reflect, runtime: drop RegabiArgs conditions

With the previous CL, internal/abi.IntArgRegs and FloatArgRegs
is controlled by RegabiArgs (or always enabled), so there is no
need to check for that goexperiment.

There are a few places we guard register-ABI specific code and
tests with the RegabiArgs flag. Switch to checking for the number
of argument registers instead.

Change-Id: I79fff9fd1e919684ffaf73aba9e7e85d5a9e1629
Reviewed-on: https://go-review.googlesource.com/c/go/+/393363
Trust: Cherry Mui <cherryyz@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Run-TryBot: Cherry Mui <cherryyz@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

src/reflect/abi.go

@@ -7,7 +7,6 @@ package reflect
 import (
 	"internal/abi"
 	"internal/goarch"
-	"internal/goexperiment"
 	"unsafe"
 )
 
@@ -30,9 +29,9 @@ import (
 // commented out there should be the actual values once
 // we're ready to use the register ABI everywhere.
 var (
-	intArgRegs   = abi.IntArgRegs * goexperiment.RegabiArgsInt
-	floatArgRegs = abi.FloatArgRegs * goexperiment.RegabiArgsInt
-	floatRegSize = uintptr(abi.EffectiveFloatRegSize * goexperiment.RegabiArgsInt)
+	intArgRegs   = abi.IntArgRegs
+	floatArgRegs = abi.FloatArgRegs
+	floatRegSize = uintptr(abi.EffectiveFloatRegSize)
 )
 
 // abiStep represents an ABI "instruction." Each instruction

src/runtime/debug_test.go

@@ -16,7 +16,6 @@ package runtime_test
 import (
 	"fmt"
 	"internal/abi"
-	"internal/goexperiment"
 	"math"
 	"os"
 	"regexp"
@@ -144,7 +143,7 @@ func TestDebugCall(t *testing.T) {
 	intRegs := regs.Ints[:]
 	floatRegs := regs.Floats[:]
 	fval := float64(42.0)
-	if goexperiment.RegabiArgs {
+	if len(intRegs) > 0 {
 		intRegs[0] = 42
 		floatRegs[0] = math.Float64bits(fval)
 	} else {
@@ -159,7 +158,7 @@ func TestDebugCall(t *testing.T) {
 	}
 	var result0 int
 	var result1 float64
-	if goexperiment.RegabiArgs {
+	if len(intRegs) > 0 {
 		result0 = int(intRegs[0])
 		result1 = math.Float64frombits(floatRegs[0])
 	} else {

src/runtime/stubs.go

@@ -7,7 +7,6 @@ package runtime
 import (
 	"internal/abi"
 	"internal/goarch"
-	"internal/goexperiment"
 	"runtime/internal/math"
 	"unsafe"
 )
@@ -434,4 +433,4 @@ func sigpanic0()
 // registers the system supports.
 //
 // Protected by finlock.
-var intArgRegs = abi.IntArgRegs * (goexperiment.RegabiArgsInt | goarch.IsAmd64)
+var intArgRegs = abi.IntArgRegs

src/runtime/traceback_test.go

@@ -6,7 +6,7 @@ package runtime_test
 
 import (
 	"bytes"
-	"internal/goexperiment"
+	"internal/abi"
 	"internal/testenv"
 	"runtime"
 	"strings"
@@ -23,7 +23,7 @@ func TestTracebackArgs(t *testing.T) {
 	abiSel := func(x, y string) string {
 		// select expected output based on ABI
 		// In noopt build we always spill arguments so the output is the same as stack ABI.
-		if optimized && goexperiment.RegabiArgs {
+		if optimized && abi.IntArgRegs > 0 {
 			return x
 		}
 		return y