Commit 90e1e160 authored by Sergei Trofimovich's avatar Sergei Trofimovich Committed by Sergei Trofimovich

Split external symbol prototypes (EF_) (Trac #11395)

Before the patch both Cmm and C symbols were declared
with 'EF_' macro:

    #define EF_(f)    extern StgFunPtr f()

but for Cmm symbols we know exact prototypes.

The patch splits there prototypes in to:

    #define EFF_(f)   void f() /* See Note [External function prototypes] */
    #define EF_(f)    StgFunPtr f(void)

Cmm functions are 'EF_' (External Functions),
C functions are 'EFF_' (External Foreign Functions).

While at it changed external C function prototype
to return 'void' to workaround ghc bug on m68k.
Described in detail in Trac #11395.

This makes simple tests work on m68k-linux target!

Thanks to Michael Karcher for awesome analysis
happening in Trac #11395.
Signed-off-by: default avatarSergei Trofimovich <>

Test Plan: ran "hello world" on m68k successfully

Reviewers: simonmar, austin, bgamari

Reviewed By: bgamari

Subscribers: thomie

Differential Revision:

GHC Trac Issues: #11395
parent 82e36edc
......@@ -88,8 +88,9 @@ module CLabel (
mkCCLabel, mkCCSLabel,
......@@ -492,6 +493,11 @@ addLabelSize (ForeignLabel str _ src fod) sz
addLabelSize label _
= label
-- | Whether label is a non-haskell label (defined in C code)
isForeignLabel :: CLabel -> Bool
isForeignLabel (ForeignLabel _ _ _ _) = True
isForeignLabel _lbl = False
-- | Get the label size field from a ForeignLabel
foreignLabelStdcallInfo :: CLabel -> Maybe Int
foreignLabelStdcallInfo (ForeignLabel _ info _ _) = info
......@@ -264,7 +264,7 @@ pprStmt stmt =
-- We also need to cast mem primops to prevent conflicts with GCC
-- builtins (see bug #5967).
| Just _align <- machOpMemcpyishAlign op
= (text ";EF_(" <> fn <> char ')' <> semi) $$
= (text ";EFF_(" <> fn <> char ')' <> semi) $$
pprForeignCall fn cconv hresults hargs
| otherwise
= pprCall fn cconv hresults hargs
......@@ -1005,7 +1005,8 @@ pprExternDecl _in_srt lbl
hcat [ visibility, label_type lbl,
lparen, ppr lbl, text ");" ]
label_type lbl | isCFunctionLabel lbl = text "F_"
label_type lbl | isForeignLabel lbl && isCFunctionLabel lbl = text "FF_"
| isCFunctionLabel lbl = text "F_"
| otherwise = text "I_"
......@@ -222,11 +222,21 @@ typedef StgFunPtr F_;
#define II_(X) static StgWordArray (X) GNU_ATTRIBUTE(aligned (8))
#define IF_(f) static StgFunPtr GNUC3_ATTRIBUTE(used) f(void)
#define FN_(f) StgFunPtr f(void)
#define EF_(f) extern StgFunPtr f() /* See Note [External function prototypes] */
#define EF_(f) StgFunPtr f(void) /* External Cmm functions */
#define EFF_(f) void f() /* See Note [External function prototypes] */
/* Note [External function prototypes] See Trac #8965
/* Note [External function prototypes] See Trac #8965, #11395
The external-function macro EF_(F) used to be defined as
In generated C code we need to distinct between two types
of external symbols:
1. Cmm functions declared by 'EF_' macro (External Functions)
2. C functions declared by 'EFF_' macro (External Foreign Functions)
Cmm functions are simple as they are internal to GHC.
C functions are trickier:
The external-function macro EFF_(F) used to be defined as
extern StgFunPtr f(void)
i.e a function of zero arguments. On most platforms this doesn't
matter very much: calls to these functions put the parameters in the
......@@ -249,6 +259,10 @@ unspecified argument list rather than a void argument list. This is no
worse for platforms that don't care either way, and allows a successful
bootstrap of GHC 7.8 on little-endian Linux ppc64 (which uses the ELFv2
Another case is m68k ABI where 'void*' return type is returned by 'a0'
register while 'long' return type is returned by 'd0'. Thus we trick
external prototype return neither of these types to workaround #11395.
......@@ -490,8 +490,19 @@ extern StgWord RTS_VAR(CCS_LIST); /* registered CCS list */
extern StgWord CCS_SYSTEM[];
extern unsigned int RTS_VAR(CC_ID); /* global ids */
extern unsigned int RTS_VAR(CCS_ID);
// Calls to these rts functions are generated directly
// by codegen (see compiler/codeGen/StgCmmProf.hs)
// and don't require (don't emit) forward declarations.
// In unregisterised mode (when building via .hc files)
// the calls are ordinary C calls. Functions must be in
// scope and must match prototype assumed by
// 'compiler/codeGen/StgCmmProf.hs'
// as opposed to real prototype declared in
// 'includes/rts/prof/CCS.h'
void enterFunCCS (void *reg, void *ccsfn);
void * pushCostCentre (void *ccs, void *cc);
// Capability.c
extern unsigned int n_capabilities;
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