fix JuliaLang#36230, more efficient lowering of if with a chain of …

…`&&` (JuliaLang#36355)

base/expr.jl

@@ -347,9 +347,9 @@ function findmeta_block(exargs, argsmatch=args->true)
  for i = 1:length(exargs)
  a = exargs[i]
  if isa(a, Expr)
- if (a::Expr).head === :meta && argsmatch((a::Expr).args)
+ if a.head === :meta && argsmatch(a.args)
  return i, exargs
- elseif (a::Expr).head === :block
+ elseif a.head === :block
  idx, exa = findmeta_block(a.args, argsmatch)
  if idx != 0
  return idx, exa

base/meta.jl

@@ -62,8 +62,9 @@ true
 ```
 """
 isexpr(@nospecialize(ex), head::Symbol) = isa(ex, Expr) && ex.head === head
-isexpr(@nospecialize(ex), heads::Union{Set,Vector,Tuple}) = isa(ex, Expr) && in(ex.head, heads)
-isexpr(@nospecialize(ex), heads, n::Int) = isexpr(ex, heads) && length((ex::Expr).args) == n
+isexpr(@nospecialize(ex), heads) = isa(ex, Expr) && in(ex.head, heads)
+isexpr(@nospecialize(ex), head::Symbol, n::Int) = isa(ex, Expr) && ex.head === head && length(ex.args) == n
+isexpr(@nospecialize(ex), heads, n::Int) = isa(ex, Expr) && in(ex.head, heads) && length(ex.args) == n
 
 """
  Meta.show_sexpr([io::IO,], ex)

src/julia-syntax.scm

@@ -1895,6 +1895,13 @@
  (else
  (error (string "invalid " syntax-str " \"" (deparse el) "\""))))))))
 
+(define (expand-if e)
+ (if (and (pair? (cadr e)) (eq? (car (cadr e)) '&&))
+ (let ((clauses (cdr (flatten-ex '&& (cadr e)))))
+ `(if (&& ,@(map expand-forms clauses))
+ ,@(map expand-forms (cddr e))))
+ (cons (car e) (map expand-forms (cdr e)))))
+
 ;; move an assignment into the last statement of a block to keep more statements at top level
 (define (sink-assignment lhs rhs)
  (if (and (pair? rhs) (eq? (car rhs) 'block))
@@ -2230,6 +2237,9 @@
  ,(expand-forms (cadr e)) ,(expand-forms (caddr e)))
  (map expand-forms e)))
 
+ 'if expand-if
+ 'elseif expand-if
+
  'while
  (lambda (e)
  `(break-block loop-exit
@@ -3709,7 +3719,8 @@ f(x) = yt(x)
  (handler-level 0) ;; exception handler nesting depth
  (catch-token-stack '())) ;; tokens identifying handler enter for current catch blocks
  (define (emit c)
- (set! code (cons c code)))
+ (set! code (cons c code))
+ c)
  (define (make-label)
  (begin0 label-counter
  (set! label-counter (+ 1 label-counter))))
@@ -3957,15 +3968,21 @@ f(x) = yt(x)
  (compile (cadr e) break-labels value tail)
  #f))
  ((if elseif)
- (let ((test `(gotoifnot ,(compile-cond (cadr e) break-labels) _))
+ (let ((tests (map (lambda (clause)
+ (emit `(gotoifnot ,(compile-cond clause break-labels) _)))
+ (if (and (pair? (cadr e)) (eq? (car (cadr e)) '&&))
+ (cdadr e)
+ (list (cadr e)))))
  (end-jump `(goto _))
  (val (if (and value (not tail)) (new-mutable-var) #f)))
- (emit test)
  (let ((v1 (compile (caddr e) break-labels value tail)))
  (if val (emit-assignment val v1))
  (if (and (not tail) (or (length> e 3) val))
  (emit end-jump))
- (set-car! (cddr test) (make&mark-label))
+ (let ((elselabel (make&mark-label)))
+ (for-each (lambda (test)
+ (set-car! (cddr test) elselabel))
+ tests))
  (let ((v2 (if (length> e 3)
  (compile (cadddr e) break-labels value tail)
  '(null))))

test/compiler/inference.jl

@@ -2650,3 +2650,13 @@ end
 f(n) = depth(n, 1)
 end
 @test Base.return_types(TestConstPropRecursion.f, (TestConstPropRecursion.Node,)) == Any[Int]
+
+# issue #36230, keeping implications of all conditions in a && chain
+function symcmp36230(vec)
+ a, b = vec[1], vec[2]
+ if isa(a, Symbol) && isa(b, Symbol)
+ return a == b
+ end
+ return false
+end
+@test Base.return_types(symcmp36230, (Vector{Any},)) == Any[Bool]