[SLP]Fix PR43799: Crash on different sizes of GEP indices.

Summary:
If the GEP instructions are going to be vectorized, the indices in those
GEP instructions must be of the same type. Otherwise, the compiler may
crash when trying to build the vector constant.

Reviewers: RKSimon, spatel

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D69627

Author: alexey-bataev

llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp

@@ -2638,9 +2638,14 @@ void BoUpSLP::buildTree_rec(ArrayRef<Value *> VL, unsigned Depth,
       }
 
       // We don't combine GEPs with non-constant indexes.
+      Type *Ty1 = VL0->getOperand(1)->getType();
       for (Value *V : VL) {
         auto Op = cast<Instruction>(V)->getOperand(1);
-        if (!isa<ConstantInt>(Op)) {
+        if (!isa<ConstantInt>(Op) ||
+            (Op->getType() != Ty1 &&
+             Op->getType()->getScalarSizeInBits() >
+                 DL->getIndexSizeInBits(
+                     V->getType()->getPointerAddressSpace()))) {
           LLVM_DEBUG(dbgs()
                      << "SLP: not-vectorizable GEP (non-constant indexes).\n");
           BS.cancelScheduling(VL, VL0);
@@ -4156,7 +4161,22 @@ Value *BoUpSLP::vectorizeTree(TreeEntry *E) {
       std::vector<Value *> OpVecs;
       for (int j = 1, e = cast<GetElementPtrInst>(VL0)->getNumOperands(); j < e;
            ++j) {
-        Value *OpVec = vectorizeTree(E->getOperand(j));
+        ValueList &VL = E->getOperand(j);
+        // Need to cast all elements to the same type before vectorization to
+        // avoid crash.
+        Type *VL0Ty = VL0->getOperand(j)->getType();
+        Type *Ty = llvm::all_of(
+                       VL, [VL0Ty](Value *V) { return VL0Ty == V->getType(); })
+                       ? VL0Ty
+                       : DL->getIndexType(cast<GetElementPtrInst>(VL0)
+                                              ->getPointerOperandType()
+                                              ->getScalarType());
+        for (Value *&V : VL) {
+          auto *CI = cast<ConstantInt>(V);
+          V = ConstantExpr::getIntegerCast(CI, Ty,
+                                           CI->getValue().isSignBitSet());
+        }
+        Value *OpVec = vectorizeTree(VL);
         OpVecs.push_back(OpVec);
       }
 

llvm/test/Transforms/SLPVectorizer/X86/crash_gep.ll

@@ -29,3 +29,26 @@ entry:
   store i64 %2, i64* %add.ptr, align 8
   ret i32 undef
 }
+
+define void @PR43799() {
+; CHECK-LABEL: @PR43799(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[BODY:%.*]]
+; CHECK:       body:
+; CHECK-NEXT:    br label [[BODY]]
+; CHECK:       epilog:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %body
+
+body:
+  %p.1.i19 = phi i8* [ undef, %entry ], [ %incdec.ptr.i.7, %body ]
+  %lsr.iv17 = phi i8* [ undef, %entry ], [ %scevgep113.7, %body ]
+  %incdec.ptr.i.7 = getelementptr inbounds i8, i8* undef, i32 1
+  %scevgep113.7 = getelementptr i8, i8* undef, i64 1
+  br label %body
+
+epilog:
+  ret void
+}