From: Nico Weber <nicolasweber@gmx.de>
Date: Sat, 1 Jun 2019 10:12:07 +0000 (+0000)
Subject: msabi: Fix exponential mangling time for certain pathological inputs
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=2c469237d842f397cb3d98ba8c243d9fbcd6d92a;p=clang

msabi: Fix exponential mangling time for certain pathological inputs

Template back references used to be recursively recomputed, add a
memoization cache to cut down on this.

Since there are now two different types of argument maps, rename the
existing TypeBackReferences to FunArgBackReferences, and rename
mangleArgumentType() to mangleFunctionArgumentType().

Fixes PR42091, the input there now takes 50ms instead of 7s to compile.

No intended behavior change.

Differential Revision: https://reviews.llvm.org/D62746

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@362293 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/AST/MicrosoftMangle.cpp b/lib/AST/MicrosoftMangle.cpp
index a021e7162e..ddc6e12d1d 100644
--- a/lib/AST/MicrosoftMangle.cpp
+++ b/lib/AST/MicrosoftMangle.cpp
@@ -265,7 +265,8 @@ class MicrosoftCXXNameMangler {
   BackRefVec NameBackReferences;
 
   typedef llvm::DenseMap<const void *, unsigned> ArgBackRefMap;
-  ArgBackRefMap TypeBackReferences;
+  ArgBackRefMap FunArgBackReferences;
+  ArgBackRefMap TemplateArgBackReferences;
 
   typedef std::set<std::pair<int, bool>> PassObjectSizeArgsSet;
   PassObjectSizeArgsSet PassObjectSizeArgs;
@@ -343,7 +344,7 @@ private:
                                   const TemplateArgumentList &TemplateArgs);
   void mangleObjCMethodName(const ObjCMethodDecl *MD);
 
-  void mangleArgumentType(QualType T, SourceRange Range);
+  void mangleFunctionArgumentType(QualType T, SourceRange Range);
   void manglePassObjectSizeArg(const PassObjectSizeAttr *POSA);
 
   bool isArtificialTagType(QualType T) const;
@@ -793,7 +794,7 @@ void MicrosoftCXXNameMangler::mangleUnqualifiedName(const NamedDecl *ND,
     // the X<Y> part is aliased. However, if you need to mangle
     //   void foo(A::X<A::Y>, A::X<B::Y>),
     // the A::X<> part is not aliased.
-    // That said, from the mangler's perspective we have a structure like this:
+    // That is, from the mangler's perspective we have a structure like this:
     //   namespace[s] -> type[ -> template-parameters]
     // but from the Clang perspective we have
     //   type [ -> template-parameters]
@@ -803,12 +804,30 @@ void MicrosoftCXXNameMangler::mangleUnqualifiedName(const NamedDecl *ND,
     // the mangled type name as a key to check the mangling of different types
     // for aliasing.
 
-    llvm::SmallString<64> TemplateMangling;
-    llvm::raw_svector_ostream Stream(TemplateMangling);
-    MicrosoftCXXNameMangler Extra(Context, Stream);
-    Extra.mangleTemplateInstantiationName(TD, *TemplateArgs);
-
-    mangleSourceName(TemplateMangling);
+    // It's important to key cache reads off ND, not TD -- the same TD can
+    // be used with different TemplateArgs, but ND uniquely identifies
+    // TD / TemplateArg pairs.
+    ArgBackRefMap::iterator Found = TemplateArgBackReferences.find(ND);
+    if (Found == TemplateArgBackReferences.end()) {
+      // Mangle full template name into temporary buffer.
+      llvm::SmallString<64> TemplateMangling;
+      llvm::raw_svector_ostream Stream(TemplateMangling);
+      MicrosoftCXXNameMangler Extra(Context, Stream);
+      Extra.mangleTemplateInstantiationName(TD, *TemplateArgs);
+
+      // Use the string backref vector to possibly get a back reference.
+      mangleSourceName(TemplateMangling);
+
+      // Memoize back reference for this type.
+      BackRefVec::iterator StringFound =
+          llvm::find(NameBackReferences, TemplateMangling);
+      if (StringFound != NameBackReferences.end()) {
+        TemplateArgBackReferences[ND] =
+            StringFound - NameBackReferences.begin();
+      }
+    } else {
+      Out << Found->second;
+    }
     return;
   }
 
@@ -1282,11 +1301,13 @@ void MicrosoftCXXNameMangler::mangleTemplateInstantiationName(
   // Always start with the unqualified name.
 
