[llvm-extract] support unnamed bbs.

[AllinLeeYL]

Dear developer:

I have recently working with LLVM IR and I want to isolate basic blocks using the command "llvm-extract". However, I found that the command option "llvm-extract --bb func_name:bb_name" will only function when dumping source code into IRs with options "-fno-discard-value-names". That is to say, the "llvm-extract" command cannot support unnamed basic blocks, which is a default output of the compiler. So, I made these changes and hope they will make LLVM better.

Best regards,

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[llvmbot]

@llvm/pr-subscribers-llvm-ir

Author: Allin Lee (AllinLeeYL)

Changes

Dear developer:

I have recently working with LLVM IR and I want to isolate basic blocks using the command "llvm-extract". However, I found that the command option "llvm-extract --bb func_name:bb_name" will only function when dumping source code into IRs with options "-fno-discard-value-names". That is to say, the "llvm-extract" command cannot support unnamed basic blocks, which is a default output of the compiler. So, I made these changes and hope they will make LLVM better.

Best regards,

---

Full diff: https://github.com/llvm/llvm-project/pull/135140.diff

3 Files Affected:

• (modified) llvm/include/llvm/IR/Value.h (-2)
• (modified) llvm/lib/IR/Value.cpp (-2)
• (modified) llvm/tools/llvm-extract/llvm-extract.cpp (+5-2)

diff --git a/llvm/include/llvm/IR/Value.h b/llvm/include/llvm/IR/Value.h
index cfed12e2f5f8d..bf1de7eef9932 100644
--- a/llvm/include/llvm/IR/Value.h
+++ b/llvm/include/llvm/IR/Value.h
@@ -290,9 +290,7 @@ class Value {
   /// \note It is an error to call V->takeName(V).
   void takeName(Value *V);
 
-#ifndef NDEBUG
   std::string getNameOrAsOperand() const;
-#endif
 
   /// Change all uses of this to point to a new Value.
   ///
diff --git a/llvm/lib/IR/Value.cpp b/llvm/lib/IR/Value.cpp
index 6c52ced5f73b2..494c77b0a4115 100644
--- a/llvm/lib/IR/Value.cpp
+++ b/llvm/lib/IR/Value.cpp
@@ -440,7 +440,6 @@ void Value::takeName(Value *V) {
     ST->reinsertValue(this);
 }
 
-#ifndef NDEBUG
 std::string Value::getNameOrAsOperand() const {
   if (!getName().empty())
     return std::string(getName());
@@ -450,7 +449,6 @@ std::string Value::getNameOrAsOperand() const {
   printAsOperand(OS, false);
   return OS.str();
 }
-#endif
 
 void Value::assertModuleIsMaterializedImpl() const {
 #ifndef NDEBUG
diff --git a/llvm/tools/llvm-extract/llvm-extract.cpp b/llvm/tools/llvm-extract/llvm-extract.cpp
index 648060acb392c..69636ca018dcb 100644
--- a/llvm/tools/llvm-extract/llvm-extract.cpp
+++ b/llvm/tools/llvm-extract/llvm-extract.cpp
@@ -90,10 +90,13 @@ static cl::list<std::string> ExtractBlocks(
         "Each pair will create a function.\n"
         "If multiple basic blocks are specified in one pair,\n"
         "the first block in the sequence should dominate the rest.\n"
+        "If an unnamed basic block is to be extracted,\n"
+        "'%' should be added before the basic block variable names.\n"
         "eg:\n"
         "  --bb=f:bb1;bb2 will extract one function with both bb1 and bb2;\n"
         "  --bb=f:bb1 --bb=f:bb2 will extract two functions, one with bb1, one "
-        "with bb2."),
+        "with bb2.\n"
+        "  --bb=f:%1 will extract one function with basic block 1;"),
     cl::value_desc("function:bb1[;bb2...]"), cl::cat(ExtractCat));
 
 // ExtractAlias - The alias to extract from the module.
@@ -356,7 +359,7 @@ int main(int argc, char **argv) {
         // The function has been materialized, so add its matching basic blocks
         // to the block extractor list, or fail if a name is not found.
         auto Res = llvm::find_if(*P.first, [&](const BasicBlock &BB) {
-          return BB.getName() == BBName;
+          return BB.getNameOrAsOperand() == BBName;
         });
         if (Res == P.first->end()) {
           errs() << argv[0] << ": function " << P.first->getName()

[MacDue]

This looks handy 🙂 Is it worth adding a small test in llvm/test/tools/llvm-extract?

[AllinLeeYL]

This looks handy 🙂 Is it worth adding a small test in llvm/test/tools/llvm-extract?

Thank you for your advice🙏. A test has been added to the latest commit.

[MacDue]

LGTM, thanks!

[MacDue]

I'll merge this tomorrow if there's no further comments 👍

[github-actions]

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