cmd/compile: move ssagen.dvarint to objw.Uvarint

Follow up discussion in CL 535077.

Change-Id: I102c90839e39c463e878ff925872376303724e12
Reviewed-on: https://go-review.googlesource.com/c/go/+/535636
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Than McIntosh <thanm@google.com>
Auto-Submit: Cuong Manh Le <cuong.manhle.vn@gmail.com>

2 files changed, 11 insertions, 16 deletions

diff --git a/src/cmd/compile/internal/objw/objw.go b/src/cmd/compile/internal/objw/objw.go
index ec1be325f7..77744672c1 100644
--- a/src/cmd/compile/internal/objw/objw.go
+++ b/src/cmd/compile/internal/objw/objw.go
@@ -9,6 +9,7 @@ import (
 	"cmd/compile/internal/bitvec"
 	"cmd/compile/internal/types"
 	"cmd/internal/obj"
+	"encoding/binary"
 )
 
 // Uint8 writes an unsigned byte v into s at offset off,
@@ -29,6 +30,14 @@ func Uintptr(s *obj.LSym, off int, v uint64) int {
 	return UintN(s, off, v, types.PtrSize)
 }
 
+// Uvarint writes a varint v into s at offset off,
+// and returns the next unused offset.
+func Uvarint(s *obj.LSym, off int, v uint64) int {
+	var buf [binary.MaxVarintLen64]byte
+	n := binary.PutUvarint(buf[:], v)
+	return int(s.WriteBytes(base.Ctxt, int64(off), buf[:n]))
+}
+
 func Bool(s *obj.LSym, off int, v bool) int {
 	w := 0
 	if v {
diff --git a/src/cmd/compile/internal/ssagen/ssa.go b/src/cmd/compile/internal/ssagen/ssa.go
index d3671a9773..5d5c79e581 100644
--- a/src/cmd/compile/internal/ssagen/ssa.go
+++ b/src/cmd/compile/internal/ssagen/ssa.go
@@ -7,7 +7,6 @@ package ssagen
 import (
 	"bufio"
 	"bytes"
-	"encoding/binary"
 	"fmt"
 	"go/constant"
 	"html"
@@ -257,19 +256,6 @@ func abiForFunc(fn *ir.Func, abi0, abi1 *abi.ABIConfig) *abi.ABIConfig {
 	return a
 }
 
-// dvarint writes a varint v to the funcdata in symbol x and returns the new offset.
-func dvarint(x *obj.LSym, off int, v int64) int {
-	if v < 0 {
-		panic(fmt.Sprintf("dvarint: bad offset for funcdata - %v", v))
-	}
-	var buf [binary.MaxVarintLen64]byte
-	n := binary.PutUvarint(buf[:], uint64(v))
-	for _, b := range buf[:n] {
-		off = objw.Uint8(x, off, b)
-	}
-	return off
-}
-
 // emitOpenDeferInfo emits FUNCDATA information about the defers in a function
 // that is using open-coded defers.  This funcdata is used to determine the active
 // defers in a function and execute those defers during panic processing.
@@ -298,8 +284,8 @@ func (s *state) emitOpenDeferInfo() {
 	s.curfn.LSym.Func().OpenCodedDeferInfo = x
 
 	off := 0
-	off = dvarint(x, off, -s.deferBitsTemp.FrameOffset())
-	off = dvarint(x, off, -firstOffset)
+	off = objw.Uvarint(x, off, uint64(-s.deferBitsTemp.FrameOffset()))
+	off = objw.Uvarint(x, off, uint64(-firstOffset))
 }
 
 // buildssa builds an SSA function for fn.