caio/clang-p2996
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Reduce amount of work ODR hashing does.

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When a FunctionProtoType is in the original type in a DecayedType, the decayed
type is a PointerType which points back the original FunctionProtoType.  The
visitor for ODRHashing will attempt to process both Type's, doing double work.
By chaining together multiple DecayedType's and FunctionProtoType's, this would
result in 2^N Type's visited only N DecayedType's and N FunctionProtoType's
exsit.  Another bug where VisitDecayedType and VisitAdjustedType did
redundant work doubled the work at each level, giving 4^N Type's visited.  This
patch removed the double work and detects when a FunctionProtoType decays to
itself to only check the Type once.  This lowers the exponential runtime to
linear runtime.  Fixes https://bugs.llvm.org/show_bug.cgi?id=41625

llvm-svn: 359960
This commit is contained in:
Richard Trieu
2019-05-04 04:22:33 +00:00
parent 28a1936f6d
commit cf9bd8ade7
2 changed files with 63 additions and 4 deletions
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30
clang/lib/AST/ODRHash.cpp
View File

@@ -703,14 +703,36 @@ public:
void VisitType(const Type *T) {}
void VisitAdjustedType(const AdjustedType *T) {
AddQualType(T->getOriginalType());
AddQualType(T->getAdjustedType());
QualType Original = T->getOriginalType();
QualType Adjusted = T->getAdjustedType();
// The original type and pointee type can be the same, as in the case of
// function pointers decaying to themselves. Set a bool and only process
// the type once, to prevent doubling the work.
SplitQualType split = Adjusted.split();
if (auto Pointer = dyn_cast<PointerType>(split.Ty)) {
if (Pointer->getPointeeType() == Original) {
Hash.AddBoolean(true);
ID.AddInteger(split.Quals.getAsOpaqueValue());
AddQualType(Original);
VisitType(T);
return;
}
}
// The original type and pointee type are different, such as in the case
// of a array decaying to an element pointer. Set a bool to false and
// process both types.
Hash.AddBoolean(false);
AddQualType(Original);
AddQualType(Adjusted);
VisitType(T);
}
void VisitDecayedType(const DecayedType *T) {
AddQualType(T->getDecayedType());
AddQualType(T->getPointeeType());
// getDecayedType and getPointeeType are derived from getAdjustedType
// and don't need to be separately processed.
VisitAdjustedType(T);
}

37
clang/test/Modules/odr_hash.cpp
View File

@@ -4587,6 +4587,43 @@ int num = bar();
#endif
}
namespace FunctionProtoTypeDecay {
#if defined(FIRST)
struct S1 {
struct X {};
using Y = X(X());
};
#elif defined(SECOND)
struct S1 {
struct X {};
using Y = X(X(X()));
};
#else
S1 s1;
// expected-error@first.h:* {{'FunctionProtoTypeDecay::S1::Y' from module 'FirstModule' is not present in definition of 'FunctionProtoTypeDecay::S1' in module 'SecondModule'}}
// expected-note@second.h:* {{declaration of 'Y' does not match}}
#endif
#if defined(FIRST)
struct S2 {
struct X {};
using Y =
X(X(X(X(X(X(X(X(X(X(X(X(X(X(X(X(
X(X(X(X(X(X(X(X(X(X(X(X(X(X(X(X(
X(X(X(X(X(X(X(X(X(X(X(X(X(X(X(X(
X(X(X(X(X(X(X(X(X(X(X(X(X(X(X(X(
))))))))))))))))
))))))))))))))))
))))))))))))))))
))))))))))))))));
};
#elif defined(SECOND)
#else
S2 s2;
#endif
}
// Keep macros contained to one file.
#ifdef FIRST
#undef FIRST