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lxdream.org :: lxdream/acinclude.m4
lxdream 0.9.1
released Jun 29
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filename acinclude.m4
changeset 927:17b6b9e245d8
prev923:13ac59a786f4
next964:f2f3c7612d06
author nkeynes
date Mon Dec 15 10:44:56 2008 +0000 (11 years ago)
permissions -rw-r--r--
last change Add return-address-modifying exception return code to mmu TLB lookups (a little bit faster)
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     1 # AC_CHECK_FASTCALL([if-ok],[if-notok])
     2 # Test if the compiler recognizes __attribute__((regparm(3))) - we don't 
     3 # currently check if it actually works correctly, but probably should...
     4 # -----------------------
     5 AC_DEFUN([AC_CHECK_FASTCALL], [
     6 AC_MSG_CHECKING([support for fastcall calling conventions]);
     7 AC_RUN_IFELSE([
     8   AC_LANG_SOURCE([[
     9 int __attribute__((regparm(3))) foo(int a, int b) { return a+b; }
    11 int main(int argc, char *argv[])
    12 {
    13    return foo( 1, 2 ) == 3 ? 0 : 1;
    14 }]])], [ 
    15    AC_MSG_RESULT([yes])
    16    $1 ], [ 
    17    AC_MSG_RESULT([no])
    18    $2 ])
    19 ])
    21 # AC_CHECK_FRAME_ADDRESS([if-ok],[if-notok])
    22 # Test if the compiler will let us modify the return address on the stack
    23 # via __builtin_frame_address()
    24 # -----------------------
    25 AC_DEFUN([AC_CHECK_FRAME_ADDRESS], [
    26 AC_MSG_CHECKING([if we have a working __builtin_frame_address()]);
    27 AC_RUN_IFELSE([
    28   AC_LANG_SOURCE([[
    29 void * __attribute__((noinline)) first_arg( void *x, void *y ) { return x; }
    30 int __attribute__((noinline)) foo( int arg, void *exc )
    31 {
    32     if( arg < 2 ) {
    33         *(((void **)__builtin_frame_address(0))+1) = exc;
    34     }
    35     return 0;
    36 }
    38 int main(int argc, char *argv[])
    39 {
    40    goto *first_arg(&&start, &&except);
    42 start:
    43    return foo( argc, &&except ) + 1;
    45 except:
    46    return 0;
    47 }]])], [ 
    48    AC_MSG_RESULT([yes])
    49    $1 ], [ 
    50    AC_MSG_RESULT([no])
    51    $2 ])
    52 ])
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