cmd/internal/obj/riscv: add comments for Go registers

Change-Id: Id9aa6ba268eee67f2dc74096d4ec3bc0a80aefe2
Reviewed-on: https://go-review.googlesource.com/c/go/+/223563
Reviewed-by: Cherry Zhang <cherryyz@google.com>

diff --git a/src/cmd/internal/obj/riscv/cpu.go b/src/cmd/internal/obj/riscv/cpu.go
index 632b3e66905bf2f0e7106b60f2d074e6b4022eeb..76457dd8d27c6123ce3f79d36f4eef42da5d83e9 100644 (file)
--- a/src/cmd/internal/obj/riscv/cpu.go
+++ b/src/cmd/internal/obj/riscv/cpu.go
@@ -106,7 +106,7 @@ const (
 
        // General registers reassigned to ABI names.
        REG_ZERO = REG_X0
-       REG_RA   = REG_X1
+       REG_RA   = REG_X1 // aka REG_LR
        REG_SP   = REG_X2
        REG_GP   = REG_X3 // aka REG_SB
        REG_TP   = REG_X4 // aka REG_G
@@ -125,7 +125,7 @@ const (
        REG_A7   = REG_X17
        REG_S2   = REG_X18
        REG_S3   = REG_X19
-       REG_S4   = REG_X20
+       REG_S4   = REG_X20 // aka REG_CTXT
        REG_S5   = REG_X21
        REG_S6   = REG_X22
        REG_S7   = REG_X23
@@ -136,7 +136,7 @@ const (
        REG_T3   = REG_X28
        REG_T4   = REG_X29
        REG_T5   = REG_X30
-       REG_T6   = REG_X31
+       REG_T6   = REG_X31 // aka REG_TMP
 
        // Go runtime register names.
        REG_G    = REG_TP // G pointer.