go-llvm: add PHI incoming block replacement

IRBindings.cpp

@@ -16,6 +16,7 @@
 #include "llvm/IR/DebugInfoMetadata.h"
 #include "llvm/IR/Function.h"
 #include "llvm/IR/IRBuilder.h"
+#include "llvm/IR/Instructions.h"
 #include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/Module.h"
 
@@ -50,6 +51,11 @@ void LLVMSetMetadata2(LLVMValueRef Inst, unsigned KindID, LLVMMetadataRef MD) {
   unwrap<Instruction>(Inst)->setMetadata(KindID, N);
 }
 
+void LLVMGoReplaceIncomingBlock(LLVMValueRef Phi, LLVMBasicBlockRef Old,
+                                LLVMBasicBlockRef New) {
+  unwrap<PHINode>(Phi)->replaceIncomingBlockWith(unwrap(Old), unwrap(New));
+}
+
 void LLVMGoSetCurrentDebugLocation(LLVMBuilderRef Bref, unsigned Line,
                                   unsigned Col, LLVMMetadataRef Scope,
                                   LLVMMetadataRef InlinedAt) {

IRBindings.h

@@ -43,6 +43,9 @@ void LLVMAddNamedMetadataOperand2(LLVMModuleRef M, const char *name,
                                   LLVMMetadataRef Val);
 void LLVMSetMetadata2(LLVMValueRef Inst, unsigned KindID, LLVMMetadataRef MD);
 
+void LLVMGoReplaceIncomingBlock(LLVMValueRef Phi, LLVMBasicBlockRef Old,
+                                LLVMBasicBlockRef New);
+
 void LLVMGoSetCurrentDebugLocation(LLVMBuilderRef Bref, unsigned Line,
                                   unsigned Col, LLVMMetadataRef Scope,
                                   LLVMMetadataRef InlinedAt);

ir.go

@@ -1260,6 +1260,9 @@ func (v Value) IncomingBlock(i int) (bb BasicBlock) {
 	bb.C = C.LLVMGetIncomingBlock(v.C, C.unsigned(i))
 	return
 }
+func (v Value) ReplaceIncomingBlock(old, new BasicBlock) {
+	C.LLVMGoReplaceIncomingBlock(v.C, old.C, new.C)
+}
 
 // Operations on inline assembly
 func InlineAsm(t Type, asmString, constraints string, hasSideEffects, isAlignStack bool, dialect InlineAsmDialect, canThrow bool) (rv Value) {

ir_test.go

@@ -18,6 +18,40 @@ import (
 	"testing"
 )
 
+func TestReplaceIncomingBlock(t *testing.T) {
+	ctx := NewContext()
+	defer ctx.Dispose()
+	mod := ctx.NewModule("phi-incoming-block")
+	defer mod.Dispose()
+	b := ctx.NewBuilder()
+	defer b.Dispose()
+
+	fn := AddFunction(mod, "f", FunctionType(ctx.Int32Type(), nil, false))
+	entry := ctx.AddBasicBlock(fn, "entry")
+	old := ctx.AddBasicBlock(fn, "old")
+	replacement := ctx.AddBasicBlock(fn, "replacement")
+	merge := ctx.AddBasicBlock(fn, "merge")
+
+	b.SetInsertPointAtEnd(entry)
+	b.CreateBr(replacement)
+	b.SetInsertPointAtEnd(old)
+	b.CreateRet(ConstInt(ctx.Int32Type(), 0, false))
+	b.SetInsertPointAtEnd(replacement)
+	b.CreateBr(merge)
+	b.SetInsertPointAtEnd(merge)
+	phi := b.CreatePHI(ctx.Int32Type(), "value")
+	phi.AddIncoming([]Value{ConstInt(ctx.Int32Type(), 7, false)}, []BasicBlock{old})
+	b.CreateRet(phi)
+
+	phi.ReplaceIncomingBlock(old, replacement)
+	if got := phi.IncomingBlock(0); got != replacement {
+		t.Fatalf("incoming block = %v, want replacement", got)
+	}
+	if err := VerifyModule(mod, ReturnStatusAction); err != nil {
+		t.Fatalf("module verification failed: %v\n%s", err, mod.String())
+	}
+}
+
 func testAttribute(t *testing.T, name string) {
 	ctx := NewContext()
 	mod := ctx.NewModule("")