add OP_ARGELEM, OP_ARGDEFELEM, OP_ARGCHECK ops

Currently subroutine signature parsing emits many small discrete ops
to implement arg handling. This commit replaces them with a couple of ops
per signature element, plus an initial signature check op.

These new ops are added to the OP tree during parsing, so will be visible
to hooks called up to and including peephole optimisation. It is intended
soon that the peephole optimiser will take these per-element ops, and
replace them with a single OP_SIGNATURE op which handles the whole
signature in a single go. So normally these ops wont actually get executed
much. But adding these intermediate-level ops gives three advantages:

1) it allows the parser to efficiently generate subtrees containing
   individual signature elements, which can't be done if only OP_SIGNATURE
   or discrete ops are available;
2) prior to optimisation, it provides a simple and straightforward
   representation of the signature;
3) hooks can mess with the signature OP subtree in ways that make it
   no longer possible to optimise into an OP_SIGNATURE, but which can
   still be executed, deparsed etc (if less efficiently).

This code:

    use feature "signatures";
    sub f($a, $, $b = 1, @c)  {$a}

under 'perl -MO=Concise,f' now gives:

    d  <1> leavesub[1 ref] K/REFC,1 ->(end)
    -     <@> lineseq KP ->d
    1        <;> nextstate(main 84 foo:6) v:%,469762048 ->2
    2        <+> argcheck(3,1,@) v ->3
    3        <;> nextstate(main 81 foo:6) v:%,469762048 ->4
    4        <+> argelem(0)[$a:81,84] v/SV ->5
    5        <;> nextstate(main 82 foo:6) v:%,469762048 ->6
    8        <+> argelem(2)[$b:82,84] vKS/SV ->9
    6           <|> argdefelem(other->7)[2] sK ->8
    7              <$> const(IV 1) s ->8
    9        <;> nextstate(main 83 foo:6) v:%,469762048 ->a
    a        <+> argelem(3)[@c:83,84] v/AV ->b
    -        <;> ex-nextstate(main 84 foo:6) v:%,469762048 ->b
    b        <;> nextstate(main 84 foo:6) v:%,469762048 ->c
    c        <0> padsv[$a:81,84] s ->d

The argcheck(3,1,@) op knows the number of positional params (3), the
number of optional params (1), and whether it has an array / hash slurpy
element at the end. This op is responsible for checking that @_ contains
the right number of args.

A simple argelem(0)[$a] op does the equivalent of 'my $a = $_[0]'.
Similarly, argelem(3)[@c] is equivalent to 'my @c = @_[3..$#_]'.
If it has a child, it gets its arg from the stack rather than using $_[N].
Currently the only used child is the logop argdefelem.

argdefelem(other->7)[2] is equivalent to '@_ > 2 ? $_[2] : other'.

[ These ops currently assume that the lexical var being introduced
is undef/empty and non-magival etc. This is an incorrect assumption and
is fixed in a few commits' time ]

