Make llvm::djbHash an inline function.

[ruiu]

Summary

djbHash() is so small that we should always inline.

[labath]

Sorry, I missed this one, I'll have to configure my email filters better.

llvm/lib/Support/DJB.cpp

22–24

It may be better to put this in the header as well (perhaps in a detail namespace) so you don't have to manually inline it below, but that's just splitting hairs. I am fine with this option as well.

[ruiu]

llvm/lib/Support/DJB.cpp

22–24

Honestly I don't think this isn't worth to be in the header as (1) there is no situation in which you want to use this function independently, and (2) this is extremely small, and (3) it is not intended to change. So I'm more comfortable to just inline it just like I did in this patch.

llvm/include/llvm/Support/DJB.h

 #ifndef LLVM_SUPPORT_DJB_H
 #define LLVM_SUPPORT_DJB_H
 
 #include "llvm/ADT/StringRef.h"
 
 namespace llvm {
 
 /// The Bernstein hash function used by the DWARF accelerator tables.
-uint32_t djbHash(StringRef Buffer, uint32_t H = 5381);
+inline uint32_t djbHash(StringRef Buffer, uint32_t H = 5381) {
+  for (unsigned char C : Buffer.bytes())
+    H = (H << 5) + H + C;
+  return H;
+}
 
 /// Computes the Bernstein hash after folding the input according to the Dwarf 5
 /// standard case folding rules.
 uint32_t caseFoldingDjbHash(StringRef Buffer, uint32_t H = 5381);
 } // namespace llvm
 
 #endif // LLVM_SUPPORT_DJB_H

llvm/lib/Support/DJB.cpp

 #include "llvm/Support/DJB.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/ConvertUTF.h"
 #include "llvm/Support/Unicode.h"
 
 using namespace llvm;
 
-static inline uint32_t djbHashChar(unsigned char C, uint32_t H) {
-  return (H << 5) + H + C;
-}
-
-uint32_t llvm::djbHash(StringRef Buffer, uint32_t H) {
-  for (unsigned char C : Buffer.bytes())
-    H = djbHashChar(C, H);
-  return H;
-}
-
 static UTF32 chopOneUTF32(StringRef &Buffer) {
   UTF32 C;
   const UTF8 *const Begin8Const =
       reinterpret_cast<const UTF8 *>(Buffer.begin());
   const UTF8 *Begin8 = Begin8Const;
   UTF32 *Begin32 = &C;
 
   // In lenient mode we will always end up with a "reasonable" value in C for

 uint32_t llvm::caseFoldingDjbHash(StringRef Buffer, uint32_t H) {
   while (!Buffer.empty()) {
     unsigned char C = Buffer.front();
     if (LLVM_LIKELY(C <= 0x7f)) {
       // US-ASCII, encoded as one character in utf-8.
       // This is by far the most common case, so handle this specially.
       if (C >= 'A' && C <= 'Z')
         C = 'a' + (C - 'A'); // fold uppercase into lowercase
-      H = djbHashChar(C, H);
+      H = (H << 5) + H + C;
       Buffer = Buffer.drop_front();
       continue;
     }
     H = caseFoldingDjbHashCharSlow(Buffer, H);
   }
   return H;
 }