Bug 99154 - Link time error when using multiple builtin functions
Summary: Link time error when using multiple builtin functions
Alias: None
Product: Mesa
Classification: Unclassified
Component: glsl-compiler (show other bugs)
Version: git
Hardware: Other All
: medium normal
Assignee: Kenneth Graunke
QA Contact: Intel 3D Bugs Mailing List
Depends on:
Reported: 2016-12-19 21:26 UTC by Niels Ole Salscheider
Modified: 2016-12-21 04:56 UTC (History)
1 user (show)

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Simple test case (123 bytes, text/plain)
2016-12-19 21:26 UTC, Niels Ole Salscheider

Description Niels Ole Salscheider 2016-12-19 21:26:25 UTC
Created attachment 128570 [details]
Simple test case

When using multiple builtin functions, linking of a shader can fail if temporary variables of the GLSL compiler collide.

builtin_builder::binop creates variables named "x" and "y" for the parameters of builtin functions. Later, ir_call::generate_inline inlines the call to the builtins. It clones the variables (without changing the name) and assigns the function inputs to them.

This can cause a collision of variable names, e. g. when using multiple builtin functions with parameters of different types. The attached test case can be used to reproduce the problem.

I can work around the problem by adding a sequence number and possibly a prefix to the variable names but I am not sure if that is the correct solution.

Thanks to imirkin and robclark for helping me to figure this out on IRC.
Comment 1 Kenneth Graunke 2016-12-19 23:32:32 UTC
Patch on list:
Comment 2 Kenneth Graunke 2016-12-21 04:56:36 UTC
Fixed on master:

commit 62b8bcda1cb7ad18acee7042d40c01b56385e124
Author: Kenneth Graunke <kenneth@whitecape.org>
Date:   Mon Dec 19 14:32:57 2016 -0800

    glsl: Use ir_var_temporary when generating inline functions.

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