name))
@@ -332,9 +333,15 @@ impl<'a> ArchiveBuilder<'a> {
         // We skip any files explicitly desired for skipping, and we also skip
         // all SYMDEF files as these are just magical placeholders which get
         // re-created when we make a new archive anyway.
-        for file in archive.iter().filter(is_relevant_child) {
+        for file in archive.iter() {
+            let file = try!(file.map_err(string2io));
+            if !is_relevant_child(&file) {
+                continue
+            }
             let filename = file.name().unwrap();
-            if skip(filename) { continue }
+            if skip(filename) {
+                continue
+            }
             let filename = Path::new(filename).file_name().unwrap()
                                               .to_str().unwrap();
 
@@ -448,6 +455,7 @@ impl<'a> ArchiveBuilder<'a> {
         unsafe {
             if let Some(archive) = self.src_archive() {
                 for child in archive.iter() {
+                    let child = try!(child.map_err(string2io));
                     let child_name = match child.name() {
                         Some(s) => s,
                         None => continue,
@@ -475,10 +483,25 @@ impl<'a> ArchiveBuilder<'a> {
                         strings.push(name);
                     }
                     Addition::Archive { archive, archive_name: _, mut skip } => {
-                        for child in archive.iter().filter(is_relevant_child) {
+                        for child in archive.iter() {
+                            let child = try!(child.map_err(string2io));
+                            if !is_relevant_child(&child) {
+                                continue
+                            }
                             let child_name = child.name().unwrap();
-                            if skip(child_name) { continue }
-
+                            if skip(child_name) {
+                                continue
+                            }
+
+                            // It appears that LLVM's archive writer is a little
+                            // buggy if the name we pass down isn't just the
+                            // filename component, so chop that off here and
+                            // pass it in.
+                            //
+                            // See LLVM bug 25877 for more info.
+                            let child_name = Path::new(child_name)
+                                                  .file_name().unwrap()
+                                                  .to_str().unwrap();
                             let name = try!(CString::new(child_name));
                             let m = llvm::LLVMRustArchiveMemberNew(ptr::null(),
                                                                    name.as_ptr(),
@@ -517,3 +540,7 @@ impl<'a> ArchiveBuilder<'a> {
         }
     }
 }
+
+fn string2io(s: String) -> io::Error {
+    io::Error::new(io::ErrorKind::Other, format!("bad archive: {}", s))
+}

src/librustc_trans/back/lto.rs

@@ -52,7 +52,7 @@ pub fn run(sess: &session::Session, llmod: ModuleRef,
     link::each_linked_rlib(sess, &mut |_, path| {
         let archive = ArchiveRO::open(&path).expect("wanted an rlib");
         let bytecodes = archive.iter().filter_map(|child| {
-            child.name().map(|name| (name, child))
+            child.ok().and_then(|c| c.name().map(|name| (name, c)))
         }).filter(|&(name, _)| name.ends_with("bytecode.deflate"));
         for (name, data) in bytecodes {
             let bc_encoded = data.data();

src/librustc_trans/back/write.rs

@@ -27,24 +27,16 @@ use std::collections::HashMap;
 use std::ffi::{CStr, CString};
 use std::fs;
 use std::path::{Path, PathBuf};
-use std::ptr;
 use std::str;
 use std::sync::{Arc, Mutex};
 use std::sync::mpsc::channel;
 use std::thread;
-use libc::{self, c_uint, c_int, c_void};
+use libc::{c_uint, c_int, c_void};
 
 pub fn llvm_err(handler: &errors::Handler, msg: String) -> ! {
-    unsafe {
-        let cstr = llvm::LLVMRustGetLastError();
-        if cstr == ptr::null() {
-            panic!(handler.fatal(&msg[..]));
-        } else {
-            let err = CStr::from_ptr(cstr).to_bytes();
-            let err = String::from_utf8_lossy(err).to_string();
-            libc::free(cstr as *mut _);
-            panic!(handler.fatal(&format!("{}: {}", &msg[..], &err[..])));
-        }
+    match llvm::last_error() {
+        Some(err) => panic!(handler.fatal(&format!("{}: {}", msg, err))),
+        None => panic!(handler.fatal(&msg)),
     }
 }
 

src/librustc_trans/trans/_match.rs

@@ -1271,7 +1271,8 @@ fn compile_submatch_continue<'a, 'p, 'blk, 'tcx>(mut bcx: Block<'blk, 'tcx>,
                 };
             }
             Variant(_, ref repr, _, _) => {
-                let (the_kind, val_opt) = adt::trans_switch(bcx, &**repr, val.val);
+                let (the_kind, val_opt) = adt::trans_switch(bcx, &repr,
+                                                            val.val, true);
                 kind = the_kind;
                 if let Some(tval) = val_opt { test_val = tval; }
             }

src/librustc_trans/trans/adt.rs

@@ -890,12 +890,15 @@ fn struct_llfields<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>, st: &Struct<'tcx>,
 ///
 /// This should ideally be less tightly tied to `_match`.
 pub fn trans_switch<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
-                                r: &Repr<'tcx>, scrutinee: ValueRef)
+                                r: &Repr<'tcx>,
+                                scrutinee: ValueRef,
+                                range_assert: bool)
                                 -> (_match::BranchKind, Option<ValueRef>) {
     match *r {
         CEnum(..) | General(..) |
         RawNullablePointer { .. } | StructWrappedNullablePointer { .. } => {
-            (_match::Switch, Some(trans_get_discr(bcx, r, scrutinee, None)))
+            (_match::Switch, Some(trans_get_discr(bcx, r, scrutinee, None,
+                                                  range_assert)))
         }
         Univariant(..) => {
             // N.B.: Univariant means <= 1 enum variants (*not* == 1 variants).
@@ -916,14 +919,18 @@ pub fn is_discr_signed<'tcx>(r: &Repr<'tcx>) -> bool {
 
