Bug 97804

Created attachment 126514 [details]
Glmark2-es2 Jellyfish shader_test triggering the bug

GLES 3.2 spec:
https://www.khronos.org/registry/gles/specs/3.2/GLSL_ES_Specification_3.20.pdf

States following in "4.7.4 Default Precision Qualifiers":
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Non-precision qualified declarations will use the precision qualifier specified in the most recent precision statement that is still in scope. The precision statement has the same scoping rules as variable declarations.
...
*Multiple precision statements for the same basic type can appear inside the same scope, with later statements overriding earlier statements within that scope.*
...
"
All languages except for the fragment language have the following predeclared globally scoped default precision statements:
   precision highp float;
...
The fragment language has no default precision qualifier for floating point types. Hence for float, floating point vector and matrix variable declarations, either the declaration must include a precision qualifier or the default float precision must have been previously declared.
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Check for latter was added with bug 60737, but precision overriding doesn't seem to work.

Attached Glmark2 shader test fails to Mesa bug 97532.  Vertex shader float uniform defaults to highp, and same should happen in fragment shader, however, that happens only if the first precision statement in shader is removed, as only then it will pass the linker check.  I.e.  precision overriding doesn't work.