[PATCH] D80346: [llvm-extract] Fix basic block extraction by delaying search until the function is materialized

[Dominic Chen via Phabricator via llvm-commits]

ddcc created this revision.
ddcc added reviewers: volkan, qcolombet.
Herald added a project: LLVM.

When I try to extract a basic block using llvm-extract, it erroneously reports that the named basic block doesn't exist. After digging into the code, it appears to be iterating over an unmaterialized function, which will fail to match any basic blocks.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D80346

Files:
  llvm/tools/llvm-extract/llvm-extract.cpp


Index: llvm/tools/llvm-extract/llvm-extract.cpp
===================================================================
--- llvm/tools/llvm-extract/llvm-extract.cpp
+++ llvm/tools/llvm-extract/llvm-extract.cpp
@@ -31,6 +31,7 @@
 #include "llvm/Support/ToolOutputFile.h"
 #include "llvm/Transforms/IPO.h"
 #include <memory>
+#include <utility>
 using namespace llvm;
 
 cl::OptionCategory ExtractCat("llvm-extract Options");
@@ -252,8 +253,9 @@
   }
 
   // Figure out which BasicBlocks we should extract.
-  SmallVector<SmallVector<BasicBlock *, 16>, 4> GroupOfBBs;
+  SmallVector<std::pair<Function *, SmallVector<StringRef, 16>>, 2> BBMap;
   for (StringRef StrPair : ExtractBlocks) {
+    SmallVector<StringRef, 16> BBNames;
     auto BBInfo = StrPair.split(':');
     // Get the function.
     Function *F = M->getFunction(BBInfo.first);
@@ -264,24 +266,8 @@
     }
     // Do not materialize this function.
     GVs.insert(F);
-    // Get the basic blocks.
-    SmallVector<BasicBlock *, 16> BBs;
-    SmallVector<StringRef, 16> BBNames;
-    BBInfo.second.split(BBNames, ';', /*MaxSplit=*/-1,
-                        /*KeepEmpty=*/false);
-    for (StringRef BBName : BBNames) {
-      auto Res = llvm::find_if(*F, [&](const BasicBlock &BB) {
-        return BB.getName().equals(BBName);
-      });
-      if (Res == F->end()) {
-        errs() << argv[0] << ": function " << F->getName()
-               << " doesn't contain a basic block named '" << BBInfo.second
-               << "'!\n";
-        return 1;
-      }
-      BBs.push_back(&*Res);
-    }
-    GroupOfBBs.push_back(BBs);
+    BBInfo.second.split(BBNames, ';', /*MaxSplit=*/-1, /*KeepEmpty=*/false);
+    BBMap.push_back({F, std::move(BBNames)});
   }
 
   // Use *argv instead of argv[0] to work around a wrong GCC warning.
@@ -345,6 +331,25 @@
   // Extract the specified basic blocks from the module and erase the existing
   // functions.
   if (!ExtractBlocks.empty()) {
+    // Figure out which BasicBlocks we should extract.
+    SmallVector<SmallVector<BasicBlock *, 16>, 4> GroupOfBBs;
+    for (auto &P : BBMap) {
+      SmallVector<BasicBlock *, 16> BBs;
+      for (StringRef BBName : P.second) {
+        auto Res = llvm::find_if(*P.first, [&](const BasicBlock &BB) {
+          return BB.getName().equals(BBName);
+        });
+        if (Res == P.first->end()) {
+          errs() << argv[0] << ": function " << P.first->getName()
+                 << " doesn't contain a basic block named '" << BBName
+                 << "'!\n";
+          return 1;
+        }
+        BBs.push_back(&*Res);
+      }
+      GroupOfBBs.push_back(BBs);
+    }
+
     legacy::PassManager PM;
     PM.add(createBlockExtractorPass(GroupOfBBs, true));
     PM.run(*M);


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