auto merge of #18410 : thestinger/rust/revert-parallel, r=alexcrichton

This reverts commit c245c5bbad10923b47c9f66d5f0da2913ef11a38.

Parallel code generation generates invalid code for librand, which is
caught by recent versions of binutils.

1 files changed, 1 insertions, 14 deletions

diff --git a/src/librustc/driver/config.rs b/src/librustc/driver/config.rs
index d6798d59ecb..1f44808275f 100644
--- a/src/librustc/driver/config.rs
+++ b/src/librustc/driver/config.rs
@@ -780,20 +780,7 @@ pub fn build_session_options(matches: &getopts::Matches) -> Options {
         early_warn("the --crate-file-name argument has been renamed to \
                     --print-file-name");
     }
-
-    let mut cg = build_codegen_options(matches);
-
-    if cg.codegen_units == 0 {
-        match opt_level {
-            // `-C lto` doesn't work with multiple codegen units.
-            _ if cg.lto => cg.codegen_units = 1,
-
-            No | Less => cg.codegen_units = 2,
-            Default | Aggressive => cg.codegen_units = 1,
-        }
-    }
-    let cg = cg;
-
+    let cg = build_codegen_options(matches);
 
     if !cg.remark.is_empty() && debuginfo == NoDebugInfo {
         early_warn("-C remark will not show source locations without --debuginfo");