942561 - ARM, build with -mhard-float

Status: RESOLVED INCOMPLETE

(Core :: JavaScript Engine, defect)

Description

[Douglas Crosher [:dougc]]

The Android NDK r9b offers an approach for building an application with the -mhard-float compilation option while still linking to system libraries that use the soft-float convention.

Functions in the Android system header files that take or return fp values have a __attribute__((pcs("aapcs"))) declaration and thisforces the use of softfp ABI even when the application is compiled with -mhard-float.

This offers a path to building FF for Android and FxOS with the hard-float ABI which might help performance.  It would still need to use the softfp ABI when calling Android system libraries, even libm.

Given that FxOS proprietary system libraries likely depend on other system libraries it may still not be practical to build the non-proprietary system libraries with the -mhard-float option, but if it really helped performance then it might be practical to have a separate libm hard-float build to be linked with the b2g application.