502078 - Allow ARM VFP to be enabled (or not) by configure.py

Status: VERIFIED FIXED

(Tamarin Graveyard :: Build Config, enhancement)

Description

[Steven Johnson]

add something like --enable-vfp to target VFP-enabled processors; currently we default to no VFP support without intrusive code hackery in avmshell

Comment 1

[Rick Reitmaier]

We'll need to enable both the compiler flags -mfloat-abi=softfp -mfpu=vfp and NJ_ARM_VFP in NativeARM.h

Comment 2

[Rick Reitmaier]

Attachment: ver1 - barebones configure.py change

Comment 3

[Steven Johnson]

cool -- this still requires hacking NativeARM to define NJ_ARM_VFP ... couldn't we make that definition conditional on __VFP_FP__ being defined ? that would at least give us the correct default for common gcc arm compilers.

Comment 4

[Rick Reitmaier]

Yes this is only 1/2 the change (or less).  avmfeatures.as needs updating for the JIT component.   

And yes good suggestion regarding pulling the compiler flag, but I'm thinking we'll want to stay away from that for the longer term.  

I'm not sure how others feel, but I'm not keen on relying on compiler defines; 90% of the time the right thing happens, but then you spend hours on the 10% case when a build doesn't work out the way you expect because some *hidden* define was [un]set.

Comment 5

[Rick Reitmaier]

Attachment: ver 2 - contains all changes

Outside of this patch, but do we want to clean up the 'memory-profiler' option.

It appears that there are a few cases (besides this one) where we need both a #define set and some additional compiler settings.  

Right now avmfeatures.featureSettings only allows the defines, but should we also put other compiler settings in there?

Comment 6

[Lars T Hansen]

Comment on attachment 386659 [details] [diff] [review]
ver 2 - contains all changes 

This is probably an AVMSYSTEM_ define and not an AVMFEATURE_ define.  Not to go all hair-splitting on you but AVMSYSTEM_ deals with environmental parameters (hw, os), and this appears to be one such.  Consider it approved with that change.

For now I would document the necessary compiler switches in the doc block in avmfeatures.as.  There's an ongoing discussion about using avmfeatures.as to hold default settings for configure.py to pick up (so that we can make --enable-X and --disable-X work properly), and I like the idea of having specific compiler settings recorded in that file as well.

Comment 7

[Lars T Hansen]

(In reply to comment #6)
> (From update of attachment 386659 [details] [diff] [review])
> 
> There's an ongoing discussion about using avmfeatures.as to
> hold default settings for configure.py to pick up 

Oops.  There's an ongoing discussion about using avmshell-features.h to hold the default settings, avmfeatures.as should be default-free (as the whole point is that it documents available functionality but is unbiased about how to provide that).

Documenting compiler switches in the doc block is probably a good idea in the short term, and then we can see if it makes sense to record them structurally either in this file or in some other file later.

Comment 8

[Edwin Smith]

If we aren't going to use compiler-defined switches to enable/disable VFP support, and instead use our feature system, then at least we should have somthing in there which will #error out if the features dont agree with predefined compiler switches (on compilers where we know they're available).

possible errors:
 - enabling VFP in JIT when C++ doesn't use it
 - using soft float when C++ uses VFP

Comment 9

[Rick Reitmaier]

pushed http://hg.mozilla.org/tamarin-redux/rev/18a04b86db8a 

have adjusted feature->system and will not cover cases outlined in comment #8 until we settle on above mentioned issues.

Comment 10

[Rick Reitmaier]

pushed http://hg.mozilla.org/tamarin-redux/rev/1a641036cacd as fix-up

Comment 11

[Rick Reitmaier]

re-opening - since debug builds are not affected by --enable-arm-fpu.

OPT_CXXFLAGS is affected which only applied to release builds.

Comment 12

[Brent Baker]

Attachment: Add fpu support for winmo builds

usage:
../configure.py --enable-shell --target=arm-windows --enable-arm-fpu

Comment 13

[Rick Reitmaier]

Oh forgot to mention...does help show the --enable-arm-fpu option?

Comment 14

[Rick Reitmaier]

moving to resolved, can open a new bug if we need any further changes.

Comment 15

[Brent Baker]

yes --enable-arm-fpu does show up in the help.

Comment 16

[Brent Baker]

Comment on attachment 410221 [details] [diff] [review]
Add fpu support for winmo builds

Pushed changeset:   3008:204bddb24cee

Comment 17

[Brent Baker]

in-testsuite+, build system is building with --enable-arm-neon for arm-linux (VFP support) and without VFP support for windows mobile