diff --git a/example_test.go b/example_test.go
new file mode 100644
index 0000000..68c30a9
--- /dev/null
+++ b/example_test.go
@@ -0,0 +1,154 @@
+package irutil_test
+
+import (
+	"fmt"
+	"log"
+
+	"github.com/llir/irutil"
+	"github.com/llir/llvm/asm"
+	"github.com/llir/llvm/ir"
+	"github.com/llir/llvm/ir/value"
+	"github.com/pkg/errors"
+)
+
+func Example() {
+	// Parse LLVM IR module.
+	const module = `
+define void @g() {
+	; potential side effects
+	ret void
+}
+
+define i32 @f(i32 %x, i32 %y) {
+; <label>:0
+	%1 = add i32 %x, %y
+	%2 = xor i32 %1, 10
+	%3 = sub i32 %x, %y
+	call void @g()
+	%4 = mul i32 3, 5
+	ret i32 %3
+}`
+	m, err := asm.ParseString("foo.ll", module)
+	if err != nil {
+		log.Fatalf("%+v", err)
+	}
+	// Perform dead code elimination (dce).
+	for _, f := range m.Funcs {
+		if err := dce(f); err != nil {
+			log.Fatalf("%+v", err)
+		}
+	}
+	// Print LLVM IR module after dce.
+	fmt.Println(m)
+
+	// Output:
+	//
+	// define void @g() {
+	// ; <label>:0
+	// 	ret void
+	// }
+	//
+	// define i32 @f(i32 %x, i32 %y) {
+	// ; <label>:0
+	// 	%1 = sub i32 %x, %y
+	// 	call void @g()
+	// 	ret i32 %1
+	// }
+}
+
+// dce performs dead code elimination on f, pruning value instructions with
+// unused results in f. Call instructions are never pruned as they may have side
+// effects.
+func dce(f *ir.Func) error {
+	// Prune until we reach fixed-point. If we prune an unused value instruction,
+	// this may result in another local variable becoming unused.
+	for {
+		// Get names of local variables used in f.
+		usedIdents, err := getUsedIdents(f)
+		if err != nil {
+			return errors.WithStack(err)
+		}
+		// Prune value instructions with unused results in f.
+		if !pruneUnusedInsts(f, usedIdents) {
+			// Fix-point reached, no more pruning possible.
+			break
+		}
+	}
+	return nil
+}
+
+// pruneUnusedInsts prunes value instructions with unused results in f. Call
+// instructions are never pruned as they may have side effects. The boolean
+// return value indicates whether an instruction was pruned.
+func pruneUnusedInsts(f *ir.Func, usedIdents map[string]bool) bool {
+	pruned := false
+	// Prune value instructions with unused results in f.
+	for _, block := range f.Blocks {
+		insts := block.Insts[:0] // filter instructions in-place.
+		for _, inst := range block.Insts {
+			if isUnused(inst, usedIdents) {
+				// Prune unused value instruction, skip append to insts.
+				pruned = true
+				continue
+			}
+			insts = append(insts, inst)
+		}
+		block.Insts = insts
+	}
+	if pruned {
+		// Reset IDs of unnamed local variables (as one or more instructions have
+		// been pruned).
+		irutil.ResetNames(f)
+	}
+	return pruned
+}
+
+// ValueInstruction is an instruction producing a local variable result.
+//
+// Note: call instructions are value instructions, but only produce a result if
+// the return type of their callee is non-void.
+type ValueInstruction interface {
+	ir.Instruction
+	value.Named
+}
+
+// isUnused reports whether the given instruction is a value instruction with
+// unused results. Call instructions are never considered unused, as they may
+// have side effects.
+func isUnused(inst ir.Instruction, usedIdents map[string]bool) bool {
+	valueInst, ok := inst.(ValueInstruction)
+	if !ok {
+		// Non-value instructions are never considered unused.
+		return false
+	}
+	if _, ok := inst.(*ir.InstCall); ok {
+		// Call instructions are never considered unused as they may have side
+		// effects.
+		return false
+	}
+	return !usedIdents[valueInst.Name()]
+}
+
+// getUsedIdents returns the names of local variables used in f.
