[llvm][CodeGen] Added a new restriction for II by pragma in window scheduler (#99448)

Added a new restriction for window scheduling.
Window scheduling is disabled when llvm.loop.pipeline.initiationinterval
is set.

1 files changed, 10 insertions, 2 deletions

diff --git a/llvm/lib/CodeGen/MachinePipeliner.cpp b/llvm/lib/CodeGen/MachinePipeliner.cpp
index 497e282..5c68711 100644
--- a/llvm/lib/CodeGen/MachinePipeliner.cpp
+++ b/llvm/lib/CodeGen/MachinePipeliner.cpp
@@ -528,8 +528,16 @@ bool MachinePipeliner::useSwingModuloScheduler() {
 }
 
 bool MachinePipeliner::useWindowScheduler(bool Changed) {
-  // WindowScheduler does not work when it is off or when SwingModuloScheduler
-  // is successfully scheduled.
+  // WindowScheduler does not work for following cases:
+  // 1. when it is off.
+  // 2. when SwingModuloScheduler is successfully scheduled.
+  // 3. when pragma II is enabled.
+  if (II_setByPragma) {
+    LLVM_DEBUG(dbgs() << "Window scheduling is disabled when "
+                         "llvm.loop.pipeline.initiationinterval is set.\n");
+    return false;
+  }
+
   return WindowSchedulingOption == WindowSchedulingFlag::WS_Force ||
          (WindowSchedulingOption == WindowSchedulingFlag::WS_On && !Changed);
 }