[LLVMbugs] [Bug 24065] New: CloneFunction ovewrites requested replacements - PATCH

[bugzilla-daemon at llvm.org]

https://llvm.org/bugs/show_bug.cgi?id=24065

            Bug ID: 24065
           Summary: CloneFunction ovewrites requested replacements - PATCH
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: Transformation Utilities
          Assignee: unassignedbugs at nondot.org
          Reporter: pedro.ferreira at imgtec.com
                CC: llvmbugs at cs.uiuc.edu
    Classification: Unclassified

The utility "CloneFunction" provides a ValueMap to describe requested
replacements of the cloned function's Values. When the cloning process goes
through the functions, it unconditionally adds the cloned instruction as a
replacement to the original.
The attached patch checks that a Value has not yet specified to replace and
instruction before adding such entry to the map.

We are not sure if this was the originally intended behaviour though and
therefore don't know if this is indeed a bug:

$ svn diff lib/Transforms/Utils/CloneFunction.cpp

Index: lib/Transforms/Utils/CloneFunction.cpp
===================================================================
--- lib/Transforms/Utils/CloneFunction.cpp      (revision 241669)
+++ lib/Transforms/Utils/CloneFunction.cpp      (working copy)
@@ -51,7 +51,8 @@
     if (II->hasName())
       NewInst->setName(II->getName()+NameSuffix);
     NewBB->getInstList().push_back(NewInst);
-    VMap[II] = NewInst;                // Add instruction map to value.
+    if (VMap.find(II) == VMap.end())
+      VMap[II] = NewInst;              // Add instruction map to value.

     hasCalls |= (isa<CallInst>(II) && !isa<DbgInfoIntrinsic>(II));
     if (const AllocaInst *AI = dyn_cast<AllocaInst>(II)) {

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