cmd/internal/obj/riscv: handle MOV rewrites in separate pass

Handle the rewriting of MOV pseudo-instructions in a separate pass. This allows
AMOV to be more readily used by other code, including AGETCALLERPC and ARET
implementations.

Updates #27532

Change-Id: Iea794121210048ed23ed0fb8f3c5e3cd5354a311
Reviewed-on: https://go-review.googlesource.com/c/go/+/212758
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

diff --git a/src/cmd/internal/obj/riscv/obj.go b/src/cmd/internal/obj/riscv/obj.go
index 4117438d9511a0e90e225943b0a150480547e08b..2e9ac6750b1ea4608bb3d2cdc6f75cc0db3665dc 100644 (file)
--- a/src/cmd/internal/obj/riscv/obj.go
+++ b/src/cmd/internal/obj/riscv/obj.go
@@ -594,9 +594,8 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
        // Additional instruction rewriting. Any rewrites that change the number
        // of instructions must occur here (before jump target resolution).
        for p := cursym.Func.Text; p != nil; p = p.Link {
-               if p.As == obj.AGETCALLERPC {
-                       // Handle AGETCALLERPC early so we can use AMOV, which is then
-                       // rewritten below.
+               switch p.As {
+               case obj.AGETCALLERPC:
                        if cursym.Leaf() {
                                // MOV LR, Rd
                                p.As = AMOV
@@ -608,14 +607,6 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
                                p.From.Type = obj.TYPE_MEM
                                p.From.Reg = REG_SP
                        }
-               }
-
-               switch p.As {
-               case AMOV, AMOVB, AMOVH, AMOVW, AMOVBU, AMOVHU, AMOVWU, AMOVF, AMOVD:
-                       // Rewrite MOV pseudo-instructions. This cannot be done in
-                       // progedit, as SP offsets need to be applied before we split
-                       // up some of the Addrs.
-                       rewriteMOV(ctxt, newprog, p)
 
                case obj.ACALL:
                        switch p.To.Type {
@@ -666,6 +657,16 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
                }
        }
 
+       // Rewrite MOV pseudo-instructions. This cannot be done in
+       // progedit, as SP offsets need to be applied before we split
+       // up some of the Addrs.
+       for p := cursym.Func.Text; p != nil; p = p.Link {
+               switch p.As {
+               case AMOV, AMOVB, AMOVH, AMOVW, AMOVBU, AMOVHU, AMOVWU, AMOVF, AMOVD:
+                       rewriteMOV(ctxt, newprog, p)
+               }
+       }
+
        // Split immediates larger than 12-bits.
        for p := cursym.Func.Text; p != nil; p = p.Link {
                switch p.As {