 /// Obtain the actual discriminant of a value.
 pub fn trans_get_discr<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, r: &Repr<'tcx>,
-                                   scrutinee: ValueRef, cast_to: Option<Type>)
+                                   scrutinee: ValueRef, cast_to: Option<Type>,
+                                   range_assert: bool)
     -> ValueRef {
     debug!("trans_get_discr r: {:?}", r);
     let val = match *r {
-        CEnum(ity, min, max) => load_discr(bcx, ity, scrutinee, min, max),
+        CEnum(ity, min, max) => {
+            load_discr(bcx, ity, scrutinee, min, max, range_assert)
+        }
         General(ity, ref cases, _) => {
             let ptr = StructGEP(bcx, scrutinee, 0);
-            load_discr(bcx, ity, ptr, Disr(0), Disr(cases.len() as u64 - 1))
+            load_discr(bcx, ity, ptr, Disr(0), Disr(cases.len() as u64 - 1),
+                       range_assert)
         }
         Univariant(..) => C_u8(bcx.ccx(), 0),
         RawNullablePointer { nndiscr, nnty, .. } =>  {
@@ -950,7 +957,8 @@ fn struct_wrapped_nullable_bitdiscr(bcx: Block, nndiscr: Disr, discrfield: &Disc
 }
 
 /// Helper for cases where the discriminant is simply loaded.
-fn load_discr(bcx: Block, ity: IntType, ptr: ValueRef, min: Disr, max: Disr)
+fn load_discr(bcx: Block, ity: IntType, ptr: ValueRef, min: Disr, max: Disr,
+              range_assert: bool)
     -> ValueRef {
     let llty = ll_inttype(bcx.ccx(), ity);
     assert_eq!(val_ty(ptr), llty.ptr_to());
@@ -960,7 +968,7 @@ fn load_discr(bcx: Block, ity: IntType, ptr: ValueRef, min: Disr, max: Disr)
     let mask = Disr(!0u64 >> (64 - bits));
     // For a (max) discr of -1, max will be `-1 as usize`, which overflows.
     // However, that is fine here (it would still represent the full range),
-    if max.wrapping_add(Disr(1)) & mask == min & mask {
+    if max.wrapping_add(Disr(1)) & mask == min & mask || !range_assert {
         // i.e., if the range is everything.  The lo==hi case would be
         // rejected by the LLVM verifier (it would mean either an
         // empty set, which is impossible, or the entire range of the
@@ -1239,10 +1247,14 @@ pub fn fold_variants<'blk, 'tcx, F>(bcx: Block<'blk, 'tcx>,
             // runtime, so the basic block isn't actually unreachable, so we
             // need to make it do something with defined behavior. In this case
             // we just return early from the function.
+            //
+            // Note that this is also why the `trans_get_discr` below has
+            // `false` to indicate that loading the discriminant should
+            // not have a range assert.
             let ret_void_cx = fcx.new_temp_block("enum-variant-iter-ret-void");
             RetVoid(ret_void_cx, DebugLoc::None);
 
-            let discr_val = trans_get_discr(bcx, r, value, None);
+            let discr_val = trans_get_discr(bcx, r, value, None, false);
             let llswitch = Switch(bcx, discr_val, ret_void_cx.llbb, cases.len());
             let bcx_next = fcx.new_temp_block("enum-variant-iter-next");
 

src/librustc_trans/trans/base.rs

@@ -556,7 +556,7 @@ pub fn iter_structural_ty<'blk, 'tcx, F>(cx: Block<'blk, 'tcx>,
             // NB: we must hit the discriminant first so that structural
             // comparison know not to proceed when the discriminants differ.
 
-            match adt::trans_switch(cx, &*repr, av) {
+            match adt::trans_switch(cx, &*repr, av, false) {
                 (_match::Single, None) => {
                     if n_variants != 0 {
                         assert!(n_variants == 1);

src/librustc_trans/trans/expr.rs

@@ -2116,7 +2116,8 @@ fn trans_imm_cast<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
         let datum = unpack_datum!(
             bcx, datum.to_lvalue_datum(bcx, "trans_imm_cast", expr.id));
         let llexpr_ptr = datum.to_llref();
-        let discr = adt::trans_get_discr(bcx, &*repr, llexpr_ptr, Some(Type::i64(ccx)));
+        let discr = adt::trans_get_discr(bcx, &*repr, llexpr_ptr,
+                                         Some(Type::i64(ccx)), true);
         ll_t_in = val_ty(discr);
         (discr, adt::is_discr_signed(&*repr))
     } else {