[clang] d4e0fe6 - Simplify RAV isSameMethod with constexpr if

[David Blaikie via cfe-commits]

Author: David Blaikie
Date: 2022-08-19T04:00:21Z
New Revision: d4e0fe62b1aa090527c0cc289cdf3eef0370f064

URL: https://github.com/llvm/llvm-project/commit/d4e0fe62b1aa090527c0cc289cdf3eef0370f064
DIFF: https://github.com/llvm/llvm-project/commit/d4e0fe62b1aa090527c0cc289cdf3eef0370f064.diff

LOG: Simplify RAV isSameMethod with constexpr if

Owing to the large number of instantiations of this function, this small
change has a small but meaningful difference on the total size of
(especially a debug) build of clang at -O0:
```
    FILE SIZE        VM SIZE
 --------------  --------------
  +0.9% +96.9Ki  +0.9% +96.9Ki    .data.rel.ro
  +0.7% +96.7Ki  +0.7% +96.7Ki    .rela.dyn
  +0.0% +18.3Ki  +0.0% +18.3Ki    .rodata
  +0.0%    +324  [ = ]       0    [2 Others]
  -0.2%    -392  -0.2%    -392    .gnu.version
  -0.0%    -441  [ = ]       0    .debug_abbrev
  -0.1%    -980  -0.1%    -980    .gnu.hash
  -0.2% -1.53Ki  -0.2% -1.53Ki    .hash
  -0.2% -4.59Ki  -0.2% -4.59Ki    .dynsym
  -0.1% -10.5Ki  [ = ]       0    .debug_rnglists
  -0.6% -59.0Ki  -0.6% -59.0Ki    .dynstr
  -0.2%  -191Ki  [ = ]       0    .debug_str_offsets
  -3.0%  -233Ki  -3.0%  -233Ki    .eh_frame_hdr
  -0.7%  -244Ki  [ = ]       0    .debug_addr
  -2.9%  -699Ki  [ = ]       0    .symtab
  -0.6%  -884Ki  [ = ]       0    .debug_line
  -3.0%  -932Ki  -3.0%  -932Ki    .eh_frame
  -1.0% -1.48Mi  -1.0% -1.48Mi    .text
  -0.6% -2.75Mi  [ = ]       0    .debug_info
  -7.3% -8.61Mi  [ = ]       0    .strtab
  -7.3% -17.2Mi  [ = ]       0    .debug_str
  -2.4% -33.0Mi  -0.9% -2.47Mi    TOTAL
```

If anyone's got other ideas for how to reduce this further - it's not
especially important, I just came across it while investigating a debug
info size regression, but thought it was interesting enough to poke
around at.

Added: 
    

Modified: 
    clang/include/clang/AST/RecursiveASTVisitor.h

Removed: 
    


################################################################################
diff  --git a/clang/include/clang/AST/RecursiveASTVisitor.h b/clang/include/clang/AST/RecursiveASTVisitor.h
index 6c6d5402d5d12..91baad51b26ea 100644
--- a/clang/include/clang/AST/RecursiveASTVisitor.h
+++ b/clang/include/clang/AST/RecursiveASTVisitor.h
@@ -69,30 +69,16 @@ template <typename T, typename U, typename R, typename... P>
 struct has_same_member_pointer_type<R (T::*)(P...), R (U::*)(P...)>
     : std::true_type {};
 
-template <bool has_same_type> struct is_same_method_impl {
-  template <typename FirstMethodPtrTy, typename SecondMethodPtrTy>
-  static bool isSameMethod(FirstMethodPtrTy FirstMethodPtr,
-                           SecondMethodPtrTy SecondMethodPtr) {
-    return false;
-  }
-};
-
-template <> struct is_same_method_impl<true> {
-  template <typename FirstMethodPtrTy, typename SecondMethodPtrTy>
-  static bool isSameMethod(FirstMethodPtrTy FirstMethodPtr,
-                           SecondMethodPtrTy SecondMethodPtr) {
-    return FirstMethodPtr == SecondMethodPtr;
-  }
-};
-
 /// Returns true if and only if \p FirstMethodPtr and \p SecondMethodPtr
 /// are pointers to the same non-static member function.
 template <typename FirstMethodPtrTy, typename SecondMethodPtrTy>
-bool isSameMethod(FirstMethodPtrTy FirstMethodPtr,
-                  SecondMethodPtrTy SecondMethodPtr) {
-  return is_same_method_impl<has_same_member_pointer_type<
-      FirstMethodPtrTy,
-      SecondMethodPtrTy>::value>::isSameMethod(FirstMethodPtr, SecondMethodPtr);
+LLVM_ATTRIBUTE_ALWAYS_INLINE LLVM_ATTRIBUTE_NODEBUG auto
+isSameMethod(FirstMethodPtrTy FirstMethodPtr, SecondMethodPtrTy SecondMethodPtr)
+    -> bool {
+  if constexpr (has_same_member_pointer_type<FirstMethodPtrTy,
+                                             SecondMethodPtrTy>::value)
+    return FirstMethodPtr == SecondMethodPtr;
+  return false;
 }
 
 } // end namespace detail