skia2/tests/sksl/inliner/InlinerAvoidsVariableNameOverlap.glsl


out vec4 sk_FragColor;
in vec2 x;
vec4 main() {
    vec2 _3_reusedName = x + vec2(1.0, 2.0);
    vec2 _5_reusedName = _3_reusedName + vec2(3.0, 4.0);

    return _5_reusedName.xyxy;

}
Demonstrate name reuse error in inliner. The following conditions lead to the error: - A pair of nested functions, both of which must be inlined. - Both inlined functions create a variable with the same name. - The outer function passes its variable to the inner function. - The initialization of the inner variable uses the value from the outer variable. - The inner function does not mutate the variable, use it as an out- parameter, or otherwise cause it to receive a temporary copy. When all these conditions are met, both variable declarations are inlined as-is without performing any name salting, because it's seemingly safe to do so. The name overlap issue is not considered in the safety checks. Inlined variable declarations are not subject to name salting but they should be; I suspect other adversarial examples could be crafted as well where unhandled name overlap leads to errors. Change-Id: Ia754bee8e45c8a5c7548436594bbf04abc7a8396 Bug: skia:10722 Reviewed-on: https://skia-review.googlesource.com/c/skia/+/316945 Reviewed-by: Brian Osman <brianosman@google.com> Commit-Queue: Brian Osman <brianosman@google.com> Auto-Submit: John Stiles <johnstiles@google.com> 2020-09-14 22:23:54 +00:00
Support half4 return values from main() in the SPIR-V code generator. This creates a helper function, _entrypoint, which invokes main() and assigns its result into sk_FragColor. We also make sure to prevent sk_FragColor from being dead-stripped from the code during IR generation. At present this is useful for allowing our SkSL test shaders to compile. Change-Id: I2d7fab0e1959a77778ffdb18ca569e869bcaeece Reviewed-on: https://skia-review.googlesource.com/c/skia/+/358525 Commit-Queue: John Stiles <johnstiles@google.com> Reviewed-by: Brian Osman <brianosman@google.com> 2021-01-27 00:58:22 +00:00			`out vec4 sk_FragColor;`
Align default values of GrShaderCaps with StandaloneShaderCaps. `fBuiltinFMASupport` is now true on both, and `fUsesPrecisionModifiers` is now false. Other mismatching flags exist, but they are non-trivial to synchronize as they are tied to extension strings. This will help our skslc-based unit tests generate the same results as our C++ unit tests did, but should not affect real-world results as these defaults will all be overwritten in a non-testing scenario. In practice, the `fUsesPrecisionModifiers` change is responsible for all of the diffs below. The other flags did not change the results of any of the currently-ported tests. Change-Id: Ieb056d852b027fa87c56fd89f971a77a10a8a124 Reviewed-on: https://skia-review.googlesource.com/c/skia/+/317204 Commit-Queue: John Stiles <johnstiles@google.com> Reviewed-by: Brian Osman <brianosman@google.com> Auto-Submit: John Stiles <johnstiles@google.com> 2020-09-15 20:09:11 +00:00			`in vec2 x;`
			`vec4 main() {`
Revert "Declare all inlined variables at the topmost scope possible." This reverts commit e8e4aca955bc87732ada3dd42ec60f6b1a37443e. Reason for revert: can break ES2 for-loop rules Original change's description: > Declare all inlined variables at the topmost scope possible. > > By itself, this is uninteresting and even perhaps slightly > counterproductive (as it separates vardecl from its initializer, > increasing LOC). However, this enables a followup CL > (http://review.skia.org/344665) which allows single-return functions to > be inlined without the creation of a temporary variable at all. This > applies to the majority of fragment processors in a typical Ganesh > hierarchy. This change will greatly reduce the number of inliner-created > temporary copies when compiling a typical tree of FPs. > > Change-Id: I03423a13cf35050637dabace4a32973a08a4ed0a > Reviewed-on: https://skia-review.googlesource.com/c/skia/+/344764 > Reviewed-by: Brian Osman <brianosman@google.com> > Commit-Queue: John Stiles <johnstiles@google.com> TBR=brianosman@google.com,ethannicholas@google.com,johnstiles@google.com Change-Id: Ica01d6906bcb9cef1f49d22dda714fc9cbfa3885 No-Presubmit: true No-Tree-Checks: true No-Try: true Reviewed-on: https://skia-review.googlesource.com/c/skia/+/345121 Reviewed-by: John Stiles <johnstiles@google.com> Commit-Queue: John Stiles <johnstiles@google.com> 2020-12-16 18:25:14 +00:00			`vec2 _3_reusedName = x + vec2(1.0, 2.0);`
