[Mlir-commits] [mlir] [MLIR][SCF] fix loop pipelining pass use of uninitialized value (PR #146991)

[Hu Yufan]

https://github.com/Hyffer updated https://github.com/llvm/llvm-project/pull/146991

>From 09e8fca881437a6f1b0ee62b4f07d9314a703bd4 Mon Sep 17 00:00:00 2001
From: huyufan <gaohuyufan at qq.com>
Date: Fri, 4 Jul 2025 10:16:11 +0800
Subject: [PATCH] [MLIR][SCF] fix pipelining pass use of uninitialized value

---
 .../Dialect/SCF/Transforms/LoopPipelining.cpp | 29 ++++++++++---------
 1 file changed, 15 insertions(+), 14 deletions(-)

diff --git a/mlir/lib/Dialect/SCF/Transforms/LoopPipelining.cpp b/mlir/lib/Dialect/SCF/Transforms/LoopPipelining.cpp
index 4aacbe739ca5d..bcecef5e6e0a9 100644
--- a/mlir/lib/Dialect/SCF/Transforms/LoopPipelining.cpp
+++ b/mlir/lib/Dialect/SCF/Transforms/LoopPipelining.cpp
@@ -106,6 +106,20 @@ bool LoopPipelinerInternal::initializeLoopInfo(
   lb = forOp.getLowerBound();
   step = forOp.getStep();
 
+  std::vector<std::pair<Operation *, unsigned>> schedule;
+  options.getScheduleFn(forOp, schedule);
+  if (schedule.empty()) {
+    LDBG("--empty schedule -> BAIL");
+    return false;
+  }
+
+  opOrder.reserve(schedule.size());
+  for (auto &opSchedule : schedule) {
+    maxStage = std::max(maxStage, opSchedule.second);
+    stages[opSchedule.first] = opSchedule.second;
+    opOrder.push_back(opSchedule.first);
+  }
+
   dynamicLoop = true;
   auto upperBoundCst = getConstantIntValue(ub);
   auto lowerBoundCst = getConstantIntValue(lb);
@@ -124,7 +138,7 @@ bool LoopPipelinerInternal::initializeLoopInfo(
       return false;
     }
     int64_t numIteration = llvm::divideCeilSigned(ubImm - lbImm, stepImm);
-    if (numIteration > maxStage) {
+    if (numIteration >= maxStage) {
       dynamicLoop = false;
     } else if (!options.supportDynamicLoops) {
       LDBG("--fewer loop iterations than pipeline stages -> BAIL");
@@ -137,19 +151,6 @@ bool LoopPipelinerInternal::initializeLoopInfo(
     LDBG("--no epilogue or predicate set -> BAIL");
     return false;
   }
-  std::vector<std::pair<Operation *, unsigned>> schedule;
-  options.getScheduleFn(forOp, schedule);
-  if (schedule.empty()) {
-    LDBG("--empty schedule -> BAIL");
-    return false;
-  }
-
-  opOrder.reserve(schedule.size());
-  for (auto &opSchedule : schedule) {
-    maxStage = std::max(maxStage, opSchedule.second);
-    stages[opSchedule.first] = opSchedule.second;
-    opOrder.push_back(opSchedule.first);
-  }
 
   // All operations need to have a stage.
   for (Operation &op : forOp.getBody()->without_terminator()) {