Fix alloc opt pass on LLVM 11+. (#39119)

(cherry picked from commit f5c8e67)

Author: maleadt

src/llvm-alloc-opt.cpp

@@ -66,7 +66,7 @@ static bool hasObjref(Type *ty)
         return ptrty->getAddressSpace() == AddressSpace::Tracked;
 #if JL_LLVM_VERSION >= 110000
     if (isa<ArrayType>(ty) || isa<VectorType>(ty))
-        return GetElementPtrInst::getTypeAtIndex(ty, (uint64_t)0);
+        return hasObjref(GetElementPtrInst::getTypeAtIndex(ty, (uint64_t)0));
 #else
     if (auto seqty = dyn_cast<SequentialType>(ty))
         return hasObjref(seqty->getElementType());

test/llvmpasses/alloc-opt3.jl

@@ -0,0 +1,23 @@
+# This file is a part of Julia. License is MIT: https://julialang.org/license
+
+# RUN: julia --startup-file=no %s %t -O
+# RUN: cat %t/* | FileCheck %s
+
+include(joinpath("..", "testhelpers", "llvmpasses.jl"))
+
+# JuliaLang/julia#38922
+function haszerolayout(x::NTuple{32, VecElement{UInt8}})
+    rx = Ref(x)
+    GC.@preserve rx begin
+        lower = iszero(unsafe_load(Ptr{UInt128}(pointer_from_objref(rx)), 1))
+        upper = iszero(unsafe_load(Ptr{UInt128}(pointer_from_objref(rx)), 2))
+        lower & upper
+    end
+end
+
+# CHECK-LABEL: @julia_haszerolayout
+# CHECK: top:
+# CHECK-NOT: @jl_gc_pool_alloc
+# CHECK: extractelement
+# CHECK: ret i8
+emit(haszerolayout, NTuple{32,VecElement{UInt8}})