cmd/compile,runtime: dedup writeBarrier needed

The writeBarrier "needed" struct member has the exact same
value as "enabled", and used interchangeably.

I'm not sure if we plan to make a distinction between the
two at some point, but today they are effectively the same,
so dedup it and keep only "enabled".

Change-Id: I65e596f174e1e820dc471a45ff70c0ef4efbc386
GitHub-Last-Rev: f8c805a91606d42c8d5b178ddd7d0bec7aaf9f55
GitHub-Pull-Request: golang/go#63814
Reviewed-on: https://go-review.googlesource.com/c/go/+/538495
Reviewed-by: Keith Randall <khr@google.com>
Reviewed-by: Heschi Kreinick <heschi@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Mauri de Souza Meneguzzo <mauri870@gmail.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

diff --git a/src/cmd/compile/internal/typecheck/_builtin/runtime.go b/src/cmd/compile/internal/typecheck/_builtin/runtime.go
index 3fc45ab80dda4f42462c268c9cbac3e2c387ec64..f16d0d48e5289d5b60c25d1ffd9cc3204612625b 100644 (file)
--- a/src/cmd/compile/internal/typecheck/_builtin/runtime.go
+++ b/src/cmd/compile/internal/typecheck/_builtin/runtime.go
@@ -160,7 +160,6 @@ func closechan(hchan any)
 var writeBarrier struct {
        enabled bool
        pad     [3]byte
-       needed  bool
        cgo     bool
        alignme uint64
 }

diff --git a/src/cmd/compile/internal/typecheck/builtin.go b/src/cmd/compile/internal/typecheck/builtin.go
index f8d8de53ce58a94c703f4053a232195877680880..96ddba8151c4b20eb91f4cc281e1eaf129cd687b 100644 (file)
--- a/src/cmd/compile/internal/typecheck/builtin.go
+++ b/src/cmd/compile/internal/typecheck/builtin.go
@@ -340,7 +340,7 @@ func runtimeTypes() []*types.Type {
        typs[102] = types.NewChan(typs[2], types.Csend)
        typs[103] = newSig(params(typs[102], typs[3]), nil)
        typs[104] = types.NewArray(typs[0], 3)
-       typs[105] = types.NewStruct([]*types.Field{types.NewField(src.NoXPos, Lookup("enabled"), typs[6]), types.NewField(src.NoXPos, Lookup("pad"), typs[104]), types.NewField(src.NoXPos, Lookup("needed"), typs[6]), types.NewField(src.NoXPos, Lookup("cgo"), typs[6]), types.NewField(src.NoXPos, Lookup("alignme"), typs[24])})
+       typs[105] = types.NewStruct([]*types.Field{types.NewField(src.NoXPos, Lookup("enabled"), typs[6]), types.NewField(src.NoXPos, Lookup("pad"), typs[104]), types.NewField(src.NoXPos, Lookup("cgo"), typs[6]), types.NewField(src.NoXPos, Lookup("alignme"), typs[24])})
        typs[106] = newSig(params(typs[1], typs[3], typs[3]), nil)
        typs[107] = newSig(params(typs[1], typs[3]), nil)
        typs[108] = newSig(params(typs[1], typs[3], typs[15], typs[3], typs[15]), params(typs[15]))

diff --git a/src/runtime/mbarrier.go b/src/runtime/mbarrier.go
index 159a298155eb950712ba1f1ddcf886df6c0ff2fa..456155e5486f155307f01f967d18385e80f26953 100644 (file)
--- a/src/runtime/mbarrier.go
+++ b/src/runtime/mbarrier.go
@@ -153,7 +153,7 @@ func typedmemmove(typ *abi.Type, dst, src unsafe.Pointer) {
        if dst == src {
                return
        }
-       if writeBarrier.needed && typ.PtrBytes != 0 {
+       if writeBarrier.enabled && typ.PtrBytes != 0 {
                bulkBarrierPreWrite(uintptr(dst), uintptr(src), typ.PtrBytes)
        }
        // There's a race here: if some other goroutine can write to
@@ -222,7 +222,7 @@ func reflectlite_typedmemmove(typ *_type, dst, src unsafe.Pointer) {
 //
 //go:nosplit
 func reflectcallmove(typ *_type, dst, src unsafe.Pointer, size uintptr, regs *abi.RegArgs) {
-       if writeBarrier.needed && typ != nil && typ.PtrBytes != 0 && size >= goarch.PtrSize {
+       if writeBarrier.enabled && typ != nil && typ.PtrBytes != 0 && size >= goarch.PtrSize {
                bulkBarrierPreWrite(uintptr(dst), uintptr(src), size)
        }
        memmove(dst, src, size)
@@ -277,7 +277,7 @@ func typedslicecopy(typ *_type, dstPtr unsafe.Pointer, dstLen int, srcPtr unsafe
        // and growslice and reflect_typedslicecopy check for pointers
        // before calling typedslicecopy.
        size := uintptr(n) * typ.Size_
-       if writeBarrier.needed {
+       if writeBarrier.enabled {
                pwsize := size - typ.Size_ + typ.PtrBytes
                bulkBarrierPreWrite(uintptr(dstPtr), uintptr(srcPtr), pwsize)
        }
@@ -307,7 +307,7 @@ func reflect_typedslicecopy(elemType *_type, dst, src slice) int {
 //
 //go:nosplit
 func typedmemclr(typ *_type, ptr unsafe.Pointer) {
-       if writeBarrier.needed && typ.PtrBytes != 0 {
+       if writeBarrier.enabled && typ.PtrBytes != 0 {
                bulkBarrierPreWrite(uintptr(ptr), 0, typ.PtrBytes)
        }
        memclrNoHeapPointers(ptr, typ.Size_)
@@ -320,7 +320,7 @@ func reflect_typedmemclr(typ *_type, ptr unsafe.Pointer) {
 
