[BasicBlockUtils] Add BasicBlock printer (#163066)

Author: ro-i

llvm/include/llvm/Transforms/Utils/BasicBlockUtils.h

@@ -21,6 +21,7 @@
 #include "llvm/IR/BasicBlock.h"
 #include "llvm/IR/Dominators.h"
 #include "llvm/Support/Compiler.h"
+#include "llvm/Support/Printable.h"
 #include <cassert>
 
 namespace llvm {
@@ -611,6 +612,10 @@ LLVM_ABI void InvertBranch(BranchInst *PBI, IRBuilderBase &Builder);
 // br/brcond/unreachable/ret
 LLVM_ABI bool hasOnlySimpleTerminator(const Function &F);
 
+/// Print BasicBlock \p BB as an operand or print "<nullptr>" if \p BB is a
+/// nullptr.
+LLVM_ABI Printable printBasicBlock(const BasicBlock *BB);
+
 } // end namespace llvm
 
 #endif // LLVM_TRANSFORMS_UTILS_BASICBLOCKUTILS_H

llvm/lib/Transforms/Utils/BasicBlockUtils.cpp

@@ -1793,3 +1793,13 @@ bool llvm::hasOnlySimpleTerminator(const Function &F) {
  }
  return true;
 }
+
+Printable llvm::printBasicBlock(const BasicBlock *BB) {
+ return Printable([BB](raw_ostream &OS) {
+ if (!BB) {
+ OS << "<nullptr>";
+ return;
+ }
+ BB->printAsOperand(OS);
+ });
+}

llvm/unittests/Transforms/Utils/BasicBlockUtilsTest.cpp

@@ -716,3 +716,32 @@ attributes #0 = { presplitcoroutine }
  EXPECT_FALSE(llvm::isPresplitCoroSuspendExitEdge(
  *ExitN.getSinglePredecessor(), ExitN));
 }
+
+TEST(BasicBlockUtils, BasicBlockPrintable) {
+ std::string S;
+ std::string SCheck;
+ llvm::raw_string_ostream OS{S};
+ llvm::raw_string_ostream OSCheck{SCheck};
+
+ LLVMContext C;
+ std::unique_ptr<Module> M = parseIR(C, R"IR(
+define void @foo() {
+ br label %bb0
+bb0:
+ br label %.exit
+.exit:
+ ret void
+}
+)IR");
+
+ Function *F = M->getFunction("foo");
+ for (const BasicBlock &BB : *F) {
+ OS << printBasicBlock(&BB);
+ BB.printAsOperand(OSCheck);
+ EXPECT_EQ(OS.str(), OSCheck.str());
+ S.clear();
+ SCheck.clear();
+ }
+ OS << printBasicBlock(nullptr);
+ EXPECT_EQ(OS.str(), "<nullptr>");
+}