Hi Nick, On 21 August 2018 at 00:40, Nick Desaulniers <ndesaulniers@xxxxxxxxxx> wrote: > It seems that: > ldr q8, =0x30000000200000001 > > is a GNU as convience notation for: > ldr q8, .Lconstant > .Lconstant > .word 0x00000001 > .word 0x00000002 > .word 0x00000003 > .word 0x00000000 > > based on this comment in binutils' source [0]. I've asked for this > non-standard convience notation to be added to other assemblers [1], but > until then, we can remove it and get equivalent disassembly: > What do you mean by 'non-standard convenience notation'? Which asm 'standard' does Clang actually claim to implement? This 'GCC/binutils is broken and we are reluctant to subvert Clang' attitude is getting a bit old tbh. In the future, could you please mention clang explicitly in the patch subject so it is obvious what the purpose of the patch is? I think we should accommodate Clang in Linux, but the attitude has got to go. > before: > 00000000000009d4 <neon_aes_ctr_encrypt>: > ... > a48: 9c000ac8 ldr q8, ba0 <neon_aes_ctr_encrypt+0x1cc> > ... > ba0: 00000001 .word 0x00000001 > ba4: 00000002 .word 0x00000002 > ba8: 00000003 .word 0x00000003 > bac: 00000000 .word 0x00000000 > > after: > > 00000000000009d4 <neon_aes_ctr_encrypt>: > ... > a48: 9c000aa8 ldr q8, b9c <neon_aes_ctr_encrypt+0x1c8> > ... > b9c: 00000001 .word 0x00000001 > ba0: 00000002 .word 0x00000002 > ba4: 00000003 .word 0x00000003 > ba8: 00000000 .word 0x00000000 > > [0] https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=blob;f=gas/testsuite/gas/aarch64/programmer-friendly.s;h=6254c6476efdc848648b05068be0574e7addc85d;hb=HEAD#l11 > [1] https://bugs.llvm.org/show_bug.cgi?id=38642 > > Signed-off-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx> > --- > arch/arm64/crypto/aes-modes.S | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/arch/arm64/crypto/aes-modes.S b/arch/arm64/crypto/aes-modes.S > index 483a7130cf0e..9288c5b0eca2 100644 > --- a/arch/arm64/crypto/aes-modes.S > +++ b/arch/arm64/crypto/aes-modes.S > @@ -232,7 +232,7 @@ AES_ENTRY(aes_ctr_encrypt) > bmi .Lctr1x > cmn w6, #4 /* 32 bit overflow? */ > bcs .Lctr1x > - ldr q8, =0x30000000200000001 /* addends 1,2,3[,0] */ > + ldr q8, .Laddends /* addends 1,2,3[,0] */ > dup v7.4s, w6 > mov v0.16b, v4.16b > add v7.4s, v7.4s, v8.4s > @@ -295,6 +295,12 @@ AES_ENTRY(aes_ctr_encrypt) > rev x7, x7 > ins v4.d[0], x7 > b .Lctrcarrydone > + > +.Laddends: > + .word 0x00000001 > + .word 0x00000002 > + .word 0x00000003 > + .word 0x00000000 As Will points out, this breaks BE builds. > AES_ENDPROC(aes_ctr_encrypt) > .ltorg You can drop this .ltorg if you get rid of all =xxx instances. Actually, though, I would prefer it if we could use some clever short sequence of movi+add instructions, and get rid of the literal altogether. Or otherwise, please use something like ldr_l q8, .Laddends, <temp register> instead, and move the literal into the .rodata section (and use .octa so you don't break BE)
