internal/buildcfg: move build configuration out of cmd/internal/objabi

The go/build package needs access to this configuration,
so move it into a new package available to the standard library.

Change-Id: I868a94148b52350c76116451f4ad9191246adcff
Reviewed-on: https://go-review.googlesource.com/c/go/+/310731
Trust: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
Reviewed-by: Jay Conrod <jayconrod@google.com>

3 files changed, 16 insertions, 13 deletions

diff --git a/src/cmd/compile/internal/ssagen/abi.go b/src/cmd/compile/internal/ssagen/abi.go
index 8103b08ce5..7d56362302 100644
--- a/src/cmd/compile/internal/ssagen/abi.go
+++ b/src/cmd/compile/internal/ssagen/abi.go
@@ -6,6 +6,7 @@ package ssagen
 
 import (
 	"fmt"
+	"internal/buildcfg"
 	"io/ioutil"
 	"log"
 	"os"
@@ -213,7 +214,7 @@ func (s *SymABIs) GenABIWrappers() {
 			base.Fatalf("cgo exported function %s cannot have ABI wrappers", fn)
 		}
 
-		if !objabi.Experiment.RegabiWrappers {
+		if !buildcfg.Experiment.RegabiWrappers {
 			// We'll generate ABI aliases instead of
 			// wrappers once we have LSyms in InitLSym.
 			continue
@@ -241,7 +242,7 @@ func InitLSym(f *ir.Func, hasBody bool) {
 		if f.Pragma&ir.Systemstack != 0 {
 			f.LSym.Set(obj.AttrCFunc, true)
 		}
-		if f.ABI == obj.ABIInternal || !objabi.Experiment.RegabiWrappers {
+		if f.ABI == obj.ABIInternal || !buildcfg.Experiment.RegabiWrappers {
 			// Function values can only point to
 			// ABIInternal entry points. This will create
 			// the funcsym for either the defining
@@ -253,7 +254,7 @@ func InitLSym(f *ir.Func, hasBody bool) {
 			// when we see that.
 			staticdata.NeedFuncSym(f)
 		}
-		if !objabi.Experiment.RegabiWrappers {
+		if !buildcfg.Experiment.RegabiWrappers {
 			// Create ABI aliases instead of wrappers.
 			forEachWrapperABI(f, makeABIAlias)
 		}
diff --git a/src/cmd/compile/internal/ssagen/pgen.go b/src/cmd/compile/internal/ssagen/pgen.go
index 92f6f562f3..62567535d7 100644
--- a/src/cmd/compile/internal/ssagen/pgen.go
+++ b/src/cmd/compile/internal/ssagen/pgen.go
@@ -5,6 +5,7 @@
 package ssagen
 
 import (
+	"internal/buildcfg"
 	"internal/race"
 	"math/rand"
 	"sort"
@@ -215,7 +216,7 @@ func StackOffset(slot ssa.LocalSlot) int32 {
 		if base.Ctxt.FixedFrameSize() == 0 {
 			off -= int64(types.PtrSize)
 		}
-		if objabi.FramePointerEnabled {
+		if buildcfg.FramePointerEnabled {
 			off -= int64(types.PtrSize)
 		}
 	}
@@ -228,7 +229,7 @@ func fieldtrack(fnsym *obj.LSym, tracked map[*obj.LSym]struct{}) {
 	if fnsym == nil {
 		return
 	}
-	if !objabi.Experiment.FieldTrack || len(tracked) == 0 {
+	if !buildcfg.Experiment.FieldTrack || len(tracked) == 0 {
 		return
 	}
 
diff --git a/src/cmd/compile/internal/ssagen/ssa.go b/src/cmd/compile/internal/ssagen/ssa.go
index 61f23a9c40..f0bce0756a 100644
--- a/src/cmd/compile/internal/ssagen/ssa.go
+++ b/src/cmd/compile/internal/ssagen/ssa.go
@@ -12,6 +12,7 @@ import (
 	"fmt"
 	"go/constant"
 	"html"
+	"internal/buildcfg"
 	"os"
 	"path/filepath"
 	"sort"
@@ -227,7 +228,7 @@ const magicLastTypeName = "MagicLastTypeNameForTestingRegisterABI"
 // abiForFunc implements ABI policy for a function, but does not return a copy of the ABI.
 // Passing a nil function returns the default ABI based on experiment configuration.
 func abiForFunc(fn *ir.Func, abi0, abi1 *abi.ABIConfig) *abi.ABIConfig {
-	if objabi.Experiment.RegabiArgs {
+	if buildcfg.Experiment.RegabiArgs {
 		// Select the ABI based on the function's defining ABI.
 		if fn == nil {
 			return abi1
@@ -4646,7 +4647,7 @@ func (s *state) openDeferRecord(n *ir.CallExpr) {
 	var args []*ssa.Value
 	var argNodes []*ir.Name
 
