Hello Bill, On Wed, 19 Nov 2014 11:31:05 -0500, Bill Pringlemeir <bpringlem...@nbsps.com> wrote: > On 19 Nov 2014, w...@denx.de wrote: > > > Dear Albert, > > > > In message <20141119074214.3d414ce6@lilith> you wrote: > >> > >> For -mauto-it, it is not documented in the gas documentation online > >> or in my current as' --target-help. I'll dig this deeper today, but > >> barring any scream from me, the change above is fine globally in > >> U-Boot. > > > Apparently this [1] is where it is coming from; no further > > documentation there, though. > > > [1] https://sourceware.org/ml/binutils/2009-05/msg00132.html > > I would think that if this worked they would make it automatic and not > an option. Probably this is only in certain binutils/as. > > With 4.6.3 and 4.9.1 I do not have this option,
Which option do you mean? -mimplicit-it or -mauto-it? > [foo.S] > .syntax unified > .thumb > foo: > cmp r0, #5 > movne r1,#6 > moveq r1,#2 > bx lr > bar: > cmp r0, #10 > movhi r1,#3 > movls r1,#7 > moveq r1,#11 > bx lr > > $ arm-none-linux-gnueabi.gcc4.6.3/bin/arm-none-linux-gnueabi-as > -mcpu=cortex-a5 -mimplicit-it=always foo.S -o foo.o > $ arm-none-linux-gnueabi-vybrid-4.9.1/bin/arm-none-linux-gnueabi-as > -mcpu=cortex-a5 -mimplicit-it=always foo.S -o foo.o > > Both give 'objdump -S foo.o', > foo.o: file format elf32-littlearm > > Disassembly of section .text: > > 00000000 <foo>: > 0: 2805 cmp r0, #5 > 2: bf14 ite ne > 4: 2106 movne r1, #6 > 6: 2102 moveq r1, #2 > 8: 4770 bx lr > > 0000000a <bar>: > a: 280a cmp r0, #10 > c: bf8c ite hi > e: 2103 movhi r1, #3 > 10: 2107 movls r1, #7 > 12: bf08 it eq > 14: 210b moveq r1, #11 > 16: 4770 bx lr > > I think before the patch there would be 'it' values before each and > every condition. In fact, if you change 'bar' to, > > bar: > cmp r0, #10 > movhi r1,#3 > movlo r1,#7 > moveq r1,#11 > bx lr > > You get three 'IT' conditions as 'HI' and 'LO' are not opposite. The > patch seem to detect things that are the exact opposite. The 'bar' > above ends up with '11' in r1 if the value is zero, but it temporarily > '7'. The 2nd bar will only place 11 in r1. > > Fwiw, > Bill Pringlemeir. > > Ref: https://wiki.ubuntu.com/ARM/Thumb2PortingHowto#Conditional_Execution All this is about -mimplicit-it, which *is* documented, *is* consistently present in common toolchains AFAICT and is and (as) logcical (as it can be when dealing with backward compatibility of command lines etc). However, my problem is not with -mimplicit-it; it is with -mauto-it. My gut feeling is that -mauto-it is a predecessor of -mimplicit-it. Amicalement, -- Albert. _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot