http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51835
Mikael Pettersson <mikpe at it dot uu.se> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |mikpe at it dot uu.se
--- Comment #5 from Mikael Pettersson <mikpe at it dot uu.se> 2012-02-05
14:07:49 UTC ---
(In reply to comment #2)
> This is only applicable to the 4.6 branch and trunk since support for the
> Cortex M4 wasn't added till 4.6.
>
> cheers
> Ramana
Maybe the Cortex M4 wasn't added until 4.6, but the other options are permitted
by 4.5 and I can easily get 4.5 to produce wrong-looking code. With -O2
-mfloat-abi=hard -mfpu=fpv4-sp-d16 -march=armv7-a -marm I see the following
code generation difference between 4.5 and 4.6:
@@ -22,8 +22,9 @@
@ frame_needed = 0, uses_anonymous_args = 0
stmfd sp!, {r3, lr}
bl __aeabi_f2d
+ fmrrd r0, r1, d0
bl __aeabi_d2iz
ldmfd sp!, {r3, pc}
.size func, .-func
- .ident "GCC: (GNU) 4.5.4 20120126 (prerelease)"
+ .ident "GCC: (GNU) 4.6.3 20120203 (prerelease)"
.section .note.GNU-stack,"",%progbits
Backporting r183734 from 4.6 to 4.5 makes 4.5 generate the same code as 4.6,
i.e., with the fmrrd between the two calls.
