I want find mechanism Encoding-Decoding of prefix REX2. I'm talking about the x64 architecture. By the way, REX2 including itself r16-r31 registers.
REX - r8-r15
Example using:
mov %r29, %r31
Are there r0-r7 registers?
(rax - r0)... (rdi - r7), r8, ...
REX2 - r16-31
EGPR - REX2.
EGPR - Extends General Purpose Registers.
Hm, by the way which registers there is in the EGPR?
Is there a ModR/M for r16-r31 registers? Also, i don’t know which Linux package using REX2 registers.
I searched information, but I found smallest parts of Information.
Example: prompt: "r16-r31 registers" Results: r8-r15 exists
prompt: "x64 registers table" Results: table registers including r16-r31 and r16-r31(w|d|l) and this registers with APX.
What is APX?
I want find mechanism Encoding-Decoding of prefix REX2. I'm talking about the x64 architecture. By the way, REX2 including itself r16-r31 registers.
REX - r8-r15
Example using:
mov %r29, %r31
Are there r0-r7 registers?
(rax - r0)... (rdi - r7), r8, ...
REX2 - r16-31
EGPR - REX2.
EGPR - Extends General Purpose Registers.
Hm, by the way which registers there is in the EGPR?
Is there a ModR/M for r16-r31 registers? Also, i don’t know which Linux package using REX2 registers.
I searched information, but I found smallest parts of Information.
Example: prompt: "r16-r31 registers" Results: r8-r15 exists
prompt: "x64 registers table" Results: table registers including r16-r31 and r16-r31(w|d|l) and this registers with APX.
What is APX?
Share Improve this question edited Mar 11 at 18:04 Peter Cordes 368k49 gold badges717 silver badges981 bronze badges asked Mar 11 at 10:07 TaylerTayler 191 silver badge3 bronze badges 1- 1 I just added a tag wiki for [apx], stackoverflow/tags/apx/info . If anyone else wants to proof-read it, that'd be great. – Peter Cordes Commented Mar 11 at 19:26
1 Answer
Reset to default 2REX2 is indeed a new valid prefix for the Intel APX extensions to x86-64. They're a successor to AVX-512 (which suffers from many incompatible variants). APX indeed adds 16 more registers. You're probably not the target audience here if you're wondering about "R0-R7" (Those have historical names, not numbers, i.e. RAX, RBX, RCX, RDX, RSI, RDI, RBP, RSP).
There are no CPU's yet that have APX support. "Panther Cove" might arrive in a few years, but with Intels current problems these timelines are not at all certain.