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Emit basic XRay instrumentation attributes

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Add the attributes to functions according to the settings.

"xray-always" overrides "xray-never", and they both override
"xray-ignore-loops" and "xray-instruction-threshold", but we'll
let lints deal with warnings about silly attribute combinations.
This commit is contained in:
Oleksii Lozovskyi 2022-09-24 22:05:25 +09:00
parent b3cadd2dcf
commit bac15db1d0
1 changed files with 28 additions and 0 deletions
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28
compiler/rustc_codegen_llvm/src/attributes.rs
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@ -134,6 +134,34 @@ fn instrument_function_attr<'ll>(cx: &CodegenCx<'ll, '_>) -> SmallVec<[&'ll Attr
&mcount_name,
));
}
if let Some(options) = &cx.sess().opts.unstable_opts.instrument_xray {
// XRay instrumentation is similar to __cyg_profile_func_{enter,exit}.
// Function prologue and epilogue are instrumented with NOP sleds,
// a runtime library later replaces them with detours into tracing code.
if options.always {
attrs.push(llvm::CreateAttrStringValue(cx.llcx, "function-instrument", "xray-always"));
}
if options.never {
attrs.push(llvm::CreateAttrStringValue(cx.llcx, "function-instrument", "xray-never"));
}
if options.ignore_loops {
attrs.push(llvm::CreateAttrString(cx.llcx, "xray-ignore-loops"));
}
// LLVM will not choose the default for us, but rather requires specific
// threshold in absence of "xray-always". Use the same default as Clang.
let threshold = options.instruction_threshold.unwrap_or(200);
attrs.push(llvm::CreateAttrStringValue(
cx.llcx,
"xray-instruction-threshold",
&threshold.to_string(),
));
if options.skip_entry {
attrs.push(llvm::CreateAttrString(cx.llcx, "xray-skip-entry"));
}
if options.skip_exit {
attrs.push(llvm::CreateAttrString(cx.llcx, "xray-skip-exit"));
}
}
attrs
}