Make lint check for undefined variables in Cmm

1 files changed, 5 insertions, 1 deletions

diff --git a/compiler/cmm/CmmLint.hs b/compiler/cmm/CmmLint.hs
index 2e24dd7f82..47c30b1a0f 100644
--- a/compiler/cmm/CmmLint.hs
+++ b/compiler/cmm/CmmLint.hs
@@ -13,6 +13,7 @@ module CmmLint (
 import Hoopl
 import Cmm
 import CmmUtils
+import CmmLive
 import PprCmm ()
 import BlockId
 import FastString
@@ -53,7 +54,10 @@ lintCmmDecl (CmmData {})
 
 
 lintCmmGraph :: CmmGraph -> CmmLint ()
-lintCmmGraph g = mapM_ (lintCmmBlock labels) blocks
+lintCmmGraph g = cmmLiveness g `seq` mapM_ (lintCmmBlock labels) blocks
+                 -- cmmLiveness throws an error if there are registers
+                 -- live on entry to the graph (i.e. undefined
+                 -- variables)
   where
        blocks = toBlockList g
        labels = setFromList (map entryLabel blocks)