[Mlir-commits] [mlir] [SCF] Fixed epilogue predicates in loop pipelining (PR #108964)

[llvmlistbot at llvm.org]

================
@@ -671,9 +674,9 @@ LoopPipelinerInternal::emitEpilogue(RewriterBase &rewriter,
     setValueMapping(forOp.getInductionVar(), newlastIter, maxStage - i);
 
     if (dynamicLoop) {
-      // pred = iterI >= lb
+      // pred = iterI < 0
       predicates[i + 1] = rewriter.create<arith::CmpIOp>(
-          loc, arith::CmpIPredicate::sge, iterI, lb);
+          loc, arith::CmpIPredicate::slt, iterI, zero);
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sjw36 wrote:

Ah, that's right.
So for:
```
scf.for (lb=3..ub=4, step=2) max_stage = 2                                                        
```
This computes:
```
  total_iterations = (4 - 3) + 2 - 1 / 2 = 1                                                    
  iterI(0) = total_iterations - 1 - 0 = 0                                                       
  newlastIter(0) = iterI(0) * 2 + 3 = 3                                                         
  pred(0) = iterI(0) >= 0 = true                                                                
  iterI(1) = total_iterations - 1 - 1 = -1                                                      
  newlastIter(1) = iterI(1) * 2 + 3 = 1                                                         
  pred(1) = iterI(1) >= 0 = false
```
I'll update now.

https://github.com/llvm/llvm-project/pull/108964