+func getUsedIdents(f *ir.Func) (map[string]bool, error) {
+	// Assign IDs to unnamed local variables (as we need to record the names of
+	// local variables used in f).
+	if err := f.AssignIDs(); err != nil {
+		return nil, errors.WithStack(err)
+	}
+	// Pre-allocate backing array on stack for uses slice.
+	var backing [100]irutil.Use
+	// Record names of local variables used used in f.
+	uses := irutil.FuncUses(backing[:0], f) // the backing array is optional, pass nil if not needed.
+	usedIdents := make(map[string]bool)
+	for _, use := range uses {
+		valueInst, ok := (*use.Val).(ValueInstruction)
+		if !ok {
+			// Only record the names of local variables produced by value
+			// instructions.
+			continue
+		}
+		usedIdents[valueInst.Name()] = true
+	}
+	return usedIdents, nil
+}
diff --git a/go.mod b/go.mod
index 1240af6..c4a7eff 100644
--- a/go.mod
+++ b/go.mod
@@ -2,4 +2,7 @@ module github.com/llir/irutil
 
 go 1.12
 
-require github.com/llir/llvm v0.3.0-pre7.0.20191220191840-fc6d0e8d9bc6
+require (
+	github.com/llir/llvm v0.3.0
+	github.com/pkg/errors v0.8.1
+)
diff --git a/go.sum b/go.sum
index 8bee212..4f18bf2 100644
--- a/go.sum
+++ b/go.sum
@@ -1,27 +1,27 @@
-github.com/d4l3k/messagediff v1.2.2-0.20190829033028-7e0a312ae40b h1:02XNVBBC2x90C1IKnZ0iyrIxL1pdIRsusn0lqSEIOD0=
-github.com/d4l3k/messagediff v1.2.2-0.20190829033028-7e0a312ae40b/go.mod h1:Oozbb1TVXFac9FtSIxHBMnBCq2qeH/2KkEQxENCrlLo=
+github.com/google/go-cmp v0.3.1 h1:Xye71clBPdm5HgqGwUkwhbynsUJZhDbS20FvLhQ2izg=
+github.com/google/go-cmp v0.3.1/go.mod h1:8QqcDgzrUqlUb/G2PQTWiueGozuR1884gddMywk6iLU=
 github.com/kr/pretty v0.1.0 h1:L/CwN0zerZDmRFUapSPitk6f+Q3+0za1rQkzVuMiMFI=
 github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
 github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
 github.com/kr/text v0.1.0 h1:45sCR5RtlFHMR4UwH9sdQ5TC8v0qDQCHnXt+kaKSTVE=
 github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
-github.com/llir/ll v0.0.0-20191205054844-50f4b743547b h1:Hc7BLGoz4hbN+8mb+JhZeYS+5mE8l+L+KWp7cJVeNrY=
-github.com/llir/ll v0.0.0-20191205054844-50f4b743547b/go.mod h1:8W5HJz80PitAyPZUpOcljQxTu6LD5YKW1URTo+OjVoc=
-github.com/llir/llvm v0.3.0-pre7.0.20191220191840-fc6d0e8d9bc6 h1:bwZWin1Q/mernGFKoNOKRysPU10+rgylUxLeJR5AOJg=
-github.com/llir/llvm v0.3.0-pre7.0.20191220191840-fc6d0e8d9bc6/go.mod h1:w6wEy+jHlAsmT+yQGYOvL1TO+JEDlzt+NnsYegCunuo=
-github.com/mewkiz/pkg v0.0.0-20190919212034-518ade7978e2 h1:EyTNMdePWaoWsRSGQnXiSoQu0r6RS1eA557AwJhlzHU=
-github.com/mewkiz/pkg v0.0.0-20190919212034-518ade7978e2/go.mod h1:3E2FUC/qYUfM8+r9zAwpeHJzqRVVMIYnpzD/clwWxyA=
-github.com/mewmew/float v0.0.0-20191218075745-e26b3d092977 h1:6+YqyNydbRNcd0azoFfSM36F1O5nbc0M3OzKqsT8YCA=
-github.com/mewmew/float v0.0.0-20191218075745-e26b3d092977/go.mod h1:O+xb+8ycBNHzJicFVs7GRWtruD4tVZI0huVnw5TM01E=
+github.com/llir/ll v0.0.0-20191229032745-05be70ade156 h1:tQ3EaDUy4rHvIyvuI2Yf1X2xPMVi4orBwX3H1NSWp74=
+github.com/llir/ll v0.0.0-20191229032745-05be70ade156/go.mod h1:8W5HJz80PitAyPZUpOcljQxTu6LD5YKW1URTo+OjVoc=
