[llvm] [LTO] Teach computeLTOCacheKey to return std::string (NFC) (PR #105331)
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Tue Aug 20 13:13:02 PDT 2024
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-lto
Author: Kazu Hirata (kazutakahirata)
<details>
<summary>Changes</summary>
Without this patch, computeLTOCacheKey computes SHA1, creates its
hexadecimal representation with toHex, which returns std::string, and
then copies it to an output parameter of type SmallString.
This patch removes the redirection and teaches computeLTOCacheKey to
directly return std::string computed by toHex. With the move
semantics, no buffer copy should be involved.
While I am at it, this patch adds a Twine to concatenate two strings.
---
Full diff: https://github.com/llvm/llvm-project/pull/105331.diff
3 Files Affected:
- (modified) llvm/include/llvm/LTO/LTO.h (+3-5)
- (modified) llvm/lib/LTO/LTO.cpp (+7-8)
- (modified) llvm/lib/LTO/ThinLTOCodeGenerator.cpp (+4-4)
``````````diff
diff --git a/llvm/include/llvm/LTO/LTO.h b/llvm/include/llvm/LTO/LTO.h
index 30eda34cd7ba54..0781d57feb5a64 100644
--- a/llvm/include/llvm/LTO/LTO.h
+++ b/llvm/include/llvm/LTO/LTO.h
@@ -62,11 +62,9 @@ void thinLTOInternalizeAndPromoteInIndex(
/// Computes a unique hash for the Module considering the current list of
/// export/import and other global analysis results.
-/// The hash is produced in \p Key.
-void computeLTOCacheKey(
- SmallString<40> &Key, const lto::Config &Conf,
- const ModuleSummaryIndex &Index, StringRef ModuleID,
- const FunctionImporter::ImportMapTy &ImportList,
+std::string computeLTOCacheKey(
+ const lto::Config &Conf, const ModuleSummaryIndex &Index,
+ StringRef ModuleID, const FunctionImporter::ImportMapTy &ImportList,
const FunctionImporter::ExportSetTy &ExportList,
const std::map<GlobalValue::GUID, GlobalValue::LinkageTypes> &ResolvedODR,
const GVSummaryMapTy &DefinedGlobals,
diff --git a/llvm/lib/LTO/LTO.cpp b/llvm/lib/LTO/LTO.cpp
index bb3c9f7acdb8e5..e0e4ab5d0f26a2 100644
--- a/llvm/lib/LTO/LTO.cpp
+++ b/llvm/lib/LTO/LTO.cpp
@@ -89,9 +89,9 @@ extern cl::opt<bool> EnableMemProfContextDisambiguation;
// Computes a unique hash for the Module considering the current list of
// export/import and other global analysis results.
// The hash is produced in \p Key.
-void llvm::computeLTOCacheKey(
- SmallString<40> &Key, const Config &Conf, const ModuleSummaryIndex &Index,
- StringRef ModuleID, const FunctionImporter::ImportMapTy &ImportList,
+std::string llvm::computeLTOCacheKey(
+ const Config &Conf, const ModuleSummaryIndex &Index, StringRef ModuleID,
+ const FunctionImporter::ImportMapTy &ImportList,
const FunctionImporter::ExportSetTy &ExportList,
const std::map<GlobalValue::GUID, GlobalValue::LinkageTypes> &ResolvedODR,
const GVSummaryMapTy &DefinedGlobals,
@@ -355,7 +355,7 @@ void llvm::computeLTOCacheKey(
}
}
- Key = toHex(Hasher.result());
+ return toHex(Hasher.result());
}
static void thinLTOResolvePrevailingGUID(
@@ -1488,11 +1488,10 @@ class InProcessThinBackend : public ThinBackendProc {
// no module hash.
return RunThinBackend(AddStream);
- SmallString<40> Key;
// The module may be cached, this helps handling it.
- computeLTOCacheKey(Key, Conf, CombinedIndex, ModuleID, ImportList,
- ExportList, ResolvedODR, DefinedGlobals, CfiFunctionDefs,
- CfiFunctionDecls);
+ std::string Key = computeLTOCacheKey(
+ Conf, CombinedIndex, ModuleID, ImportList, ExportList, ResolvedODR,
+ DefinedGlobals, CfiFunctionDefs, CfiFunctionDecls);
Expected<AddStreamFn> CacheAddStreamOrErr = Cache(Task, Key, ModuleID);
if (Error Err = CacheAddStreamOrErr.takeError())
return Err;
diff --git a/llvm/lib/LTO/ThinLTOCodeGenerator.cpp b/llvm/lib/LTO/ThinLTOCodeGenerator.cpp
index b982df7c6e5d3f..0ba3093637aacf 100644
--- a/llvm/lib/LTO/ThinLTOCodeGenerator.cpp
+++ b/llvm/lib/LTO/ThinLTOCodeGenerator.cpp
@@ -382,13 +382,13 @@ class ModuleCacheEntry {
Conf.RelocModel = TMBuilder.RelocModel;
Conf.CGOptLevel = TMBuilder.CGOptLevel;
Conf.Freestanding = Freestanding;
- SmallString<40> Key;
- computeLTOCacheKey(Key, Conf, Index, ModuleID, ImportList, ExportList,
- ResolvedODR, DefinedGVSummaries);
+ std::string Key =
+ computeLTOCacheKey(Conf, Index, ModuleID, ImportList, ExportList,
+ ResolvedODR, DefinedGVSummaries);
// This choice of file name allows the cache to be pruned (see pruneCache()
// in include/llvm/Support/CachePruning.h).
- sys::path::append(EntryPath, CachePath, "llvmcache-" + Key);
+ sys::path::append(EntryPath, CachePath, Twine("llvmcache-", Key));
}
// Access the path to this entry in the cache.
``````````
</details>
https://github.com/llvm/llvm-project/pull/105331
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