user/sven/linux.git/include/math-emu, branch v5.4.175

nds32: Mark expected switch fall-throughs

2019-08-29T16:06:56Z

Mark switch cases where we are expecting to fall through. This patch fixes the following warnings (Building: allmodconfig nds32): include/math-emu/soft-fp.h:124:8: warning: this statement may fall through [-Wimplicit-fallthrough=] arch/nds32/kernel/signal.c:362:20: warning: this statement may fall through [-Wimplicit-fallthrough=] arch/nds32/kernel/signal.c:315:7: warning: this statement may fall through [-Wimplicit-fallthrough=] include/math-emu/op-common.h:417:11: warning: this statement may fall through [-Wimplicit-fallthrough=] include/math-emu/op-common.h:430:11: warning: this statement may fall through [-Wimplicit-fallthrough=] include/math-emu/op-common.h:310:11: warning: this statement may fall through [-Wimplicit-fallthrough=] include/math-emu/op-common.h:320:11: warning: this statement may fall through [-Wimplicit-fallthrough=] include/math-emu/op-common.h:310:11: warning: this statement may fall through [-Wimplicit-fallthrough=] include/math-emu/op-common.h:320:11: warning: this statement may fall through [-Wimplicit-fallthrough=] include/math-emu/soft-fp.h:124:8: warning: this statement may fall through [-Wimplicit-fallthrough=] include/math-emu/op-common.h:417:11: warning: this statement may fall through [-Wimplicit-fallthrough=] include/math-emu/op-common.h:430:11: warning: this statement may fall through [-Wimplicit-fallthrough=] include/math-emu/op-common.h:310:11: warning: this statement may fall through [-Wimplicit-fallthrough=] include/math-emu/op-common.h:320:11: warning: this statement may fall through [-Wimplicit-fallthrough=] include/math-emu/op-common.h:310:11: warning: this statement may fall through [-Wimplicit-fallthrough=] include/math-emu/op-common.h:320:11: warning: this statement may fall through [-Wimplicit-fallthrough=] Reported-by: Michael Ellerman Signed-off-by: Gustavo A. R. Silva

math-emu: Use statement expressions to fix Wshift-count-overflow warning

2019-05-31T07:23:25Z

To avoid "shift count >= width of type" warning, using statement expressions to implement the conditional controlling before constant shift The modification in op-2.h is taken from the glibc commit 'sysdeps/unix/sysv/lin ("fe0b1e854ad32")'. Signed-off-by: Vincent Chen Acked-by: Greentime Hu Signed-off-by: Greentime Hu

math-emu/soft-fp.h: (_FP_ROUND_ZERO) cast 0 to void to fix warning

2018-11-22T10:13:42Z

_FP_ROUND_ZERO is defined as 0 and used as a statemente in macro _FP_ROUND. This generates "error: statement with no effect [-Werror=unused-value]" from gcc. Defining _FP_ROUND_ZERO as (void)0 to fix it. This modification is quoted from glibc 'commit (8ed1e7d5894000c155acbd06f)' Signed-off-by: Vincent Chen Acked-by: Greentime Hu Signed-off-by: Greentime Hu

math-emu/op-2.h: Use statement expressions to prevent negative constant shift

2018-11-22T10:13:33Z

This modification is quoted from glibc 'commit < sysdeps/unix/sysv/linux/sparc/sparc64/dl-procinfo.c: Moved to> (fe0b1e854ad32a69b260)' Signed-off-by: Vincent Chen Acked-by: Greentime Hu Signed-off-by: Greentime Hu

math-emu: fix floating-point to integer overflow detection

2014-01-08T00:36:24Z

On overflow, the math-emu macro _FP_TO_INT_ROUND tries to saturate its result (subject to the value of rsigned specifying the desired overflow semantics). However, if the rounding step has the effect of increasing the exponent so as to cause overflow (if the rounded result is 1 larger than the largest positive value with the given number of bits, allowing for signedness), the overflow does not get detected, meaning that for unsigned results 0 is produced instead of the maximum unsigned integer with the give number of bits, without an exception being raised for overflow, and that for signed results the minimum (negative) value is produced instead of the maximum (positive) value, again without an exception. This patch makes the code check for rounding increasing the exponent and adjusts the exponent value as needed for the overflow check. Signed-off-by: Joseph Myers Signed-off-by: Scott Wood

math-emu: fix floating-point to integer unsigned saturation

2014-01-08T00:34:47Z

The math-emu macros _FP_TO_INT and _FP_TO_INT_ROUND are supposed to saturate their results for out-of-range arguments, except in the case rsigned == 2 (when instead the low bits of the result are taken). However, in the case rsigned == 0 (converting to unsigned integers), they mistakenly produce 0 for positive results and the maximum unsigned integer for negative results, the opposite of correct unsigned saturation. This patch fixes the logic. Signed-off-by: Joseph Myers Signed-off-by: Scott Wood

math-emu: correct test for downshifting fraction in _FP_FROM_INT()