+github.com/llir/llvm v0.3.0 h1:A4lHTPerMXrHYWJZF80XsnerraV8PKEqhBG+4wedSHg=
+github.com/llir/llvm v0.3.0/go.mod h1:yjHRZjO9xc1uLUS69qO2qYjS95XFdfd2odSdSnufS10=
+github.com/mewmew/float v0.0.0-20191226120903-16bbe2fdd85e h1:KCD7E/8LKwDsC5ymlEWJ3xCiSPaCywrS/psToBMOBH4=
+github.com/mewmew/float v0.0.0-20191226120903-16bbe2fdd85e/go.mod h1:O+xb+8ycBNHzJicFVs7GRWtruD4tVZI0huVnw5TM01E=
 github.com/pkg/errors v0.8.1 h1:iURUrRGxPUNPdy5/HRSm+Yj6okJ6UtLINN0Q9M4+h3I=
 github.com/pkg/errors v0.8.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
-golang.org/x/image v0.0.0-20190220214146-31aff87c08e9/go.mod h1:kZ7UVZpmo3dzQBMxlp+ypCbDeSB+sBbTgSJuh5dn5js=
-golang.org/x/net v0.0.0-20190213061140-3a22650c66bd/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
+golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
+golang.org/x/mod v0.1.1-0.20191105210325-c90efee705ee/go.mod h1:QqPTAvyqsEbceGzBzNggFXnrqF1CaUcvgkdR5Ot7KZg=
+golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
 golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
 golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
-golang.org/x/tools v0.0.0-20191028143239-8715e36070db h1:xzcb0oYS6YlLAFxFJtuJ5GS6TVcVi3zQsh5Pf6LtASA=
-golang.org/x/tools v0.0.0-20191028143239-8715e36070db/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
-golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
+golang.org/x/tools v0.0.0-20191227053925-7b8e75db28f4 h1:Toz2IK7k8rbltAXwNAxKcn9OzqyNfMUhUNjz3sL0NMk=
+golang.org/x/tools v0.0.0-20191227053925-7b8e75db28f4/go.mod h1:TB2adYChydJhpapKDTa4BR/hXlZSLoq2Wpct/0txZ28=
+golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
diff --git a/use.go b/use.go
new file mode 100644
index 0000000..6780503
--- /dev/null
+++ b/use.go
@@ -0,0 +1,372 @@
+package irutil
+
+import (
+	"fmt"
+
+	"github.com/llir/llvm/ir"
+	"github.com/llir/llvm/ir/value"
+)
+
+// User is a user of a value.
+//
+// A User has one of the following underlying types.
+//
+//    ir.Instruction   // https://godoc.org/github.com/llir/llvm/ir#Instruction
+//    ir.Terminator    // https://godoc.org/github.com/llir/llvm/ir#Terminator
+type User interface {
+	ir.LLStringer
+}
+
+// Use tracks the use of a value and its parent instruction or terminator.
+type Use struct {
+	// Use of value.
+	Val *value.Value
+	// Parent instruction or terminator which uses value as operand.
+	User User // ir.Instruction or ir.Terminator
+}
+
+// Replace replaces the use of a value with the new value.
+func (use Use) Replace(new value.Value) {
+	*use.Val = new
+}
+
+// FuncUses returns value uses of instructions and terminators in the given
+// function. To avoid memory allocation, an optional backing slice may be
+// provided; if nil or insufficient space, a new backing slice will be
+// allocated.
+func FuncUses(backing []Use, f *ir.Func) []Use {
+	for _, block := range f.Blocks {
+		for _, inst := range block.Insts {
+			backing = InstUses(backing, inst)
+		}
+		backing = TermUses(backing, block.Term)
+	}
+	return backing
+}
+
+// TODO: consider renaming InstUses to InstOperands.
