From 122f5e5a5b04e3c364d13913c14ee14f9b7ba387 Mon Sep 17 00:00:00 2001
From: Benjamin Kramer <benny.kra@googlemail.com>
Date: Fri, 21 Sep 2012 14:34:31 +0000
Subject: [PATCH] BitcodeReader: Correctly insert blockaddress constant
 referring to a already parsed function.

We inserted a placeholder that was never replaced because the function was
already visited. Assert that all placeholders have been resolved when tearing
down the bitcode reader.

Fixes PR13895.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@164369 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Bitcode/Reader/BitcodeReader.cpp | 28 ++++++++++++++++++++++------
 test/Bitcode/blockaddress.ll         | 15 +++++++++++++++
 2 files changed, 37 insertions(+), 6 deletions(-)

diff --git a/lib/Bitcode/Reader/BitcodeReader.cpp b/lib/Bitcode/Reader/BitcodeReader.cpp
index 0ff4664b2e4..2b2c36ba0f3 100644
--- a/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -52,6 +52,8 @@ void BitcodeReader::FreeState() {
   std::vector<Function*>().swap(FunctionsWithBodies);
   DeferredFunctionInfo.clear();
   MDKindMap.clear();
+
+  assert(BlockAddrFwdRefs.empty() && "Unresolved blockaddress fwd references");
 }
 
 //===----------------------------------------------------------------------===//
@@ -1300,13 +1302,27 @@ bool BitcodeReader::ParseConstants() {
       Function *Fn =
         dyn_cast_or_null<Function>(ValueList.getConstantFwdRef(Record[1],FnTy));
       if (Fn == 0) return Error("Invalid CE_BLOCKADDRESS record");
-      
-      GlobalVariable *FwdRef = new GlobalVariable(*Fn->getParent(),
-                                                  Type::getInt8Ty(Context),
+
+      // If the function is already parsed we can insert the block address right
+      // away.
+      if (!Fn->empty()) {
+        Function::iterator BBI = Fn->begin(), BBE = Fn->end();
+        for (size_t I = 0, E = Record[2]; I != E; ++I) {
+          if (BBI == BBE)
+            return Error("Invalid blockaddress block #");
+          ++BBI;
+        }
+        V = BlockAddress::get(Fn, BBI);
+      } else {
+        // Otherwise insert a placeholder and remember it so it can be inserted
+        // when the function is parsed.
+        GlobalVariable *FwdRef = new GlobalVariable(*Fn->getParent(),
+                                                    Type::getInt8Ty(Context),
                                             false, GlobalValue::InternalLinkage,
-                                                  0, "");
-      BlockAddrFwdRefs[Fn].push_back(std::make_pair(Record[2], FwdRef));
-      V = FwdRef;
+                                                    0, "");
+        BlockAddrFwdRefs[Fn].push_back(std::make_pair(Record[2], FwdRef));
+        V = FwdRef;
+      }
       break;
     }  
     }
diff --git a/test/Bitcode/blockaddress.ll b/test/Bitcode/blockaddress.ll
index b9f334176ca..8ac54be00d5 100644
--- a/test/Bitcode/blockaddress.ll
+++ b/test/Bitcode/blockaddress.ll
@@ -28,3 +28,18 @@ here:
 end:
   ret void
 }
+
+; PR13895
+define void @doitagain(i8** nocapture %pptr) {
+; CHECK: define void @doitagain
+entry:
+  br label %here
+
+here:
+  store i8* blockaddress(@doit, %here), i8** %pptr, align 8
+; CHECK: blockaddress(@doit, %here)
+  br label %end
+
+end:
+  ret void
+}