2010-07-21T01:45:14Z

The kernel's math-emu code contains a macro _FP_FROM_INT() which is used to convert an integer to a raw normalized floating-point value. It does this basically in three steps: 1. Compute the exponent from the number of leading zero bits. 2. Downshift large fractions to put the MSB in the right position for normalized fractions. 3. Upshift small fractions to put the MSB in the right position. There is an boundary error in step 2, causing a fraction with its MSB exactly one bit above the normalized MSB position to not be downshifted. This results in a non-normalized raw float, which when packed becomes a massively inaccurate representation for that input. The impact of this depends on a number of arch-specific factors, but it is known to have broken emulation of FXTOD instructions on UltraSPARC III, which was originally reported as GCC bug 44631 . Any arch which uses math-emu to emulate conversions from integers to same-size floats may be affected. The fix is simple: the exponent comparison used to determine if the fraction should be downshifted must be "<=" not "<". I'm sending a kernel module to test this as a reply to this message. There are also SPARC user-space test cases in the GCC bug entry. Signed-off-by: Mikael Pettersson Signed-off-by: David S. Miller

Fix misspellings of "truly" in comments.

2010-02-04T10:55:45Z

Some comments misspell "truly"; this fixes them. No code changes. Signed-off-by: Adam Buchbinder Signed-off-by: Jiri Kosina

math-emu: Fix thinko in _FP_DIV

2008-10-23T05:09:59Z

In commit 48d6c64311ddb6417b901639530ccbc47bdc7635 ("math-emu: Add support for reporting exact invalid exception") code was added to set the new FP_EX_INVALID_{IDI,ZDZ} exception flag bits. However there is a missing break statement for the _FP_CLS_COMBINE(FP_CLS_INF,FP_CLS_INF) switch case, the code just falls into _FP_CLS_COMBINE(FP_CLS_ZERO,FP_CLS_ZERO) which then proceeds to overwrite all of the settings. Fix by adding the missing break. Signed-off-by: David S. Miller

math-emu: Fix signalling of underflow and inexact while packing result.

2008-10-23T04:53:53Z

I'm trying to move the powerpc math-emu code to use the include/math-emu bits. In doing so I've been using TestFloat to see how good or bad we are doing. For the most part the current math-emu code that PPC uses has a number of issues that the code in include/math-emu seems to solve (plus bugs we've had for ever that no one every realized). Anyways, I've come across a case that we are flagging underflow and inexact because we think we have a denormalized result from a double precision divide: 000.FFFFFFFFFFFFF / 3FE.FFFFFFFFFFFFE soft: 001.0000000000000 ..... syst: 001.0000000000000 ...ux What it looks like is the results out of FP_DIV_D are: D: sign: 0 mantissa: 01000000 00000000 exp: -1023 (0) The problem seems like we aren't normalizing the result and bumping the exp. Now that I'm digging into this a bit I'm thinking my issue has to do with the fix DaveM put in place from back in Aug 2007 (commit 405849610fd96b4f34cd1875c4c033228fea6c0f): [MATH-EMU]: Fix underflow exception reporting. 2) we ended up rounding back up to normal (this is the case where we set the exponent to 1 and set the fraction to zero), this should set inexact too ... Another example, "0x0.0000000000001p-1022 / 16.0", should signal both inexact and underflow. The cpu implementations and ieee1754 literature is very clear about this. This is case #2 above. Here is the distilled glibc test case from Jakub Jelinek which prompted that commit: -------------------- #include #include #include volatile double d = DBL_MIN; volatile double e = 0x0.0000000000001p-1022; volatile double f = 16.0; int main (void) { printf ("%x\n", fetestexcept (FE_UNDERFLOW)); d /= f; printf ("%x\n", fetestexcept (FE_UNDERFLOW)); e /= f; printf ("%x\n", fetestexcept (FE_UNDERFLOW)); return 0; } -------------------- It looks like the case I have we are exact before rounding, but think it looks like the rounding case since it appears as if "overflow is set". 000.FFFFFFFFFFFFF / 3FE.FFFFFFFFFFFFE = 001.0000000000000 I think the following adds the check for my case and still works for the issue your commit was trying to resolve. Signed-off-by: David S. Miller