cmd/compile: some minor cleanups

Change-Id: Icdf3320814ad4a86a5ae532f4fcb899da3f46ae3
Reviewed-on: https://go-review.googlesource.com/c/go/+/248186
Trust: David Chase <drchase@google.com>
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

diff --git a/src/cmd/compile/internal/gc/ssa.go b/src/cmd/compile/internal/gc/ssa.go
index 7bde7f7c659165ba8e844f391f474b8329cb1a31..90ce9e54f8a2aba0927935c1ff503b4a9e52ccbf 100644 (file)
--- a/src/cmd/compile/internal/gc/ssa.go
+++ b/src/cmd/compile/internal/gc/ssa.go
@@ -4375,9 +4375,7 @@ func (s *state) call(n *Node, k callKind, returnResultAddr bool) *ssa.Value {
 
        switch n.Op {
        case OCALLFUNC:
-               if k != callDeferStack && ssa.LateCallExpansionEnabledWithin(s.f) {
-                       testLateExpansion = true
-               }
+               testLateExpansion = k != callDeferStack && ssa.LateCallExpansionEnabledWithin(s.f)
                if k == callNormal && fn.Op == ONAME && fn.Class() == PFUNC {
                        sym = fn.Sym
                        break
@@ -4392,9 +4390,7 @@ func (s *state) call(n *Node, k callKind, returnResultAddr bool) *ssa.Value {
                if fn.Op != ODOTMETH {
                        s.Fatalf("OCALLMETH: n.Left not an ODOTMETH: %v", fn)
                }
-               if k != callDeferStack && ssa.LateCallExpansionEnabledWithin(s.f) {
-                       testLateExpansion = true
-               }
+               testLateExpansion = k != callDeferStack && ssa.LateCallExpansionEnabledWithin(s.f)
                if k == callNormal {
                        sym = fn.Sym
                        break
@@ -4406,9 +4402,7 @@ func (s *state) call(n *Node, k callKind, returnResultAddr bool) *ssa.Value {
                if fn.Op != ODOTINTER {
                        s.Fatalf("OCALLINTER: n.Left not an ODOTINTER: %v", fn.Op)
                }
-               if k != callDeferStack && ssa.LateCallExpansionEnabledWithin(s.f) {
-                       testLateExpansion = true
-               }
+               testLateExpansion = k != callDeferStack && ssa.LateCallExpansionEnabledWithin(s.f)
                var iclosure *ssa.Value
                iclosure, rcvr = s.getClosureAndRcvr(fn)
                if k == callNormal {

diff --git a/src/cmd/compile/internal/ssa/expand_calls.go b/src/cmd/compile/internal/ssa/expand_calls.go
index 8c06040542e6f23bfe60353ea83e2b3cadb765c0..bbd9aeee51249aa813463020f556c1b74310426f 100644 (file)
--- a/src/cmd/compile/internal/ssa/expand_calls.go
+++ b/src/cmd/compile/internal/ssa/expand_calls.go
@@ -39,7 +39,9 @@ func expandCalls(f *Func) {
                hiOffset = 4
        }
 
-       pairTypes := func(et types.EType) (tHi, tLo *types.Type) {
+       // intPairTypes returns the pair of 32-bit int types needed to encode a 64-bit integer type on a target
+       // that has no 64-bit integer registers.
+       intPairTypes := func(et types.EType) (tHi, tLo *types.Type) {
                tHi = tUint32
                if et == types.TINT64 {
                        tHi = tInt32
@@ -147,8 +149,8 @@ func expandCalls(f *Func) {
                }
        }
 
-       // storeArg converts stores of SSA-able aggregates into a series of stores of smaller types into
-       // individual parameter slots.
+       // storeArg converts stores of SSA-able aggregate arguments (passed to a call) into a series of stores of
+       // smaller types into individual parameter slots.
        // TODO when registers really arrive, must also decompose anything split across two registers or registers and memory.
        var storeArg func(pos src.XPos, b *Block, a *Value, t *types.Type, offset int64, mem *Value) *Value
        storeArg = func(pos src.XPos, b *Block, a *Value, t *types.Type, offset int64, mem *Value) *Value {
@@ -165,7 +167,7 @@ func expandCalls(f *Func) {
                        return storeArg(pos, b, a.Args[0], t.Elem(), offset, mem)
 
                case OpInt64Make:
-                       tHi, tLo := pairTypes(t.Etype)
+                       tHi, tLo := intPairTypes(t.Etype)
                        mem = storeArg(pos, b, a.Args[0], tHi, offset+hiOffset, mem)
                        return storeArg(pos, b, a.Args[1], tLo, offset+lowOffset, mem)
                }
@@ -207,7 +209,7 @@ func expandCalls(f *Func) {
                        if t.Width == regSize {
                                break
                        }
-                       tHi, tLo := pairTypes(t.Etype)
+                       tHi, tLo := intPairTypes(t.Etype)
                        sel := src.Block.NewValue1(pos, OpInt64Hi, tHi, src)
                        mem = splitStore(dst, sel, mem, v, tHi, offset+hiOffset, firstStorePos)
                        firstStorePos = firstStorePos.WithNotStmt()
@@ -261,6 +263,9 @@ func expandCalls(f *Func) {
                return x
        }
 
+       // rewriteArgs removes all the Args from a call and converts the call args into appropriate
+       // stores (or later, register movement).  Extra args for interface and closure calls are ignored,
+       // but removed.
        rewriteArgs := func(v *Value, firstArg int) *Value {
                // Thread the stores on the memory arg
                aux := v.Aux.(*AuxCall)