[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

llvm-svn: 327638

4 files changed, 64 insertions, 9 deletions

diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp
index 5e43cb7cec1..67669c2eca1 100644
--- a/llvm/lib/Analysis/InstructionSimplify.cpp
+++ b/llvm/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
diff --git a/llvm/lib/IR/ConstantFold.cpp b/llvm/lib/IR/ConstantFold.cpp
index 92d35a27d69..7ad2d46bfb6 100644
--- a/llvm/lib/IR/ConstantFold.cpp
+++ b/llvm/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;
diff --git a/llvm/test/Analysis/ConstantFolding/vectorgep-crash.ll b/llvm/test/Analysis/ConstantFolding/vectorgep-crash.ll
index e7a5117d6ed..b2faf89c2b7 100644
--- a/llvm/test/Analysis/ConstantFolding/vectorgep-crash.ll
+++ b/llvm/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
+}
diff --git a/llvm/test/Transforms/InstSimplify/vector_gep.ll b/llvm/test/Transforms/InstSimplify/vector_gep.ll
index 25f2255a2a7..42916c4c07a 100644
--- a/llvm/test/Transforms/InstSimplify/vector_gep.ll
+++ b/llvm/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
+}