cmd/compile: some minor cleanups

Change-Id: Icdf3320814ad4a86a5ae532f4fcb899da3f46ae3 Reviewed-on: https://go-review.googlesource.com/c/go/+/248186 Trust: David Chase <[email protected]> Run-TryBot: David Chase <[email protected]> TryBot-Result: Go Bot <[email protected]> Reviewed-by: Cherry Zhang <[email protected]>
cloudflare · Oct 9, 2020 · 51690f7 · 51690f7
1 parent 33511fb
commit 51690f7
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Showing 2 changed files with 13 additions and 14 deletions.
diff --git 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
@@ -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)