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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)
file annotate diff log raw
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# AC_CHECK_FASTCALL([if-ok],[if-notok])
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# Test if the compiler recognizes __attribute__((regparm(3))) - we don't 
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# currently check if it actually works correctly, but probably should...
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# -----------------------
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AC_DEFUN([AC_CHECK_FASTCALL], [
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AC_MSG_CHECKING([support for fastcall calling conventions]);
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AC_RUN_IFELSE([
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  AC_LANG_SOURCE([[
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int __attribute__((regparm(3))) foo(int a, int b) { return a+b; }
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int main(int argc, char *argv[])
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{
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   return foo( 1, 2 ) == 3 ? 0 : 1;
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}]])], [ 
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   AC_MSG_RESULT([yes])
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   $1 ], [ 
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   AC_MSG_RESULT([no])
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   $2 ])
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])
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# AC_CHECK_FRAME_ADDRESS([if-ok],[if-notok])
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# Test if the compiler will let us modify the return address on the stack
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# via __builtin_frame_address()
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# -----------------------
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AC_DEFUN([AC_CHECK_FRAME_ADDRESS], [
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AC_MSG_CHECKING([if we have a working __builtin_frame_address()]);
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AC_RUN_IFELSE([
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  AC_LANG_SOURCE([[
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void * __attribute__((noinline)) first_arg( void *x, void *y ) { return x; }
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int __attribute__((noinline)) foo( int arg, void *exc )
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{
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    if( arg < 2 ) {
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        *(((void **)__builtin_frame_address(0))+1) = exc;
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    }
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    return 0;
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}
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int main(int argc, char *argv[])
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{
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   goto *first_arg(&&start, &&except);
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start:
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   return foo( argc, &&except ) + 1;
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except:
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   return 0;
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}]])], [ 
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   AC_MSG_RESULT([yes])
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   $1 ], [ 
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   AC_MSG_RESULT([no])
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   $2 ])
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])
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.