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Re: [fortran, patch] Add Fortran 2003 IEEE intrinsic modules
- From: Uros Bizjak <ubizjak at gmail dot com>
- To: "gcc-patches at gcc dot gnu dot org" <gcc-patches at gcc dot gnu dot org>
- Cc: FX <fxcoudert at gmail dot com>
- Date: Thu, 21 Nov 2013 13:19:22 +0100
- Subject: Re: [fortran, patch] Add Fortran 2003 IEEE intrinsic modules
- Authentication-results: sourceware.org; auth=none
> Here’s my patch submission for adding IEEE intrinsic modules (following Fortran 2003 and 2008
> standards) to gfortran. It implements the item 1, and part of item 2, of my initial plan . All the
> IEEE modules, types, named constants, procedures are defined and fully working. The patch
> comes of course with plenty of testcases, and I can add some more if you can think of things I’ve
> forgotten. I’ve bootstrapped and regtested the patch on:
__asm__ __volatile__ ("fnclex\n\tfldcw\t%0" : : "m" (cw));
@@ -136,16 +165,54 @@ set_fpu (void)
__asm__ __volatile__ ("%vstmxcsr\t%0" : "=m" (cw_sse));
/* The SSE exception masks are shifted by 7 bits. */
- cw_sse |= _FPU_MASK_ALL << 7;
- cw_sse &= ~(excepts << 7);
- /* Clear stalled exception flags. */
- cw_sse &= ~_FPU_EX_ALL;
You have to clear stalled SSE exceptions here. Their flags are in LSB
bits, so their position is different than the position of exception
mask bits in the control word.
+ /* Change the flags. This is tricky on 387 (unlike SSE), because we have
+ FNSTSW but no FLDSW instruction. */
+ __asm__ __volatile__ ("fnstenv\t%0" : "=m" (*&temp));
+ temp.__status_word &= ~exc_clr;
+ temp.__status_word |= exc_set;
+ __asm__ __volatile__ ("fldenv\t%0" : : "m" (*&temp));
Why do you need "*&" here?
fldenv will also trigger exceptions with set flags on the next x87 FP insn ...
+ __asm__ __volatile__ ("%vstmxcsr\t%0" : "=m" (cw_sse));
+ cw_sse &= ~exc_clr;
+ cw_sse |= exc_set;
+ __asm__ __volatile__ ("%vldmxcsr\t%0" : : "m" (cw_sse));
... and ldmxcsr won't trigger exceptions, neither with SSE insn.
Please see Intel documentation on FP exceptions.