+
+// InstUses returns value uses of the given instruction. To avoid memory
+// allocation, an optional backing slice may be provided; if nil or insufficient
+// space, a new backing slice will be allocated.
+func InstUses(backing []Use, inst ir.Instruction) []Use {
+	switch inst := inst.(type) {
+	// Unary instructions
+	case *ir.InstFNeg:
+		backing = append(backing, Use{Val: &inst.X, User: inst})
+		return backing
+	// Binary instructions
+	case *ir.InstAdd:
+		backing = append(backing, Use{Val: &inst.X, User: inst})
+		backing = append(backing, Use{Val: &inst.Y, User: inst})
+		return backing
+	case *ir.InstFAdd:
+		backing = append(backing, Use{Val: &inst.X, User: inst})
+		backing = append(backing, Use{Val: &inst.Y, User: inst})
+		return backing
+	case *ir.InstSub:
+		backing = append(backing, Use{Val: &inst.X, User: inst})
+		backing = append(backing, Use{Val: &inst.Y, User: inst})
+		return backing
+	case *ir.InstFSub:
+		backing = append(backing, Use{Val: &inst.X, User: inst})
+		backing = append(backing, Use{Val: &inst.Y, User: inst})
+		return backing
+	case *ir.InstMul:
+		backing = append(backing, Use{Val: &inst.X, User: inst})
+		backing = append(backing, Use{Val: &inst.Y, User: inst})
+		return backing
+	case *ir.InstFMul:
+		backing = append(backing, Use{Val: &inst.X, User: inst})
+		backing = append(backing, Use{Val: &inst.Y, User: inst})
+		return backing
+	case *ir.InstUDiv:
+		backing = append(backing, Use{Val: &inst.X, User: inst})
+		backing = append(backing, Use{Val: &inst.Y, User: inst})
+		return backing
+	case *ir.InstSDiv:
+		backing = append(backing, Use{Val: &inst.X, User: inst})
+		backing = append(backing, Use{Val: &inst.Y, User: inst})
+		return backing
+	case *ir.InstFDiv:
+		backing = append(backing, Use{Val: &inst.X, User: inst})
+		backing = append(backing, Use{Val: &inst.Y, User: inst})
+		return backing
+	case *ir.InstURem:
+		backing = append(backing, Use{Val: &inst.X, User: inst})
+		backing = append(backing, Use{Val: &inst.Y, User: inst})
+		return backing
+	case *ir.InstSRem:
+		backing = append(backing, Use{Val: &inst.X, User: inst})
+		backing = append(backing, Use{Val: &inst.Y, User: inst})
+		return backing
+	case *ir.InstFRem:
+		backing = append(backing, Use{Val: &inst.X, User: inst})
+		backing = append(backing, Use{Val: &inst.Y, User: inst})
+		return backing
+	// Bitwise instructions
+	case *ir.InstShl:
+		backing = append(backing, Use{Val: &inst.X, User: inst})
+		backing = append(backing, Use{Val: &inst.Y, User: inst})
+		return backing
+	case *ir.InstLShr:
+		backing = append(backing, Use{Val: &inst.X, User: inst})
+		backing = append(backing, Use{Val: &inst.Y, User: inst})
+		return backing
+	case *ir.InstAShr:
+		backing = append(backing, Use{Val: &inst.X, User: inst})
+		backing = append(backing, Use{Val: &inst.Y, User: inst})
+		return backing
+	case *ir.InstAnd:
+		backing = append(backing, Use{Val: &inst.X, User: inst})
+		backing = append(backing, Use{Val: &inst.Y, User: inst})
+		return backing
+	case *ir.InstOr:
+		backing = append(backing, Use{Val: &inst.X, User: inst})
+		backing = append(backing, Use{Val: &inst.Y, User: inst})
+		return backing
+	case *ir.InstXor:
+		backing = append(backing, Use{Val: &inst.X, User: inst})
+		backing = append(backing, Use{Val: &inst.Y, User: inst})
