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bpo-41463: Generate information about jumps from 'opcode.py' rather than duplicating it in 'compile.c' #21714

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Merged
markshannon merged 3 commits into from
Aug 4, 2020
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bpo-41463: Generate information about jumps from 'opcode.py' rather than duplicating it in 'compile.c' #21714

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9728d21
Generate information about jumps from 'opcode.py' rather than duplica…
markshannon Aug 3, 2020
210e582
Minor clarifications.
markshannon Aug 4, 2020
5c6594c
Clarify logic used to pick bit marking jumps.
markshannon Aug 4, 2020
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Minor clarifications.
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@markshannon
markshannon committed Aug 4, 2020
commit 210e5824773cdd5b43c3b3b0e6e5738b3aeecf0e
11 changes: 7 additions & 4 deletions Python/compile.c
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Original file line number Diff line number Diff line change
Expand Up @@ -52,18 +52,21 @@ struct instr {
int i_lineno;
};

static int
#define LOG_BITS_PER_INT 5
#define MASK_LOW_LOG_BITS 31

static inline int
is_relative_jump(struct instr *i)
{
int opcode = i->i_opcode;
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@pablogsal pablogsal Aug 4, 2020

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Apologies for insisting a bit but it still took me a minute to parse the expression to follow how the function is determining if is a relative jump. I would suggest to maybe add a comment here briefly explaining the process as someone with less context will certainly struggle

return (_PyOpcode_RelativeJump[opcode>>5]>>(opcode&31))&1;
return (_PyOpcode_RelativeJump[opcode>>LOG_BITS_PER_INT]>>(opcode&MASK_LOW_LOG_BITS))&1;
}

static int
static inline int
is_jump(struct instr *i)
{
int opcode = i->i_opcode;
return (_PyOpcode_Jump[opcode>>5]>>(opcode&31))&1;
return (_PyOpcode_Jump[opcode>>LOG_BITS_PER_INT]>>(opcode&MASK_LOW_LOG_BITS))&1;
}

typedef struct basicblock_ {
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