[llvm-commits] [dragonegg] r94983 - /dragonegg/trunk/llvm-convert.cpp

[Duncan Sands]

Author: baldrick
Date: Mon Feb  1 10:44:34 2010
New Revision: 94983

URL: http://llvm.org/viewvc/llvm-project?rev=94983&view=rev
Log:
Use a LoadInst rather than a BitCastInst as the placeholder instruction:
BitCastInst doesn't cut the mustard since the register might be a complex
number (i.e. have struct type), which cannot be used with bitcast.

Modified:
    dragonegg/trunk/llvm-convert.cpp

Modified: dragonegg/trunk/llvm-convert.cpp
URL: http://llvm.org/viewvc/llvm-project/dragonegg/trunk/llvm-convert.cpp?rev=94983&r1=94982&r2=94983&view=diff

==============================================================================
--- dragonegg/trunk/llvm-convert.cpp (original)
+++ dragonegg/trunk/llvm-convert.cpp Mon Feb  1 10:44:34 2010
@@ -160,14 +160,20 @@
 /// output in dominator order).  Replaced with the correct value when the SSA
 /// name's definition is encountered.
 static Value *GetSSAPlaceholder(const Type *Ty) {
-  return new BitCastInst(UndefValue::get(Ty), Ty);
+  // Cannot use a constant, since there is no way to distinguish a fake value
+  // from a real value.  So use an instruction with no parent.  This needs to
+  // be an instruction that can return a struct type, since the SSA name might
+  // be a complex number.  It could be a PHINode, except that the GCC phi node
+  // conversion logic also constructs phi nodes with no parent.  A SelectInst
+  // would work, but a LoadInst seemed neater.
+  return new LoadInst(UndefValue::get(Ty->getPointerTo()), NULL);
 }
 
 /// isSSAPlaceholder - Whether this is a fake value being used as a placeholder
 /// for the definition of an SSA name.
 static bool isSSAPlaceholder(Value *V) {
-  BitCastInst *BC = dyn_cast<BitCastInst>(V);
-  return BC && !BC->getParent();
+  LoadInst *LI = dyn_cast<LoadInst>(V);
+  return LI && !LI->getParent();
 }
 
 /// NameValue - Try to name the given value after the given GCC tree node.  If