1 files changed, 86 insertions, 59 deletions

diff --git a/opcode.h b/opcode.h
index 0aaefb64a4..24f5a672f6 100644
--- a/opcode.h
+++ b/opcode.h
@@ -334,6 +334,9 @@ EXTCONST char* const PL_op_name[] = {
 	"entersub",
 	"leavesub",
 	"leavesublv",
+	"argcheck",
+	"argelem",
+	"argdefelem",
 	"caller",
 	"warn",
 	"die",
@@ -736,6 +739,9 @@ EXTCONST char* const PL_op_desc[] = {
 	"subroutine entry",
 	"subroutine exit",
 	"lvalue subroutine return",
+	"check subroutine arguments",
+	"subroutine argument",
+	"subroutine argument default value",
 	"caller",
 	"warn",
 	"die",
@@ -1152,6 +1158,9 @@ EXT Perl_ppaddr_t PL_ppaddr[] /* or perlvars.h */
 	Perl_pp_entersub,
 	Perl_pp_leavesub,
 	Perl_pp_leavesublv,
+	Perl_pp_argcheck,
+	Perl_pp_argelem,
+	Perl_pp_argdefelem,
 	Perl_pp_caller,
 	Perl_pp_warn,
 	Perl_pp_die,
@@ -1564,6 +1573,9 @@ EXT Perl_check_t PL_check[] /* or perlvars.h */
 	Perl_ck_subr,		/* entersub */
 	Perl_ck_null,		/* leavesub */
 	Perl_ck_null,		/* leavesublv */
+	Perl_ck_null,		/* argcheck */
+	Perl_ck_null,		/* argelem */
+	Perl_ck_null,		/* argdefelem */
 	Perl_ck_fun,		/* caller */
 	Perl_ck_fun,		/* warn */
 	Perl_ck_fun,		/* die */
@@ -1970,6 +1982,9 @@ EXTCONST U32 PL_opargs[] = {
 	0x00002141,	/* entersub */
 	0x00000100,	/* leavesub */
 	0x00000100,	/* leavesublv */
+	0x00000f00,	/* argcheck */
+	0x00000f00,	/* argelem */
+	0x00000300,	/* argdefelem */
 	0x00009b08,	/* caller */
 	0x0000240d,	/* warn */
 	0x0000240d,	/* die */
@@ -2184,12 +2199,14 @@ EXTCONST U32 PL_opargs[] = {
 END_EXTERN_C
 
 
+#define OPpARGELEM_SV           0x00
 #define OPpLVREF_SV             0x00
 #define OPpARG1_MASK            0x01
 #define OPpCOREARGS_DEREF1      0x01
 #define OPpENTERSUB_INARGS      0x01
 #define OPpSORT_NUMERIC         0x01
 #define OPpTRANS_FROM_UTF       0x01
+#define OPpARGELEM_AV           0x02
 #define OPpCONST_NOVER          0x02
 #define OPpCOREARGS_DEREF2      0x02
 #define OPpEVAL_HAS_HH          0x02
@@ -2199,6 +2216,7 @@ END_EXTERN_C
 #define OPpSORT_INTEGER         0x02
 #define OPpTRANS_TO_UTF         0x02
 #define OPpARG2_MASK            0x03
+#define OPpARGELEM_HV           0x04
 #define OPpCONST_SHORTCIRCUIT   0x04
 #define OPpDONT_INIT_GV         0x04
 #define OPpENTERSUB_HASTARG     0x04
@@ -2208,6 +2226,7 @@ END_EXTERN_C
 #define OPpSLICEWARNING         0x04
 #define OPpSORT_REVERSE         0x04
 #define OPpTRANS_IDENTICAL      0x04
+#define OPpARGELEM_MASK         0x06
 #define OPpARG3_MASK            0x07
 #define OPpPADRANGE_COUNTSHIFT  0x07
 #define OPpCONST_STRICT         0x08
@@ -2411,6 +2430,7 @@ EXTCONST I16 PL_op_private_bitfields[] = {
     0, 8, -1,
     0, 8, -1,
     0, 8, -1,
+    1, -1, 0, 507, 1, 26, 2, 276, -1,
     4, -1, 1, 157, 2, 164, 3, 171, -1,
     4, -1, 0, 507, 1, 26, 2, 276, 3, 103, -1,
 