+		return backing
+	// Vector instructions
+	case *ir.InstExtractElement:
+		backing = append(backing, Use{Val: &inst.X, User: inst})
+		backing = append(backing, Use{Val: &inst.Index, User: inst})
+		return backing
+	case *ir.InstInsertElement:
+		backing = append(backing, Use{Val: &inst.X, User: inst})
+		backing = append(backing, Use{Val: &inst.Elem, User: inst})
+		backing = append(backing, Use{Val: &inst.Index, User: inst})
+		return backing
+	case *ir.InstShuffleVector:
+		backing = append(backing, Use{Val: &inst.X, User: inst})
+		backing = append(backing, Use{Val: &inst.Y, User: inst})
+		backing = append(backing, Use{Val: &inst.Mask, User: inst})
+		return backing
+	// Aggregate instructions
+	case *ir.InstExtractValue:
+		backing = append(backing, Use{Val: &inst.X, User: inst})
+		return backing
+	case *ir.InstInsertValue:
+		backing = append(backing, Use{Val: &inst.X, User: inst})
+		backing = append(backing, Use{Val: &inst.Elem, User: inst})
+		return backing
+	// Memory instructions
+	case *ir.InstAlloca:
+		if inst.NElems != nil {
+			backing = append(backing, Use{Val: &inst.NElems, User: inst})
+		}
+		return backing
+	case *ir.InstLoad:
+		backing = append(backing, Use{Val: &inst.Src, User: inst})
+		return backing
+	case *ir.InstStore:
+		backing = append(backing, Use{Val: &inst.Src, User: inst})
+		backing = append(backing, Use{Val: &inst.Dst, User: inst})
+		return backing
+	case *ir.InstFence:
+		// no value operands.
+		return backing
+	case *ir.InstCmpXchg:
+		backing = append(backing, Use{Val: &inst.Ptr, User: inst})
+		backing = append(backing, Use{Val: &inst.Cmp, User: inst})
+		backing = append(backing, Use{Val: &inst.New, User: inst})
+		return backing
+	case *ir.InstAtomicRMW:
+		backing = append(backing, Use{Val: &inst.Dst, User: inst})
+		backing = append(backing, Use{Val: &inst.X, User: inst})
+		return backing
+	case *ir.InstGetElementPtr:
+		backing = append(backing, Use{Val: &inst.Src, User: inst})
+		for i := range inst.Indices {
+			backing = append(backing, Use{Val: &inst.Indices[i], User: inst})
+		}
+		return backing
+	// Conversion instructions
+	case *ir.InstTrunc:
+		backing = append(backing, Use{Val: &inst.From, User: inst})
+		return backing
+	case *ir.InstZExt:
+		backing = append(backing, Use{Val: &inst.From, User: inst})
+		return backing
+	case *ir.InstSExt:
+		backing = append(backing, Use{Val: &inst.From, User: inst})
+		return backing
+	case *ir.InstFPTrunc:
+		backing = append(backing, Use{Val: &inst.From, User: inst})
+		return backing
+	case *ir.InstFPExt:
+		backing = append(backing, Use{Val: &inst.From, User: inst})
+		return backing
+	case *ir.InstFPToUI:
+		backing = append(backing, Use{Val: &inst.From, User: inst})
+		return backing
+	case *ir.InstFPToSI:
+		backing = append(backing, Use{Val: &inst.From, User: inst})
+		return backing
+	case *ir.InstUIToFP:
+		backing = append(backing, Use{Val: &inst.From, User: inst})
+		return backing
+	case *ir.InstSIToFP:
+		backing = append(backing, Use{Val: &inst.From, User: inst})
+		return backing
+	case *ir.InstPtrToInt:
+		backing = append(backing, Use{Val: &inst.From, User: inst})
+		return backing
+	case *ir.InstIntToPtr:
+		backing = append(backing, Use{Val: &inst.From, User: inst})
+		return backing
+	case *ir.InstBitCast:
