[commit: ghc] master: update comment (aab5937)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/ghc

On branch  : master
Link       : http://ghc.haskell.org/trac/ghc/changeset/aab5937405d379ee2e9ac0a54f145ca4005cf283/ghc

>---------------------------------------------------------------

commit aab5937405d379ee2e9ac0a54f145ca4005cf283
Author: Simon Marlow <marlowsd at gmail.com>
Date:   Thu Jul 31 11:47:35 2014 +0100

    update comment


>---------------------------------------------------------------

aab5937405d379ee2e9ac0a54f145ca4005cf283
 compiler/cmm/CmmPipeline.hs | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/compiler/cmm/CmmPipeline.hs b/compiler/cmm/CmmPipeline.hs
index 4314695..af4f62a 100644
--- a/compiler/cmm/CmmPipeline.hs
+++ b/compiler/cmm/CmmPipeline.hs
@@ -326,10 +326,9 @@ _GLOBAL_OFFSET_TABLE_, regardless of which entry point we arrived via.
 {- Note [unreachable blocks]
 
 The control-flow optimiser sometimes leaves unreachable blocks behind
-containing junk code.  If these blocks make it into the native code
-generator then they trigger a register allocator panic because they
-refer to undefined LocalRegs, so we must eliminate any unreachable
-blocks before passing the code onwards.
+containing junk code.  These aren't necessarily a problem, but
+removing them is good because it might save time in the native code
+generator later.
 
 -}