@@ -2609,27 +2629,30 @@ EXTCONST I16  PL_op_private_bitdef_ix[] = {
      137, /* entersub */
      144, /* leavesub */
      144, /* leavesublv */
-     146, /* caller */
+       0, /* argcheck */
+     146, /* argelem */
+       0, /* argdefelem */
+     148, /* caller */
       48, /* warn */
       48, /* die */
       48, /* reset */
       -1, /* lineseq */
-     148, /* nextstate */
-     148, /* dbstate */
+     150, /* nextstate */
+     150, /* dbstate */
       -1, /* unstack */
       -1, /* enter */
-     149, /* leave */
+     151, /* leave */
       -1, /* scope */
-     151, /* enteriter */
-     155, /* iter */
+     153, /* enteriter */
+     157, /* iter */
       -1, /* enterloop */
-     156, /* leaveloop */
+     158, /* leaveloop */
       -1, /* return */
-     158, /* last */
-     158, /* next */
-     158, /* redo */
-     158, /* dump */
-     158, /* goto */
+     160, /* last */
+     160, /* next */
+     160, /* redo */
+     160, /* dump */
+     160, /* goto */
       48, /* exit */
        0, /* method_named */
        0, /* method_super */
@@ -2641,7 +2664,7 @@ EXTCONST I16  PL_op_private_bitdef_ix[] = {
        0, /* leavewhen */
       -1, /* break */
       -1, /* continue */
-     160, /* open */
+     162, /* open */
       48, /* close */
       48, /* pipe_op */
       48, /* fileno */
@@ -2687,33 +2710,33 @@ EXTCONST I16  PL_op_private_bitdef_ix[] = {
        0, /* getpeername */
        0, /* lstat */
        0, /* stat */
-     165, /* ftrread */
-     165, /* ftrwrite */
-     165, /* ftrexec */
-     165, /* fteread */
-     165, /* ftewrite */
-     165, /* fteexec */
-     170, /* ftis */
-     170, /* ftsize */
-     170, /* ftmtime */
-     170, /* ftatime */
-     170, /* ftctime */
-     170, /* ftrowned */
-     170, /* fteowned */
-     170, /* ftzero */
-     170, /* ftsock */
-     170, /* ftchr */
-     170, /* ftblk */
-     170, /* ftfile */
-     170, /* ftdir */
-     170, /* ftpipe */
-     170, /* ftsuid */
-     170, /* ftsgid */
-     170, /* ftsvtx */
-     170, /* ftlink */
-     170, /* fttty */
-     170, /* fttext */
-     170, /* ftbinary */
+     167, /* ftrread */
+     167, /* ftrwrite */
+     167, /* ftrexec */
+     167, /* fteread */
+     167, /* ftewrite */
+     167, /* fteexec */
+     172, /* ftis */
+     172, /* ftsize */
+     172, /* ftmtime */
+     172, /* ftatime */
+     172, /* ftctime */
+     172, /* ftrowned */
+     172, /* fteowned */
+     172, /* ftzero */
+     172, /* ftsock */
+     172, /* ftchr */
+     172, /* ftblk */
+     172, /* ftfile */
+     172, /* ftdir */
+     172, /* ftpipe */
+     172, /* ftsuid */
+     172, /* ftsgid */
+     172, /* ftsvtx */
+     172, /* ftlink */
+     172, /* fttty */
+     172, /* fttext */
+     172, /* ftbinary */
       77, /* chdir */
       77, /* chown */
       71, /* chroot */
@@ -2733,17 +2756,17 @@ EXTCONST I16  PL_op_private_bitdef_ix[] = {
        0, /* rewinddir */
        0, /* closedir */
       -1, /* fork */
-     174, /* wait */
+     176, /* wait */
       77, /* waitpid */
       77, /* system */
       77, /* exec */
       77, /* kill */
-     174, /* getppid */
+     176, /* getppid */
       77, /* getpgrp */
       77, /* setpgrp */
       77, /* getpriority */
       77, /* setpriority */
-     174, /* time */
+     176, /* time */
       -1, /* tms */
        0, /* localtime */
       48, /* gmtime */
@@ -2763,7 +2786,7 @@ EXTCONST I16  PL_op_private_bitdef_ix[] = {
        0, /* require */
        0, /* dofile */
       -1, /* hintseval */
-     175, /* entereval */
+     177, /* entereval */
      144, /* leaveeval */
        0, /* entertry */
       -1, /* leavetry */
@@ -2802,18 +2825,18 @@ EXTCONST I16  PL_op_private_bitdef_ix[] = {
        0, /* lock */
        0, /* once */
       -1, /* custom */
-     181, /* coreargs */
-     185, /* avhvswitch */
+     183, /* coreargs */
+     187, /* avhvswitch */
        3, /* runcv */
        0, /* fc */
       -1, /* padcv */
       -1, /* introcv */
       -1, /* clonecv */
-     187, /* padrange */
-     189, /* refassign */
-     195, /* lvref */
-     201, /* lvrefslice */
-     202, /* lvavref */
+     189, /* padrange */
+     191, /* refassign */
+     197, /* lvref */
+     203, /* lvrefslice */
+     204, /* lvavref */
        0, /* anonconst */
 
