[Layout] Add a new option (NFC)
Currently cost based loop rotation algo can only be turned on with
two conditions: the function has real profile data, and -precise-rotation-cost
flag is turned on. This is not convenient for developers to experiment
when profile is not available. Add a new option to force the new
rotation algorithm -force-precise-rotation-cost
llvm-svn: 269266
diff --git a/llvm/lib/CodeGen/MachineBlockPlacement.cpp b/llvm/lib/CodeGen/MachineBlockPlacement.cpp
index d849509..ad73449 100644
--- a/llvm/lib/CodeGen/MachineBlockPlacement.cpp
+++ b/llvm/lib/CodeGen/MachineBlockPlacement.cpp
@@ -99,6 +99,11 @@
cl::desc("Model the cost of loop rotation more "
"precisely by using profile data."),
cl::init(false), cl::Hidden);
+static cl::opt<bool>
+ ForcePreciseRotationCost("force-precise-rotation-cost",
+ cl::desc("Model the cost of loop rotation more "
+ "precisely by using profile data."),
+ cl::init(false), cl::Hidden);
static cl::opt<unsigned> MisfetchCost(
"misfetch-cost",
@@ -1126,7 +1131,8 @@
// this loop by modeling costs more precisely which requires the profile data
// for better layout.
bool RotateLoopWithProfile =
- PreciseRotationCost && F.getFunction()->getEntryCount();
+ ForcePreciseRotationCost ||
+ (PreciseRotationCost && F.getFunction()->getEntryCount());
// First check to see if there is an obviously preferable top block for the
// loop. This will default to the header, but may end up as one of the