Change a reachable unreachable to a fatal error.

[filcab]

Summary

Also tagged a FIXME comment, and added information about why it breaks.

Bug found using AFL fuzz.

[filcab]

ping!

Filipe

[• rafael]

LGTM

Thanks

include/llvm/Support/StreamingMemoryObject.h

 /// setKnownObjectSize methods which are not applicable to non-streamed objects.
 class StreamingMemoryObject : public MemoryObject {
 public:
   StreamingMemoryObject(DataStreamer *streamer);
   uint64_t getExtent() const override;
   uint64_t readBytes(uint8_t *Buf, uint64_t Size,
                      uint64_t Address) const override;
   const uint8_t *getPointer(uint64_t address, uint64_t size) const override {
-    // This could be fixed by ensuring the bytes are fetched and making a copy,
-    // requiring that the bitcode size be known, or otherwise ensuring that
-    // the memory doesn't go away/get reallocated, but it's
-    // not currently necessary. Users that need the pointer don't stream.
-    llvm_unreachable("getPointer in streaming memory objects not allowed");
+    // FIXME: This could be fixed by ensuring the bytes are fetched and
+    // making a copy, requiring that the bitcode size be known, or
+    // otherwise ensuring that the memory doesn't go away/get reallocated,
+    // but it's not currently necessary. Users that need the pointer (any
+    // that need Blobs) don't stream.
+    report_fatal_error("getPointer in streaming memory objects not allowed");
     return nullptr;
   }
   bool isValidAddress(uint64_t address) const override;
 
   /// Drop s bytes from the front of the stream, pushing the positions of the
   /// remaining bytes down by s. This is used to skip past the bitcode header,
   /// since we don't know a priori if it's present, and we can't put bytes
   /// back into the stream once we've read them.

test/Bitcode/invalid.test

 RUN:   FileCheck --check-prefix=LOAD-BAD-TYPE %s
 
 LOAD-BAD-TYPE: Load operand is not a pointer type
 
 RUN: not llvm-dis -disable-output %p/Inputs/invalid-GCTable-overflow.bc 2>&1 | \
 RUN:   FileCheck --check-prefix=GCTABLE-OFLOW %s
 
 GCTABLE-OFLOW: Invalid ID
+
+RUN: not llvm-dis -disable-output %p/Inputs/invalid-fixme-streaming-blob.bc 2>&1 | \
+RUN:   FileCheck --check-prefix=STREAMING-BLOB %s
+
+STREAMING-BLOB: getPointer in streaming memory objects not allowed