op_dump(): display names of variables for pad ops #23917
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Make S_deb_padvar() a thin wrapper over a new S_deb_padvar_cv() function, which does the same thing (display a pad variable name), but does it for a specified CV rather than only for the currently executing CV. This function will be used shorty.
The existing S_get_sv_from_pad() function does two things: it finds the CV associated with the specified op, and then extracts something from that CV's pad. This commit splits the 'find the associated CV' part of the code out into a separate function, which will be used elsewhere shortly.
Make op_dump(), as used by 'perl -Dx', display the names of pad
variables when dumping pad ops.
The runtime perl -Dt already does this (note the $x, $y etc appearing in
the op name displays):
$ perl -Dt -e'my ($x, $y); $y = 1+$x'
(-e:0) enter
(-e:0) nextstate
(-e:1) padrange($x,$y)
(-e:1) nextstate
(-e:1) const(IV(1))
(-e:1) padsv($x)
(-e:1) add($y)
(-e:1) leave
While the (typically compile-time) -Dx detailed optree dumping didn't.
Here are some 'before this commit' and 'after' examples of how some of
those ops were/are now displayed. Note the changes in the 'TARG = N'
lines for the following code:
$ perl -Dx -e'my ($x, $y); $y = 1+$x'
Before:
4 | +--padrange OP(0x31b08960) ===> 6 [nextstate 0x31b09fc0]
| | TARG = 1
| | FLAGS = (VOID,MOD,SLABBED,MORESIB)
| | PRIVATE = (LVINTRO,range=0x2)
10 +--add BINOP(0x31b0a060) ===> 1 [leave 0x31b08880]
TARG = 2
FLAGS = (VOID,KIDS,SLABBED)
PRIVATE = (TARGMY,0x2)
11 +--padsv OP(0x31b0a0a0) ===> 10 [add 0x31b0a060]
TARG = 1
FLAGS = (SCALAR,SLABBED)
After:
4 | +--padrange OP(0x18ffe920) ===> 6 [nextstate 0x18ffff80]
| | TARG = 1 ($x,$y)
| | FLAGS = (VOID,MOD,SLABBED,MORESIB)
| | PRIVATE = (LVINTRO,range=0x2)
10 +--add BINOP(0x19000020) ===> 1 [leave 0x18ffe840]
TARG = 2 ($y)
FLAGS = (VOID,KIDS,SLABBED)
PRIVATE = (TARGMY,0x2)
11 +--padsv OP(0x19000060) ===> 10 [add 0x19000020]
TARG = 1 ($x)
FLAGS = (SCALAR,SLABBED)
tonycoz
approved these changes
Nov 12, 2025
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This commit, and its two precursors, makes the output of perl -Dx, a.k.a op_dump(), display the names of pad variables as well as the target number on pad ops.