This is the mail archive of the
gcc-bugs@gcc.gnu.org
mailing list for the GCC project.
[Bug inline-asm/37621] New: Missing documentation for x86 inline assembler modifiers
- From: "n dot pipenbrinck at cubic dot org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 23 Sep 2008 12:12:52 -0000
- Subject: [Bug inline-asm/37621] New: Missing documentation for x86 inline assembler modifiers
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
I came across the following modifiers for inline assembler:
asm ("rorw $8, %w0" : "=q" (y) : "0" (x));
asm ("xchg %b0, %h0" : "=q" (y) : "0" (x));
They work very well. No bug in the compiler itself, but I haven't found
anything about them in the online documentation.
Note: The %w0, %b0 and %h0 modifiers allows us to access thesub-registers of a
32 bit register. E.g. if %0 is EAX, %w0 becomes AX, %b0 becomes AL and %h0
becomes AH.
--
Summary: Missing documentation for x86 inline assembler modifiers
Product: gcc
Version: 4.4.0
Status: UNCONFIRMED
Severity: minor
Priority: P3
Component: inline-asm
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: n dot pipenbrinck at cubic dot org
GCC host triplet: x86
GCC target triplet: x86
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37621