Improve inliner variable name mangling. Previously, multiple inliner passes in a row would each apply a separate name mangling to variable names, so names like "_25_14_3_1_pos" were not uncommon. This change demangles the name before re-mangling it, so we would have just "_25_pos" instead. It's not important, but it makes things easier to read. Change-Id: I1257222dac2a68e337f431af230ce50730cedc9b Reviewed-on: https://skia-review.googlesource.com/c/skia/+/345116 Commit-Queue: Brian Osman <brianosman@google.com> Reviewed-by: Brian Osman <brianosman@google.com> Auto-Submit: John Stiles <johnstiles@google.com> 2020-12-16 18:30:54 +00:00			`vec2 _5_reusedName = _3_reusedName + vec2(3.0, 4.0);`
Avoid creating unnecessary scopes during inlining. The additional scopes were harmless, but didn't really add any value. Originally they were used to tightly scope inlined variables, but we now mangle inlined variable names. Change-Id: I7b35e737598036c0b6d3d9f71cbcd4a53d609ce9 Reviewed-on: https://skia-review.googlesource.com/c/skia/+/344757 Auto-Submit: John Stiles <johnstiles@google.com> Reviewed-by: Brian Osman <brianosman@google.com> Commit-Queue: John Stiles <johnstiles@google.com> 2020-12-15 20:21:03 +00:00
Eliminate inliner temporary variables for top-level-exit functions. When we determine that a function only contains a single return statement and it is at the top level (i.e. not inside any scopes), there is no need to create a temporary variable and store the result expression into a variable. Instead, we can directly replace the function-call expression with the return-statement's expression. Unlike my previous solution, this does not require variable declarations to be rewritten. The no-scopes limitation makes it slightly less effective in theory, but in practice we still get almost all of the benefit. The no-scope limitation bites us on structures like @if (true) { return x; } else { return y; } Which will optimize away the if, but leave the scope: { return x; } However, this is not a big deal; the biggest wins are single-line helper functions like `guarded_divide` and `unpremul` which retain the full benefit. Change-Id: I7fbb725e65db021b9795c04c816819669815578f Reviewed-on: https://skia-review.googlesource.com/c/skia/+/345167 Commit-Queue: John Stiles <johnstiles@google.com> Auto-Submit: John Stiles <johnstiles@google.com> Reviewed-by: Ethan Nicholas <ethannicholas@google.com> 2020-12-17 19:38:56 +00:00			`return _5_reusedName.xyxy;`
Demonstrate name reuse error in inliner. The following conditions lead to the error: - A pair of nested functions, both of which must be inlined. - Both inlined functions create a variable with the same name. - The outer function passes its variable to the inner function. - The initialization of the inner variable uses the value from the outer variable. - The inner function does not mutate the variable, use it as an out- parameter, or otherwise cause it to receive a temporary copy. When all these conditions are met, both variable declarations are inlined as-is without performing any name salting, because it's seemingly safe to do so. The name overlap issue is not considered in the safety checks. Inlined variable declarations are not subject to name salting but they should be; I suspect other adversarial examples could be crafted as well where unhandled name overlap leads to errors. Change-Id: Ia754bee8e45c8a5c7548436594bbf04abc7a8396 Bug: skia:10722 Reviewed-on: https://skia-review.googlesource.com/c/skia/+/316945 Reviewed-by: Brian Osman <brianosman@google.com> Commit-Queue: Brian Osman <brianosman@google.com> Auto-Submit: John Stiles <johnstiles@google.com> 2020-09-14 22:23:54 +00:00
			`}`