For the current Atom processor, the fastest way to handle a call

indirect through a memory address is to load the memory address into
a register and then call indirect through the register.

This patch implements this improvement by modifying SelectionDAG to
force a function address which is a memory reference to be loaded
into a virtual register.

Patch by Sriram Murali.

llvm-svn: 178171

1 files changed, 5 insertions, 0 deletions

diff --git a/llvm/lib/Target/X86/X86Subtarget.h b/llvm/lib/Target/X86/X86Subtarget.h
index 108ef0eb1c2..cac3f579b00 100644
--- a/llvm/lib/Target/X86/X86Subtarget.h
+++ b/llvm/lib/Target/X86/X86Subtarget.h
@@ -159,6 +159,10 @@ protected:
   /// a stall when returning too early.
   bool PadShortFunctions;
 
+  /// CallRegIndirect - True if the Calls with memory reference should be converted
+  /// to a register-based indirect call.
+  bool CallRegIndirect;
+
   /// stackAlignment - The minimum alignment known to hold of the stack frame on
   /// entry to the function and which must be maintained by every function.
   unsigned stackAlignment;
@@ -269,6 +273,7 @@ public:
   bool useLeaForSP() const { return UseLeaForSP; }
   bool hasSlowDivide() const { return HasSlowDivide; }
   bool padShortFunctions() const { return PadShortFunctions; }
+  bool callRegIndirect() const { return CallRegIndirect; }
 
   bool isAtom() const { return X86ProcFamily == IntelAtom; }