diff --git a/src/cmd/compile/internal/rangefunc/rewrite.go b/src/cmd/compile/internal/rangefunc/rewrite.go index ac12c53c2b..c28c9a1207 100644 --- a/src/cmd/compile/internal/rangefunc/rewrite.go +++ b/src/cmd/compile/internal/rangefunc/rewrite.go @@ -640,6 +640,13 @@ func (r *rewriter) editReturn(x *syntax.ReturnStmt) syntax.Stmt { return bl } +// perLoopStep is part of the encoding of loop-spanning control flow +// for function range iterators. Each multiple of two encodes a "return false" +// passing control to an enclosing iterator; a terminal value of 1 encodes +// "return true" (i.e., local continue) from the body function, and a terminal +// value of 0 encodes executing the remainder of the body function. +const perLoopStep = 2 + // editBranch returns the replacement for the branch statement x, // or x itself if it should be left alone. // See the package doc comment above for more context. @@ -734,7 +741,7 @@ func (r *rewriter) editBranch(x *syntax.BranchStmt) syntax.Stmt { // Set next to break the appropriate number of times; // the final time may be a continue, not a break. - next = 2 * depth + next = perLoopStep * depth if x.Tok == syntax.Continue { next-- } @@ -948,10 +955,10 @@ func (r *rewriter) checks(loop *forLoop, pos syntax.Pos) []syntax.Stmt { list = append(list, r.ifNext(syntax.Lss, 0, retStmt(r.useVar(r.false)))) } if loop.checkBreak { - list = append(list, r.ifNext(syntax.Geq, 2, retStmt(r.useVar(r.false)))) + list = append(list, r.ifNext(syntax.Geq, perLoopStep, retStmt(r.useVar(r.false)))) } if loop.checkContinue { - list = append(list, r.ifNext(syntax.Eql, 1, retStmt(r.useVar(r.true)))) + list = append(list, r.ifNext(syntax.Eql, perLoopStep-1, retStmt(r.useVar(r.true)))) } }