ANN: ghc 6.8.2 from MacPorts
After what many would consider an unconscionable delay, I am happy to announce that ghc 6.8.2 is available from MacPorts. The ghc 6.8.2 port is available for Tiger/ppc, Tiger/intel and Leopard/ intel. Users with Leopard/ppc are out of luck until for now, for reason discussed earlier on this list. In partial recompense for their patience, users will get a ghc with more patches than any previous MacPorts ghc. A few notes: The file locking bugs #1992 and #2134 are fixed. Bug #1992 was a simple lock logic error and should be killed dead. Bug #2134 was the result of a lazy readFile holding a lock for an unpredictable time. There may be more cases like this one, and I would appreciate a note from anyone who come across a lock error during building. Users on Leopard/intel must upgrade to 10.5.2 to avoid an OS bug which under unusual circumstances would repeatably (and mysteriously) crash the build. This was first noticed running the building in an eshell under Aquamacs. Archives were built without tables of contents because ranlib wasn't being run or wasn't running to completion. Builds in the usual Terminal.app didn't trip over this bug. OpenGL support is built by default. It can be turned off using the no_opengl variant. OpenAL support is disabled. Apple's OpenAL framework lacks ALUT support (needed for the ghc binding) but has name clashes with the freealut library from the OpenAL.org website. Fixing this is probably straightforward. If someone is interested, I can give them some pointers on getting started. MacPort's ghc ought to always link with the correct libgmp (the one provided by the gmp port). The latest versions of alex, happy, haddock and hs-Edison are also available. Best Wishes, Greg ___ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Assembly decoding help?
I'm trying to get a feel for the assembly output by GHC on my
platform. Below is a module containing one function and the associated
assembly. I've put in comments what I think is going on, but I'd
appreciate it if anyone could give me some pointers. I'd really like
to know three things:
* Why does _Add_unsafeShiftR_info check if (%esi) is 3?
* What's going on in _s86_info?
* At the end of _s87_info, 8 is added to %ebp and then jumped to. Is
that a jump to the I# constructor and, if so, how did it's address get
to that offset from %ebp?
Thanks in advance for any assistance!
Justin
--- cut here
# Compiled with
#
# ghc -c Add.hs -fext-core -keep-s-files -fasm -O2 -ddump-to-file
-ddump-stg -ddump-cmm
#
# Platform: Windows XP.
# Processor Pentium 4.
# GHC Version: 6.8.2.
#
# {-# OPTIONS_GHC -fglasgow-exts -fbang-patterns #-}
# module Add (unsafeShiftR)
#
# where
#
# import Data.Bits
# import GHC.Base (uncheckedShiftRL#, Int(..), word2Int#, int2Word#)
#
# I# a `unsafeShiftR` I# b = I# (word2Int# (int2Word# a
`uncheckedShiftRL#` b))
#
.data
.align 4
.globl _Add_unsafeShiftR_closure
_Add_unsafeShiftR_closure:
.long _Add_unsafeShiftR_info # Specifies entry point for unsafeShiftR?
.text
.align 4,0x90
.long 33
.long 34
_s87_info:
addl $8,%edi
cmpl 92(%ebx),%edi # Stack
check?
ja .Lc8n
movl 4(%ebp),%eax
# Get value to be shifted
movl 3(%esi),%ecx
# Get shift amount
shrl %cl,%eax
# Shift value
movl $_base_GHCziBase_Izh_con_info,-4(%edi) # Get ready to call I#?
movl %eax,(%edi)
# Constructor value
leal -3(%edi),%esi #
Address to what in I#?
addl $8,%ebp
# Make room on stack for next caller?
jmp *(%ebp)
# Go to constructor? Tail call?
.Lc8n:
movl $8,112(%ebx)
jmp *-8(%ebx)
# Error routine if stack overflows?
.text
.align 4,0x90
.long 1
.long 34
_s86_info:
movl 4(%ebp),%eax
# Testing what here?
movl 3(%esi),%ecx
movl %ecx,4(%ebp)
movl %eax,%esi
movl $_s87_info,(%ebp)
testl $3,%esi
jne _s87_info
jmp *(%esi)
.text
.align 4,0x90
.long 131084
.long 0
.long 15
.globl _Add_unsafeShiftR_info
_Add_unsafeShiftR_info:
movl (%ebp),%esi
movl $_s86_info,(%ebp)
testl $3,%esi
# Looking at StgRetInfoTable here?
jne _s86_info
# Enter body of unsafeShiftR?
jmp *(%esi)
.data
.align 4
__module_registered:
.long 0
.text
.align 4,0x90
.globl ___stginit_Add_
___stginit_Add_:
cmpl $0,__module_registered
jne .Lc8E
.Lc8F:
movl $1,__module_registered
addl $-4,%ebp
movl $___stginit_base_GHCziBase_,(%ebp)
addl $-4,%ebp
movl $___stginit_base_Prelude_,(%ebp)
addl $-4,%ebp
movl $___stginit_base_DataziBits_,(%ebp)
.Lc8E:
addl $4,%ebp
jmp *-4(%ebp)
.text
.align 4,0x90
.globl ___stginit_Add
___stginit_Add:
jmp ___stginit_Add_
.ident GHC 6.8.2
___
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Re: Assembly decoding help?
