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Perl_op_convert_list: Avoid unnecessary processing of CONST OPs #22116

Merged
merged 1 commit into from
Jun 10, 2024
Merged

Perl_op_convert_list: Avoid unnecessary processing of CONST OPs #22116

merged 1 commit into from
Jun 10, 2024

Commits on Apr 3, 2024

  1. Perl_op_convert_list: No unnecessary processing of unfolded CONSTs 

    When Perl_op_convert_list is called to stringify a CONST OP, but the
`op_folded` flag has not been passed in, a fair amount of activity
occurs before the function returns the original CONST OP unchanged.
After this commit, the CONST OP is returned directly.

For example, prior to this commit, given the statement 'print "2\n',
the function is passed a simple CONST OP:

1    const SVOP(0x55c99432c0b8) ===> [SELF]
     PARENT ===> [0x0]
     FLAGS = (SCALAR,SLABBED)
     SV = PV("2\n"\0)

List context is forced upon it to yield:

2    list LISTOP(0x55c99432c048) ===> [0x0]
     PARENT ===> [0x0]
     FLAGS = (UNKNOWN,KIDS,SLABBED)
     |
3    +--pushmark OP(0x55c99432c088) ===> [SELF]
     |   FLAGS = (SCALAR,SLABBED,MORESIB)
     |
1    +--const SVOP(0x55c99432c0b8) ===> [SELF]
         FLAGS = (SCALAR,SLABBED)
         SV = PV("2\n"\0)

The pushmark is nullified and the parent type set:

2    stringify LISTOP(0x55c99432c048) ===> [0x0]
     PARENT ===> [0x0]
     FLAGS = (UNKNOWN,KIDS,SLABBED)
     |
3    +--null (ex-pushmark) OP(0x55c99432c088) ===> [SELF]
     |   FLAGS = (SCALAR,SLABBED,MORESIB)
     |
1    +--const SVOP(0x55c99432c0b8) ===> [SELF]
         FLAGS = (SCALAR,SLABBED)
         SV = PV("2\n"\0)

CHECKOP sets the number of non-null KIDS for the stringify:

2    stringify LISTOP(0x55c99432c048) ===> [0x0]
     PARENT ===> [0x0]
     FLAGS = (UNKNOWN,KIDS,SLABBED)
     PRIVATE = (0x1)
     |
3    +--null (ex-pushmark) OP(0x55c99432c088) ===> [SELF]
     |   FLAGS = (SCALAR,SLABBED,MORESIB)
     |
1    +--const SVOP(0x55c99432c0b8) ===> [SELF]
         FLAGS = (SCALAR,SLABBED)
         SV = PV("2\n"\0)

Then it is constant folded back to:

1    const SVOP(0x55c99432c0b8) ===> [SELF]
     PARENT ===> [0x0]
     FLAGS = (SCALAR,SLABBED)
     SV = PV("2\n"\0)
    @richardleach
    richardleach committed Apr 3, 2024
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