SIL: fix memory behavior of global_addr for globals with non-fixed layout. #31205
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…yout. Global variables with resilient types might be allocated into a buffer and not statically in the data segment. In this case, the global_addr depends on alloc_global being executed first. We model this by letting global_addr have a side effect. It prevents e.g. LICM to move a global_addr out of a loop while keeping the alloc_global inside the loop. rdar://problem/61602640
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@swift-ci test |
slavapestov
approved these changes
Apr 22, 2020
| // It prevents e.g. LICM to move a global_addr out of a loop while keeping | ||
| // the alloc_global inside the loop. | ||
| SILModule &M = ga->getFunction()->getModule(); | ||
| auto expansion = TypeExpansionContext::maximal(M.getAssociatedContext(), |
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Since IRGen makes a similar calculation when lowering the instruction to decide if it should allocate the box or not, should we factor it out somewhere?
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IRGen uses the TypeInfo machinery for this, which is only available in IRgen
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FYI: This broke the Android CI |
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Global variables with resilient types might be allocated into a buffer and not statically in the data segment.
In this case, the global_addr depends on alloc_global being executed first.
Letting global_addr have a side effect ensures that this dependency is kept.
It prevents e.g. LICM to move a global_addr out of a loop while keeping the alloc_global inside the loop.
rdar://problem/61602640