1b09aae82a
Summary:
This change depends on D23986 which adds tail call-specific sleds. For
now we treat them first as normal exits, and in the future leave room
for implementing this as a different kind of log entry.
The reason for deferring the change is so that we can keep the naive
logging implementation more accurate without additional complexity for
reading the log. The accuracy is gained in effectively interpreting call
stacks like:
A()
B()
C()
Which when tail-call merged will end up not having any exit entries for
A() nor B(), but effectively in turn can be reasoned about as:
A()
B()
C()
Although we lose the fact that A() had called B() then had called C()
with the naive approach, a later iteration that adds the explicit tail
call entries would be a change in the log format and thus necessitate a
version change for the header. We can do this later to have a chance at
releasing some tools (in D21987) that are able to handle the naive log
format, then support higher version numbers of the log format too.
Reviewers: echristo, kcc, rSerge, majnemer
Subscribers: mehdi_amini, llvm-commits, dberris
Differential Revision: https://reviews.llvm.org/D23988
llvm-svn: 284178
59 lines
2.0 KiB
C++
59 lines
2.0 KiB
C++
//===-- xray_interface.h ----------------------------------------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file is a part of XRay, a dynamic runtime instrumentation system.
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//
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// APIs for controlling XRay functionality explicitly.
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//===----------------------------------------------------------------------===//
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#ifndef XRAY_XRAY_INTERFACE_H
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#define XRAY_XRAY_INTERFACE_H
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#include <cstdint>
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extern "C" {
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enum XRayEntryType { ENTRY = 0, EXIT = 1, TAIL = 2 };
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// Provide a function to invoke for when instrumentation points are hit. This is
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// a user-visible control surface that overrides the default implementation. The
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// function provided should take the following arguments:
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//
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// - function id: an identifier that indicates the id of a function; this id
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// is generated by xray; the mapping between the function id
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// and the actual function pointer is available through
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// __xray_table.
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// - entry type: identifies what kind of instrumentation point was encountered
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// (function entry, function exit, etc.). See the enum
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// XRayEntryType for more details.
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//
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// Returns 1 on success, 0 on error.
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extern int __xray_set_handler(void (*entry)(int32_t, XRayEntryType));
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// This removes whatever the currently provided handler is. Returns 1 on
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// success, 0 on error.
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extern int __xray_remove_handler();
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enum XRayPatchingStatus {
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NOT_INITIALIZED = 0,
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SUCCESS = 1,
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ONGOING = 2,
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FAILED = 3,
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};
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// This tells XRay to patch the instrumentation points. See XRayPatchingStatus
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// for possible result values.
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extern XRayPatchingStatus __xray_patch();
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// Reverses the effect of __xray_patch(). See XRayPatchingStatus for possible
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// result values.
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extern XRayPatchingStatus __xray_unpatch();
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}
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#endif
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