+++ /dev/null
-/* -----------------------------------------------------------------------------
- *
- * (c) The GHC Team, 1998-1999
- *
- * Stuff for implementing proper tail jumps.
- *
- * ---------------------------------------------------------------------------*/
-
-#ifndef TAILCALLS_H
-#define TAILCALLS_H
-
-/* -----------------------------------------------------------------------------
- Unmangled tail-jumping: use the mini interpretter.
- -------------------------------------------------------------------------- */
-
-#ifdef USE_MINIINTERPRETER
-
-#define JMP_(cont) return((StgFunPtr)(cont))
-#define FB_
-#define FE_
-
-#else
-
-extern void __DISCARD__(void);
-
-/* -----------------------------------------------------------------------------
- Tail calling on x86
- -------------------------------------------------------------------------- */
-
-#if i386_HOST_ARCH
-
-/* Note about discard: possibly there to fool GCC into clearing up
- before we do the jump eg. if there are some arguments left on the C
- stack that GCC hasn't popped yet. Also possibly to fool any
- optimisations (a function call often acts as a barrier). Not sure
- if any of this is necessary now -- SDM
-
- Comment to above note: I don't think the __DISCARD__() in JMP_ is
- necessary. Arguments should be popped from the C stack immediately
- after returning from a function, as long as we pass -fno-defer-pop
- to gcc. Moreover, a goto to a first-class label acts as a barrier
- for optimisations in the same way a function call does.
- -= chak
- */
-
-/* The goto here seems to cause gcc -O2 to delete all the code after
- it - including the FE_ marker and the epilogue code - exactly what
- we want! -- SDM
- */
-
-#define JMP_(cont) \
- { \
- void *__target; \
- __DISCARD__(); \
- __target = (void *)(cont); \
- goto *__target; \
- }
-
-#endif /* i386_HOST_ARCH */
-
-/* -----------------------------------------------------------------------------
- Tail calling on x86_64
- -------------------------------------------------------------------------- */
-
-#if x86_64_HOST_ARCH
-
-/*
- NOTE about __DISCARD__():
-
- On x86_64 this is necessary to work around bugs in the register
- variable support in gcc. Without the __DISCARD__() call, gcc will
- silently throw away assignements to global register variables that
- happen before the jump.
-
- Here's the example:
-
- extern void g(void);
- static void f(void) {
- R1 = g;
- __DISCARD__()
- goto *R1;
- }
-
- without the dummy function call, gcc throws away the assignment to R1
- (gcc 3.4.3) gcc bug #20359.
-*/
-
-#define JMP_(cont) \
- { \
- __DISCARD__(); \
- goto *(void *)(cont); \
- }
-
-#endif /* x86_64_HOST_ARCH */
-
-/* -----------------------------------------------------------------------------
- Tail calling on Sparc
- -------------------------------------------------------------------------- */
-
-#ifdef sparc_HOST_ARCH
-
-#define JMP_(cont) ((F_) (cont))()
- /* Oh so happily, the above turns into a "call" instruction,
- which, on a SPARC, is nothing but a "jmpl" with the
- return address in %o7 [which we don't care about].
- */
-
-/* Don't need these for sparc mangling */
-#define FB_
-#define FE_
-
-#endif /* sparc_HOST_ARCH */
-
-/* -----------------------------------------------------------------------------
- Tail calling on Alpha
- -------------------------------------------------------------------------- */
-
-#ifdef alpha_HOST_ARCH
-
-#if IN_STG_CODE
-register void *_procedure __asm__("$27");
-#endif
-
-#define JMP_(cont) \
- do { _procedure = (void *)(cont); \
- __DISCARD__(); \
- goto *_procedure; \
- } while(0)
-
-/* Don't need these for alpha mangling */
-#define FB_
-#define FE_
-
-#endif /* alpha_HOST_ARCH */
-
-/* -----------------------------------------------------------------------------
- Tail calling on HP
-
-Description of HP's weird procedure linkage, many thanks to Andy Bennet
-<andy_bennett@hp.com>:
-
-I've been digging a little further into the problem of how HP-UX does
-dynamic procedure calls. My solution in the last e-mail inserting an extra
-'if' statement into the JMP_ I think is probably the best general solution I
-can come up with. There are still a few problems with it however: It wont
-work, if JMP_ ever has to call anything in a shared library, if this is
-likely to be required it'll need something more elaborate. It also wont work
-with PA-RISC 2.0 wide mode (64-bit) which uses a different format PLT.
-
-I had some feedback from someone in HP's compiler lab and the problem
-relates to the linker on HP-UX, not gcc as I first suspected. The reason the
-'hsc' executable works is most likely due to a change in 'ld's behaviour for
-performance reasons between your revision and mine.
-
-The major issue relating to this is shared libraries and how they are
-implented under HP-UX. The whole point of the Procedure Label Table (PLT) is
-to allow a function pointer to hold the address of the function and a
-pointer to the library's global data lookup table (DLT) used by position
-independent code (PIC). This makes the PLT absolutely essential for shared
-library calls. HP has two linker introduced assembly functions for dealing
-with dynamic calls, $$dyncall and $$dyncall_external. The former does a
-check to see if the address is a PLT pointer and dereferences if necessary
-or just calls the address otherwise; the latter skips the check and just
-does the indirect jump no matter what.
