This patch is to fix radar://8426430. It is about llvm support of __builtin_debugtrap()

which is supposed to consistently raise SIGTRAP across all systems. In contrast,
__builtin_trap() behave differently on different systems. e.g. it raises SIGTRAP on ARM, and
SIGILL on X86. The purpose of __builtin_debugtrap() is to consistently provide "trap"
functionality, in the mean time preserve the compatibility with on gcc on __builtin_trap().

  The X86 backend is already able to handle debugtrap(). This patch is to:
  1) make front-end recognize "__builtin_debugtrap()" (emboddied in the one-line change to Clang).
  2) In DAG legalization phase, by default, "debugtrap" will be replaced with "trap", which
     make the __builtin_debugtrap() "available" to all existing ports without the hassle of
     changing their code.
  3) If trap-function is specified (via -trap-func=xyz to llc), both __builtin_debugtrap() and
     __builtin_trap() will be expanded into the function call of the specified trap function.
    This behavior may need change in the future.

  The provided testing-case is to make sure 2) and 3) are working for ARM port, and we
already have a testing case for x86. 


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166300 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 13 insertions, 0 deletions

diff --git a/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp b/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
index 2ec129f730..c46df30935 100644
--- a/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
@@ -1240,6 +1240,19 @@ void SelectionDAGLegalize::LegalizeOp(SDNode *Node) {
     if (Action == TargetLowering::Legal)
       Action = TargetLowering::Custom;
     break;
+  case ISD::DEBUGTRAP:
+    Action = TLI.getOperationAction(Node->getOpcode(), Node->getValueType(0));
+    if (Action == TargetLowering::Expand) {
+      // replace ISD::DEBUGTRAP with ISD::TRAP
+      SDValue NewVal;
+      NewVal = DAG.getNode (ISD::TRAP, Node->getDebugLoc(), Node->getVTList(),
+                            Node->getOperand(0));
+      ReplaceNode(Node, NewVal.getNode());
+      LegalizeOp(NewVal.getNode());
+      return;
+    }
+    break;
+
   default:
     if (Node->getOpcode() >= ISD::BUILTIN_OP_END) {
       Action = TargetLowering::Legal;