From fd065bbed1d731b49b1b4a5c4c050ce461be80b4 Mon Sep 17 00:00:00 2001
From: Chad Rosier <mcrosier@apple.com>
Date: Fri, 6 Jul 2012 17:33:39 +0000
Subject: [PATCH] [fast-isel] Tell fast-isel to do nothing with the new
 donothing intrinsic.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@159837 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/SelectionDAG/FastISel.cpp | 3 +++
 test/CodeGen/X86/fast-isel.ll         | 8 ++++++++
 2 files changed, 11 insertions(+)

diff --git a/lib/CodeGen/SelectionDAG/FastISel.cpp b/lib/CodeGen/SelectionDAG/FastISel.cpp
index 07dc36577f9..20848b403a1 100644
--- a/lib/CodeGen/SelectionDAG/FastISel.cpp
+++ b/lib/CodeGen/SelectionDAG/FastISel.cpp
@@ -573,7 +573,10 @@ bool FastISel::SelectCall(const User *I) {
     // At -O0 we don't care about the lifetime intrinsics.
   case Intrinsic::lifetime_start:
   case Intrinsic::lifetime_end:
+    // The donothing intrinsic does, well, nothing.
+  case Intrinsic::donothing:
     return true;
+
   case Intrinsic::dbg_declare: {
     const DbgDeclareInst *DI = cast<DbgDeclareInst>(Call);
     if (!DIVariable(DI->getVariable()).Verify() ||
diff --git a/test/CodeGen/X86/fast-isel.ll b/test/CodeGen/X86/fast-isel.ll
index 9d9a520c6a2..132df2b0ab4 100644
--- a/test/CodeGen/X86/fast-isel.ll
+++ b/test/CodeGen/X86/fast-isel.ll
@@ -117,3 +117,11 @@ define i64* @life() nounwind {
   ret i64* %a3
 }
 
+declare void @llvm.donothing() readnone
+
+; CHECK: donada
+define void @donada() nounwind {
+entry:
+  call void @llvm.donothing()
+  ret void
+}