fixed #95641 pointless string copy

[sommersun]

fixed #95641 by using std::move for T&&.

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[llvmbot]

@llvm/pr-subscribers-tablegen

Author: sommersun (sommersun)

Changes

fixed #95641 by using std::move for T&&.

---

Full diff: https://github.com/llvm/llvm-project/pull/127325.diff

2 Files Affected:

• (modified) llvm/include/llvm/TableGen/Record.h (+2-1)
• (modified) llvm/lib/TableGen/Main.cpp (+1-1)

diff --git a/llvm/include/llvm/TableGen/Record.h b/llvm/include/llvm/TableGen/Record.h
index e04ed34823148..08d8e2a94c0aa 100644
--- a/llvm/include/llvm/TableGen/Record.h
+++ b/llvm/include/llvm/TableGen/Record.h
@@ -142,6 +142,7 @@ class BitsRecTy : public RecTy {
 
   unsigned getNumBits() const { return Size; }
 
+
   std::string getAsString() const override;
 
   bool typeIsConvertibleTo(const RecTy *RHS) const override;
@@ -1966,7 +1967,7 @@ class RecordKeeper {
     return It == ExtraGlobals.end() ? nullptr : It->second;
   }
 
-  void saveInputFilename(std::string Filename) {
+  void saveInputFilename(std::string && Filename) {
     InputFilename = Filename;
   }
 
diff --git a/llvm/lib/TableGen/Main.cpp b/llvm/lib/TableGen/Main.cpp
index 35600bf2f1f86..81b2e81dc6064 100644
--- a/llvm/lib/TableGen/Main.cpp
+++ b/llvm/lib/TableGen/Main.cpp
@@ -113,7 +113,7 @@ int llvm::TableGenMain(const char *argv0,
     return reportError(argv0, "Could not open input file '" + InputFilename +
                                   "': " + EC.message() + "\n");
 
-  Records.saveInputFilename(InputFilename);
+  Records.saveInputFilename(std::move(InputFilename));
 
   // Tell SrcMgr about this buffer, which is what TGParser will pick up.
   SrcMgr.AddNewSourceBuffer(std::move(*FileOrErr), SMLoc());

[github-actions]

✅ With the latest revision this PR passed the C/C++ code formatter.

[RKSimon]

Why not this instead?

void saveInputFilename(std::string Filename) { InputFilename = std::move(Filename); }

[sommersun]

Why not this instead?

void saveInputFilename(std::string Filename) { InputFilename = std::move(Filename); }

why using this ? I am a bit confused, by using this copy from pass by left value of string is still exist. Thanks. @RKSimon

[RKSimon]

drop the std::move here and just rely on the saveInputFilename - its not out of the question that someone could try to use InputFilename again later

[sommersun]

ok, I understand. Thanks.

[RKSimon]

LGTM - cheers

[github-actions]

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