cmd/dist,cmd/go: broaden use of asm macro GOEXPERIMENT_REGABI

This extends a change made in https://golang.org/cl/252258 to the go
command (to define an asm macro when GOEXPERIMENT=regabi is in
effect); we need this same macro during the bootstrap build in order
to build the runtime correctly.

In addition, expand the set of packages where the macro is applied to
{runtime, reflect, syscall, runtime/internal/*}, and move the logic
for deciding when something is a "runtime package" out of the
assembler and into cmd/{go,dist}, introducing a new assembler command
line flag instead.

Updates #27539, #40724.

Change-Id: Ifcc7f029f56873584de1e543c55b0d3e54ad6c49
Reviewed-on: https://go-review.googlesource.com/c/go/+/262317
Trust: Than McIntosh <thanm@google.com>
Run-TryBot: Than McIntosh <thanm@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

1 files changed, 35 insertions, 0 deletions

diff --git a/src/cmd/dist/build.go b/src/cmd/dist/build.go
index 398ed6bce1..11da38ebdf 100644
--- a/src/cmd/dist/build.go
+++ b/src/cmd/dist/build.go
@@ -832,6 +832,21 @@ func runInstall(pkg string, ch chan struct{}) {
 		asmArgs = append(asmArgs, "-D", "GOMIPS64_"+gomips64)
 	}
 	goasmh := pathf("%s/go_asm.h", workdir)
+	if IsRuntimePackagePath(pkg) {
+		asmArgs = append(asmArgs, "-compilingRuntime")
+		if os.Getenv("GOEXPERIMENT") == "regabi" {
+			// In order to make it easier to port runtime assembly
+			// to the register ABI, we introduce a macro
+			// indicating the experiment is enabled.
+			//
+			// Note: a similar change also appears in
+			// cmd/go/internal/work/gc.go.
+			//
+			// TODO(austin): Remove this once we commit to the
+			// register ABI (#40724).
+			asmArgs = append(asmArgs, "-D=GOEXPERIMENT_REGABI=1")
+		}
+	}
 
 	// Collect symabis from assembly code.
 	var symabis string
@@ -1733,3 +1748,23 @@ func cmdlist() {
 		fatalf("write failed: %v", err)
 	}
 }
+
+// IsRuntimePackagePath examines 'pkgpath' and returns TRUE if it
+// belongs to the collection of "runtime-related" packages, including
+// "runtime" itself, "reflect", "syscall", and the
+// "runtime/internal/*" packages. See also the function of the same
+// name in cmd/internal/objabi/path.go.
+func IsRuntimePackagePath(pkgpath string) bool {
+	rval := false
+	switch pkgpath {
+	case "runtime":
+		rval = true
+	case "reflect":
+		rval = true
+	case "syscall":
+		rval = true
+	default:
+		rval = strings.HasPrefix(pkgpath, "runtime/internal")
+	}
+	return rval
+}