id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc	os	architecture	failure	difficulty	testcase	blockedby	blocking	related
1424	Argument corruption in FFI with many arguments (maybe 64-bit related)	guest		"With many arguments, something strange occurs in argument passing with FFI.  The misbehaviour only occurs on my 64-bit machine; the program works correctly on my 32-bit one.  It seems as though an extra value is inserted into the argument list.

First, here is the code.  There's a foreign function that takes 10 doubles.

----
{{{
chris@mars:~/dev/haskell/ffi$ cat c.c
fC (double a,
    double b,
    double c,
    double d,
    double e,
    double f,
    double g,
    double h,
    double i,
    double j)
{
    printf(""%f %f %f %f %f %f %f %f %f %f\n"", a,b,c,d,e,f,g,h,i,j);
}
chris@mars:~/dev/haskell/ffi$ cat Ffi.hs
{-# OPTIONS_GHC -fglasgow-exts #-}

f :: Double -> Double -> Double -> Double -> Double -> Double -> Double -> Double -> Double -> Double -> IO ()
f a b c d e f g h i j = do
  print [a, b, c, d, e, f, g, h, i, j]
  fC a b c d e f g h i j

foreign import ccall unsafe ""fC"" fC ::
      Double -> Double -> Double
   -> Double -> Double -> Double
   -> Double -> Double -> Double -> Double -> IO ()

main = do
  f 1 2 3 4 5 6 7 8 9 10
}}}
----

Here is the correct behaviour, on my 32-bit machine.  The important output is the line starting with ""1.000000 2.000000 3.00[...]""

----
{{{
chris@loki:~/tmp/ffi$ gcc -c c.c
c.c: In function ‘fC’:
c.c:12: warning: incompatible implicit declaration of built-in function ‘printf’
chris@loki:~/tmp/ffi$ ghc --make Ffi c.o
[1 of 1] Compiling Main             ( Ffi.hs, Ffi.o )
Linking Ffi ...
./chris@loki:~/tmp/ffi$ ./Ffi 
[1.0,2.0,3.0,4.0,5.0,6.0,7.0,8.0,9.0,10.0]
1.000000 2.000000 3.000000 4.000000 5.000000 6.000000 7.000000 8.000000 9.000000 10.000000
chris@loki:~/tmp/ffi$ ghc -v
Glasgow Haskell Compiler, Version 6.6.1, for Haskell 98, compiled by GHC version 6.6.1
Using package config file: /usr/lib/ghc-6.6.1/package.conf
Using package config file: /home/chris/.ghc/i386-linux-6.6.1/package.conf
wired-in package base mapped to base-2.1.1
wired-in package rts mapped to rts-1.0
wired-in package haskell98 mapped to haskell98-1.0
wired-in package template-haskell mapped to template-haskell-2.1
Hsc static flags: -static
*** Deleting temp files:
Deleting: 
*** Deleting temp dirs:
Deleting: 
ghc-6.6.1: no input files
Usage: For basic information, try the `--help' option.
chris@loki:~/tmp/ffi$ gcc -v
Using built-in specs.
Target: i486-linux-gnu
Configured with: ../src/configure -v --enable-languages=c,c++,fortran,objc,obj-c++,treelang --prefix=/usr --enable-shared --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --enable-nls --with-gxx-include-dir=/usr/include/c++/4.1.3 --program-suffix=-4.1 --enable-__cxa_atexit --enable-clocale=gnu --enable-libstdcxx-debug --enable-mpfr --with-tune=i686 --enable-checking=release i486-linux-gnu
Thread model: posix
gcc version 4.1.3 20070601 (prerelease) (Debian 4.1.2-12)
}}}
----

Here is the bad behaviour, on my 64-bit machine.  Note that the Haskell list has the values [1..10], but the C arguments are 1,2,3,4,5,6,7,8,0,9 (a zero is inserted between 8 and 9).

----
{{{
chris@mars:~/dev/haskell/ffi$ gcc -c c.c
c.c: In function ‘fC’:
c.c:12: warning: incompatible implicit declaration of built-in function ‘printf’
chris@mars:~/dev/haskell/ffi$ ghc --make Ffi c.o
[1 of 1] Compiling Main             ( Ffi.hs, Ffi.o )
Linking Ffi ...
chris@mars:~/dev/haskell/ffi$ ./Ffi 
[1.0,2.0,3.0,4.0,5.0,6.0,7.0,8.0,9.0,10.0]
1.000000 2.000000 3.000000 4.000000 5.000000 6.000000 7.000000 8.000000 0.000000 9.000000
chris@mars:~/dev/haskell/ffi$ ghc -v
Glasgow Haskell Compiler, Version 6.6.1, for Haskell 98, compiled by GHC version 6.6.1
Using package config file: /usr/lib/ghc-6.6.1/package.conf
Using package config file: /home/chris/.ghc/x86_64-linux-6.6.1/package.conf
wired-in package base mapped to base-2.1.1
wired-in package rts mapped to rts-1.0
wired-in package haskell98 mapped to haskell98-1.0
wired-in package template-haskell mapped to template-haskell-2.1
Hsc static flags: -static
*** Deleting temp files:
Deleting: 
*** Deleting temp dirs:
Deleting: 
ghc-6.6.1: no input files
Usage: For basic information, try the `--help' option.
chris@mars:~/dev/haskell/ffi$ gcc -v
Using built-in specs.
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --enable-languages=c,c++,fortran,objc,obj-c++,treelang --prefix=/usr --enable-shared --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --enable-nls --with-gxx-include-dir=/usr/include/c++/4.1.3 --program-suffix=-4.1 --enable-__cxa_atexit --enable-clocale=gnu --enable-libstdcxx-debug --enable-mpfr --enable-checking=release x86_64-linux-gnu
Thread model: posix
gcc version 4.1.3 20070429 (prerelease) (Debian 4.1.2-5)
}}}"	bug	closed	normal		Compiler (FFI)	6.6.1	fixed	ffi	chris@…	Linux	x86_64 (amd64)		Unknown	ffi009