[commit: ghc] ghc-7.4: Hide STG register declarations for LLVM C compilers (a71edf5)

[Ian Lynagh]

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

On branch  : ghc-7.4

http://hackage.haskell.org/trac/ghc/changeset/a71edf5f59574ccb7a1040c5fdbc3d85927525df

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

commit a71edf5f59574ccb7a1040c5fdbc3d85927525df
Author: David M Peixotto <dmp at rice.edu>
Date:   Wed Dec 7 08:20:47 2011 -0600

    Hide STG register declarations for LLVM C compilers
    
    This commit swaps the import order of Rts.h and Stg.h in
    StgCRun.c for non-SPARC architectures. Swapping the import
    order prevents the declaration of the global registers thus
    allowing the GHC runtime to be compiled by LLVM-based C
    compilers.
    
    LLVM-base C compilers cannot use the global register
    declarations (for R1, R2, etc.) because they use
    GCC-specific extensions. The declarations are not needed in
    StgCRun.c except for the SPARC architecture. The other
    architectures use hand-written assembly that accesses the
    appropriate register directly.

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

 rts/StgCRun.c |   12 ++++++++++++
 1 files changed, 12 insertions(+), 0 deletions(-)

diff --git a/rts/StgCRun.c b/rts/StgCRun.c
index 7ae5bac..89aa0a3 100644
--- a/rts/StgCRun.c
+++ b/rts/StgCRun.c
@@ -29,12 +29,24 @@
 #include "PosixSource.h"
 #include "ghcconfig.h"
 
+#ifdef sparc_HOST_ARCH
 /* include Stg.h first because we want real machine regs in here: we
  * have to get the value of R1 back from Stg land to C land intact.
  */
 #define IN_STGCRUN 1
 #include "Stg.h"
 #include "Rts.h"
+#else
+/* The other architectures do not require the actual register macro definitions
+ * here because they use hand written assembly to implement the StgRun
+ * function. Including Stg.h first will define the R1 values using GCC specific
+ * techniques, which we don't want for LLVM based C compilers. Since we don't
+ * actually need the real machine register definitions here, we include the
+ * headers in the opposite order to allow LLVM-based C compilers to work.
+ */
+#include "Rts.h"
+#include "Stg.h"
+#endif
 
 #include "StgRun.h"
 #include "Capability.h"