-
-Since $$dyncall_external runs faster due to its not having the test, the
-linker nowadays prefers to generate calls to that, rather than $$dyncall. It
-makes this decision based on the presence of any shared library. If it even
-smells an sl's existence at link time, it rigs the runtime system to
-generate PLT references for everything on the assumption that the result
-will be slightly more efficient. This is what is crashing GHC since the
-calls it is generating have no understanding of the procedure label proper.
-The only way to get real addresses is to link everything archive, including
-system libraries, at which point it assumes you probably are going to be
-using calls similar to GHC's (its rigged for HP's +ESfic compiler option)
-but uses $$dyncall if necessary to cope, just in case you aren't.
-
- -------------------------------------------------------------------------- */
-
-#ifdef hppa1_1_hp_hpux_TARGET
-
-#define JMP_(cont) \
- do { void *_procedure = (void *)(cont); \
- if (((int) _procedure) & 2) \
- _procedure = (void *)(*((int *) (_procedure - 2))); \
- goto *_procedure; \
- } while(0)
-
-#endif /* hppa1_1_hp_hpux_TARGET */
-
-/* -----------------------------------------------------------------------------
- Tail calling on PowerPC
- -------------------------------------------------------------------------- */
-
-#ifdef powerpc_HOST_ARCH
-
-#define JMP_(cont) \
- { \
- void *target; \
- target = (void *)(cont); \
- __DISCARD__(); \
- goto *target; \
- }
-
-/*
- The __DISCARD__ is there because Apple's April 2002 Beta of GCC 3.1
- sometimes generates incorrect code otherwise.
- It tends to "forget" to update global register variables in the presence
- of decrement/increment operators:
- JMP_(*(--Sp)) is wrongly compiled as JMP_(Sp[-1]).
- Calling __DISCARD__ in between works around this problem.
-*/
-
-/*
- I would _love_ to use the following instead,
- but some versions of Apple's GCC fail to generate code for it
- if it is called for a casted data pointer - which is exactly what
- we are going to do...
-
- #define JMP_(cont) ((F_) (cont))()
-*/
-
-#endif /* powerpc_HOST_ARCH */
-
-#ifdef powerpc64_HOST_ARCH
-#define JMP_(cont) ((F_) (cont))()
-#endif
-
-/* -----------------------------------------------------------------------------
- Tail calling on IA64
- -------------------------------------------------------------------------- */
-
-#ifdef ia64_HOST_ARCH
-
-/* The compiler can more intelligently decide how to do this. We therefore
- * implement it as a call and optimise to a jump at mangle time.
- *
- * Sometimes GCC likes to move instructions between the function call and
- * the "--- TAILCALL ---". To stop it from finding instructions to put
- * there, we insert a jump to the end of the function after the TAILCALL. */
-#define JMP_(cont) \
- ((F_) (cont))(); \
- __asm__ volatile ("--- TAILCALL ---"); \
- goto _function_end;
-
-#define FE_ _function_end: __asm__ volatile ("--- END ---");
-
-/* Don't emit calls to __DISCARD__ as this causes hassles */
-#define __DISCARD__()
-
-#endif
-
-/* -----------------------------------------------------------------------------
- Tail calling on MIPS
- -------------------------------------------------------------------------- */
-
-#ifdef mips_HOST_ARCH
-
-#if IN_STG_CODE
-register void *_procedure __asm__("$25");
-#endif
-
-#define JMP_(cont) \
- { \
- _procedure = (void *)(cont); \
- __DISCARD__(); \
- goto *_procedure; \
- }
-
-/* Don't need these for MIPS mangling */
-#define FB_
-#define FE_
-
-#endif /* mips_HOST_ARCH */
-
-/* -----------------------------------------------------------------------------
- FUNBEGIN and FUNEND.
-
- These are markers indicating the start and end of Real Code in a
- function. All instructions between the actual start and end of the
- function and these markers is shredded by the mangler.
- -------------------------------------------------------------------------- */
-
-/* The following __DISCARD__() has become necessary with gcc 2.96 on x86.
- * It prevents gcc from moving stack manipulation code from the function
- * body (aka the Real Code) into the function prologue, ie, from moving it
- * over the --- BEGIN --- marker. It should be noted that (like some
- * other black magic in GHC's code), there is no essential reason why gcc
- * could not move some stack manipulation code across the __DISCARD__() -
- * it just doesn't choose to do it at the moment.
- * -= chak
- */
-
-#ifndef FB_
-#define FB_ __asm__ volatile ("--- BEGIN ---"); __DISCARD__ ();
-#endif
-
-#ifndef FE_
-#define FE_ __asm__ volatile ("--- END ---");
-#endif
-
-#endif /* !USE_MINIINTERPRETER */
-
-#endif /* TAILCALLS_H */
projects / ghc-hetmet.git / blobdiff