Provide a place for targets to insert ILP optimization passes.

Move the early if-conversion pass into this group.

ILP optimizations usually need to find the right balance between
register pressure and ILP using the MachineTraceMetrics analysis to
identify critical paths and estimate other costs. Such passes should run
together so they can share dominator tree and loop info analyses.

Besides if-conversion, future passes to run here here could include
expression height reduction and ARM's MLxExpansion pass.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@172687 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 10 insertions, 0 deletions

diff --git a/include/llvm/CodeGen/Passes.h b/include/llvm/CodeGen/Passes.h
index 1746fd4c14..5f710e68fe 100644
--- a/include/llvm/CodeGen/Passes.h
+++ b/include/llvm/CodeGen/Passes.h
@@ -181,6 +181,16 @@ protected:
   /// instructions in SSA form.
   virtual void addMachineSSAOptimization();
 
+  /// Add passes that optimize instruction level parallelism for out-of-order
+  /// targets. These passes are run while the machine code is still in SSA
+  /// form, so they can use MachineTraceMetrics to control their heuristics.
+  ///
+  /// All passes added here should preserve the MachineDominatorTree,
+  /// MachineLoopInfo, and MachineTraceMetrics analyses.
+  virtual bool addILPOpts() {
+    return false;
+  }
+
   /// addPreRegAlloc - This method may be implemented by targets that want to
   /// run passes immediately before register allocation. This should return
   /// true if -print-machineinstrs should print after these passes.