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Auto merge of #102963 - ilammy:xray-basic, r=estebank

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Add `-Z instrument-xray` flag

Implement MCP https://github.com/rust-lang/compiler-team/issues/561, adding `-Z instrument-xray` flag which enables XRay instrumentation in LLVM.
This commit is contained in:
bors 2023-02-10 00:02:43 +00:00
commit a12d31d5a6
35 changed files with 312 additions and 9 deletions
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38
compiler/rustc_codegen_llvm/src/attributes.rs
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@ -118,7 +118,8 @@ pub fn frame_pointer_type_attr<'ll>(cx: &CodegenCx<'ll, '_>) -> Option<&'ll Attr
/// Tell LLVM what instrument function to insert.
#[inline]
fn instrument_function_attr<'ll>(cx: &CodegenCx<'ll, '_>) -> Option<&'ll Attribute> {
fn instrument_function_attr<'ll>(cx: &CodegenCx<'ll, '_>) -> SmallVec<[&'ll Attribute; 4]> {
let mut attrs = SmallVec::new();
if cx.sess().opts.unstable_opts.instrument_mcount {
// Similar to `clang -pg` behavior. Handled by the
// `post-inline-ee-instrument` LLVM pass.
@ -127,14 +128,41 @@ fn instrument_function_attr<'ll>(cx: &CodegenCx<'ll, '_>) -> Option<&'ll Attribu
// See test/CodeGen/mcount.c in clang.
let mcount_name = cx.sess().target.mcount.as_ref();
Some(llvm::CreateAttrStringValue(
attrs.push(llvm::CreateAttrStringValue(
cx.llcx,
"instrument-function-entry-inlined",
&mcount_name,
))
} else {
None
));
}
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
}
fn nojumptables_attr<'ll>(cx: &CodegenCx<'ll, '_>) -> Option<&'ll Attribute> {