At top of generated isel SelectCode() is this:

  if (!N.Val->hasOneUse()) {
    std::map<SDOperand, SDOperand>::iterator CGMI = CodeGenMap.find(N);
    if (CGMI != CodeGenMap.end()) return CGMI->second;
  }

Suppose a DAG like this:

           X
         ^   ^
        /     \
      USE1    USE2

Suppose USE1 is being selected first and during which X is selected and
returned a new node. After this, USE1 is no longer an use of X. During USE2
selection, X will be selected again since it has only one use!

The fix is to always query CodeGenMap.

llvm-svn: 24679

1 files changed, 2 insertions, 4 deletions

diff --git a/llvm/utils/TableGen/DAGISelEmitter.cpp b/llvm/utils/TableGen/DAGISelEmitter.cpp
index bcb28a628e6..0a8b989b37c 100644
--- a/llvm/utils/TableGen/DAGISelEmitter.cpp
+++ b/llvm/utils/TableGen/DAGISelEmitter.cpp
@@ -2234,10 +2234,8 @@ void DAGISelEmitter::EmitInstructionSelector(std::ostream &OS) {
      << "      N.getOpcode() < (ISD::BUILTIN_OP_END+" << InstNS
      << "INSTRUCTION_LIST_END))\n"
      << "    return N;   // Already selected.\n\n"
-     << "  if (!N.Val->hasOneUse()) {\n"
-  << "    std::map<SDOperand, SDOperand>::iterator CGMI = CodeGenMap.find(N);\n"
-     << "    if (CGMI != CodeGenMap.end()) return CGMI->second;\n"
-     << "  }\n"
+  << "  std::map<SDOperand, SDOperand>::iterator CGMI = CodeGenMap.find(N);\n"
+     << "  if (CGMI != CodeGenMap.end()) return CGMI->second;\n"
      << "  switch (N.getOpcode()) {\n"
      << "  default: break;\n"
      << "  case ISD::EntryToken:       // These leaves remain the same.\n"