0000181: FIRM does not optimize loads from read-only (module-)global variables

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Severity

Reproducibility

Date Submitted

Last Update

0000181

[libFirm] optimisations

minor

always

2016-10-10 13:35

2016-10-20 18:06

Reporter

mohr

View Status

public

Assigned To

Priority

normal

Resolution

fixed

Status

resolved

Product Version

development

Summary

0000181: FIRM does not optimize loads from read-only (module-)global variables

Description

FIRM fails to optimize the following program (also attached):

static int g = 0;
int main()
{
    if (g)
        return 1;
    return 0;
}

FIRM does not reduce this program to "return 0;", nor does it remove 'g'.

It seems that ir/ana/irmemory.c computes all necessary information about the usage of the entity 'g'. However, ir/opt/ldstopt.c seems not to consider read-only entities. Hence, 'g' is also not removed in the following (which FIRM can do as soon as the entity does not have any users any more).

Additional Information

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Attached Files

bla.c [^] (65 bytes) 2016-10-10 13:35

Relationships

Notes
(0000274) mohr (developer) 2016-10-20 18:06	Implemented necessary optimization in 20c9ab7ed2a19e3de4353263bc4431cd31291b1f.

Issue History
Date Modified	Username	Field	Change
2016-10-10 13:35	mohr	New Issue
2016-10-10 13:35	mohr	File Added: bla.c
2016-10-20 18:06	mohr	Note Added: 0000274
2016-10-20 18:06	mohr	Status	new => resolved
2016-10-20 18:06	mohr	Resolution	open => fixed

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