cmd/compile: modify regalloc/stackalloc to use the cmd line debug args

Change the existing flags from compile time consts to be configurable
from the command line.

Change-Id: I4aab4bf3dfcbdd8e2b5a2ff51af95c2543967769
Reviewed-on: https://go-review.googlesource.com/20560Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Todd Neal <todd@tneal.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/cmd/compile/internal/ssa/TODO

@@ -45,3 +45,4 @@ Future/other
 - Should we get rid of named types in favor of underlying types during SSA generation?
 - Should we introduce a new type equality routine that is less strict than the frontend's?
 - Infrastructure for enabling/disabling/configuring passes
+- Modify logging for at least pass=1, to be Warnl compatible

src/cmd/compile/internal/ssa/regalloc.go

@@ -99,8 +99,11 @@ import (
 	"unsafe"
 )
 
-const regDebug = false // TODO: compiler flag
-const logSpills = false
+const (
+	logSpills = iota
+	regDebug
+	stackDebug
+)
 
 // distance is a measure of how far into the future values are used.
 // distance is measured in units of instructions.
@@ -292,7 +295,7 @@ func (s *regAllocState) freeReg(r register) {
 	}
 
 	// Mark r as unused.
-	if regDebug {
+	if s.f.pass.debug > regDebug {
 		fmt.Printf("freeReg %s (dump %s/%s)\n", registers[r].Name(), v, s.regs[r].c)
 	}
 	s.regs[r] = regState{}
@@ -322,7 +325,7 @@ func (s *regAllocState) setOrig(c *Value, v *Value) {
 // assignReg assigns register r to hold c, a copy of v.
 // r must be unused.
 func (s *regAllocState) assignReg(r register, v *Value, c *Value) {
-	if regDebug {
+	if s.f.pass.debug > regDebug {
 		fmt.Printf("assignReg %s %s/%s\n", registers[r].Name(), v, c)
 	}
 	if s.regs[r].v != nil {
@@ -446,7 +449,7 @@ func (s *regAllocState) allocValToReg(v *Value, mask regMask, nospill bool, line
 		switch {
 		// Load v from its spill location.
 		case vi.spill != nil:
-			if logSpills {
+			if s.f.pass.debug > logSpills {
 				fmt.Println("regalloc: load spill")
 			}
 			c = s.curBlock.NewValue1(line, OpLoadReg, v.Type, vi.spill)
@@ -613,7 +616,7 @@ func (s *regAllocState) regalloc(f *Func) {
 				liveSet.add(a.ID)
 			}
 		}
-		if regDebug {
+		if s.f.pass.debug > regDebug {
 			fmt.Printf("uses for %s:%s\n", s.f.Name, b)
 			for i := range s.values {
 				vi := &s.values[i]
@@ -679,7 +682,7 @@ func (s *regAllocState) regalloc(f *Func) {
 			p := b.Preds[idx]
 			s.setState(s.endRegs[p.ID])
 
-			if regDebug {
+			if s.f.pass.debug > regDebug {
 				fmt.Printf("starting merge block %s with end state of %s:\n", b, p)
 				for _, x := range s.endRegs[p.ID] {
 					fmt.Printf("  %s: orig:%s cache:%s\n", registers[x.r].Name(), x.v, x.c)
@@ -778,7 +781,7 @@ func (s *regAllocState) regalloc(f *Func) {
 			}
 			s.startRegs[b.ID] = regList
 
-			if regDebug {
+			if s.f.pass.debug > regDebug {
 				fmt.Printf("after phis\n")
 				for _, x := range s.startRegs[b.ID] {
 					fmt.Printf("  %s: v%d\n", registers[x.r].Name(), x.vid)
@@ -854,7 +857,7 @@ func (s *regAllocState) regalloc(f *Func) {
 
 		// Process all the non-phi values.
 		for _, v := range oldSched {
-			if regDebug {
+			if s.f.pass.debug > regDebug {
 				fmt.Printf("  processing %s\n", v.LongString())
 			}
 			if v.Op == OpPhi {
@@ -958,7 +961,7 @@ func (s *regAllocState) regalloc(f *Func) {
 