+		backing = append(backing, Use{Val: &inst.From, User: inst})
+		return backing
+	case *ir.InstAddrSpaceCast:
+		backing = append(backing, Use{Val: &inst.From, User: inst})
+		return backing
+	// Other instructions
+	case *ir.InstICmp:
+		backing = append(backing, Use{Val: &inst.X, User: inst})
+		backing = append(backing, Use{Val: &inst.Y, User: inst})
+		return backing
+	case *ir.InstFCmp:
+		backing = append(backing, Use{Val: &inst.X, User: inst})
+		backing = append(backing, Use{Val: &inst.Y, User: inst})
+		return backing
+	case *ir.InstPhi:
+		for i := range inst.Incs {
+			backing = append(backing, Use{Val: &inst.Incs[i].X, User: inst})
+			backing = append(backing, Use{Val: &inst.Incs[i].Pred, User: inst})
+		}
+		return backing
+	case *ir.InstSelect:
+		backing = append(backing, Use{Val: &inst.Cond, User: inst})
+		backing = append(backing, Use{Val: &inst.ValueTrue, User: inst})
+		backing = append(backing, Use{Val: &inst.ValueFalse, User: inst})
+		return backing
+	case *ir.InstCall:
+		backing = append(backing, Use{Val: &inst.Callee, User: inst})
+		for i := range inst.Args {
+			backing = append(backing, Use{Val: &inst.Args[i], User: inst})
+		}
+		for i := range inst.OperandBundles {
+			for j := range inst.OperandBundles[i].Inputs {
+				backing = append(backing, Use{Val: &inst.OperandBundles[i].Inputs[j], User: inst})
+			}
+		}
+		return backing
+	case *ir.InstVAArg:
+		backing = append(backing, Use{Val: &inst.ArgList, User: inst})
+		return backing
+	case *ir.InstLandingPad:
+		for i := range inst.Clauses {
+			backing = append(backing, Use{Val: &inst.Clauses[i].X, User: inst})
+		}
+		return backing
+	case *ir.InstCatchPad:
+		backing = append(backing, Use{Val: &inst.CatchSwitch, User: inst})
+		for i := range inst.Args {
+			backing = append(backing, Use{Val: &inst.Args[i], User: inst})
+		}
+		return backing
+	case *ir.InstCleanupPad:
+		backing = append(backing, Use{Val: &inst.ParentPad, User: inst})
+		for i := range inst.Args {
+			backing = append(backing, Use{Val: &inst.Args[i], User: inst})
+		}
+		return backing
+	// TODO: figure out how to handle user defined instructions (e.g. Comment).
+	// TODO: remove *Comment case and add support for more general way of
+	// identifying user-defined instructions.
+	case *Comment:
+		// no value operands.
+		return backing
+	default:
+		panic(fmt.Errorf("support for instruction %T not yet implemented", inst))
+	}
+}
+
+// TermUses returns value uses of the given terminator. To avoid memory
+// allocation, an optional backing slice may be provided; if nil or insufficient
+// space, a new backing slice will be allocated.
+func TermUses(backing []Use, term ir.Terminator) []Use {
+	switch term := term.(type) {
+	case *ir.TermRet:
+		if term.X != nil {
+			backing = append(backing, Use{Val: &term.X, User: term})
+		}
+		return backing
+	case *ir.TermBr:
+		backing = append(backing, Use{Val: &term.Target, User: term})
+		return backing
+	case *ir.TermCondBr:
+		backing = append(backing, Use{Val: &term.Cond, User: term})
+		backing = append(backing, Use{Val: &term.TargetTrue, User: term})
+		backing = append(backing, Use{Val: &term.TargetFalse, User: term})
+		return backing
+	case *ir.TermSwitch:
+		backing = append(backing, Use{Val: &term.X, User: term})
