hi,
good news to hear they are being fixed. I reported this problem
about one month ago,it was fixed in gcc3.1. But i have no time
to investigate other math test problems,wish you good luck:)
ÔÚ 2002-03-17 11:52:00 you wrote£º
>I have found a problem in glibc caused by the gcc-2.96-99.1 compiler
>from H.J's miniport.
>
>in the exp() function (file w_expf.c), there is code like:
>
>#ifdef __STDC__
> float __expf(float x) /* wrapper expf */
>#else
> float __expf(x) /* wrapper expf */
> float x;
>#endif
>{
>#ifdef _IEEE_LIBM
> return __ieee754_expf(x);
>#else
> float z;
> z = __ieee754_expf(x);
> if(_LIB_VERSION == _IEEE_) return z;
>
> if(__finitef(x)) {
> if(x>o_threshold)
>
>
>(IEEE_LIBM is not set). Note that there are two function calls (ieee754_expf
>and finitef()) followed by a FP if-statement (x>o_threshold). This
>translates into:
>
>00400570 <__expf>:
> 400570: 3c1c0fc1 lui gp,0xfc1
> 400574: 279cc090 addiu gp,gp,-16240
> 400578: 0399e021 addu gp,gp,t9
> 40057c: 27bdffc8 addiu sp,sp,-56
> 400580: afbc0018 sw gp,24(sp)
> 400584: e7b60030 swc1 $f22,48(sp)
> 400588: e7b70034 swc1 $f23,52(sp)
> 40058c: e7b40028 swc1 $f20,40(sp)
> 400590: e7b5002c swc1 $f21,44(sp)
> 400594: afbf0024 sw ra,36(sp)
> 400598: 46006506 mov.s $f20,$f12
> 40059c: afbc0020 sw gp,32(sp)
> 4005a0: 8f998630 lw t9,-31184(gp)
> 4005a4: 00000000 nop
> 4005a8: 0320f809 jalr t9 __ieee754_expf
> 4005ac: 00000000 nop
> 4005b0: 8fbc0018 lw gp,24(sp)
> 4005b4: 00000000 nop
> 4005b8: 8f8388f4 lw v1,-30476(gp)
> 4005bc: 00000000 nop
> 4005c0: 8c630000 lw v1,0(v1)
> 4005c4: 2402ffff li v0,-1
> 4005c8: 46000586 mov.s $f22,$f0
> 4005cc: 1062002d beq v1,v0,400684 <__expf+0x114>
> 4005d0: 4600a306 mov.s $f12,$f20
> 4005d4: 8f9986d0 lw t9,-31024(gp)
> 4005d8: 00000000 nop
> 4005dc: 0320f809 jalr t9 finitef()
> 4005e0: 00000000 nop
> 4005e4: 8fbc0018 lw gp,24(sp)
> 4005e8: 00000000 nop
> 4005ec: 3c0142b1 lui at,0x42b1
> 4005f0: 34217180 ori at,at,0x7180
> 4005f4: 44810000 mtc1 at,$f0
> 4005f8: 00000000 nop
> 4005fc: 4614003c c.lt.s $f0,$f20 Wow!!!!
> ...
> 400608: 1040001e beqz v0,400684 <__expf+0x114>
> 40060c: 4600b006 mov.s $f0,$f22
> 400610: 4500000b bc1f 400640 <__expf+0xd0>
>
>
>Note that the c.lt.s (from the FP compare) is done before the finitef()
>value has been checked (beqz in 400608). This particular issue causes
>the wrong setting of bits in the FPU SR in some cases (with exp(nan)),
>and "make check" in glibc to fail.
>
>BTW, the "make check" in glibc has so far turned up a few other items in
>glibc as well as in the kernel (FPU emulator), which are being fixed.
>
>/Hartvig
>
>--
> _ _ _____ ____ Hartvig Ekner Mailto:hartvige@mips.com
> |\ /| | |____)(____ Direct: +45 4486 5503
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Regards
Zhang Fuxin
fxzhang@ict.ac.cn
