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//===-- cache_frag.cpp ----------------------------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file is a part of EfficiencySanitizer, a family of performance tuners.
//
// This file contains cache fragmentation-specific code.
//===----------------------------------------------------------------------===//
#include "esan.h"
#include "esan_flags.h"
#include "sanitizer_common/sanitizer_addrhashmap.h"
#include "sanitizer_common/sanitizer_common.h"
#include "sanitizer_common/sanitizer_placement_new.h"
#include <string.h>
namespace __esan {
//===-- Struct field access counter runtime -------------------------------===//
// This should be kept consistent with LLVM's EfficiencySanitizer StructInfo.
struct StructInfo {
const char *StructName;
u32 Size;
u32 NumFields;
u32 *FieldOffset; // auxiliary struct field info.
u32 *FieldSize; // auxiliary struct field info.
const char **FieldTypeName; // auxiliary struct field info.
u64 *FieldCounters;
u64 *ArrayCounter;
bool hasAuxFieldInfo() { return FieldOffset != nullptr; }
};
// This should be kept consistent with LLVM's EfficiencySanitizer CacheFragInfo.
// The tool-specific information per compilation unit (module).
struct CacheFragInfo {
const char *UnitName;
u32 NumStructs;
StructInfo *Structs;
};
struct StructCounter {
StructInfo *Struct;
u64 Count; // The total access count of the struct.
u64 Ratio; // Difference ratio for the struct layout access.
};
// We use StructHashMap to keep track of an unique copy of StructCounter.
typedef AddrHashMap<StructCounter, 31051> StructHashMap;
struct Context {
StructHashMap StructMap;
u32 NumStructs;
u64 TotalCount; // The total access count of all structs.
};
static Context *Ctx;
static void reportStructSummary() {
// FIXME: provide a better struct field access summary report.
Report("%s: total struct field access count = %llu\n", SanitizerToolName,
Ctx->TotalCount);
}
// FIXME: we are still exploring proper ways to evaluate the difference between
// struct field counts. Currently, we use a simple formula to calculate the
// difference ratio: V1/V2.
static inline u64 computeDifferenceRatio(u64 Val1, u64 Val2) {
if (Val2 > Val1) {
Swap(Val1, Val2);
}
if (Val2 == 0)
Val2 = 1;
return (Val1 / Val2);
}
static void reportStructCounter(StructHashMap::Handle &Handle) {
const u32 TypePrintLimit = 512;
const char *type, *start, *end;
StructInfo *Struct = Handle->Struct;
// Union field address calculation is done via bitcast instead of GEP,
// so the count for union is always 0.
// We skip the union report to avoid confusion.
if (strncmp(Struct->StructName, "union.", 6) == 0)
return;
// Remove the '.' after class/struct during print.
if (strncmp(Struct->StructName, "class.", 6) == 0) {
type = "class";
start = &Struct->StructName[6];
} else {
type = "struct";
start = &Struct->StructName[7];
}
// Remove the suffixes with '$' during print.
end = strchr(start, '$');
CHECK(end != nullptr);
Report(" %s %.*s\n", type, end - start, start);
Report(" size = %u, count = %llu, ratio = %llu, array access = %llu\n",
Struct->Size, Handle->Count, Handle->Ratio, *Struct->ArrayCounter);
if (Struct->hasAuxFieldInfo()) {
for (u32 i = 0; i < Struct->NumFields; ++i) {
Report(" #%2u: offset = %u,\t size = %u,"
"\t count = %llu,\t type = %.*s\n",
i, Struct->FieldOffset[i], Struct->FieldSize[i],
Struct->FieldCounters[i], TypePrintLimit, Struct->FieldTypeName[i]);
}
} else {
for (u32 i = 0; i < Struct->NumFields; ++i) {
Report(" #%2u: count = %llu\n", i, Struct->FieldCounters[i]);
}
}
}
static void computeStructRatio(StructHashMap::Handle &Handle) {
Handle->Ratio = 0;
Handle->Count = Handle->Struct->FieldCounters[0];
for (u32 i = 1; i < Handle->Struct->NumFields; ++i) {
Handle->Count += Handle->Struct->FieldCounters[i];
Handle->Ratio += computeDifferenceRatio(
Handle->Struct->FieldCounters[i - 1], Handle->Struct->FieldCounters[i]);
}
Ctx->TotalCount += Handle->Count;
if (Handle->Ratio >= (u64)getFlags()->report_threshold ||
(Verbosity() >= 1 && Handle->Count > 0))
reportStructCounter(Handle);
}
static void registerStructInfo(CacheFragInfo *CacheFrag) {
for (u32 i = 0; i < CacheFrag->NumStructs; ++i) {
StructInfo *Struct = &CacheFrag->Structs[i];
StructHashMap::Handle H(&Ctx->StructMap, (uptr)Struct->FieldCounters);
if (H.created()) {
VPrintf(2, " Register %s: %u fields\n", Struct->StructName,
Struct->NumFields);
H->Struct = Struct;
++Ctx->NumStructs;
} else {
VPrintf(2, " Duplicated %s: %u fields\n", Struct->StructName,
Struct->NumFields);
}
}
}
static void unregisterStructInfo(CacheFragInfo *CacheFrag) {
// FIXME: if the library is unloaded before finalizeCacheFrag, we should
// collect the result for later report.
for (u32 i = 0; i < CacheFrag->NumStructs; ++i) {
StructInfo *Struct = &CacheFrag->Structs[i];
StructHashMap::Handle H(&Ctx->StructMap, (uptr)Struct->FieldCounters, true);
if (H.exists()) {
VPrintf(2, " Unregister %s: %u fields\n", Struct->StructName,
Struct->NumFields);
// FIXME: we should move this call to finalizeCacheFrag once we can
// iterate over the hash map there.
computeStructRatio(H);
--Ctx->NumStructs;
} else {
VPrintf(2, " Duplicated %s: %u fields\n", Struct->StructName,
Struct->NumFields);
}
}
static bool Reported = false;
if (Ctx->NumStructs == 0 && !Reported) {
Reported = true;
reportStructSummary();
}
}
//===-- Init/exit functions -----------------------------------------------===//
void processCacheFragCompilationUnitInit(void *Ptr) {
CacheFragInfo *CacheFrag = (CacheFragInfo *)Ptr;
VPrintf(2, "in esan::%s: %s with %u class(es)/struct(s)\n", __FUNCTION__,
CacheFrag->UnitName, CacheFrag->NumStructs);
registerStructInfo(CacheFrag);
}
void processCacheFragCompilationUnitExit(void *Ptr) {
CacheFragInfo *CacheFrag = (CacheFragInfo *)Ptr;
VPrintf(2, "in esan::%s: %s with %u class(es)/struct(s)\n", __FUNCTION__,
CacheFrag->UnitName, CacheFrag->NumStructs);
unregisterStructInfo(CacheFrag);
}
void initializeCacheFrag() {
VPrintf(2, "in esan::%s\n", __FUNCTION__);
// We use placement new to initialize Ctx before C++ static initializaion.
// We make CtxMem 8-byte aligned for atomic operations in AddrHashMap.
static u64 CtxMem[sizeof(Context) / sizeof(u64) + 1];
Ctx = new (CtxMem) Context();
Ctx->NumStructs = 0;
}
int finalizeCacheFrag() {
VPrintf(2, "in esan::%s\n", __FUNCTION__);
return 0;
}
void reportCacheFrag() {
VPrintf(2, "in esan::%s\n", __FUNCTION__);
// FIXME: Not yet implemented. We need to iterate over all of the
// compilation unit data.
}
} // namespace __esan
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