cmd/compile: register abi, morestack work and mole whacking

Morestack works for non-pointer register parameters

Within a function body, pointer-typed parameters are correctly
tracked.

Results still not hooked up.

For #40724.

Change-Id: Icaee0b51d0da54af983662d945d939b756088746
Reviewed-on: https://go-review.googlesource.com/c/go/+/294410
Trust: David Chase <drchase@google.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

1 files changed, 24 insertions, 17 deletions

diff --git a/src/cmd/compile/internal/ssa/stackalloc.go b/src/cmd/compile/internal/ssa/stackalloc.go
index 041e7855f6..45058d4e72 100644
--- a/src/cmd/compile/internal/ssa/stackalloc.go
+++ b/src/cmd/compile/internal/ssa/stackalloc.go
@@ -112,7 +112,7 @@ 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() && !v.OnWasmStack
-			s.values[v.ID].isArg = v.Op == OpArg
+			s.values[v.ID].isArg = hasAnyArgOp(v)
 			if f.pass.debug > stackDebug && s.values[v.ID].needSlot {
 				fmt.Printf("%s needs a stack slot\n", v)
 			}
@@ -151,28 +151,29 @@ func (s *stackAllocState) stackalloc() {
 
 	// Allocate args to their assigned locations.
 	for _, v := range f.Entry.Values {
-		if v.Op != OpArg { // && v.Op != OpArgFReg && v.Op != OpArgIReg  {
+		if !hasAnyArgOp(v) {
 			continue
 		}
 		if v.Aux == nil {
 			f.Fatalf("%s has nil Aux\n", v.LongString())
 		}
-		var loc LocalSlot
-		var name *ir.Name
-		var offset int64
 		if v.Op == OpArg {
-			name = v.Aux.(*ir.Name)
-			offset = v.AuxInt
-		} else {
-			nameOff := v.Aux.(*AuxNameOffset)
-			name = nameOff.Name
-			offset = nameOff.Offset
+			loc := LocalSlot{N: v.Aux.(*ir.Name), Type: v.Type, Off: v.AuxInt}
+			if f.pass.debug > stackDebug {
+				fmt.Printf("stackalloc OpArg %s to %s\n", v, loc)
+			}
+			f.setHome(v, loc)
+			continue
 		}
-		loc = LocalSlot{N: name, Type: v.Type, Off: offset}
+
+		nameOff := v.Aux.(*AuxNameOffset)
+		loc := LocalSlot{N: nameOff.Name, Type: v.Type, Off: nameOff.Offset}
 		if f.pass.debug > stackDebug {
-			fmt.Printf("stackalloc %s to %s\n", v, loc)
+			fmt.Printf("stackalloc Op%s %s to %s\n", v.Op, v, loc)
 		}
-		f.setHome(v, loc)
+		// register args already allocated to registers, but need to know the stack allocation for later
+		reg := f.getHome(v.ID).(*Register)
+		f.RegArgs = append(f.RegArgs, ArgPair{reg: reg, mem: loc})
 	}
 
 	// For each type, we keep track of all the stack slots we
@@ -209,7 +210,7 @@ func (s *stackAllocState) stackalloc() {
 				s.nNotNeed++
 				continue
 			}
-			if v.Op == OpArg {
+			if hasAnyArgOp(v) {
 				s.nArgSlot++
 				continue // already picked
 			}
@@ -396,7 +397,7 @@ func (s *stackAllocState) buildInterferenceGraph() {
 				for _, id := range live.contents() {
 					// Note: args can have different types and still interfere
 					// (with each other or with other values). See issue 23522.
-					if s.values[v.ID].typ.Compare(s.values[id].typ) == types.CMPeq || v.Op == OpArg || s.values[id].isArg {
+					if s.values[v.ID].typ.Compare(s.values[id].typ) == types.CMPeq || hasAnyArgOp(v) || s.values[id].isArg {
 						s.interfere[v.ID] = append(s.interfere[v.ID], id)
 						s.interfere[id] = append(s.interfere[id], v.ID)
 					}
@@ -407,13 +408,15 @@ func (s *stackAllocState) buildInterferenceGraph() {
 					live.add(a.ID)
 				}
 			}
-			if v.Op == OpArg && s.values[v.ID].needSlot {
+			if hasAnyArgOp(v) && s.values[v.ID].needSlot {
 				// OpArg is an input argument which is pre-spilled.
 				// We add back v.ID here because we want this value
 				// to appear live even before this point. Being live
 				// all the way to the start of the entry block prevents other
 				// values from being allocated to the same slot and clobbering
 				// the input value before we have a chance to load it.
+
+				// TODO(register args) this is apparently not wrong for register args -- is it necessary?
 				live.add(v.ID)
 			}
 		}
@@ -430,3 +433,7 @@ func (s *stackAllocState) buildInterferenceGraph() {
 		}
 	}
 }
+
+func hasAnyArgOp(v *Value) bool {
+	return v.Op == OpArg || v.Op == OpArgIntReg || v.Op == OpArgFloatReg
+}