Subzero: Fix address mode optimization involving phi temporaries.

src/IceTargetLowering.cpp

 //===- subzero/src/IceTargetLowering.cpp - Basic lowering implementation --===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file implements the skeleton of the TargetLowering class,
@@ skipping 118 matching lines @@
 //
 // The lowering method may look ahead in the instruction stream as
 // desired, and lower additional instructions in conjunction with the
 // current one, for example fusing a compare and branch.  If it does,
 // it should advance Context.Cur to point to the next non-deleted
 // instruction to process, and it should delete any additional
 // instructions it consumes.
 void TargetLowering::lower() {
   assert(!Context.atEnd());
   Inst *Inst = *Context.getCur();
+  // Mark the current instruction as deleted before lowering,
+  // otherwise the Dest variable will likely get marked as non-SSA.
+  // See Variable::setDefinition().
+  Inst->setDeleted();
   switch (Inst->getKind()) {
   case Inst::Alloca:
     lowerAlloca(llvm::dyn_cast<InstAlloca>(Inst));
     break;
   case Inst::Arithmetic:
     lowerArithmetic(llvm::dyn_cast<InstArithmetic>(Inst));
     break;
   case Inst::Assign:
     lowerAssign(llvm::dyn_cast<InstAssign>(Inst));
     break;
@@ skipping 44 matching lines @@
     break;
   case Inst::FakeDef:
   case Inst::FakeUse:
   case Inst::FakeKill:
   case Inst::Target:
     // These are all Target instruction types and shouldn't be
     // encountered at this stage.
     Func->setError("Can't lower unsupported instruction type");
     break;
   }
-  Inst->setDeleted();
 
   postLower();
 
   Context.advanceCur();
   Context.advanceNext();
 }
 
 // Drives register allocation, allowing all physical registers (except
 // perhaps for the frame pointer) to be allocated.  This set of
 // registers could potentially be parameterized if we want to restrict
@@ skipping 25 matching lines @@
   if (Target == Target_ARM64)
     return IceTargetGlobalInitARM64::create(Ctx);
 #endif
   llvm_unreachable("Unsupported target");
   return NULL;
 }
 
 TargetGlobalInitLowering::~TargetGlobalInitLowering() {}
 
 } // end of namespace Ice