cmd/compile: manage Slot array better

steals idea from CL 312093

further investigation revealed additional duplicate
slots (equivalent, but not equal), so delete those too.

Rearranged Func.Names to be addresses of slots,
create canonical addresses so that split slots
(which use those addresses to refer to their parent,
and split slots can be further split)
will preserve "equivalent slots are equal".

Removes duplicates, improves metrics for "args at entry".

Change-Id: I5bbdcb50bd33655abcab3d27ad8cdce25499faaf
Reviewed-on: https://go-review.googlesource.com/c/go/+/312292
Trust: David Chase <drchase@google.com>
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>

1 files changed, 2 insertions, 78 deletions

diff --git a/src/cmd/compile/internal/ssagen/ssa.go b/src/cmd/compile/internal/ssagen/ssa.go
index 2abd70169e..004e084f72 100644
--- a/src/cmd/compile/internal/ssagen/ssa.go
+++ b/src/cmd/compile/internal/ssagen/ssa.go
@@ -8,7 +8,6 @@ import (
 	"bufio"
 	"bytes"
 	"cmd/compile/internal/abi"
-	"encoding/binary"
 	"fmt"
 	"go/constant"
 	"html"
@@ -6463,7 +6462,8 @@ func (s *state) addNamedValue(n *ir.Name, v *ssa.Value) {
 	loc := ssa.LocalSlot{N: n, Type: n.Type(), Off: 0}
 	values, ok := s.f.NamedValues[loc]
 	if !ok {
-		s.f.Names = append(s.f.Names, loc)
+		s.f.Names = append(s.f.Names, &loc)
+		s.f.CanonicalLocalSlots[loc] = &loc
 	}
 	s.f.NamedValues[loc] = append(values, v)
 }
@@ -7552,82 +7552,6 @@ func (e *ssafn) Auto(pos src.XPos, t *types.Type) *ir.Name {
 	return typecheck.TempAt(pos, e.curfn, t) // Note: adds new auto to e.curfn.Func.Dcl list
 }
 
-func (e *ssafn) SplitString(name ssa.LocalSlot) (ssa.LocalSlot, ssa.LocalSlot) {
-	ptrType := types.NewPtr(types.Types[types.TUINT8])
-	lenType := types.Types[types.TINT]
-	// Split this string up into two separate variables.
-	p := e.SplitSlot(&name, ".ptr", 0, ptrType)
-	l := e.SplitSlot(&name, ".len", ptrType.Size(), lenType)
-	return p, l
-}
-
-func (e *ssafn) SplitInterface(name ssa.LocalSlot) (ssa.LocalSlot, ssa.LocalSlot) {
-	n := name.N
-	u := types.Types[types.TUINTPTR]
-	t := types.NewPtr(types.Types[types.TUINT8])
-	// Split this interface up into two separate variables.
-	f := ".itab"
-	if n.Type().IsEmptyInterface() {
-		f = ".type"
-	}
-	c := e.SplitSlot(&name, f, 0, u) // see comment in typebits.Set
-	d := e.SplitSlot(&name, ".data", u.Size(), t)
-	return c, d
-}
-
-func (e *ssafn) SplitSlice(name ssa.LocalSlot) (ssa.LocalSlot, ssa.LocalSlot, ssa.LocalSlot) {
-	ptrType := types.NewPtr(name.Type.Elem())
-	lenType := types.Types[types.TINT]
-	p := e.SplitSlot(&name, ".ptr", 0, ptrType)
-	l := e.SplitSlot(&name, ".len", ptrType.Size(), lenType)
-	c := e.SplitSlot(&name, ".cap", ptrType.Size()+lenType.Size(), lenType)
-	return p, l, c
-}
-
-func (e *ssafn) SplitComplex(name ssa.LocalSlot) (ssa.LocalSlot, ssa.LocalSlot) {
-	s := name.Type.Size() / 2
-	var t *types.Type
-	if s == 8 {
-		t = types.Types[types.TFLOAT64]
-	} else {
-		t = types.Types[types.TFLOAT32]
-	}
-	r := e.SplitSlot(&name, ".real", 0, t)
-	i := e.SplitSlot(&name, ".imag", t.Size(), t)
-	return r, i
-}
-
-func (e *ssafn) SplitInt64(name ssa.LocalSlot) (ssa.LocalSlot, ssa.LocalSlot) {
-	var t *types.Type
-	if name.Type.IsSigned() {
-		t = types.Types[types.TINT32]
-	} else {
-		t = types.Types[types.TUINT32]
-	}
-	if Arch.LinkArch.ByteOrder == binary.BigEndian {
-		return e.SplitSlot(&name, ".hi", 0, t), e.SplitSlot(&name, ".lo", t.Size(), types.Types[types.TUINT32])
-	}
-	return e.SplitSlot(&name, ".hi", t.Size(), t), e.SplitSlot(&name, ".lo", 0, types.Types[types.TUINT32])
-}
-
-func (e *ssafn) SplitStruct(name ssa.LocalSlot, i int) ssa.LocalSlot {
-	st := name.Type
-	// Note: the _ field may appear several times.  But
-	// have no fear, identically-named but distinct Autos are
-	// ok, albeit maybe confusing for a debugger.
-	return e.SplitSlot(&name, "."+st.FieldName(i), st.FieldOff(i), st.FieldType(i))
-}
-
-func (e *ssafn) SplitArray(name ssa.LocalSlot) ssa.LocalSlot {
-	n := name.N
-	at := name.Type
-	if at.NumElem() != 1 {
-		e.Fatalf(n.Pos(), "bad array size")
-	}
-	et := at.Elem()
-	return e.SplitSlot(&name, "[0]", 0, et)
-}
-
 func (e *ssafn) DerefItab(it *obj.LSym, offset int64) *obj.LSym {
 	return reflectdata.ITabSym(it, offset)
 }