[InstSimplify] Deduce correct type for vector gep

[davide]

Summary

Fixes
http://bugs.llvm.org/show_bug.cgi?id=32697

Thanks to Filipe for pointing out the three gep vector variants to cover

[filcab]

LGTM

[spatel]

Since we already have a test file specifically for vector gep simplifications (test/Transforms/InstSimplify/vector_gep.ll), can you please add these new tests there? I find it easier to locate and fix bugs when related tests are co-located. A comment/link back to http://bugs.llvm.org/show_bug.cgi?id=32697 above the regression test also saves time for future bug hunting. Thanks!

[davide]

In D32180#730382, @spatel wrote:

Since we already have a test file specifically for vector gep simplifications (test/Transforms/InstSimplify/vector_gep.ll), can you please add these new tests there? I find it easier to locate and fix bugs when related tests are co-located. A comment/link back to http://bugs.llvm.org/show_bug.cgi?id=32697 above the regression test also saves time for future bug hunting. Thanks!

Sure.

llvm/trunk/lib/Analysis/InstructionSimplify.cpp

static Value *SimplifyGEPInst(Type *SrcTy, ArrayRef<Value *> Ops,
   if (Ops.size() == 1)
     return Ops[0];
 
   // Compute the (pointer) type returned by the GEP instruction.
   Type *LastType = GetElementPtrInst::getIndexedType(SrcTy, Ops.slice(1));
   Type *GEPTy = PointerType::get(LastType, AS);
   if (VectorType *VT = dyn_cast<VectorType>(Ops[0]->getType()))
     GEPTy = VectorType::get(GEPTy, VT->getNumElements());
+  else if (VectorType *VT = dyn_cast<VectorType>(Ops[1]->getType()))
+    GEPTy = VectorType::get(GEPTy, VT->getNumElements());
 
   if (isa<UndefValue>(Ops[0]))
     return UndefValue::get(GEPTy);
 
   if (Ops.size() == 2) {
     // getelementptr P, 0 -> P.
     if (match(Ops[1], m_Zero()))
       return Ops[0];

llvm/trunk/test/Transforms/InstSimplify/vector_gep.ll

 
 @v = global [24 x [42 x [3 x i32]]] zeroinitializer, align 16
 
 define <16 x i32*> @test6() {
 ; CHECK-LABEL: @test6
 ; CHECK-NEXT: ret <16 x i32*> getelementptr ([24 x [42 x [3 x i32]]], [24 x [42 x [3 x i32]]]* @v, <16 x i64> zeroinitializer, <16 x i64> zeroinitializer, <16 x i64> <i64 0, 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>, <16 x i64> zeroinitializer)
   %VectorGep = getelementptr [24 x [42 x [3 x i32]]], [24 x [42 x [3 x i32]]]* @v, i64 0, i64 0, <16 x i64> <i64 0, 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 0
   ret <16 x i32*> %VectorGep
-}
+}
+
+; PR32697
+; CHECK-LABEL: tinkywinky(
+; CHECK-NEXT: ret <4 x i8*> undef
+define <4 x i8*> @tinkywinky() {
+  %patatino = getelementptr i8, i8* undef, <4 x i64> undef
+  ret <4 x i8*> %patatino
+}
+
+; PR32697
+; CHECK-LABEL: dipsy(
+; CHECK-NEXT: ret <4 x i8*> undef
+define <4 x i8*> @dipsy() {
+  %patatino = getelementptr i8, <4 x i8 *> undef, <4 x i64> undef
+  ret <4 x i8*> %patatino
+}
+
+; PR32697
+; CHECK-LABEL: laalaa(
+; CHECK-NEXT: ret <4 x i8*> undef
+define <4 x i8*> @laalaa() {
+  %patatino = getelementptr i8, <4 x i8 *> undef, i64 undef
+  ret <4 x i8*> %patatino
+}