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be19eda0dc
Skip no-op drop glue Since rust-lang/rust#122662 this no longer gets used in vtables, so we're safe to fully drop generating functions from vtables. Those are eventually cleaned up by LLVM, but it's wasteful to produce them in the first place. This doesn't appear to be a significant win (and shows some slight regressions) but seems like the right thing to do. At minimum it reduces noise in the LLVM IR we generate, which seems like a good thing.
The files here use the LLVM FileCheck framework, documented at https://llvm.org/docs/CommandGuide/FileCheck.html.
One extension worth noting is the use of revisions as custom prefixes for FileCheck. If your codegen test has different behavior based on the chosen target or different compiler flags that you want to exercise, you can use a revisions annotation, like so:
// revisions: aaa bbb
// [bbb] compile-flags: --flags-for-bbb
After specifying those variations, you can write different expected, or
explicitly unexpected output by using <prefix>-SAME: and <prefix>-NOT:,
like so:
// CHECK: expected code
// aaa-SAME: emitted-only-for-aaa
// aaa-NOT: emitted-only-for-bbb
// bbb-NOT: emitted-only-for-aaa
// bbb-SAME: emitted-only-for-bbb