Valu("sp", OpSP, c.config.Types.Uintptr, 0, nil),
			Goto("loop")),
		Bloc("loop",
			Valu("phi", OpPhi, types.TypeMem, 0, nil, "start", "wb"),
			Valu("v", OpConstNil, ptrType, 0, nil),
			Valu("addr", OpAddr, ptrType, 0, nil, "sb"),
			Valu("wb", OpStore, types.TypeMem, 0, ptrType, "addr", "v", "phi"), // has write barrier
			Goto("loop")))

	CheckFunc(fun.f)
	writebarrier(fun.f)
	CheckFunc(fun.f)

	// Recursively decompose phis for each field.
	for _, f := range fields[:n] {
		decomposeUserPhi(f)
	}
}

// decomposeArrayPhi replaces phi-of-array with arraymake(phi-of-array-element),
// and then recursively decomposes the element phi.
func decomposeArrayPhi(v *Value) {
	t := v.Type
	if t.NumElem() == 0 {
		v.reset(OpArrayMake0)
		return
	}
	if t.NumElem() != 1 {

	for _, use := range t.defUse[val] {
		if val == use {
			// Phi may refer to itself as uses, ignore them to avoid re-visiting phi
			// for performance reason
			continue
		}
		t.uses = append(t.uses, use)
	}
	for _, block := range t.defBlock[val] {
		if t.visitedBlock[block.ID] {
			t.propagate(block)
		}
	}
}

// meet meets all of phi arguments and computes result lattice

	case "amd64":
		const maxcost = 2
		phi := 0
		other := 0
		for _, v := range post.Values {
			if v.Op == OpPhi {
				// Each phi results in CondSelect, which lowers into CMOV,
				// CMOV has latency >1 on most CPUs.
				phi++
			}
			for _, x := range v.Args {
				if x.Block == no || x.Block == yes {
					other++
				}
			}
		}
		cost := phi * 1
		if phi > 1 {

					v.reset(OpAndB)
					v.SetArgs2(b0.Controls[0], tmp)
					if f.pass.debug > 0 {
						f.Warnl(b.Pos, "converted OpPhi to %v", v.Op)
					}
					continue
				}
			}
		}
	}
	// strengthen phi optimization.
	// Main use case is to transform:
	//   x := false
	//   if c {
	//     x = true
	//     ...
	//   }
	// into
	//   x := c
	//   if x { ... }
	//

//  1. The start memory state of a block is InitMem, a Phi node of type mem or
//     an incoming memory value.
//  2. The start memory state of a block is consistent with the end memory state
//     of its parent nodes. If the start memory state of a block is a Phi value,
//     then the end memory state of its parent nodes is consistent with the
//     corresponding argument value of the Phi node.

	// between assignments (typically branch-dependent
	// conditionals) occurring "before" the block (e.g., as inputs
	// to the block and its phi functions), "within" the block,
	// and "after" the block.
	AdjustBefore = -1 // defined before phi
	AdjustWithin = 0  // defined by phi
	AdjustAfter  = 1  // defined within block
)

// A SparseTree is a tree of Blocks.
// It allows rapid ancestor queries,

//
// Phi values are special, as always. We define two kinds of phis, those
// where the merge happens in a register (a "register" phi) and those where
// the merge happens in a stack location (a "stack" phi).
//
// A register phi must have the phi and all of its inputs allocated to the
// same register. Register phis are spilled similarly to regular ops.
//

		Bloc("b7",
			Exit("mem")))

	CheckFunc(fun.f)
	shortcircuit(fun.f)
	CheckFunc(fun.f)

	for _, b := range fun.f.Blocks {
		for _, v := range b.Values {
			if v.Op == OpPhi {
				t.Errorf("phi %s remains", v)
			}
		}
	}

			Valu("addr", OpAddr, ptrType, 0, nil, "sb"),
			Goto("loop")),
		Bloc("loop",
			Valu("phi", OpPhi, types.TypeMem, 0, nil, "start", "store"),
			Valu("store", OpStore, types.TypeMem, 0, c.config.Types.Bool, "addr", "v", "phi"),
			If("v", "loop", "exit")),
		Bloc("exit",
			Exit("store")))

	CheckFunc(fun.f)
	dse(fun.f)
	CheckFunc(fun.f)
}

func TestDeadStoreTypes(t *testing.T) {