XCore target: Make handling of large frames not dependent upon an FP.

[oota-llvm.git] / lib / Target / XCore / XCoreMachineFunctionInfo.cpp

diff --git a/lib/Target/XCore/XCoreMachineFunctionInfo.cpp b/lib/Target/XCore/XCoreMachineFunctionInfo.cpp
index 7ca06729120efbe5b3955e654e3000472cd1d90e..91b29760080771c8b839e1b22031a2100233ab66 100644 (file)
--- a/lib/Target/XCore/XCoreMachineFunctionInfo.cpp
+++ b/lib/Target/XCore/XCoreMachineFunctionInfo.cpp
@@ -12,3 +12,19 @@
 using namespace llvm;
 
 void XCoreFunctionInfo::anchor() { }
+
+bool XCoreFunctionInfo::isLargeFrame(const MachineFunction &MF) const {
+  if (CachedEStackSize == -1) {
+    CachedEStackSize = MF.getFrameInfo()->estimateStackSize(MF);
+  }
+  // isLargeFrame() is used when deciding if spill slots should be added to
+  // allow eliminateFrameIndex() to scavenge registers.
+  // This is only required when there is no FP and offsets are greater than
+  // ~256KB (~64Kwords). Thus only for code run on the emulator!
+  //
+  // The arbitrary value of 0xf000 allows frames of up to ~240KB before spill
+  // slots are added for the use of eliminateFrameIndex() register scavenging.
+  // For frames less than 240KB, it is assumed that there will be less than
+  // 16KB of function arguments.
+  return CachedEStackSize > 0xf000;
+}