[Verifier] Check that GEP indexes has correct types

[igor-laevsky]

Summary

This is minor issue inspired by the llvm-opt-fuzzer.

Verifier will accept GEP's with first index of any arbitrary type. IR parser checks this independently so we can only achieve this by explicitly generating this code using llvm library (and this is what happened in the llvm-opt-fuzzer).

[igor-laevsky]

Slight ping? This change is not overly important but seems reasonable to me.

[bogner]

Sorry, I didn't see this one (I think llvm-commits was missing on the initial patch creation and it didn't make it to the list).

LGTM

llvm/trunk/lib/IR/Verifier.cpp

 }
 
 void Verifier::visitGetElementPtrInst(GetElementPtrInst &GEP) {
   Type *TargetTy = GEP.getPointerOperandType()->getScalarType();
 
   Assert(isa<PointerType>(TargetTy),
          "GEP base pointer is not a vector or a vector of pointers", &GEP);
   Assert(GEP.getSourceElementType()->isSized(), "GEP into unsized type!", &GEP);
+
   SmallVector<Value*, 16> Idxs(GEP.idx_begin(), GEP.idx_end());
+  Assert(all_of(
+      Idxs, [](Value* V) { return V->getType()->isIntOrIntVectorTy(); }),
+      "GEP indexes must be integers", &GEP);
   Type *ElTy =
       GetElementPtrInst::getIndexedType(GEP.getSourceElementType(), Idxs);
   Assert(ElTy, "Invalid indices for GEP pointer type!", &GEP);
 
   Assert(GEP.getType()->isPtrOrPtrVectorTy() &&
              GEP.getResultElementType() == ElTy,
          "GEP is not of right type for indices!", &GEP, ElTy);
 

llvm/trunk/test/Verifier/non-integer-gep-index.ll

+; RUN: not opt -verify %s.bc -disable-output
+
+; Test that verifier checks that gep indexes has correct type
+; Specifically we want to check for the following pattern:
+;   %A1 = alloca i64
+;   %G = getelementptr i64, i64* %A1, %A1
+; IR parser checks for this pattern independently from the verifier, so it's
+; impossible to load from .ll file. Hence in this test we use bytecode input.