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cmd/compile: add ABI register definations for loong64

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Updates #40724

Co-authored-by: Xiaolin Zhao <zhaoxiaolin@loongson.cn>
Change-Id: I56f7382dda58a565b8c3256f1c7845a3031f67de
Reviewed-on: https://go-review.googlesource.com/c/go/+/521776
Reviewed-by: Cherry Mui <cherryyz@google.com>
Run-TryBot: David Chase <drchase@google.com>
Auto-Submit: David Chase <drchase@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
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Guoqi Chen 2023-08-15 17:11:19 +08:00 committed by Gopher Robot
parent 08b9640333
commit 945c2bc74e
1 changed files with 50 additions and 0 deletions
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src/cmd/compile/abi-internal.md
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@ -633,6 +633,56 @@ modifying or saving the FPCR.
Functions are allowed to modify it between calls (as long as they
restore it), but as of this writing Go code never does.
### loong64 architecture
The loong64 architecture uses R4 – R19 for integer arguments and integer results.
It uses F0 – F15 for floating-point arguments and results.
Registers R20 - R21, R23 – R28, R30 - R31, F16 – F31 are permanent scratch registers.
Register R2 is reserved and never used.
Register R20, R21 is Used by runtime.duffcopy, runtime.duffzero.
Special-purpose registers used within Go generated code and Go assembly code
are as follows:
| Register | Call meaning | Return meaning | Body meaning |
| --- | --- | --- | --- |
| R0 | Zero value | Same | Same |
| R1 | Link register | Link register | Scratch |
| R3 | Stack pointer | Same | Same |
| R20,R21 | Scratch | Scratch | Used by duffcopy, duffzero |
| R22 | Current goroutine | Same | Same |
| R29 | Closure context pointer | Same | Same |
| R30, R31 | used by the assembler | Same | Same |
*Rationale*: These register meanings are compatible with Go’s stack-based
calling convention.
#### Stack layout
The stack pointer, R3, grows down and is aligned to 8 bytes.
A function's stack frame, after the frame is created, is laid out as
follows:
+------------------------------+
| ... locals ... |
| ... outgoing arguments ... |
| return PC | ← R3 points to
+------------------------------+ ↓ lower addresses
This stack layout is used by both register-based (ABIInternal) and
stack-based (ABI0) calling conventions.
The "return PC" is loaded to the link register, R1, as part of the
loong64 `JAL` operation.
#### Flags
All bits in CSR are system flags and are not modified by Go.
### ppc64 architecture
The ppc64 architecture uses R3 – R10 and R14 – R17 for integer arguments