 };
@@ -2833,19 +2856,19 @@ EXTCONST I16  PL_op_private_bitdef_ix[] = {
  */
 
 EXTCONST U16  PL_op_private_bitdefs[] = {
-    0x0003, /* scalar, prototype, refgen, srefgen, ref, readline, regcmaybe, regcreset, regcomp, chop, schop, defined, undef, study, preinc, i_preinc, predec, i_predec, postinc, i_postinc, postdec, i_postdec, negate, i_negate, not, complement, ucfirst, lcfirst, uc, lc, quotemeta, aeach, avalues, each, values, pop, shift, grepstart, grepwhile, mapstart, mapwhile, range, and, or, dor, andassign, orassign, dorassign, method, method_named, method_super, method_redir, method_redir_super, entergiven, leavegiven, enterwhen, leavewhen, untie, tied, dbmclose, getsockname, getpeername, lstat, stat, readlink, readdir, telldir, rewinddir, closedir, localtime, alarm, require, dofile, entertry, ghbyname, gnbyname, gpbyname, shostent, snetent, sprotoent, sservent, gpwnam, gpwuid, ggrnam, ggrgid, lock, once, fc, anonconst */
+    0x0003, /* scalar, prototype, refgen, srefgen, ref, readline, regcmaybe, regcreset, regcomp, chop, schop, defined, undef, study, preinc, i_preinc, predec, i_predec, postinc, i_postinc, postdec, i_postdec, negate, i_negate, not, complement, ucfirst, lcfirst, uc, lc, quotemeta, aeach, avalues, each, values, pop, shift, grepstart, grepwhile, mapstart, mapwhile, range, and, or, dor, andassign, orassign, dorassign, method, argcheck, argdefelem, method_named, method_super, method_redir, method_redir_super, entergiven, leavegiven, enterwhen, leavewhen, untie, tied, dbmclose, getsockname, getpeername, lstat, stat, readlink, readdir, telldir, rewinddir, closedir, localtime, alarm, require, dofile, entertry, ghbyname, gnbyname, gpbyname, shostent, snetent, sprotoent, sservent, gpwnam, gpwuid, ggrnam, ggrgid, lock, once, fc, anonconst */
     0x2b5c, 0x3d59, /* pushmark */
     0x00bd, /* wantarray, runcv */
     0x03b8, 0x17f0, 0x3e0c, 0x38c8, 0x2f25, /* const */
     0x2b5c, 0x3079, /* gvsv */
     0x1655, /* gv */
     0x0067, /* gelem, lt, i_lt, gt, i_gt, le, i_le, ge, i_ge, eq, i_eq, ne, i_ne, ncmp, i_ncmp, slt, sgt, sle, sge, seq, sne, scmp, bit_and, bit_xor, bit_or, sbit_and, sbit_xor, sbit_or, smartmatch, lslice, xor */
-    0x2b5c, 0x3d58, 0x02b7, /* padsv */
+    0x2b5c, 0x3d58, 0x03d7, /* padsv */
     0x2b5c, 0x3d58, 0x2c4c, 0x3a49, /* padav */
     0x2b5c, 0x3d58, 0x0534, 0x05d0, 0x2c4c, 0x3a49, /* padhv */
     0x3819, /* pushre, match, qr, subst */
-    0x2b5c, 0x19d8, 0x02b6, 0x2c4c, 0x2e48, 0x3e04, 0x0003, /* rv2gv */
-    0x2b5c, 0x3078, 0x02b6, 0x3e04, 0x0003, /* rv2sv */
+    0x2b5c, 0x19d8, 0x03d6, 0x2c4c, 0x2e48, 0x3e04, 0x0003, /* rv2gv */
+    0x2b5c, 0x3078, 0x03d6, 0x3e04, 0x0003, /* rv2sv */
     0x2c4c, 0x0003, /* av2arylen, pos, akeys, keys */
