SimplifyGlobals: Apply known constant values in linear traces #2340
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| auto* global = getModule()->getGlobal(curr->name); | ||
| assert(global->init->is<Const>()); | ||
| replaceCurrent(ExpressionManipulator::copy(global->init, *getModule())); | ||
| void visitExpression(Expression* curr) { |
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I'm a little confused about the purpose of optimize, since it isn't used in visitExpression.
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It's whether to optimize after doing a successful replacement. I'm adding some comments now to clarify.
| @@ -267,6 +267,10 @@ void PassRegistry::registerPasses() { | |||
| registerPass("simplify-globals", | |||
| "miscellaneous globals-related optimizations", | |||
| createSimplifyGlobalsPass); | |||
| registerPass("simplify-globals-optimizing", | |||
| "miscellaneous globals-related optimizations, and optimizes " | |||
| "where we replaced global.gets with constants", | |||
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Maybe say "optimizes locally" or similar to indicate the difference between these additional optimizations and the baseline miscellaneous optimizations?
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I get the point that this could be clearer, but I'm not sure "locally" is the right term...?
This is the same as with inlining and dae - they also have text like "and optimizes where we removed/inlined/replaced" etc. Maybe we can find something better for all of them?
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Ah, I thought optimize was supposed to control the new linear-execution optimization. This makes more sense now. 👍
| (global.set $g2 | ||
| (local.get $x) | ||
| ) | ||
| (i32.const 100) |
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Looks like this still got optimized.
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Correct, it does the optimization itself, but doesn't also run general optimization passes as a followup to that optimization.
This optimizes stuff like
into
This doesn't help much with LLVM output as it's rare to use globals (except for the stack pointer, and that's already well optimized), but it may help on general wasm. It can also help with Asyncify that does use globals extensively.