[llvm-branch-commits] [clang] [Clang] Add pointer field protection feature. (PR #172119)

[Florian Mayer via llvm-branch-commits]

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@@ -1310,21 +1310,92 @@ static llvm::Value *CoerceIntOrPtrToIntOrPtr(llvm::Value *Val, llvm::Type *Ty,
   return Val;
 }
 
+static std::vector<PFPField> findPFPCoercedFields(CodeGenFunction &CGF,
+                                                  QualType SrcFETy) {
+  // Coercion directly through memory does not work if the structure has pointer
+  // field protection because the struct in registers has a different bit
+  // pattern to the struct in memory, so we must read the elements one by one
+  // and use them to form the coerced structure.
+  std::vector<PFPField> PFPFields;
+  CGF.getContext().findPFPFields(SrcFETy, CharUnits::Zero(), PFPFields,
+                                 /*IncludeVBases=*/true);
+
+  // Because we don't know which union member is selected, we don't modify the
+  // in-memory representation when passing a pointer that is part of a union
+  // field. This requires the union member to be trivially copyable;
+  // non-trivially-copyable unions cannot be directly passed by value.
+  llvm::erase_if(PFPFields, [](PFPField F) { return F.isWithinUnion; });
+  return PFPFields;
+}
+
+static llvm::Value *CreatePFPCoercedLoad(Address Src, QualType SrcFETy,
+                                         llvm::Type *Ty, CodeGenFunction &CGF) {
+  std::vector<PFPField> PFPFields = findPFPCoercedFields(CGF, SrcFETy);
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fmayer wrote:

maybe let's use a different name? Throughout this change, `PFPFields` is for the result of `findPFPFields`

https://github.com/llvm/llvm-project/pull/172119