Added tail call optimization to the x86 back end. It can be

enabled by passing -tailcallopt to llc.  The optimization is
performed if the following conditions are satisfied:
* caller/callee are fastcc
* elf/pic is disabled OR
  elf/pic enabled + callee is in module + callee has
  visibility protected or hidden

llvm-svn: 42870

1 files changed, 7 insertions, 0 deletions

diff --git a/llvm/lib/Target/TargetMachine.cpp b/llvm/lib/Target/TargetMachine.cpp
index 6c00a3f492b..9caea11dd39 100644
--- a/llvm/lib/Target/TargetMachine.cpp
+++ b/llvm/lib/Target/TargetMachine.cpp
@@ -33,6 +33,7 @@ namespace llvm {
   bool ExceptionHandling;
   Reloc::Model RelocationModel;
   CodeModel::Model CMModel;
+  bool PerformTailCallOpt;
 }
 namespace {
   cl::opt<bool, true> PrintCode("print-machineinstrs",
@@ -116,6 +117,12 @@ namespace {
       clEnumValN(CodeModel::Large, "large",
                  "  Large code model"),
       clEnumValEnd));
+
+  cl::opt<bool, true>
+  EnablePerformTailCallOpt("tailcallopt",
+                           cl::desc("Turn on tail call optimization."),
+                           cl::location(PerformTailCallOpt),
+                           cl::init(false));
 }
 
 //---------------------------------------------------------------------------