[commit: ghc] master: For BC labels, emit empty data section instead of empty proc. (b1cf9aa)

[Edward Z. Yang]

Repository : ssh://darcs.haskell.org//srv/darcs/ghc

On branch  : master

http://hackage.haskell.org/trac/ghc/changeset/b1cf9aae4a495b619375da716d6d14f7cb494f8e

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

commit b1cf9aae4a495b619375da716d6d14f7cb494f8e
Author: Edward Z. Yang <ezyang at mit.edu>
Date:   Wed Apr 13 15:29:48 2011 +0100

    For BC labels, emit empty data section instead of empty proc.
    
    This fixes two bugs:
    
        - The new code generator doesn't like procedures with
          empty graphs, and panicked in labelAGraph.
    
        - LLVM optimizes away empty procedures but not empty
          data sections, so now the backwards-compatibility
          labels actually work with -fllvm.
    
    Signed-off-by: Edward Z. Yang <ezyang at mit.edu>

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

 compiler/codeGen/CodeGen.lhs |    2 +-
 compiler/codeGen/StgCmm.hs   |    3 ++-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/compiler/codeGen/CodeGen.lhs b/compiler/codeGen/CodeGen.lhs
index 81a65f7..7a7bf48 100644
--- a/compiler/codeGen/CodeGen.lhs
+++ b/compiler/codeGen/CodeGen.lhs
@@ -105,7 +105,7 @@ mkModuleInit dflags cost_centre_info this_mod hpc_info
 
             -- For backwards compatibility: user code may refer to this
             -- label for calling hs_add_root().
-        ; emitSimpleProc (mkPlainModuleInitLabel this_mod) $ return ()
+        ; emitData Data $ [ CmmDataLabel (mkPlainModuleInitLabel this_mod) ]
 
         ; whenC (this_mod == mainModIs dflags) $
              emitSimpleProc (mkPlainModuleInitLabel rOOT_MAIN) $ return ()
diff --git a/compiler/codeGen/StgCmm.hs b/compiler/codeGen/StgCmm.hs
index fa3dcfe..2bfe187 100644
--- a/compiler/codeGen/StgCmm.hs
+++ b/compiler/codeGen/StgCmm.hs
@@ -25,6 +25,7 @@ import StgCmmTicky
 
 import MkGraph
 import CmmExpr
+import CmmDecl
 import CLabel
 import PprCmm
 
@@ -181,7 +182,7 @@ mkModuleInit cost_centre_info this_mod hpc_info
         ; initCostCentres cost_centre_info
             -- For backwards compatibility: user code may refer to this
             -- label for calling hs_add_root().
-        ; emitSimpleProc (mkPlainModuleInitLabel this_mod) $ emptyAGraph
+        ; emitData Data $ [ CmmDataLabel (mkPlainModuleInitLabel this_mod) ]
         }
 
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