   // Templates have their own context for back references.
-  ArgBackRefMap OuterArgsContext;
+  ArgBackRefMap OuterFunArgsContext;
+  ArgBackRefMap OuterTemplateArgsContext;
   BackRefVec OuterTemplateContext;
   PassObjectSizeArgsSet OuterPassObjectSizeArgs;
   NameBackReferences.swap(OuterTemplateContext);
-  TypeBackReferences.swap(OuterArgsContext);
+  FunArgBackReferences.swap(OuterFunArgsContext);
+  TemplateArgBackReferences.swap(OuterTemplateArgsContext);
   PassObjectSizeArgs.swap(OuterPassObjectSizeArgs);
 
   mangleUnscopedTemplateName(TD);
@@ -1294,7 +1315,8 @@ void MicrosoftCXXNameMangler::mangleTemplateInstantiationName(
 
   // Restore the previous back reference contexts.
   NameBackReferences.swap(OuterTemplateContext);
-  TypeBackReferences.swap(OuterArgsContext);
+  FunArgBackReferences.swap(OuterFunArgsContext);
+  TemplateArgBackReferences.swap(OuterTemplateArgsContext);
   PassObjectSizeArgs.swap(OuterPassObjectSizeArgs);
 }
 
@@ -1699,8 +1721,8 @@ void MicrosoftCXXNameMangler::manglePointerCVQualifiers(Qualifiers Quals) {
   }
 }
 
-void MicrosoftCXXNameMangler::mangleArgumentType(QualType T,
-                                                 SourceRange Range) {
+void MicrosoftCXXNameMangler::mangleFunctionArgumentType(QualType T,
+                                                         SourceRange Range) {
   // MSVC will backreference two canonically equivalent types that have slightly
   // different manglings when mangled alone.
 
@@ -1730,9 +1752,9 @@ void MicrosoftCXXNameMangler::mangleArgumentType(QualType T,
     TypePtr = T.getCanonicalType().getAsOpaquePtr();
   }
 
-  ArgBackRefMap::iterator Found = TypeBackReferences.find(TypePtr);
+  ArgBackRefMap::iterator Found = FunArgBackReferences.find(TypePtr);
 
-  if (Found == TypeBackReferences.end()) {
+  if (Found == FunArgBackReferences.end()) {
     size_t OutSizeBefore = Out.tell();
 
     mangleType(T, Range, QMM_Drop);
@@ -1741,9 +1763,9 @@ void MicrosoftCXXNameMangler::mangleArgumentType(QualType T,
     // Only types longer than 1 character are considered
     // and only 10 back references slots are available:
     bool LongerThanOneChar = (Out.tell() - OutSizeBefore > 1);
-    if (LongerThanOneChar && TypeBackReferences.size() < 10) {
-      size_t Size = TypeBackReferences.size();
-      TypeBackReferences[TypePtr] = Size;
+    if (LongerThanOneChar && FunArgBackReferences.size() < 10) {
+      size_t Size = FunArgBackReferences.size();
+      FunArgBackReferences[TypePtr] = Size;
     }
   } else {
     Out << Found->second;
@@ -1757,16 +1779,16 @@ void MicrosoftCXXNameMangler::manglePassObjectSizeArg(
 
   auto Iter = PassObjectSizeArgs.insert({Type, Dynamic}).first;
   auto *TypePtr = (const void *)&*Iter;
-  ArgBackRefMap::iterator Found = TypeBackReferences.find(TypePtr);
+  ArgBackRefMap::iterator Found = FunArgBackReferences.find(TypePtr);
 
