lanx@lanx-1005HA:~$ perl -Mre=debug -e' print "aaa" =~ /(a+){1}+a/ '
Compiling REx "(a+){1}+a"
Final program:
   1: SUSPEND (16)
   3:   CURLYX[0] {1,1} (13)
   5:     OPEN1 (7)
   7:       PLUS (10)
   8:         EXACT <a> (0)
  10:     CLOSE1 (12)
  12:   WHILEM (0)
  13:   NOTHING (14)
  14:   SUCCEED (0)
  15: TAIL (16)
  16: EXACT <a> (18)
  18: END (0)
anchored "a" at 0 floating "aa" at 0..2147483647 (checking floating) minlen 2 
Guessing start of match in sv for REx "(a+){1}+a" against "aaa"
Found floating substr "aa" at offset 0...
Found anchored substr "a" at offset 0...
Guessed: match at offset 0
Matching REx "(a+){1}+a" against "aaa"
   0 <> <aaa>                |  1:SUSPEND(16)
   0 <> <aaa>                |  3:  CURLYX[0] {1,1}(13)
   0 <> <aaa>                | 12:    WHILEM(0)
                                      whilem: matched 0 out of 1..1
   0 <> <aaa>                |  5:      OPEN1(7)
   0 <> <aaa>                |  7:      PLUS(10)
                                        EXACT <a> can match 3 times out of 2147483647...
   3 <aaa> <>                | 10:        CLOSE1(12)
   3 <aaa> <>                | 12:        WHILEM(0)
                                          whilem: matched 1 out of 1..1
   3 <aaa> <>                | 13:          NOTHING(14)
   3 <aaa> <>                | 14:          SUCCEED(0)
                                            subpattern success...
   3 <aaa> <>                | 16:EXACT <a>(18)
                                  failed...
   1 <a> <aa>                |  1:SUSPEND(16)
   1 <a> <aa>                |  3:  CURLYX[0] {1,1}(13)
   1 <a> <aa>                | 12:    WHILEM(0)
                                      whilem: matched 0 out of 1..1
   1 <a> <aa>                |  5:      OPEN1(7)
   1 <a> <aa>                |  7:      PLUS(10)
                                        EXACT <a> can match 2 times out of 2147483647...
   3 <aaa> <>                | 10:        CLOSE1(12)
   3 <aaa> <>                | 12:        WHILEM(0)
                                          whilem: matched 1 out of 1..1
   3 <aaa> <>                | 13:          NOTHING(14)
   3 <aaa> <>                | 14:          SUCCEED(0)
                                            subpattern success...
   3 <aaa> <>                | 16:EXACT <a>(18)
                                  failed...
   2 <aa> <a>                |  1:SUSPEND(16)
   2 <aa> <a>                |  3:  CURLYX[0] {1,1}(13)
   2 <aa> <a>                | 12:    WHILEM(0)
                                      whilem: matched 0 out of 1..1
   2 <aa> <a>                |  5:      OPEN1(7)
   2 <aa> <a>                |  7:      PLUS(10)
                                        EXACT <a> can match 1 times out of 2147483647...
   3 <aaa> <>                | 10:        CLOSE1(12)
   3 <aaa> <>                | 12:        WHILEM(0)
                                          whilem: matched 1 out of 1..1
   3 <aaa> <>                | 13:          NOTHING(14)
   3 <aaa> <>                | 14:          SUCCEED(0)
                                            subpattern success...
   3 <aaa> <>                | 16:EXACT <a>(18)
                                  failed...
Match failed
Freeing REx: "(a+){1}+a"