[ConstantFolding, InstSimplify] Handle more vector GEPs

This patch addresses some additional cases where the compiler crashes upon
encountering vector GEPs. This should fix PR36116.

Differential Revision: https://reviews.llvm.org/D44219
Reference: https://bugs.llvm.org/show_bug.cgi?id=36116

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@327638 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Analysis/InstructionSimplify.cpp

@@ -3723,7 +3723,7 @@ static Value *SimplifyGEPInst(Type *SrcTy, ArrayRef<Value *> Ops,
 
   if (Ops.size() == 2) {
     // getelementptr P, 0 -> P.
-    if (match(Ops[1], m_Zero()))
+    if (match(Ops[1], m_Zero()) && Ops[0]->getType() == GEPTy)
       return Ops[0];
 
     Type *Ty = SrcTy;
@@ -3732,7 +3732,7 @@ static Value *SimplifyGEPInst(Type *SrcTy, ArrayRef<Value *> Ops,
       uint64_t C;
       uint64_t TyAllocSize = Q.DL.getTypeAllocSize(Ty);
       // getelementptr P, N -> P if P points to a type of zero size.
-      if (TyAllocSize == 0)
+      if (TyAllocSize == 0 && Ops[0]->getType() == GEPTy)
         return Ops[0];
 
       // The following transforms are only safe if the ptrtoint cast

lib/IR/ConstantFold.cpp

@@ -2027,8 +2027,16 @@ static bool isInBoundsIndices(ArrayRef<IndexTy> Idxs) {
 
   // If the first index is one and all the rest are zero, it's in bounds,
   // by the one-past-the-end rule.
-  if (!cast<ConstantInt>(Idxs[0])->isOne())
-    return false;
+  if (auto *CI = dyn_cast<ConstantInt>(Idxs[0])) {
+    if (!CI->isOne())
+      return false;
+  } else {
+    auto *CV = cast<ConstantDataVector>(Idxs[0]);
+    CI = dyn_cast_or_null<ConstantInt>(CV->getSplatValue());
+    if (!CI || !CI->isOne())
+      return false;
+  }
+
   for (unsigned i = 1, e = Idxs.size(); i != e; ++i)
     if (!cast<Constant>(Idxs[i])->isNullValue())
       return false;
@@ -2058,15 +2066,18 @@ Constant *llvm::ConstantFoldGetElementPtr(Type *PointeeTy, Constant *C,
                                           ArrayRef<Value *> Idxs) {
   if (Idxs.empty()) return C;
 
-  if (isa<UndefValue>(C)) {
-    Type *GEPTy = GetElementPtrInst::getGEPReturnType(
-        C, makeArrayRef((Value * const *)Idxs.data(), Idxs.size()));
+  Type *GEPTy = GetElementPtrInst::getGEPReturnType(
+      C, makeArrayRef((Value *const *)Idxs.data(), Idxs.size()));
+
+  if (isa<UndefValue>(C))
     return UndefValue::get(GEPTy);
-  }
 
   Constant *Idx0 = cast<Constant>(Idxs[0]);
   if (Idxs.size() == 1 && (Idx0->isNullValue() || isa<UndefValue>(Idx0)))
-    return C;
+    return GEPTy->isVectorTy() && !C->getType()->isVectorTy()
+               ? ConstantVector::getSplat(
+                     cast<VectorType>(GEPTy)->getNumElements(), C)
+               : C;
 
   if (C->isNullValue()) {
     bool isNull = true;

test/Analysis/ConstantFolding/vectorgep-crash.ll

@@ -38,3 +38,29 @@ vector.body:
   %VectorGep = getelementptr [65 x %struct.A], [65 x %struct.A]* @G, <16 x i32> zeroinitializer, <16 x i64> <i64 1, i64 2, i64 3, i64 4, i64 5, i64 6, i64 7, i64 8, i64 9, i64 10, i64 11, i64 12, i64 13, i64 14, i64 15, i64 16>, <16 x i32> zeroinitializer
   ret <16 x i32*> %VectorGep
 }
+
+@g = external global i8, align 1
+
+define <2 x i8*> @constant_zero_index() {
+; CHECK-LABEL: @constant_zero_index(
+; CHECK-NEXT:    ret <2 x i8*> <i8* @g, i8* @g>
+;
+  %gep = getelementptr i8, i8* @g, <2 x i64> zeroinitializer
+  ret <2 x i8*> %gep
+}
+
+define <2 x i8*> @constant_undef_index() {
+; CHECK-LABEL: @constant_undef_index(
+; CHECK-NEXT:    ret <2 x i8*> <i8* @g, i8* @g>
+;
+  %gep = getelementptr i8, i8* @g, <2 x i64> undef
+  ret <2 x i8*> %gep
+}
+
+define <2 x i8*> @constant_inbounds() {
+; CHECK-LABEL: @constant_inbounds(
+; CHECK-NEXT:    ret <2 x i8*> getelementptr inbounds (i8, i8* @g, <2 x i64> <i64 1, i64 1>)
+;
+  %gep = getelementptr i8, i8* @g, <2 x i64> <i64 1, i64 1>
+  ret <2 x i8*> %gep
+}

test/Transforms/InstSimplify/vector_gep.ll

@@ -86,3 +86,21 @@ define <4 x i8*> @laalaa() {
   %patatino = getelementptr i8, <4 x i8 *> undef, i64 undef
   ret <4 x i8*> %patatino
 }
+
+define <2 x i8*> @zero_index(i8* %p) {
+; CHECK-LABEL: @zero_index(
+; CHECK-NEXT:    %gep = getelementptr i8, i8* %p, <2 x i64> zeroinitializer
+; CHECK-NEXT:    ret <2 x i8*> %gep
+;
+  %gep = getelementptr i8, i8* %p, <2 x i64> zeroinitializer
+  ret <2 x i8*> %gep
+}
+
+define <2 x {}*> @unsized({}* %p) {
+; CHECK-LABEL: @unsized(
+; CHECK-NEXT:    %gep = getelementptr {}, {}* %p, <2 x i64> undef
+; CHECK-NEXT:    ret <2 x {}*> %gep
+;
+  %gep = getelementptr {}, {}* %p, <2 x i64> undef
+  ret <2 x {}*> %gep
+}