On Tue, Mar 04, 2008 at 05:07:03PM -0800, Justin Bailey wrote: I'm trying to get a feel for the assembly output by GHC on my platform. Below is a module containing one function and the associated assembly. I've put in comments what I think is going on, but I'd appreciate it if anyone could give me some pointers. I'd really like to know three things: * Why does _Add_unsafeShiftR_info check if (%esi) is 3? * What's going on in _s86_info? * At the end of _s87_info, 8 is added to %ebp and then jumped to. Is that a jump to the I# constructor and, if so, how did it's address get to that offset from %ebp? Thanks in advance for any assistance! It would be more helpful if you didn't try to go from Haskell to assembly in one step - it's a lot easier to understand each big step of the GHC pipeline individually. Haskell | \- Core (ghc -ddump-simpl Foo.hs Foo.core; or -fext-core if you want something ugly but parsable; an unrestricted but simple expression-functional language) | \- STG (ghc -ddump-stg ...) (Much more regular than Core; more like functional C) | \- C-- (ghc -ddump-cmm) (just what it says: Simplified C for compiler writers. The universal assembly language for the 21st century) | \- assembly Stefan signature.asc Description: Digital signature ___ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: Assembly decoding help?
On 3/4/08, Justin Bailey [EMAIL PROTECTED] wrote: I'm trying to get a feel for the assembly output by GHC on my platform. Below is a module containing one function and the associated assembly. I've put in comments what I think is going on, but I'd appreciate it if anyone could give me some pointers. I'd really like to know three things: * Why does _Add_unsafeShiftR_info check if (%esi) is 3? * What's going on in _s86_info? * At the end of _s87_info, 8 is added to %ebp and then jumped to. Is that a jump to the I# constructor and, if so, how did it's address get to that offset from %ebp? I agree with Stefan's advice: read the STG code, especially to answer the second two questions (-ddump-stg), and read the STG paper (if you haven't already): Implementing lazy functional languages on stock hardware: the Spineless Tagless G-machine, SL Peyton Jones, Journal of Functional Programming 2(2), Apr 1992, pp127-202. Then if anything's still not clear, ask on the mailing list. Cheers, Tim -- Tim Chevalier * http://cs.pdx.edu/~tjc * Often in error, never in doubt The future is not google-able. -- William Gibson ___ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: Assembly decoding help?
Justin Bailey wrote: I'm trying to get a feel for the assembly output by GHC on my platform. Below is a module containing one function and the associated assembly. I've put in comments what I think is going on, but I'd appreciate it if anyone could give me some pointers. I'd really like to know three things: * Why does _Add_unsafeShiftR_info check if (%esi) is 3? * What's going on in _s86_info? * At the end of _s87_info, 8 is added to %ebp and then jumped to. Is that a jump to the I# constructor and, if so, how did it's address get to that offset from %ebp? One point that seems to irritate you is that ghc does pointer tagging; the lower 2 bits of a pointer are zero if it points to an unevaluated closure (a thunk); otherwise they encode a constructor. (I'm not sure what happens in the case when there are more than 3 constructors. But in your case there's only one, I#, with tag 01.) Register usage (as far as I can see): %ebp - STG stack pointer %edi - Heap pointer (in particular cmpl 92(%ebx),%edi is a heap check and will trigger a GC) %esi - at start of *_info, points to most recently evaluated value. %ebx - points to some RTS global variables. Rough outline of the code: _Add_unsafeShiftR_info: find first argument, and evaluate it if it's not yet fully evaluated. continue at _s86_info. (note that a pointer to _s86_info, a continuation, is stored on the control stack) _s86_info: store the first argument value on the stack, load the second one, and evaluate it if necessary. continue at _s87_info. _s87_info: load both arguments, and compute result. The result is fully evaluated, so a tagged pointer is returned. (the -3 is -4, plus 1 for the tag) clean up the stack (the space for the two arguments is no longer needed) and jump to the continuation stored by the caller. HTH, Bertram ___ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