-  if (Found == TypeBackReferences.end()) {
+  if (Found == FunArgBackReferences.end()) {
     std::string Name =
         Dynamic ? "__pass_dynamic_object_size" : "__pass_object_size";
     mangleArtificialTagType(TTK_Enum, Name + llvm::utostr(Type), {"__clang"});
 
-    if (TypeBackReferences.size() < 10) {
-      size_t Size = TypeBackReferences.size();
-      TypeBackReferences[TypePtr] = Size;
+    if (FunArgBackReferences.size() < 10) {
+      size_t Size = FunArgBackReferences.size();
+      FunArgBackReferences[TypePtr] = Size;
     }
   } else {
     Out << Found->second;
@@ -2192,12 +2214,12 @@ void MicrosoftCXXNameMangler::mangleFunctionType(const FunctionType *T,
         Out << 'X';
       } else if (StructorType == Ctor_CopyingClosure) {
         // Copy constructor closure always takes an unqualified reference.
-        mangleArgumentType(getASTContext().getLValueReferenceType(
-                               Proto->getParamType(0)
-                                   ->getAs<LValueReferenceType>()
-                                   ->getPointeeType(),
-                               /*SpelledAsLValue=*/true),
-                           Range);
+        mangleFunctionArgumentType(getASTContext().getLValueReferenceType(
+                                       Proto->getParamType(0)
+                                           ->getAs<LValueReferenceType>()
+                                           ->getPointeeType(),
+                                       /*SpelledAsLValue=*/true),
+                                   Range);
         Out << '@';
       } else {
         llvm_unreachable("unexpected constructor closure!");
@@ -2239,7 +2261,7 @@ void MicrosoftCXXNameMangler::mangleFunctionType(const FunctionType *T,
   } else {
     // Happens for function pointer type arguments for example.
     for (unsigned I = 0, E = Proto->getNumParams(); I != E; ++I) {
-      mangleArgumentType(Proto->getParamType(I), Range);
+      mangleFunctionArgumentType(Proto->getParamType(I), Range);
       // Mangle each pass_object_size parameter as if it's a parameter of enum
       // type passed directly after the parameter with the pass_object_size
       // attribute. The aforementioned enum's name is __pass_object_size, and we
@@ -2731,10 +2753,12 @@ void MicrosoftCXXNameMangler::mangleType(const ObjCObjectType *T,
   if (T->qual_empty() && !T->isSpecialized())
     return mangleType(T->getBaseType(), Range, QMM_Drop);
 
-  ArgBackRefMap OuterArgsContext;
+  ArgBackRefMap OuterFunArgsContext;
+  ArgBackRefMap OuterTemplateArgsContext;
   BackRefVec OuterTemplateContext;
 
-  TypeBackReferences.swap(OuterArgsContext);
+  FunArgBackReferences.swap(OuterFunArgsContext);
+  TemplateArgBackReferences.swap(OuterTemplateArgsContext);
   NameBackReferences.swap(OuterTemplateContext);
 
   mangleTagTypeKind(TTK_Struct);
@@ -2758,7 +2782,8 @@ void MicrosoftCXXNameMangler::mangleType(const ObjCObjectType *T,
 
   Out << '@';
 
-  TypeBackReferences.swap(OuterArgsContext);
+  FunArgBackReferences.swap(OuterFunArgsContext);
+  TemplateArgBackReferences.swap(OuterTemplateArgsContext);
   NameBackReferences.swap(OuterTemplateContext);
 }
 