-	if objabi.Experiment.RegabiDefer && (len(n.Args) != 0 || n.Op() == ir.OCALLINTER || n.X.Type().NumResults() != 0) {
+	if buildcfg.Experiment.RegabiDefer && (len(n.Args) != 0 || n.Op() == ir.OCALLINTER || n.X.Type().NumResults() != 0) {
 		s.Fatalf("defer call with arguments or results: %v", n)
 	}
 
@@ -4883,7 +4884,7 @@ func (s *state) call(n *ir.CallExpr, k callKind, returnResultAddr bool) *ssa.Val
 
 	callABI := s.f.ABIDefault
 
-	if !objabi.Experiment.RegabiArgs {
+	if !buildcfg.Experiment.RegabiArgs {
 		var magicFnNameSym *types.Sym
 		if fn.Name() != nil {
 			magicFnNameSym = fn.Name().Sym()
@@ -4901,7 +4902,7 @@ func (s *state) call(n *ir.CallExpr, k callKind, returnResultAddr bool) *ssa.Val
 		}
 	}
 
-	if objabi.Experiment.RegabiDefer && k != callNormal && (len(n.Args) != 0 || n.Op() == ir.OCALLINTER || n.X.Type().NumResults() != 0) {
+	if buildcfg.Experiment.RegabiDefer && k != callNormal && (len(n.Args) != 0 || n.Op() == ir.OCALLINTER || n.X.Type().NumResults() != 0) {
 		s.Fatalf("go/defer call with arguments: %v", n)
 	}
 
@@ -4910,7 +4911,7 @@ func (s *state) call(n *ir.CallExpr, k callKind, returnResultAddr bool) *ssa.Val
 		if k == callNormal && fn.Op() == ir.ONAME && fn.(*ir.Name).Class == ir.PFUNC {
 			fn := fn.(*ir.Name)
 			callee = fn
-			if objabi.Experiment.RegabiArgs {
+			if buildcfg.Experiment.RegabiArgs {
 				// This is a static call, so it may be
 				// a direct call to a non-ABIInternal
 				// function. fn.Func may be nil for
@@ -4951,7 +4952,7 @@ func (s *state) call(n *ir.CallExpr, k callKind, returnResultAddr bool) *ssa.Val
 		}
 	}
 
-	if !objabi.Experiment.RegabiArgs {
+	if !buildcfg.Experiment.RegabiArgs {
 		if regAbiForFuncType(n.X.Type().FuncType()) {
 			// Magic last type in input args to call
 			callABI = s.f.ABI1
@@ -5135,7 +5136,7 @@ func (s *state) call(n *ir.CallExpr, k callKind, returnResultAddr bool) *ssa.Val
 // maybeNilCheckClosure checks if a nil check of a closure is needed in some
 // architecture-dependent situations and, if so, emits the nil check.
 func (s *state) maybeNilCheckClosure(closure *ssa.Value, k callKind) {
-	if Arch.LinkArch.Family == sys.Wasm || objabi.GOOS == "aix" && k != callGo {
+	if Arch.LinkArch.Family == sys.Wasm || buildcfg.GOOS == "aix" && k != callGo {
 		// On AIX, the closure needs to be verified as fn can be nil, except if it's a call go. This needs to be handled by the runtime to have the "go of nil func value" error.
 		// TODO(neelance): On other architectures this should be eliminated by the optimization steps
 		s.nilCheck(closure)
@@ -6881,7 +6882,7 @@ func defframe(s *State, e *ssafn, f *ssa.Func) {
 	// and not address-taken (for non-SSA-able or address-taken arguments we always
 	// spill upfront).
 	// TODO(register args) Make liveness more fine-grained to that partial spilling is okay.
-	if objabi.Experiment.RegabiArgs {
+	if buildcfg.Experiment.RegabiArgs {
 		// First, see if it is already spilled before it may be live. Look for a spill
 		// in the entry block up to the first safepoint.
 		type nameOff struct {