[llvm] [ADT,CodeGen] Remove stable_hash_combine_string (PR #100668)
Fangrui Song via llvm-commits
llvm-commits at lists.llvm.org
Thu Jul 25 15:59:46 PDT 2024
https://github.com/MaskRay created https://github.com/llvm/llvm-project/pull/100668
FNV, used by stable_hash_combine_string is extremely slow. For string
hashing with good avalanche effects, we prefer xxh3_64bits.
StableHashing.h might still be useful as Hashing.h hashes might be
non-deterministic.
>From 5dfa81416913b67e9589989e850c5d0e6c132963 Mon Sep 17 00:00:00 2001
From: Fangrui Song <i at maskray.me>
Date: Thu, 25 Jul 2024 15:59:37 -0700
Subject: [PATCH] =?UTF-8?q?[=F0=9D=98=80=F0=9D=97=BD=F0=9D=97=BF]=20initia?=
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Created using spr 1.3.5-bogner
---
llvm/include/llvm/ADT/StableHashing.h | 12 ------------
llvm/lib/CodeGen/MachineStableHash.cpp | 8 ++++----
2 files changed, 4 insertions(+), 16 deletions(-)
diff --git a/llvm/include/llvm/ADT/StableHashing.h b/llvm/include/llvm/ADT/StableHashing.h
index 884b5752d9bb0..f675f828f702e 100644
--- a/llvm/include/llvm/ADT/StableHashing.h
+++ b/llvm/include/llvm/ADT/StableHashing.h
@@ -95,18 +95,6 @@ inline stable_hash stable_hash_combine_array(const stable_hash *P, size_t C) {
hashing::detail::stable_hash_append(Hash, P[I]);
return Hash;
}
-
-inline stable_hash stable_hash_combine_string(const StringRef &S) {
- return stable_hash_combine_range(S.begin(), S.end());
-}
-
-inline stable_hash stable_hash_combine_string(const char *C) {
- stable_hash Hash = hashing::detail::FNV_OFFSET_64;
- while (*C)
- hashing::detail::stable_hash_append(Hash, *(C++));
- return Hash;
-}
-
} // namespace llvm
#endif
diff --git a/llvm/lib/CodeGen/MachineStableHash.cpp b/llvm/lib/CodeGen/MachineStableHash.cpp
index 5abfbd5981fba..d2e02a2d739c1 100644
--- a/llvm/lib/CodeGen/MachineStableHash.cpp
+++ b/llvm/lib/CodeGen/MachineStableHash.cpp
@@ -33,6 +33,7 @@
#include "llvm/MC/MCSymbol.h"
#include "llvm/Support/Alignment.h"
#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/xxhash.h"
#define DEBUG_TYPE "machine-stable-hash"
@@ -100,8 +101,7 @@ stable_hash llvm::stableHashValue(const MachineOperand &MO) {
case MachineOperand::MO_TargetIndex: {
if (const char *Name = MO.getTargetIndexName())
return stable_hash_combine(MO.getType(), MO.getTargetFlags(),
- stable_hash_combine_string(Name),
- MO.getOffset());
+ xxh3_64bits(Name), MO.getOffset());
StableHashBailingTargetIndexNoName++;
return 0;
}
@@ -113,7 +113,7 @@ stable_hash llvm::stableHashValue(const MachineOperand &MO) {
case MachineOperand::MO_ExternalSymbol:
return hash_combine(MO.getType(), MO.getTargetFlags(), MO.getOffset(),
- stable_hash_combine_string(MO.getSymbolName()));
+ xxh3_64bits(MO.getSymbolName()));
case MachineOperand::MO_RegisterMask:
case MachineOperand::MO_RegisterLiveOut: {
@@ -151,7 +151,7 @@ stable_hash llvm::stableHashValue(const MachineOperand &MO) {
case MachineOperand::MO_MCSymbol: {
auto SymbolName = MO.getMCSymbol()->getName();
return hash_combine(MO.getType(), MO.getTargetFlags(),
- stable_hash_combine_string(SymbolName));
+ xxh3_64bits(SymbolName));
}
case MachineOperand::MO_CFIIndex:
return stable_hash_combine(MO.getType(), MO.getTargetFlags(),
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