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* middle-end/9009: floating-point negate and abs optimizations incorrect for ARM
@ 2002-12-19 9:36 rearnsha
0 siblings, 0 replies; 2+ messages in thread
From: rearnsha @ 2002-12-19 9:36 UTC (permalink / raw)
To: gcc-gnats; +Cc: roger
>Number: 9009
>Category: middle-end
>Synopsis: floating-point negate and abs optimizations incorrect for ARM
>Confidential: no
>Severity: serious
>Priority: medium
>Responsible: unassigned
>State: open
>Class: sw-bug
>Submitter-Id: net
>Arrival-Date: Thu Dec 19 09:36:01 PST 2002
>Closed-Date:
>Last-Modified:
>Originator: Richard Earnshaw
>Release: unknown-1.0
>Organization:
>Environment:
arm-elf cross
>Description:
Testsuite gcc.c-torture/exectue/930614-1.c fails after this patch:
2002-12-07 Roger Sayle <roger@eyesopen.com>
* real.h (real_format): Add signbit field.
* real.c (ieee_single_format, ieee_double_format,
ieee_extended_motorola_format, ieee_extended_intel_96_format,
ieee_extended_intel_128_format, ibm_extended_format,
ieee_quad_format, vax_f_format, vax_d_format,
vax_g_format, i370_single_format, i370_double_format,
c4x_single_format, c4x_extended_format, real_internal_format):
Provide suitable signbit value, or -1 to avoid bit twiddling.
* optabs.c (expand_unop): Try implementing negation of
floating point modes by flipping the sign bit.
(expand_abs): Try implementing abs of floating point modes
by clearing the sign bit.
>How-To-Repeat:
Run the testsuite
>Fix:
The reason for the failure is that on an ARM little-endian system the floating-point sign bit is in the lowest addressed word (that is, the sign bit is at position 31 (not 63) when the floating point value is considered as a 'long long' (ARM FPA double format is motorola word order, even when the system is little-endian).
The code needs to take this into account (FLOAT_WORDS_BIG_ENDIAN != WORDS_BIG_ENDIAN) => the hi and lo fields should be swapped over.
>Release-Note:
>Audit-Trail:
>Unformatted:
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: middle-end/9009: floating-point negate and abs optimizations incorrect for ARM
@ 2002-12-19 9:37 rearnsha
0 siblings, 0 replies; 2+ messages in thread
From: rearnsha @ 2002-12-19 9:37 UTC (permalink / raw)
To: gcc-bugs, gcc-prs, nobody, rearnsha, roger
Synopsis: floating-point negate and abs optimizations incorrect for ARM
State-Changed-From-To: open->analyzed
State-Changed-By: rearnsha
State-Changed-When: Thu Dec 19 09:37:53 2002
State-Changed-Why:
Analysis provided with report. This is a regression introduced by the 3.4 BIB merge.
http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=9009
^ permalink raw reply [flat|nested] 2+ messages in thread
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