[PATCH] D26014: [ConstantFold] Get the correct vector type when folding a getelementptr instruction with vector indices

[Davide Italiano via llvm-commits]

davide updated this revision to Diff 76083.
davide added a comment.

David's comments (also added again the overload which I previously removed because it was unused).


https://reviews.llvm.org/D26014

Files:
  include/llvm/IR/Instructions.h
  lib/IR/ConstantFold.cpp
  test/Transforms/InstCombine/gep-vector.ll


Index: test/Transforms/InstCombine/gep-vector.ll
===================================================================
--- /dev/null
+++ test/Transforms/InstCombine/gep-vector.ll
@@ -0,0 +1,15 @@
+; RUN: opt -instcombine %s -S | FileCheck %s
+
+; CHECK-LABEL: patatino
+; CHECK-NEXT: ret <8 x i64*> undef
+define <8 x i64*> @patatino() {
+  %el = getelementptr i64, <8 x i64*> undef, <8 x i64> undef
+  ret <8 x i64*> %el
+}
+
+; CHECK-LABEL: patatino2
+; CHECK-NEXT: ret <8 x i64*> undef
+define <8 x i64*> @patatino2() {
+  %el = getelementptr inbounds i64, i64* undef, <8 x i64> undef
+  ret <8 x i64*> %el
+}
Index: lib/IR/ConstantFold.cpp
===================================================================
--- lib/IR/ConstantFold.cpp
+++ lib/IR/ConstantFold.cpp
@@ -2062,6 +2062,11 @@
     Type *GEPTy = PointerType::get(Ty, PtrTy->getAddressSpace());
     if (VectorType *VT = dyn_cast<VectorType>(C->getType()))
       GEPTy = VectorType::get(GEPTy, VT->getNumElements());
+    // When the getelementptr has one or more vector indices, it will
+    // return a vector of pointers.
+    else
+      GEPTy = GetElementPtrInst::getGEPReturnType(C,
+        makeArrayRef((Value * const *)Idxs.data(), Idxs.size()));
     return UndefValue::get(GEPTy);
   }
 
Index: include/llvm/IR/Instructions.h
===================================================================
--- include/llvm/IR/Instructions.h
+++ include/llvm/IR/Instructions.h
@@ -959,6 +959,11 @@
 
   /// Returns the pointer type returned by the GEP
   /// instruction, which may be a vector of pointers.
+  static Type *getGEPReturnType(Value *Ptr, ArrayRef<Value *> IdxList) {
+    return getGEPReturnType(
+      cast<PointerType>(Ptr->getType()->getScalarType())->getElementType(),
+      Ptr, IdxList);
+  }
   static Type *getGEPReturnType(Type *ElTy, Value *Ptr,
                                 ArrayRef<Value *> IdxList) {
     Type *PtrTy = PointerType::get(checkGEPType(getIndexedType(ElTy, IdxList)),


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