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GeezerVison is showing github.com — bpo-41463: Generate information about jumps from 'opcode.py' rather than duplicating it in 'compile.c' by markshannon · Pull Request #21714 · python/cpython

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@markshannon

@markshannon markshannon commented Aug 3, 2020 •
edited by bedevere-bot
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The motivation for this PR is to avoid errors when modifying compile.c.
Setting the i_jabs and i_jrel fields of every instruction is error prone and unnecessary.

https://bugs.python.org/issue41463

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@markshannon
Generate information about jumps from 'opcode.py' rather than duplica…
9728d21 
…te it in 'compile.c'
@the-knights-who-say-ni the-knights-who-say-ni added the CLA signed label Aug 3, 2020
@bedevere-bot bedevere-bot added the awaiting core review label Aug 3, 2020
@markshannon markshannon added the skip news label Aug 3, 2020
@markshannon
markshannon requested a review from pablogsal August 4, 2020 10:01
pablogsal
pablogsal reviewed Aug 4, 2020
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Comment thread Python/compile.c Outdated
int i_lineno;
};

static int

@pablogsal pablogsal Aug 4, 2020

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Suggested change
static int
static inline int

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pablogsal
pablogsal reviewed Aug 4, 2020
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Comment thread Python/compile.c Outdated
return (_PyOpcode_RelativeJump[opcode>>5]>>(opcode&31))&1;
}

static int

@pablogsal pablogsal Aug 4, 2020

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Suggested change
static int
static inline int

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pablogsal
pablogsal reviewed Aug 4, 2020
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Comment thread Python/compile.c Outdated
is_relative_jump(struct instr *i)
{
int opcode = i->i_opcode;
return (_PyOpcode_RelativeJump[opcode>>5]>>(opcode&31))&1;

@pablogsal pablogsal Aug 4, 2020

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Can you define 5 and 31 as globals with a name (using #define or with static variables). That way this will read a bit better

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pablogsal
pablogsal reviewed Aug 4, 2020
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Look great, I left some minor comments

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pablogsal
pablogsal reviewed Aug 4, 2020
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Comment thread Python/compile.c
int oparg = inst->i_oparg;
int nextop = i+1 < bb->b_iused ? bb->b_instr[i+1].i_opcode : 0;
if (inst->i_jabs || inst->i_jrel) {
if (is_jump(inst)) {

@pablogsal pablogsal Aug 4, 2020

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Great!

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@markshannon
Minor clarifications.
210e582
pablogsal
pablogsal reviewed Aug 4, 2020
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Comment thread Python/compile.c Outdated
static inline int
is_relative_jump(struct instr *i)
{
int opcode = i->i_opcode;

@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

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pablogsal
pablogsal approved these changes Aug 4, 2020
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LGTM

I left a comment, feel free to address it before landing

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@bedevere-bot bedevere-bot added awaiting merge and removed awaiting core review labels Aug 4, 2020
@markshannon
Clarify logic used to pick bit marking jumps.
5c6594c
pablogsal
pablogsal approved these changes Aug 4, 2020
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Perfect!

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@markshannon
markshannon merged commit 582aaf1 into python:master Aug 4, 2020
@bedevere-bot bedevere-bot removed the awaiting merge label Aug 4, 2020
@markshannon
markshannon deleted the remove-i-fields branch August 4, 2020 22:05
shihai1991 pushed a commit to shihai1991/cpython that referenced this pull request Aug 20, 2020
@markshannon @shihai1991
bpo-41463: Generate information about jumps from 'opcode.py' rather t…
fdaafe0 
…han duplicating it in 'compile.c' (pythonGH-21714)

Generate information about jumps from 'opcode.py' rather than duplicate it in 'compile.c'
xzy3 pushed a commit to xzy3/cpython that referenced this pull request Oct 18, 2020
@markshannon @xzy3-cdc
bpo-41463: Generate information about jumps from 'opcode.py' rather t…
b47b85b 
…han duplicating it in 'compile.c' (pythonGH-21714)

Generate information about jumps from 'opcode.py' rather than duplicate it in 'compile.c'
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@pablogsal pablogsal pablogsal approved these changes

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4 participants

@markshannon @pablogsal @the-knights-who-say-ni @bedevere-bot
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