[clang] [Clang][RVV][SVE] Cache getScalableVectorType lookups (PR #160108)

[Shaoce SUN via cfe-commits]

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@@ -4567,6 +4567,11 @@ QualType ASTContext::getWebAssemblyExternrefType() const {
 /// type.
 QualType ASTContext::getScalableVectorType(QualType EltTy, unsigned NumElts,
                                            unsigned NumFields) const {
+  auto K = llvm::ScalableVecTyKey{
+      reinterpret_cast<uintptr_t>(EltTy.getAsOpaquePtr()), NumElts, NumFields};
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sunshaoce wrote:

Thanks for your comments and the example. I think using `OpaquePtr` is safe, since `DenseMapInfo<clang::QualType>` in `clang/include/clang/AST/TypeOrdering.h` also uses `OpaquePtr`. I initially chose `OpaquePtr` because it is more lightweight. I’ve now submitted a commit that uses `QualType` directly instead. Which approach do you think is better?

https://github.com/llvm/llvm-project/pull/160108