[dev.regabi] cmd/compile: reshuffle type-checking code [generated]

This commit splits up typecheck.Package and moves the code
elsewhere. The type-checking code is moved into noder, so that it can
eventually be interleaved with the noding process. The
non-type-checking code is moved back into package gc, so that it can
be incorporated into appropriate compiler backend phases.

While here, deadcode removal is moved into its own package.

Passes toolstash -cmp.

[git-generate]
cd src/cmd/compile/internal/typecheck

: Split into two functions.
sed -i -e '/Phase 6/i}\n\nfunc postTypecheck() {' typecheck.go

rf '
	# Export needed identifiers.
	mv deadcode Deadcode
	mv loadsys InitRuntime
	mv declareUniverse DeclareUniverse
	mv dirtyAddrtaken DirtyAddrtaken
	mv computeAddrtaken ComputeAddrtaken
	mv incrementalAddrtaken IncrementalAddrtaken

	# Move into new package.
	mv Deadcode deadcodeslice deadcodeexpr deadcode.go
	mv deadcode.go cmd/compile/internal/deadcode

	# Move top-level type-checking code into noder.
	# Move DeclVars there too, now that nothing else uses it.
	mv DeclVars Package noder.go
	mv noder.go cmd/compile/internal/noder

	# Move non-type-checking code back into gc.
	mv postTypecheck main.go
	mv main.go cmd/compile/internal/gc
'

cd ../deadcode
rf '
	# Destutter names.
	mv Deadcode Func
	mv deadcodeslice stmts
	mv deadcodeexpr expr
'

cd ../noder
rf '
	# Move functions up, next to their related code.
	mv noder.go:/func Package/-1,$ \
		noder.go:/makeSrcPosBase translates/-1
	mv noder.go:/func DeclVars/-3,$ \
		noder.go:/constState tracks/-1
'

cd ../gc
rf '
	# Inline postTypecheck code back into gc.Main.
	mv main.go:/func postTypecheck/+0,/AllImportedBodies/+1 \
		main.go:/Build init task/-1
	rm postTypecheck
'

Change-Id: Ie5e992ece4a42204cce6aa98dd6eb52112d098c8
Reviewed-on: https://go-review.googlesource.com/c/go/+/280974
Trust: Matthew Dempsky <mdempsky@google.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>

1 files changed, 41 insertions, 1 deletions

diff --git a/src/cmd/compile/internal/gc/main.go b/src/cmd/compile/internal/gc/main.go
index 45219801f0..603619eb5a 100644
--- a/src/cmd/compile/internal/gc/main.go
+++ b/src/cmd/compile/internal/gc/main.go
@@ -8,6 +8,7 @@ import (
 	"bufio"
 	"bytes"
 	"cmd/compile/internal/base"
+	"cmd/compile/internal/deadcode"
 	"cmd/compile/internal/devirtualize"
 	"cmd/compile/internal/dwarfgen"
 	"cmd/compile/internal/escape"
@@ -210,12 +211,51 @@ func Main(archInit func(*ssagen.ArchInfo)) {
 	dwarfgen.RecordPackageName()
 
 	// Typecheck.
-	typecheck.Package()
+	noder.Package()
 
 	// With all user code typechecked, it's now safe to verify unused dot imports.
 	noder.CheckDotImports()
 	base.ExitIfErrors()
+	// Phase 6: Compute Addrtaken for names.
+	// We need to wait until typechecking is done so that when we see &x[i]
+	// we know that x has its address taken if x is an array, but not if x is a slice.
+	// We compute Addrtaken in bulk here.
+	// After this phase, we maintain Addrtaken incrementally.
+	if typecheck.DirtyAddrtaken {
+		typecheck.ComputeAddrtaken(typecheck.Target.Decls)
+		typecheck.DirtyAddrtaken = false
+	}
+	typecheck.IncrementalAddrtaken = true
 
+	// Phase 7: Eliminate some obviously dead code.
+	// Must happen after typechecking.
+	for _, n := range typecheck.Target.Decls {
+		if n.Op() == ir.ODCLFUNC {
+			deadcode.Func(n.(*ir.Func))
+		}
+	}
+
+	// Phase 8: Decide how to capture closed variables.
+	// This needs to run before escape analysis,
+	// because variables captured by value do not escape.
+	base.Timer.Start("fe", "capturevars")
+	for _, n := range typecheck.Target.Decls {
+		if n.Op() == ir.ODCLFUNC {
+			n := n.(*ir.Func)
+			if n.OClosure != nil {
+				ir.CurFunc = n
+				typecheck.CaptureVars(n)
+			}
+		}
+	}
+	typecheck.CaptureVarsComplete = true
+	ir.CurFunc = nil
+
+	if base.Debug.TypecheckInl != 0 {
+		// Typecheck imported function bodies if Debug.l > 1,
+		// otherwise lazily when used or re-exported.
+		typecheck.AllImportedBodies()
+	}
 	// Build init task.
 	if initTask := pkginit.Task(); initTask != nil {
 		typecheck.Export(initTask)