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On 05/29/14 13:19, Yufeng Zhang wrote:
Hi Martin, On 05/29/14 13:00, Martin Storsjo wrote:The syntax described, including a leading '#', was not supported in practice. (For :lo12: it is optional.)I believe this is an issue in the parser; '#' should be optional in either case. It looks like gas/config/tc-aarch64.c:parse_adrp () is missing the skip_past_char (&p, '#') at its beginning; see parse_half () for an example.
After spending some time this afternoon reading ARMv8 Architecture Reference Manual (ARMARM) and having a discussion with a colleague, I think I'll have to take back what I just said. Sorry!
The A64 assembly language allows the optional # character to introduce constant immediate operands, e.g. in LDR instructions with immediate offset:
LDR <Wt>, [<Xn|SP>], #<simm> and in the bitfield move instructions: BFM <Wd>, <Wn>, #<immr>, #<imms> The ADRP instruction, however, has the following syntax: ADRP <Xd>, <label>whose second operand is a program label whose 4KB page address is to be calculated, and for such a operand, it doesn't make much sense to allow the # character as an optional prefix, e.g. ADRP X0, #foo would look weird and confusing.
So I think your original patch is the right one to go with, and my only comment is to remove both # characters from the line of
" @samp{#:pg_hi21:} and @samp{#:lo12:} respectively. " Apologize again for the previous wrong direction. Please get an approval from Marcus. Thanks, Yufeng
Yufeng--- gas/doc/c-aarch64.texi | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/gas/doc/c-aarch64.texi b/gas/doc/c-aarch64.texi index cce4f61..1f4ce4c 100644 --- a/gas/doc/c-aarch64.texi +++ b/gas/doc/c-aarch64.texi @@ -186,24 +186,24 @@ For example to load the 48-bit absolute address of @var{foo} into x0: @cindex ADRP, ADD, LDR/STR group relocations, AArch64 Relocations for @samp{ADRP}, and @samp{ADD}, @samp{LDR} or @samp{STR} instructions can be generated by prefixing the label with -@samp{#:pg_hi21:} and @samp{#:lo12:} respectively. +@samp{:pg_hi21:} and @samp{#:lo12:} respectively. For example to use 33-bit (+/-4GB) pc-relative addressing to load the address of @var{foo} into x0: @smallexample - adrp x0, #:pg_hi21:foo + adrp x0, :pg_hi21:foo add x0, x0, #:lo12:foo @end smallexample Or to load the value of @var{foo} into x0: @smallexample - adrp x0, #:pg_hi21:foo + adrp x0, :pg_hi21:foo ldr x0, [x0, #:lo12:foo] @end smallexample -Note that @samp{#:pg_hi21:} is optional. +Note that @samp{:pg_hi21:} is optional. @smallexample adrp x0, foo @@ -212,7 +212,7 @@ Note that @samp{#:pg_hi21:} is optional. is equivalent to @smallexample - adrp x0, #:pg_hi21:foo + adrp x0, :pg_hi21:foo @end smallexample @node AArch64 Floating Point
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