diff --git a/test/CodeGenCXX/mangle-ms-back-references-pr13207.cpp b/test/CodeGenCXX/mangle-ms-back-references-pr13207.cpp
index c68b97e68c..653937917b 100644
--- a/test/CodeGenCXX/mangle-ms-back-references-pr13207.cpp
+++ b/test/CodeGenCXX/mangle-ms-back-references-pr13207.cpp
@@ -191,3 +191,44 @@ void fun_instantiate2() {
 // CHECK: "??$fun_tmpl_recurse@H$1??$fun_tmpl_recurse@H$1?ident@fn_space@@YA?AURetVal@2@H@Z@fn_space@@YA?AURetVal@1@H@Z@fn_space@@YA?AURetVal@0@H@Z"
 // CHECK: "??$fun_tmpl_recurse@H$1?ident@fn_space@@YA?AURetVal@2@H@Z@fn_space@@YA?AURetVal@0@H@Z"
 }
+
+
+template <class T1, class T2, class T3, class T4, class T5, class T6, class T7,
+          class T8, class T9, class T10>
+struct Fooob {};
+
+using A0 = Fooob<int, int, int, int, int, int, int, int, int, int>;
+using A1 = Fooob<A0, A0, A0, A0, A0, A0, A0, A0, A0, A0>;
+using A2 = Fooob<A1, A1, A1, A1, A1, A1, A1, A1, A1, A1>;
+using A3 = Fooob<A2, A2, A2, A2, A2, A2, A2, A2, A2, A2>;
+using A4 = Fooob<A3, A3, A3, A3, A3, A3, A3, A3, A3, A3>;
+using A5 = Fooob<A4, A4, A4, A4, A4, A4, A4, A4, A4, A4>;
+using A6 = Fooob<A5, A5, A5, A5, A5, A5, A5, A5, A5, A5>;
+using A7 = Fooob<A6, A6, A6, A6, A6, A6, A6, A6, A6, A6>;
+using A8 = Fooob<A7, A7, A7, A7, A7, A7, A7, A7, A7, A7>;
+using A9 = Fooob<A8, A8, A8, A8, A8, A8, A8, A8, A8, A8>;
+using A10 = Fooob<A9, A9, A9, A9, A9, A9, A9, A9, A9, A9>;
+
+// This should take milliseconds, not minutes.
+void f(A9 a) {}
+// CHECK: "?f@@YAXU?$Fooob@U?$Fooob@U?$Fooob@U?$Fooob@U?$Fooob@U?$Fooob@U?$Fooob@U?$Fooob@U?$Fooob@U?$Fooob@HHHHHHHHHH@@U1@U1@U1@U1@U1@U1@U1@U1@U1@@@U1@U1@U1@U1@U1@U1@U1@U1@U1@@@U1@U1@U1@U1@U1@U1@U1@U1@U1@@@U1@U1@U1@U1@U1@U1@U1@U1@U1@@@U1@U1@U1@U1@U1@U1@U1@U1@U1@@@U1@U1@U1@U1@U1@U1@U1@U1@U1@@@U1@U1@U1@U1@U1@U1@U1@U1@U1@@@U1@U1@U1@U1@U1@U1@U1@U1@U1@@@U1@U1@U1@U1@U1@U1@U1@U1@U1@@@@Z"
+
+
+template <class T1, class T2, class T3, class T4, class T5, class T6, class T7,
+          class T8, class T9, class T10, class T11, class T12, class T13,
+          class T14, class T15, class T16, class T17, class T18, class T19,
+          class T20>
+struct Food {};
+
+using B0 = Food<int, int, int, int, int, int, int, int, int, int,  int, int, int, int, int, int, int, int, int, int>;
+using B1 = Food<B0, B0, B0, B0, B0, B0, B0, B0, B0, B0,  B0, B0, B0, B0, B0, B0, B0, B0, B0, B0>;
+using B2 = Food<B1, B0, B0, B0, B0, B0, B0, B0, B0, B0,  B1, B1, B1, B1, B1, B1, B1, B1, B1, B1>;
+using B3 = Food<B2, B1, B0, B0, B0, B0, B0, B0, B0, B0,  B2, B2, B2, B2, B2, B2, B2, B2, B2, B2>;
+using B4 = Food<B3, B2, B1, B0, B0, B0, B0, B0, B0, B0,  B3, B3, B3, B3, B3, B3, B3, B3, B3, B3>;
+using B5 = Food<B4, B3, B2, B1, B0, B0, B0, B0, B0, B0,  B4, B4, B4, B4, B4, B4, B4, B4, B4, B4>;
+using B6 = Food<B5, B4, B3, B2, B1, B0, B0, B0, B0, B0,  B5, B5, B5, B5, B5, B5, B5, B5, B5, B5>;
+
+// This too should take milliseconds, not minutes.
+void f(B6 a) {}
+