+		backing = append(backing, Use{Val: &term.TargetDefault, User: term})
+		for i := range term.Cases {
+			backing = append(backing, Use{Val: &term.Cases[i].X, User: term})
+			backing = append(backing, Use{Val: &term.Cases[i].Target, User: term})
+		}
+		return backing
+	case *ir.TermIndirectBr:
+		backing = append(backing, Use{Val: &term.Addr, User: term})
+		for i := range term.ValidTargets {
+			backing = append(backing, Use{Val: &term.ValidTargets[i], User: term})
+		}
+		return backing
+	case *ir.TermInvoke:
+		backing = append(backing, Use{Val: &term.Invokee, User: term})
+		for i := range term.Args {
+			backing = append(backing, Use{Val: &term.Args[i], User: term})
+		}
+		backing = append(backing, Use{Val: &term.NormalRetTarget, User: term})
+		backing = append(backing, Use{Val: &term.ExceptionRetTarget, User: term})
+		for i := range term.OperandBundles {
+			for j := range term.OperandBundles[i].Inputs {
+				backing = append(backing, Use{Val: &term.OperandBundles[i].Inputs[j], User: term})
+			}
+		}
+		return backing
+	case *ir.TermCallBr:
+		backing = append(backing, Use{Val: &term.Callee, User: term})
+		for i := range term.Args {
+			backing = append(backing, Use{Val: &term.Args[i], User: term})
+		}
+		backing = append(backing, Use{Val: &term.NormalRetTarget, User: term})
+		for i := range term.OtherRetTargets {
+			backing = append(backing, Use{Val: &term.OtherRetTargets[i], User: term})
+		}
+		for i := range term.OperandBundles {
+			for j := range term.OperandBundles[i].Inputs {
+				backing = append(backing, Use{Val: &term.OperandBundles[i].Inputs[j], User: term})
+			}
+		}
+		return backing
+	case *ir.TermResume:
+		backing = append(backing, Use{Val: &term.X, User: term})
+		return backing
+	case *ir.TermCatchSwitch:
+		backing = append(backing, Use{Val: &term.ParentPad, User: term})
+		for i := range term.Handlers {
+			backing = append(backing, Use{Val: &term.Handlers[i], User: term})
+		}
+		backing = append(backing, Use{Val: &term.DefaultUnwindTarget, User: term})
+		return backing
+	case *ir.TermCatchRet:
+		backing = append(backing, Use{Val: &term.CatchPad, User: term})
+		backing = append(backing, Use{Val: &term.Target, User: term})
+		return backing
+	case *ir.TermCleanupRet:
+		backing = append(backing, Use{Val: &term.CleanupPad, User: term})
+		backing = append(backing, Use{Val: &term.UnwindTarget, User: term})
+		return backing
+	case *ir.TermUnreachable:
+		// no value operands.
+		return backing
+	default:
+		panic(fmt.Errorf("support for terminator %T not yet implemented", term))
+	}
+}
diff --git a/walk.go b/walk.go
index 99b7dcb..35d6ac4 100644
--- a/walk.go
+++ b/walk.go
@@ -310,6 +310,8 @@ func walk(root interface{}, visit func(n interface{}) bool, visited map[interfac
 		walk(*root, visit, visited)
 	case **ir.TermInvoke:
 		walk(*root, visit, visited)
+	case **ir.TermCallBr:
+		walk(*root, visit, visited)
 	case **ir.TermResume:
 		walk(*root, visit, visited)
 	case **ir.TermCatchSwitch:
@@ -408,9 +410,7 @@ func walk(root interface{}, visit func(n interface{}) bool, visited map[interfac
 		walk(*root, visit, visited)
 	case *value.Named:
 		walk(*root, visit, visited)
-	case *ir.ExceptionScope:
-		walk(*root, visit, visited)
-	case *ir.UnwindTarget:
+	case *ir.ExceptionPad:
 		walk(*root, visit, visited)
 	// Metadata.