     0x2dbc, 0x0e18, 0x0b74, 0x028c, 0x3fc8, 0x3e04, 0x0003, /* rv2cv */
     0x018f, /* bless, glob, sprintf, formline, unpack, pack, join, anonlist, anonhash, splice, warn, die, reset, exit, close, pipe_op, fileno, umask, binmode, tie, dbmopen, sselect, select, getc, read, enterwrite, sysopen, sysseek, sysread, syswrite, eof, tell, seek, truncate, fcntl, ioctl, send, recv, socket, sockpair, bind, connect, listen, accept, shutdown, gsockopt, ssockopt, open_dir, seekdir, gmtime, shmget, shmctl, shmread, shmwrite, msgget, msgctl, msgsnd, msgrcv, semop, semget, semctl, ghbyaddr, gnbyaddr, gpbynumber, gsbyname, gsbyport, syscall */
@@ -2862,7 +2885,7 @@ EXTCONST U16  PL_op_private_bitdefs[] = {
     0x2c4c, 0x0067, /* vec */
     0x2b5c, 0x3078, 0x2c4c, 0x3a48, 0x3e04, 0x0003, /* rv2av */
     0x025f, /* aelemfast, aelemfast_lex */
-    0x2b5c, 0x2a58, 0x02b6, 0x2c4c, 0x0067, /* aelem, helem */
+    0x2b5c, 0x2a58, 0x03d6, 0x2c4c, 0x0067, /* aelem, helem */
     0x2b5c, 0x2c4c, 0x3a49, /* aslice, hslice */
     0x2c4d, /* kvaslice, kvhslice */
     0x2b5c, 0x3998, 0x0003, /* delete */
@@ -2875,8 +2898,9 @@ EXTCONST U16  PL_op_private_bitdefs[] = {
     0x26cc, 0x0003, /* reverse */
     0x28f8, 0x0003, /* flip, flop */
     0x2b5c, 0x0003, /* cond_expr */
-    0x2b5c, 0x0e18, 0x02b6, 0x028c, 0x3fc8, 0x3e04, 0x2481, /* entersub */
+    0x2b5c, 0x0e18, 0x03d6, 0x028c, 0x3fc8, 0x3e04, 0x2481, /* entersub */
     0x33d8, 0x0003, /* leavesub, leavesublv, leavewrite, leaveeval */
+    0x02aa, 0x0003, /* argelem */
     0x00bc, 0x018f, /* caller */
     0x21f5, /* nextstate, dbstate */
     0x29fc, 0x33d9, /* leave */
@@ -2892,8 +2916,8 @@ EXTCONST U16  PL_op_private_bitdefs[] = {
     0x2d1c, 0x0018, 0x1144, 0x1061, /* coreargs */
     0x2c4c, 0x00c7, /* avhvswitch */
     0x2b5c, 0x01fb, /* padrange */
-    0x2b5c, 0x3d58, 0x03d6, 0x284c, 0x1748, 0x0067, /* refassign */
-    0x2b5c, 0x3d58, 0x03d6, 0x284c, 0x1748, 0x0003, /* lvref */
+    0x2b5c, 0x3d58, 0x04f6, 0x284c, 0x1748, 0x0067, /* refassign */
+    0x2b5c, 0x3d58, 0x04f6, 0x284c, 0x1748, 0x0003, /* lvref */
     0x2b5d, /* lvrefslice */
     0x2b5c, 0x3d58, 0x0003, /* lvavref */
 
@@ -3092,6 +3116,9 @@ EXTCONST U8 PL_op_private_valid[] = {
     /* ENTERSUB   */ (OPpENTERSUB_INARGS|OPpHINT_STRICT_REFS|OPpENTERSUB_HASTARG|OPpENTERSUB_AMPER|OPpDEREF|OPpENTERSUB_DB|OPpLVAL_INTRO),
     /* LEAVESUB   */ (OPpARG1_MASK|OPpREFCOUNTED),
     /* LEAVESUBLV */ (OPpARG1_MASK|OPpREFCOUNTED),
+    /* ARGCHECK   */ (OPpARG1_MASK),
+    /* ARGELEM    */ (OPpARG1_MASK|OPpARGELEM_MASK),
+    /* ARGDEFELEM */ (OPpARG1_MASK),
     /* CALLER     */ (OPpARG4_MASK|OPpOFFBYONE),
     /* WARN       */ (OPpARG4_MASK),
     /* DIE        */ (OPpARG4_MASK),