DeadArgElim: don't eliminate arguments from naked functions

Differential Revision: http://reviews.llvm.org/D12534

llvm-svn: 246564

1 files changed, 21 insertions, 0 deletions

diff --git a/llvm/lib/Transforms/IPO/DeadArgumentElimination.cpp b/llvm/lib/Transforms/IPO/DeadArgumentElimination.cpp
index d0447640259..64c5ab9cb1b 100644
--- a/llvm/lib/Transforms/IPO/DeadArgumentElimination.cpp
+++ b/llvm/lib/Transforms/IPO/DeadArgumentElimination.cpp
@@ -198,6 +198,13 @@ bool DAE::DeleteDeadVarargs(Function &Fn) {
   if (Fn.hasAddressTaken())
     return false;
 
+  // Don't touch naked functions. The assembly might be using an argument, or
+  // otherwise rely on the frame layout in a way that this analysis will not
+  // see.
+  if (Fn.hasFnAttribute(Attribute::Naked)) {
+    return false;
+  }
+
   // Okay, we know we can transform this function if safe.  Scan its body
   // looking for calls marked musttail or calls to llvm.vastart.
   for (Function::iterator BB = Fn.begin(), E = Fn.end(); BB != E; ++BB) {
@@ -345,6 +352,12 @@ bool DAE::RemoveDeadArgumentsFromCallers(Function &Fn)
   if (Fn.hasLocalLinkage() && !Fn.getFunctionType()->isVarArg())
     return false;
 
+  // Don't touch naked functions. The assembly might be using an argument, or
+  // otherwise rely on the frame layout in a way that this analysis will not
+  // see.
+  if (Fn.hasFnAttribute(Attribute::Naked))
+    return false;
+
   if (Fn.use_empty())
     return false;
 
@@ -543,6 +556,14 @@ void DAE::SurveyFunction(const Function &F) {
     return;
   }
 
+  // Don't touch naked functions. The assembly might be using an argument, or
+  // otherwise rely on the frame layout in a way that this analysis will not
+  // see.
+  if (F.hasFnAttribute(Attribute::Naked)) {
+    MarkLive(F);
+    return;
+  }
+
   unsigned RetCount = NumRetVals(&F);
   // Assume all return values are dead
   typedef SmallVector<Liveness, 5> RetVals;