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cmd/compile: eliminate prectab

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While here, merge LINC and LDEC into LINCOP.

Fixes #13244.

Change-Id: I8ea426f986d60d35c3b1a80c056a7aa49d22d802
Reviewed-on: https://go-review.googlesource.com/19928
Reviewed-by: Robert Griesemer <gri@golang.org>
This commit is contained in:
Matthew Dempsky 2016-02-25 17:27:10 -08:00
parent 6abc8c9a88
commit f5f8b38462
2 changed files with 111 additions and 142 deletions
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72
src/cmd/compile/internal/gc/parser.go
View file

@ -102,6 +102,8 @@ func (p *parser) syntax_error(msg string) {
}
case LASOP:
tok = goopnames[p.op] + "="
case LINCOP:
tok = goopnames[p.op] + goopnames[p.op]
default:
tok = tokstring(p.tok)
}
@ -219,12 +221,11 @@ var tokstrings = map[int32]string{
LANDAND: "&&",
LANDNOT: "&^",
LCOMM: "<-",
LDEC: "--",
LEQ: "==",
LGE: ">=",
LGT: ">",
LIGNORE: "LIGNORE", // we should never see this one
LINC: "++",
LINCOP: "opop",
LLE: "<=",
LLSH: "<<",
LLT: "<",
@ -562,22 +563,13 @@ func (p *parser) simple_stmt(labelOk, rangeOk bool) *Node {
stmt.Etype = EType(op) // rathole to pass opcode
return stmt
case LINC:
// expr LINC
case LINCOP:
// expr LINCOP
p.next()
stmt := Nod(OASOP, lhs, Nodintconst(1))
stmt.Implicit = true
stmt.Etype = EType(OADD)
return stmt
case LDEC:
// expr LDEC
p.next()
stmt := Nod(OASOP, lhs, Nodintconst(1))
stmt.Implicit = true
stmt.Etype = EType(OSUB)
stmt.Etype = EType(p.op)
return stmt
case ':':
@ -1104,54 +1096,20 @@ func (p *parser) select_stmt() *Node {
return hdr
}
// TODO(gri) should have lexer return this info - no need for separate lookup
// (issue 13244)
var prectab = map[int32]struct {
prec int // > 0 (0 indicates not found)
op Op
}{
// not an expression anymore, but left in so we can give a good error
// message when used in expression context
LCOMM: {1, OSEND},
LOROR: {2, OOROR},
LANDAND: {3, OANDAND},
LEQ: {4, OEQ},
LNE: {4, ONE},
LLE: {4, OLE},
LGE: {4, OGE},
LLT: {4, OLT},
LGT: {4, OGT},
'+': {5, OADD},
'-': {5, OSUB},
'|': {5, OOR},
'^': {5, OXOR},
'*': {6, OMUL},
'/': {6, ODIV},
'%': {6, OMOD},
'&': {6, OAND},
LLSH: {6, OLSH},
LRSH: {6, ORSH},
LANDNOT: {6, OANDNOT},
}
// Expression = UnaryExpr | Expression binary_op Expression .
func (p *parser) bexpr(prec int) *Node {
func (p *parser) bexpr(prec OpPrec) *Node {
// don't trace bexpr - only leads to overly nested trace output
// prec is precedence of the prior/enclosing binary operator (if any),
// so we only want to parse tokens of greater precedence.
x := p.uexpr()
for {
t := prectab[p.tok]
if t.prec < prec {
return x
}
for p.prec > prec {
op, prec1 := p.op, p.prec
p.next()
x = Nod(t.op, x, p.bexpr(t.prec+1))
x = Nod(op, x, p.bexpr(prec1))
}
return x
}
func (p *parser) expr() *Node {
@ -1159,7 +1117,7 @@ func (p *parser) expr() *Node {
defer p.trace("expr")()
}
return p.bexpr(1)
return p.bexpr(0)
}
func unparen(x *Node) *Node {