cmd/compile: implement simple register results

at least for ints and strings

includes simple test

For #40724.

Change-Id: Ib8484e5b957b08f961574a67cfd93d3d26551558
Reviewed-on: https://go-review.googlesource.com/c/go/+/295309
Trust: David Chase <drchase@google.com>
Run-TryBot: David Chase <drchase@google.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

1 files changed, 38 insertions, 20 deletions

diff --git a/src/cmd/compile/internal/ssa/expand_calls.go b/src/cmd/compile/internal/ssa/expand_calls.go
index ff16eac90f..6e14a90e79 100644
--- a/src/cmd/compile/internal/ssa/expand_calls.go
+++ b/src/cmd/compile/internal/ssa/expand_calls.go
@@ -14,10 +14,10 @@ import (
 )
 
 type selKey struct {
-	from   *Value
-	offset int64
-	size   int64
-	typ    *types.Type
+	from          *Value // what is selected from
+	offsetOrIndex int64  // whatever is appropriate for the selector
+	size          int64
+	typ           *types.Type
 }
 
 type offsetKey struct {
@@ -372,6 +372,7 @@ func (x *expandState) rewriteSelect(leaf *Value, selector *Value, offset int64,
 		// if applied to Op-mumble-call, the Aux tells us which result, regOffset specifies offset within result.  If a register, should rewrite to OpSelectN for new call.
 		// TODO these may be duplicated. Should memoize. Intermediate selectors will go dead, no worries there.
 		call := selector.Args[0]
+		call0 := call
 		aux := call.Aux.(*AuxCall)
 		which := selector.AuxInt
 		if which == aux.NResults() { // mem is after the results.
@@ -398,7 +399,6 @@ func (x *expandState) rewriteSelect(leaf *Value, selector *Value, offset int64,
 			leafType := removeTrivialWrapperTypes(leaf.Type)
 			if x.canSSAType(leafType) {
 				pt := types.NewPtr(leafType)
-				off := x.offsetFrom(x.sp, offset+aux.OffsetOfResult(which), pt)
 				// Any selection right out of the arg area/registers has to be same Block as call, use call as mem input.
 				if call.Op == OpStaticLECall { // TODO this is temporary until all calls are register-able
 					// Create a "mem" for any loads that need to occur.
@@ -413,15 +413,30 @@ func (x *expandState) rewriteSelect(leaf *Value, selector *Value, offset int64,
 						call = mem
 					}
 				}
-				if leaf.Block == call.Block {
-					leaf.reset(OpLoad)
-					leaf.SetArgs2(off, call)
-					leaf.Type = leafType
+				outParam := aux.abiInfo.OutParam(int(which))
+				if len(outParam.Registers) > 0 {
+					reg := int64(outParam.Registers[regOffset])
+					if leaf.Block == call.Block {
+						leaf.reset(OpSelectN)
+						leaf.SetArgs1(call0)
+						leaf.Type = leafType
+						leaf.AuxInt = reg
+					} else {
+						w := call.Block.NewValue1I(leaf.Pos, OpSelectN, leafType, reg, call0)
+						leaf.copyOf(w)
+					}
 				} else {
-					w := call.Block.NewValue2(leaf.Pos, OpLoad, leafType, off, call)
-					leaf.copyOf(w)
-					if x.debug {
-						fmt.Printf("\tnew %s\n", w.LongString())
+					off := x.offsetFrom(x.sp, offset+aux.OffsetOfResult(which), pt)
+					if leaf.Block == call.Block {
+						leaf.reset(OpLoad)
+						leaf.SetArgs2(off, call)
+						leaf.Type = leafType
+					} else {
+						w := call.Block.NewValue2(leaf.Pos, OpLoad, leafType, off, call)
+						leaf.copyOf(w)
+						if x.debug {
+							fmt.Printf("\tnew %s\n", w.LongString())
+						}
 					}
 				}
 				for _, s := range x.namedSelects[selector] {
@@ -812,7 +827,7 @@ func (x *expandState) storeArgOrLoad(pos src.XPos, b *Block, source, mem *Value,
 		s = b.NewValue3A(pos, OpStore, types.TypeMem, t, dst, source, mem)
 	}
 	if x.debug {
-		fmt.Printf("\t\tstoreArg returns %s\n", s.LongString())
+		fmt.Printf("\t\tstoreArg returns %s, storeRc=%s\n", s.LongString(), storeRc.String())
 	}
 	return s
 }
@@ -983,9 +998,11 @@ func expandCalls(f *Func) {
 					mem = x.storeArgOrLoad(v.Pos, b, a, mem, aux.TypeOfResult(i), auxOffset, 0, rc)
 				}
 			}
-			// TODO REGISTER -- keep the Result for block control, splice in contents of AllResults
-			b.SetControl(mem)
-			v.reset(OpInvalid) // otherwise it can have a mem operand which will fail check(), even though it is dead.
+			v.resetArgs()
+			v.AddArgs(allResults...)
+			v.AddArg(mem)
+			v.Type = types.NewResults(append(abi.RegisterTypes(aux.abiInfo.OutParams()), types.TypeMem))
+			b.SetControl(v)
 		}
 	}
 
@@ -1170,7 +1187,7 @@ func expandCalls(f *Func) {
 		case OpArraySelect:
 			offset = size * v.AuxInt
 		case OpSelectN:
-			offset = w.Aux.(*AuxCall).OffsetOfResult(v.AuxInt)
+			offset = v.AuxInt // offset is just a key, really.
 		case OpInt64Hi:
 			offset = x.hiOffset
 		case OpInt64Lo:
@@ -1182,7 +1199,7 @@ func expandCalls(f *Func) {
 		case OpComplexImag:
 			offset = size
 		}
-		sk := selKey{from: w, size: size, offset: offset, typ: typ}
+		sk := selKey{from: w, size: size, offsetOrIndex: offset, typ: typ}
 		dupe := x.commonSelectors[sk]
 		if dupe == nil {
 			x.commonSelectors[sk] = v
@@ -1240,8 +1257,9 @@ func expandCalls(f *Func) {
 				x.rewriteArgToMemOrRegs(v)
 			case OpStaticLECall:
 				v.Op = OpStaticCall
+				rts := abi.RegisterTypes(v.Aux.(*AuxCall).abiInfo.OutParams())
 				// TODO need to insert all the register types.
-				v.Type = types.NewResults([]*types.Type{types.TypeMem})
+				v.Type = types.NewResults(append(rts, types.TypeMem))
 			case OpClosureLECall:
 				v.Op = OpClosureCall
 				v.Type = types.TypeMem