LTO can re-order top-level assembly blocks, which can cause this
macro definition to appear after its use (or not at all), causing
compilation failures. On modern toolchains (armv4t+), assembly
should write `bx lr` in all cases, and linkers will transparently
convert them to `mov pc, lr`, allowing us to simply remove the
macro.
(source: https://groups.google.com/forum/#!topic/comp.sys.arm/3l7fVGX-Wug
and verified empirically)
For the armv4.S file, preserve this macro to maximize backwards
compatibility.
ARM newlib has various strcmp implementations that use .cfi_*
directives to generate unwind information.
The effect of this is that the generated objects contain .eh_frame
sections. However, ARM uses its own unwind info format, not
.eh_frame, which is generated by ARM-specific directives, not .cfi_*.
The .eh_frame sections are useless, but also not removed by strip and
may be loaded into memory at runtime.
This patch fixes this by using .cfi_sections .debug_frame (as in
glibc) so that the directives generate .debug_frame instead.
.debug_frame is useful for the debugger, can be removed by strip, and
is not loaded into memory at runtime.
* libc/machine/arm/strcmp-arm-tiny.S: Use .cfi_sections
.debug_frame.
* libc/machine/arm/strcmp-armv4.S: Likewise.
* libc/machine/arm/strcmp-armv4t.S: Likewise.
* libc/machine/arm/strcmp-armv6.S: Likewise.
* libc/machine/arm/strcmp-armv6m.S: Likewise.
* libc/machine/arm/strcmp-armv7.S: Likewise.
* libc/machine/arm/strcmp-armv7m.S: Likewise.
* libc/machine/arm/strcmp-armv4.S: New file.
* libc/machine/arm/strcmp-armv4t.S: New file.
* libc/machine/arm/strcmp-armv6.S: New file.
* libc/machine/arm/strcmp-armv7.S: New file.
* libc/machine/arm/strcmp-armv7m.S: New file.
* libc/machine/arm/strcmp.S: Replace with wrapper for various
implementations.
* libc/machine/arm/Makefile.am (strcmp.o, strcmp.obj): Add
dependencies.
* libc/machine/arm/Makefile.in: Regenerated.
Pat Pannuto
Joseph Myers
Richard Earnshaw