[Mesa-dev] [PATCH] linker: Only over-ride built-ins when a prototype has been seen

[Chad Versace]

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On 07/11/2011 10:50 AM, Ian Romanick wrote:
> From: Ian Romanick <ian.d.romanick at intel.com>
> 
> The GLSL spec says:
> 
>     "If a built-in function is redeclared in a shader (i.e., a
>     prototype is visible) before a call to it, then the linker will
>     only attempt to resolve that call within the set of shaders that
>     are linked with it."
> 
> This patch enforces this behavior.  When a function call is processed
> a flag is set in the ir_call to indicate whether the previously seen
> prototype is the built-in or not.  At link time a call will only bind
> to an instance of a function that matches the "want built-in" setting
> in the ir_call.
> 
> This has the odd side effect that first call to abs() in the shader
> below will call the built-in and the second will not:
> 
> float foo(float x) { return abs(x); }
> float abs(float x) { return -x; }
> float bar(float x) { return abs(x); }
> 
> This seems insane, but it matches what the spec says.
> 
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=31744
> ---
>  src/glsl/ir.h               |    4 ++++
>  src/glsl/link_functions.cpp |   22 +++++++++++++++++-----
>  2 files changed, 21 insertions(+), 5 deletions(-)


This patch causes link failures in the following tests:

glsl/overide-builtin
spec/glsl-1.10/linker/overide-builtin-const-02
spec/glsl-1.10/linker/overide-builtin-const-04
spec/glsl-1.10/linker/overide-builtin-const-08
spec/glsl-1.10/linker/overide-builtin-uniform-02
spec/glsl-1.10/linker/overide-builtin-uniform-04
spec/glsl-1.10/linker/overide-builtin-uniform-08

- -- 
Chad Versace
chad at chad-versace.us
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