+// CHECK: "?f@@YAXU?$Food@U?$Food@U?$Food@U?$Food@U?$Food@U?$Food@U?$Food@HHHHHHHHHHHHHHHHHHHH@@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@@@U?$Food@HHHHHHHHHHHHHHHHHHHH@@U2@U2@U2@U2@U2@U2@U2@U2@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@@@U?$Food@U?$Food@HHHHHHHHHHHHHHHHHHHH@@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@@@U?$Food@HHHHHHHHHHHHHHHHHHHH@@U3@U3@U3@U3@U3@U3@U3@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@@@U?$Food@U?$Food@U?$Food@HHHHHHHHHHHHHHHHHHHH@@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@@@U?$Food@HHHHHHHHHHHHHHHHHHHH@@U2@U2@U2@U2@U2@U2@U2@U2@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@@@U?$Food@U?$Food@HHHHHHHHHHHHHHHHHHHH@@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@@@U?$Food@HHHHHHHHHHHHHHHHHHHH@@U4@U4@U4@U4@U4@U4@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@@@U?$Food@U?$Food@U?$Food@U?$Food@HHHHHHHHHHHHHHHHHHHH@@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@@@U?$Food@HHHHHHHHHHHHHHHHHHHH@@U2@U2@U2@U2@U2@U2@U2@U2@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@@@U?$Food@U?$Food@HHHHHHHHHHHHHHHHHHHH@@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@@@U?$Food@HHHHHHHHHHHHHHHHHHHH@@U3@U3@U3@U3@U3@U3@U3@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@@@U?$Food@U?$Food@U?$Food@HHHHHHHHHHHHHHHHHHHH@@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@@@U?$Food@HHHHHHHHHHHHHHHHHHHH@@U2@U2@U2@U2@U2@U2@U2@U2@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@@@U?$Food@U?$Food@HHHHHHHHHHHHHHHHHHHH@@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@@@U?$Food@HHHHHHHHHHHHHHHHHHHH@@U5@U5@U5@U5@U5@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@@@U?$Food@U?$Food@U?$Food@U?$Food@U?$Food@HHHHHHHHHHHHHHHHHHHH@@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@@@U?$Food@HHHHHHHHHHHHHHHHHHHH@@U2@U2@U2@U2@U2@U2@U2@U2@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@@@U?$Food@U?$Food@HHHHHHHHHHHHHHHHHHHH@@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@@@U?$Food@HHHHHHHHHHHHHHHHHHHH@@U3@U3@U3@U3@U3@U3@U3@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@@@U?$Food@U?$Food@U?$Food@HHHHHHHHHHHHHHHHHHHH@@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@@@U?$Food@HHHHHHHHHHHHHHHHHHHH@@U2@U2@U2@U2@U2@U2@U2@U2@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@@@U?$Food@U?$Food@HHHHHHHHHHHHHHHHHHHH@@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@@@U?$Food@HHHHHHHHHHHHHHHHHHHH@@U4@U4@U4@U4@U4@U4@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@@@U?$Food@U?$Food@U?$Food@U?$Food@HHHHHHHHHHHHHHHHHHHH@@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@@@U?$Food@HHHHHHHHHHHHHHHHHHHH@@U2@U2@U2@U2@U2@U2@U2@U2@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@@@U?$Food@U?$Food@HHHHHHHHHHHHHHHHHHHH@@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@@@U?$Food@HHHHHHHHHHHHHHHHHHHH@@U3@U3@U3@U3@U3@U3@U3@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@@@U?$Food@U?$Food@U?$Food@HHHHHHHHHHHHHHHHHHHH@@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@@@U?$Food@HHHHHHHHHHHHHHHHHHHH@@U2@U2@U2@U2@U2@U2@U2@U2@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@@@U?$Food@U?$Food@HHHHHHHHHHHHHHHHHHHH@@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@@@U?$Food@HHHHHHHHHHHHHHHHHHHH@@U6@U6@U6@U6@U1@U1@U1@U1@U1@U1@U1@U1@U1@U1@@@@Z"