 //go:linkname reflect_typedmemclrpartial reflect.typedmemclrpartial
 func reflect_typedmemclrpartial(typ *_type, ptr unsafe.Pointer, off, size uintptr) {
-       if writeBarrier.needed && typ.PtrBytes != 0 {
+       if writeBarrier.enabled && typ.PtrBytes != 0 {
                bulkBarrierPreWrite(uintptr(ptr), 0, size)
        }
        memclrNoHeapPointers(ptr, size)
@@ -329,7 +329,7 @@ func reflect_typedmemclrpartial(typ *_type, ptr unsafe.Pointer, off, size uintpt
 //go:linkname reflect_typedarrayclear reflect.typedarrayclear
 func reflect_typedarrayclear(typ *_type, ptr unsafe.Pointer, len int) {
        size := typ.Size_ * uintptr(len)
-       if writeBarrier.needed && typ.PtrBytes != 0 {
+       if writeBarrier.enabled && typ.PtrBytes != 0 {
                bulkBarrierPreWrite(uintptr(ptr), 0, size)
        }
        memclrNoHeapPointers(ptr, size)

diff --git a/src/runtime/mbitmap.go b/src/runtime/mbitmap.go
index bae90c665a30a66fde7ace93194be117c5599a45..2bcf454797fbc57b870e2bb4a2b3a889dcf3d631 100644 (file)
--- a/src/runtime/mbitmap.go
+++ b/src/runtime/mbitmap.go
@@ -563,7 +563,7 @@ func bulkBarrierPreWrite(dst, src, size uintptr) {
        if (dst|src|size)&(goarch.PtrSize-1) != 0 {
                throw("bulkBarrierPreWrite: unaligned arguments")
        }
-       if !writeBarrier.needed {
+       if !writeBarrier.enabled {
                return
        }
        if s := spanOf(dst); s == nil {
@@ -633,7 +633,7 @@ func bulkBarrierPreWriteSrcOnly(dst, src, size uintptr) {
        if (dst|src|size)&(goarch.PtrSize-1) != 0 {
                throw("bulkBarrierPreWrite: unaligned arguments")
        }
-       if !writeBarrier.needed {
+       if !writeBarrier.enabled {
                return
        }
        buf := &getg().m.p.ptr().wbBuf
@@ -718,7 +718,7 @@ func typeBitsBulkBarrier(typ *_type, dst, src, size uintptr) {
                println("runtime: typeBitsBulkBarrier with type ", toRType(typ).string(), " with GC prog")
                throw("runtime: invalid typeBitsBulkBarrier")
        }
-       if !writeBarrier.needed {
+       if !writeBarrier.enabled {
                return
        }
        ptrmask := typ.GCData

diff --git a/src/runtime/mgc.go b/src/runtime/mgc.go
index f7f7eb45287f261fc8af81d9f0a60a638d47ca94..8a4c58888ed4745bb1e6151434160193474a2fba 100644 (file)
--- a/src/runtime/mgc.go
+++ b/src/runtime/mgc.go
@@ -218,7 +218,6 @@ var gcphase uint32
 var writeBarrier struct {
        enabled bool    // compiler emits a check of this before calling write barrier
        pad     [3]byte // compiler uses 32-bit load for "enabled" field
-       needed  bool    // identical to enabled, for now (TODO: dedup)
        alignme uint64  // guarantee alignment so that compiler can use a 32 or 64-bit load
 }
 
@@ -236,8 +235,7 @@ const (
 //go:nosplit
 func setGCPhase(x uint32) {
        atomic.Store(&gcphase, x)
-       writeBarrier.needed = gcphase == _GCmark || gcphase == _GCmarktermination
-       writeBarrier.enabled = writeBarrier.needed
+       writeBarrier.enabled = gcphase == _GCmark || gcphase == _GCmarktermination
 }
 
 // gcMarkWorkerMode represents the mode that a concurrent mark worker

diff --git a/src/runtime/mgcmark.go b/src/runtime/mgcmark.go
index aff6c2fb99255ff946b9d32f096803dff059a788..adf1d4fa2817b9f6106ac2f969ad9af5906b8aca 100644 (file)
--- a/src/runtime/mgcmark.go
+++ b/src/runtime/mgcmark.go
@@ -1064,7 +1064,7 @@ func gcDrainMarkWorkerFractional(gcw *gcWork) {
 //
 //go:nowritebarrier
 func gcDrain(gcw *gcWork, flags gcDrainFlags) {
-       if !writeBarrier.needed {
+       if !writeBarrier.enabled {
                throw("gcDrain phase incorrect")
        }
 
@@ -1178,7 +1178,7 @@ done:
 //go:nowritebarrier
 //go:systemstack
 func gcDrainN(gcw *gcWork, scanWork int64) int64 {
-       if !writeBarrier.needed {
+       if !writeBarrier.enabled {
                throw("gcDrainN phase incorrect")
        }