 		// Load control value into reg.
 		if v := b.Control; v != nil && s.values[v.ID].needReg {
-			if regDebug {
+			if s.f.pass.debug > regDebug {
 				fmt.Printf("  processing control %s\n", v.LongString())
 			}
 			// TODO: regspec for block control values, instead of using
@@ -1098,7 +1101,7 @@ func (s *regAllocState) regalloc(f *Func) {
 	for i := range s.values {
 		vi := s.values[i]
 		if vi.spillUsed {
-			if logSpills {
+			if s.f.pass.debug > logSpills {
 				fmt.Println("regalloc: spilled value")
 			}
 			continue
@@ -1138,7 +1141,7 @@ func (s *regAllocState) shuffle(stacklive [][]ID) {
 	e.s = s
 	e.cache = map[ID][]*Value{}
 	e.contents = map[Location]contentRecord{}
-	if regDebug {
+	if s.f.pass.debug > regDebug {
 		fmt.Printf("shuffle %s\n", s.f.Name)
 		fmt.Println(s.f.String())
 	}
@@ -1190,7 +1193,7 @@ type dstRecord struct {
 
 // setup initializes the edge state for shuffling.
 func (e *edgeState) setup(idx int, srcReg []endReg, dstReg []startReg, stacklive []ID) {
-	if regDebug {
+	if e.s.f.pass.debug > regDebug {
 		fmt.Printf("edge %s->%s\n", e.p, e.b)
 	}
 
@@ -1235,7 +1238,7 @@ func (e *edgeState) setup(idx int, srcReg []endReg, dstReg []startReg, stacklive
 	}
 	e.destinations = dsts
 
-	if regDebug {
+	if e.s.f.pass.debug > regDebug {
 		for _, vid := range e.cachedVals {
 			a := e.cache[vid]
 			for _, c := range a {
@@ -1298,7 +1301,7 @@ func (e *edgeState) process() {
 		vid := e.contents[loc].vid
 		c := e.contents[loc].c
 		r := e.findRegFor(c.Type)
-		if regDebug {
+		if e.s.f.pass.debug > regDebug {
 			fmt.Printf("breaking cycle with v%d in %s:%s\n", vid, loc.Name(), c)
 		}
 		if _, isReg := loc.(*Register); isReg {
@@ -1337,13 +1340,13 @@ func (e *edgeState) processDest(loc Location, vid ID, splice **Value) bool {
 	v := e.s.orig[vid]
 	var c *Value
 	var src Location
-	if regDebug {
+	if e.s.f.pass.debug > regDebug {
 		fmt.Printf("moving v%d to %s\n", vid, loc.Name())
 		fmt.Printf("sources of v%d:", vid)
 	}
 	for _, w := range e.cache[vid] {
 		h := e.s.f.getHome(w.ID)
-		if regDebug {
+		if e.s.f.pass.debug > regDebug {
 			fmt.Printf(" %s:%s", h.Name(), w)
 		}
 		_, isreg := h.(*Register)
@@ -1352,7 +1355,7 @@ func (e *edgeState) processDest(loc Location, vid ID, splice **Value) bool {
 			src = h
 		}
 	}
-	if regDebug {
+	if e.s.f.pass.debug > regDebug {
 		if src != nil {
 			fmt.Printf(" [use %s]\n", src.Name())
 		} else {
@@ -1445,7 +1448,7 @@ func (e *edgeState) set(loc Location, vid ID, c *Value, final bool) {
 			}
 		}
 	}
-	if regDebug {
+	if e.s.f.pass.debug > regDebug {
 		fmt.Printf("%s\n", c.LongString())
 		fmt.Printf("v%d now available in %s:%s\n", vid, loc.Name(), c)
 	}
@@ -1470,7 +1473,7 @@ func (e *edgeState) erase(loc Location) {
 	a := e.cache[vid]
 	for i, c := range a {
 		if e.s.f.getHome(c.ID) == loc {
-			if regDebug {
+			if e.s.f.pass.debug > regDebug {
 				fmt.Printf("v%d no longer available in %s:%s\n", vid, loc.Name(), c)
 			}
 			a[i], a = a[len(a)-1], a[:len(a)-1]
@@ -1534,7 +1537,7 @@ func (e *edgeState) findRegFor(typ Type) Location {
 			if r, ok := e.s.f.getHome(c.ID).(*Register); ok && m>>uint(r.Num)&1 != 0 {
 				x := e.p.NewValue1(c.Line, OpStoreReg, c.Type, c)
 				e.set(t, vid, x, false)
-				if regDebug {
+				if e.s.f.pass.debug > regDebug {
 					fmt.Printf("  SPILL %s->%s %s\n", r.Name(), t.Name(), x.LongString())
 				}
 				// r will now be overwritten by the caller. At some point
@@ -1703,7 +1706,7 @@ func (s *regAllocState) computeLive() {
 			break
 		}
 	}
-	if regDebug {
+	if f.pass.debug > regDebug {
 		fmt.Println("live values at end of each block")
 		for _, b := range f.Blocks {
 			fmt.Printf("  %s:", b)