 	case *metadata.Node:
@@ -516,10 +516,8 @@ func walk(root interface{}, visit func(n interface{}) bool, visited map[interfac
 		walkValue(root, visit, visited)
 	case value.Named:
 		walkValueNamed(root, visit, visited)
-	case ir.ExceptionScope:
+	case ir.ExceptionPad:
 		walkValue(root, visit, visited)
-	case ir.UnwindTarget:
-		walkUnwindTarget(root, visit, visited)
 	case metadata.SpecializedNode:
 		walkSpecializedMetadataNode(root, visit, visited)
 	default:
@@ -878,8 +876,8 @@ func walkInst(root ir.Instruction, visit func(n interface{}) bool, visited map[i
 		}
 	case *ir.InstSelect:
 		walk(&root.Cond, visit, visited)
-		walk(&root.X, visit, visited)
-		walk(&root.Y, visit, visited)
+		walk(&root.ValueTrue, visit, visited)
+		walk(&root.ValueFalse, visit, visited)
 	case *ir.InstCall:
 		walk(&root.Callee, visit, visited)
 		for i := range root.Args {
@@ -892,12 +890,12 @@ func walkInst(root ir.Instruction, visit func(n interface{}) bool, visited map[i
 			walk(&root.Clauses[i], visit, visited)
 		}
 	case *ir.InstCatchPad:
-		walk(&root.Scope, visit, visited)
+		walk(&root.CatchSwitch, visit, visited)
 		for i := range root.Args {
 			walk(&root.Args[i], visit, visited)
 		}
 	case *ir.InstCleanupPad:
-		walk(&root.Scope, visit, visited)
+		walk(&root.ParentPad, visit, visited)
 		for i := range root.Args {
 			walk(&root.Args[i], visit, visited)
 		}
@@ -938,24 +936,38 @@ func walkTerm(root ir.Terminator, visit func(n interface{}) bool, visited map[in
 		for i := range root.Args {
 			walk(&root.Args[i], visit, visited)
 		}
-		walk(&root.Normal, visit, visited)
-		walk(&root.Exception, visit, visited)
+		walk(&root.NormalRetTarget, visit, visited)
+		walk(&root.ExceptionRetTarget, visit, visited)
+		for i := range root.OperandBundles {
+			walk(&root.OperandBundles[i], visit, visited)
+		}
+	case *ir.TermCallBr:
+		walk(&root.Callee, visit, visited)
+		for i := range root.Args {
+			walk(&root.Args[i], visit, visited)
+		}
+		walk(&root.NormalRetTarget, visit, visited)
+		for i := range root.OtherRetTargets {
+			walk(&root.OtherRetTargets[i], visit, visited)
+		}
 		for i := range root.OperandBundles {
 			walk(&root.OperandBundles[i], visit, visited)
 		}
 	case *ir.TermResume:
 		walk(&root.X, visit, visited)
 	case *ir.TermCatchSwitch:
-		walk(&root.Scope, visit, visited)
+		walk(&root.ParentPad, visit, visited)
 		for i := range root.Handlers {
 			walk(&root.Handlers[i], visit, visited)
 		}
-		walk(&root.UnwindTarget, visit, visited)
+		if root.DefaultUnwindTarget != nil {
+			walk(&root.DefaultUnwindTarget, visit, visited)
+		}
 	case *ir.TermCatchRet:
-		walk(&root.From, visit, visited)
-		walk(&root.To, visit, visited)
+		walk(&root.CatchPad, visit, visited)
+		walk(&root.Target, visit, visited)
 	case *ir.TermCleanupRet:
-		walk(&root.From, visit, visited)
+		walk(&root.CleanupPad, visit, visited)
 		walk(&root.UnwindTarget, visit, visited)
 	case *ir.TermUnreachable:
 		// nothing to do
@@ -995,22 +1007,10 @@ func walkValueNamed(root value.Named, visit func(n interface{}) bool, visited ma
 		walk(root, visit, visited)
 	case *ir.TermInvoke:
 		walk(root, visit, visited)
-	case *ir.TermCatchSwitch:
+	case *ir.TermCallBr:
 		walk(root, visit, visited)
-	default:
-		panic(fmt.Errorf("support for LLVM IR AST node type %T not yet implemented", root))
-	}
-}
-
-// walkUnwindTarget walks the LLVM IR AST in depth-first order; invoking visit
-// recursively for each non-nil child of root. If visit returns false, the walk
-// is terminated. Visited tracks visited nodes.
-func walkUnwindTarget(root ir.UnwindTarget, visit func(n interface{}) bool, visited map[interface{}]bool) {
-	switch root := root.(type) {
-	case *ir.Block:
+	case *ir.TermCatchSwitch:
 		walk(root, visit, visited)
-	case ir.UnwindToCaller:
-		// nothing to do
 	default:
 		panic(fmt.Errorf("support for LLVM IR AST node type %T not yet implemented", root))
 	}