Update comments and unit test

Author: haopliu

llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp

@@ -165,6 +165,7 @@ static cl::opt<bool>
     OptimizeMemorySSA("dse-optimize-memoryssa", cl::init(true), cl::Hidden,
                       cl::desc("Allow DSE to optimize memory accesses."));
 
+// TODO: turn on and remove this flag.
 static cl::opt<bool> EnableInitializesImprovement(
     "enable-dse-initializes-attr-improvement", cl::init(false), cl::Hidden,
     cl::desc("Enable the initializes attr improvement in DSE"));
@@ -2364,6 +2365,9 @@ DSEState::eliminateDeadDefs(const MemoryLocationWrapper &KillingLocWrapper) {
       }
       continue;
     }
+    // We cannot apply the initializes attribute to DeadAccess/DeadDef.
+    // It would incorrectly consider a call instruction as redundant store
+    // and remove this call instruction.
     MemoryDefWrapper DeadDefWrapper(
         cast<MemoryDef>(DeadAccess),
         getLocForInst(cast<MemoryDef>(DeadAccess)->getMemoryInst(),

llvm/test/Transforms/DeadStoreElimination/inter-procedural.ll

@@ -1,5 +1,5 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt < %s -aa-pipeline=basic-aa -passes=function-attrs,dse -enable-dse-initializes-attr-improvement -S | FileCheck %s
+; RUN: opt < %s -passes=dse -enable-dse-initializes-attr-improvement -S | FileCheck %s
 
 declare void @p1_write_only(ptr nocapture noundef writeonly initializes((0, 2)) dead_on_unwind)
 declare void @p1_write_then_read(ptr nocapture noundef initializes((0, 2)) dead_on_unwind)