Attach attribute "trap-func-name" to call sites of llvm.trap and llvm.debugtrap.

This is needed to use clang's command line option "-ftrap-function" for LTO and
enable changing the trap function name on a per-call-site basis.

rdar://problem/21225723

Differential Revision: http://reviews.llvm.org/D10831

llvm-svn: 241306
diff --git a/clang/lib/CodeGen/CGExpr.cpp b/clang/lib/CodeGen/CGExpr.cpp
index 1a76afa..175763c 100644
--- a/clang/lib/CodeGen/CGExpr.cpp
+++ b/clang/lib/CodeGen/CGExpr.cpp
@@ -2403,8 +2403,7 @@
     TrapBB = createBasicBlock("trap");
     Builder.CreateCondBr(Checked, Cont, TrapBB);
     EmitBlock(TrapBB);
-    llvm::Value *F = CGM.getIntrinsic(llvm::Intrinsic::trap);
-    llvm::CallInst *TrapCall = Builder.CreateCall(F, {});
+    llvm::CallInst *TrapCall = EmitTrapCall(llvm::Intrinsic::trap);
     TrapCall->setDoesNotReturn();
     TrapCall->setDoesNotThrow();
     Builder.CreateUnreachable();
@@ -2415,6 +2414,18 @@
   EmitBlock(Cont);
 }
 
+llvm::CallInst *CodeGenFunction::EmitTrapCall(llvm::Intrinsic::ID IntrID) {
+  llvm::CallInst *TrapCall =
+      Builder.CreateCall(CGM.getIntrinsic(IntrID), {});
+
+  if (!CGM.getCodeGenOpts().TrapFuncName.empty())
+    TrapCall->addAttribute(llvm::AttributeSet::FunctionIndex,
+                           "trap-func-name",
+                           CGM.getCodeGenOpts().TrapFuncName);
+
+  return TrapCall;
+}
+
 /// isSimpleArrayDecayOperand - If the specified expr is a simple decay from an
 /// array to pointer, return the array subexpression.
 static const Expr *isSimpleArrayDecayOperand(const Expr *E) {