compiler/cmm/PprC.hs: constify labels in .rodata

Consider one-line module
    module B (v) where v = "hello"
in -fvia-C mode it generates code like
    static char gibberish_str[] = "hello";

It resides in data section (precious resource on ia64!).
The patch switches genrator to emit:
    static const char gibberish_str[] = "hello";

Other types if symbols that gained 'const' qualifier are:

- info tables (from haskell and CMM)
- static reference tables (from haskell and CMM)

Cleanups along the way:

- fixed info tables defined in .cmm to reside in .rodata
- split out closure declaration into 'IC_' / 'EC_'
- added label declaration (based on label type) right before
  each label definition (based on section type) so that C
  compiler could check if declaration and definition matches
  at definition site.

Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org>

Test Plan: ran testsuite on unregisterised x86_64 compiler

Reviewers: simonmar, ezyang, austin, bgamari, erikd

Reviewed By: bgamari, erikd

Subscribers: rwbarton, thomie

GHC Trac Issues: #8996

Differential Revision: https://phabricator.haskell.org/D3481

1 files changed, 1 insertions, 1 deletions

diff --git a/includes/rts/storage/InfoTables.h b/includes/rts/storage/InfoTables.h
index e732a30daf..3201c105e1 100644
--- a/includes/rts/storage/InfoTables.h
+++ b/includes/rts/storage/InfoTables.h
@@ -265,7 +265,7 @@ typedef struct {
 } StgFunInfoTable;
 
 // canned bitmap for each arg type, indexed by constants in FunTypes.h
-extern StgWord stg_arg_bitmaps[];
+extern const StgWord stg_arg_bitmaps[];
 
 /* -----------------------------------------------------------------------------
    Return info tables