cmd/compile: optimize abi.Type.GCData loads

This fires in just one place; stkframe.go's stkobjinit. But, it does
make the struct literal entirely constants.

Change-Id: Ice76cb3cddd97adee011fdaab40597839da2e89f
Reviewed-on: https://go-review.googlesource.com/c/go/+/701300
Reviewed-by: Keith Randall <khr@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Keith Randall <khr@google.com>
Reviewed-by: Mark Freeman <markfreeman@google.com>
Auto-Submit: Michael Pratt <mpratt@google.com>

diff --git a/src/cmd/compile/internal/liveness/plive.go b/src/cmd/compile/internal/liveness/plive.go
index 7e724397dcfd6278d2b5254e396c803cdf59b34f..9b8f15e9c276f78042824fb4ade3d96780b08d0e 100644 (file)
--- a/src/cmd/compile/internal/liveness/plive.go
+++ b/src/cmd/compile/internal/liveness/plive.go
@@ -1493,7 +1493,7 @@ func (lv *Liveness) emitStackObjects() *obj.LSym {
                if sz != int64(int32(sz)) {
                        base.Fatalf("stack object too big: %v of type %v, size %d", v, t, sz)
                }
-               lsym, ptrBytes := reflectdata.GCSym(t)
+               lsym, ptrBytes := reflectdata.GCSym(t, false)
                off = objw.Uint32(x, off, uint32(sz))
                off = objw.Uint32(x, off, uint32(ptrBytes))
                off = objw.SymPtrOff(x, off, lsym)

diff --git a/src/cmd/compile/internal/reflectdata/reflect.go b/src/cmd/compile/internal/reflectdata/reflect.go
index 15173c54dcc2a357c11a7c27ab94748cd9308e41..38b9391c5f1a572cc0e9d88b61aa83b2d28d55fd 100644 (file)
--- a/src/cmd/compile/internal/reflectdata/reflect.go
+++ b/src/cmd/compile/internal/reflectdata/reflect.go
@@ -1229,7 +1229,7 @@ func typesStrCmp(a, b typeAndStr) int {
 // GC information is always a bitmask, never a gc program.
 // GCSym may be called in concurrent backend, so it does not emit the symbol
 // content.
-func GCSym(t *types.Type) (lsym *obj.LSym, ptrdata int64) {
+func GCSym(t *types.Type, onDemandAllowed bool) (lsym *obj.LSym, ptrdata int64) {
        // Record that we need to emit the GC symbol.
        gcsymmu.Lock()
        if _, ok := gcsymset[t]; !ok {
@@ -1237,7 +1237,7 @@ func GCSym(t *types.Type) (lsym *obj.LSym, ptrdata int64) {
        }
        gcsymmu.Unlock()
 
-       lsym, _, ptrdata = dgcsym(t, false, false)
+       lsym, _, ptrdata = dgcsym(t, false, onDemandAllowed)
        return
 }
 

diff --git a/src/cmd/compile/internal/ssa/rewrite.go b/src/cmd/compile/internal/ssa/rewrite.go
index 6fb2689d180f3835bffcdd9da87bfab9d45a312b..6d83ba565317a3e56fd62d41f5e94f61305b896e 100644 (file)
--- a/src/cmd/compile/internal/ssa/rewrite.go
+++ b/src/cmd/compile/internal/ssa/rewrite.go
@@ -2067,7 +2067,7 @@ func isFixedLoad(v *Value, sym Sym, off int64) bool {
                for _, f := range rttype.Type.Fields() {
                        if f.Offset == off && copyCompatibleType(v.Type, f.Type) {
                                switch f.Sym.Name {
-                               case "Size_", "PtrBytes", "Hash", "Kind_":
+                               case "Size_", "PtrBytes", "Hash", "Kind_", "GCData":
                                        return true
                                default:
                                        // fmt.Println("unknown field", f.Sym.Name)
@@ -2147,6 +2147,12 @@ func rewriteFixedLoad(v *Value, sym Sym, sb *Value, off int64) *Value {
                                        v.reset(OpConst8)
                                        v.AuxInt = int64(reflectdata.ABIKindOfType(t))
                                        return v
+                               case "GCData":
+                                       gcdata, _ := reflectdata.GCSym(t, true)
+                                       v.reset(OpAddr)
+                                       v.Aux = symToAux(gcdata)
+                                       v.AddArg(sb)
+                                       return v
                                default:
                                        base.Fatalf("unknown field %s for fixedLoad of %s at offset %d", f.Sym.Name, lsym.Name, off)
                                }