src/cmd/compile/internal/ssa/stackalloc.go

@@ -8,8 +8,6 @@ package ssa
 
 import "fmt"
 
-const stackDebug = false // TODO: compiler flag
-
 type stackAllocState struct {
 	f         *Func
 	values    []stackValState
@@ -27,7 +25,7 @@ type stackValState struct {
 // all Values that did not get a register.
 // Returns a map from block ID to the stack values live at the end of that block.
 func stackalloc(f *Func, spillLive [][]ID) [][]ID {
-	if stackDebug {
+	if f.pass.debug > stackDebug {
 		fmt.Println("before stackalloc")
 		fmt.Println(f.String())
 	}
@@ -46,7 +44,7 @@ func (s *stackAllocState) init(f *Func, spillLive [][]ID) {
 		for _, v := range b.Values {
 			s.values[v.ID].typ = v.Type
 			s.values[v.ID].needSlot = !v.Type.IsMemory() && !v.Type.IsVoid() && !v.Type.IsFlags() && f.getHome(v.ID) == nil && !v.rematerializeable()
-			if stackDebug && s.values[v.ID].needSlot {
+			if f.pass.debug > stackDebug && s.values[v.ID].needSlot {
 				fmt.Printf("%s needs a stack slot\n", v)
 			}
 			if v.Op == OpStoreReg {
@@ -83,7 +81,7 @@ func (s *stackAllocState) stackalloc() {
 			continue
 		}
 		loc := LocalSlot{v.Aux.(GCNode), v.Type, v.AuxInt}
-		if stackDebug {
+		if f.pass.debug > stackDebug {
 			fmt.Printf("stackalloc %s to %s\n", v, loc.Name())
 		}
 		f.setHome(v, loc)
@@ -131,7 +129,7 @@ func (s *stackAllocState) stackalloc() {
 						goto noname
 					}
 				}
-				if stackDebug {
+				if f.pass.debug > stackDebug {
 					fmt.Printf("stackalloc %s to %s\n", v, name.Name())
 				}
 				f.setHome(v, name)
@@ -165,7 +163,7 @@ func (s *stackAllocState) stackalloc() {
 			}
 			// Use the stack variable at that index for v.
 			loc := locs[i]
-			if stackDebug {
+			if f.pass.debug > stackDebug {
 				fmt.Printf("stackalloc %s to %s\n", v, loc.Name())
 			}
 			f.setHome(v, loc)
@@ -249,7 +247,7 @@ func (s *stackAllocState) computeLive(spillLive [][]ID) {
 			break
 		}
 	}
-	if stackDebug {
+	if s.f.pass.debug > stackDebug {
 		for _, b := range s.f.Blocks {
 			fmt.Printf("stacklive %s %v\n", b, s.live[b.ID])
 		}
@@ -307,7 +305,7 @@ func (s *stackAllocState) buildInterferenceGraph() {
 			}
 		}
 	}
-	if stackDebug {
+	if f.pass.debug > stackDebug {
 		for vid, i := range s.interfere {
 			if len(i) > 0 {
 				fmt.Printf("v%d interferes with", vid)