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[llvm-profdata] Handle internal linkage functions in profile supplementation

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This patch has the following changes:
(1) Handling of internal linkage functions (static functions)
Static functions in FDO have a prefix of source file name, while they do not
have one in SampleFDO. Current implementation does not handle this and we are
not updating the profile for static functions. This patch fixes this.

(2) Handling of -funique-internal-linakge-symbols
Again this is for the internal linkage functions. Option
-funique-internal-linakge-symbols can now be applied to both FDO and SampleFDO
compilation. When it is used, it demangles internal linkage function names and
adds a hash value as the postfix.

When both SampleFDO and FDO profiles use this option, or both
not use this option, changes in (1) should handle this.

Here we also handle when the SampleFDO profile using this option while FDO
profile not using this option, or vice versa.

There is one case where this patch won't work: If one of the profiles used
mangled name and the other does not. For example, if the SampleFDO profile
uses clang c-compiler and without -funique-internal-linakge-symbols, while
the FDO profile uses -funique-internal-linakge-symbols. The SampleFDO profile
contains unmangled names while the FDO profile contains mangled names. If
both profiles use c++ compiler, this won't happen. We think this use case
is rare and does not justify the effort to fix.

Differential Revision: https://reviews.llvm.org/D132600
This commit is contained in:
Rong Xu
2022-08-24 12:20:46 -07:00
parent 27e8ee208c
commit db18f26567
8 changed files with 226 additions and 26 deletions
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19
clang/lib/CodeGen/CodeGenModule.cpp
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@@ -60,12 +60,12 @@
#include "llvm/IR/Module.h"
#include "llvm/IR/ProfileSummary.h"
#include "llvm/ProfileData/InstrProfReader.h"
#include "llvm/ProfileData/SampleProf.h"
#include "llvm/Support/CRC.h"
#include "llvm/Support/CodeGen.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/ConvertUTF.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/MD5.h"
#include "llvm/Support/TimeProfiler.h"
#include "llvm/Support/X86TargetParser.h"
#include "llvm/Support/xxhash.h"
@@ -208,22 +208,7 @@ CodeGenModule::CodeGenModule(ASTContext &C,
Path = Entry.second + Path.substr(Entry.first.size());
break;
}
llvm::MD5 Md5;
Md5.update(Path);
llvm::MD5::MD5Result R;
Md5.final(R);
SmallString<32> Str;
llvm::MD5::stringifyResult(R, Str);
// Convert MD5hash to Decimal. Demangler suffixes can either contain
// numbers or characters but not both.
llvm::APInt IntHash(128, Str.str(), 16);
// Prepend "__uniq" before the hash for tools like profilers to understand
// that this symbol is of internal linkage type. The "__uniq" is the
// pre-determined prefix that is used to tell tools that this symbol was
// created with -funique-internal-linakge-symbols and the tools can strip or
// keep the prefix as needed.
ModuleNameHash = (Twine(".__uniq.") +
Twine(toString(IntHash, /* Radix = */ 10, /* Signed = */false))).str();
ModuleNameHash = llvm::getUniqueInternalLinkagePostfix(Path);
}
}