[libcxx-commits] [libcxxabi] 4e5fce5 - [demangler] refactor SpecialSubKind

[Nathan Sidwell via libcxx-commits]

Author: Nathan Sidwell
Date: 2022-01-26T04:59:25-08:00
New Revision: 4e5fce58485cc69ee69da10e26a338ceeef280a0

URL: https://github.com/llvm/llvm-project/commit/4e5fce58485cc69ee69da10e26a338ceeef280a0
DIFF: https://github.com/llvm/llvm-project/commit/4e5fce58485cc69ee69da10e26a338ceeef280a0.diff

LOG: [demangler] refactor SpecialSubKind

Code generating the special substitutions in std is a switch statement
with each case block containing the same conststruction template.  It
is more efficient to commonize that after the switch, having
determined which SubKind to create.  Also, let's sort the cases.

Reviewed By: ChuanqiXu

Differential Revision: https://reviews.llvm.org/D118131

Added: 
    

Modified: 
    libcxxabi/src/demangle/ItaniumDemangle.h
    llvm/include/llvm/Demangle/ItaniumDemangle.h

Removed: 
    


################################################################################
diff  --git a/libcxxabi/src/demangle/ItaniumDemangle.h b/libcxxabi/src/demangle/ItaniumDemangle.h
index 45bb741f5629f..98489e4dc802f 100644
--- a/libcxxabi/src/demangle/ItaniumDemangle.h
+++ b/libcxxabi/src/demangle/ItaniumDemangle.h
@@ -5448,37 +5448,34 @@ Node *AbstractManglingParser<Derived, Alloc>::parseSubstitution() {
     return nullptr;
 
   if (look() >= 'a' && look() <= 'z') {
-    Node *SpecialSub;
+    SpecialSubKind Kind;
     switch (look()) {
     case 'a':
-      ++First;
-      SpecialSub = make<SpecialSubstitution>(SpecialSubKind::allocator);
+      Kind = SpecialSubKind::allocator;
       break;
     case 'b':
-      ++First;
-      SpecialSub = make<SpecialSubstitution>(SpecialSubKind::basic_string);
+      Kind = SpecialSubKind::basic_string;
       break;
-    case 's':
-      ++First;
-      SpecialSub = make<SpecialSubstitution>(SpecialSubKind::string);
+    case 'd':
+      Kind = SpecialSubKind::iostream;
       break;
     case 'i':
-      ++First;
-      SpecialSub = make<SpecialSubstitution>(SpecialSubKind::istream);
+      Kind = SpecialSubKind::istream;
       break;
     case 'o':
-      ++First;
-      SpecialSub = make<SpecialSubstitution>(SpecialSubKind::ostream);
+      Kind = SpecialSubKind::ostream;
       break;
-    case 'd':
-      ++First;
-      SpecialSub = make<SpecialSubstitution>(SpecialSubKind::iostream);
+    case 's':
+      Kind = SpecialSubKind::string;
       break;
     default:
       return nullptr;
     }
+    ++First;
+    auto *SpecialSub = make<SpecialSubstitution>(Kind);
     if (!SpecialSub)
       return nullptr;
+
     // Itanium C++ ABI 5.1.2: If a name that would use a built-in <substitution>
     // has ABI tags, the tags are appended to the substitution; the result is a
     // substitutable component.

diff  --git a/llvm/include/llvm/Demangle/ItaniumDemangle.h b/llvm/include/llvm/Demangle/ItaniumDemangle.h
index a3a0381edf97d..28545ed068367 100644
--- a/llvm/include/llvm/Demangle/ItaniumDemangle.h
+++ b/llvm/include/llvm/Demangle/ItaniumDemangle.h
@@ -5450,37 +5450,34 @@ Node *AbstractManglingParser<Derived, Alloc>::parseSubstitution() {
     return nullptr;
 
   if (look() >= 'a' && look() <= 'z') {
-    Node *SpecialSub;
+    SpecialSubKind Kind;
     switch (look()) {
     case 'a':
-      ++First;
-      SpecialSub = make<SpecialSubstitution>(SpecialSubKind::allocator);
+      Kind = SpecialSubKind::allocator;
       break;
     case 'b':
-      ++First;
-      SpecialSub = make<SpecialSubstitution>(SpecialSubKind::basic_string);
+      Kind = SpecialSubKind::basic_string;
       break;
-    case 's':
-      ++First;
-      SpecialSub = make<SpecialSubstitution>(SpecialSubKind::string);
+    case 'd':
+      Kind = SpecialSubKind::iostream;
       break;
     case 'i':
-      ++First;
-      SpecialSub = make<SpecialSubstitution>(SpecialSubKind::istream);
+      Kind = SpecialSubKind::istream;
       break;
     case 'o':
-      ++First;
-      SpecialSub = make<SpecialSubstitution>(SpecialSubKind::ostream);
+      Kind = SpecialSubKind::ostream;
       break;
-    case 'd':
-      ++First;
-      SpecialSub = make<SpecialSubstitution>(SpecialSubKind::iostream);
+    case 's':
+      Kind = SpecialSubKind::string;
       break;
     default:
       return nullptr;
     }
+    ++First;
+    auto *SpecialSub = make<SpecialSubstitution>(Kind);
     if (!SpecialSub)
       return nullptr;
+
     // Itanium C++ ABI 5.1.2: If a name that would use a built-in <substitution>
     // has ABI tags, the tags are appended to the substitution; the result is a
     // substitutable component.