Letting FusionOfTensorOps apply patterns forever. (#11336)

The way the patterns interact causes what is effectively folding to
count against the max iteration limit. The default of 10 is
insufficient when the input program has a lot of constants to fold.
In the future we could explore top-down traversal as an alternative.

Also added logging so when this pass fails we see something on stderr.
Fixes #11333.

compiler/src/iree/compiler/Dialect/Flow/Transforms/FusionOfTensorOps.cpp

diff --git a/compiler/src/iree/compiler/Dialect/Flow/Transforms/FusionOfTensorOps.cpp b/compiler/src/iree/compiler/Dialect/Flow/Transforms/FusionOfTensorOps.cpp
index de17c45..f446903 100644
--- a/compiler/src/iree/compiler/Dialect/Flow/Transforms/FusionOfTensorOps.cpp
+++ b/compiler/src/iree/compiler/Dialect/Flow/Transforms/FusionOfTensorOps.cpp
@@ -271,8 +271,12 @@
           ->getCanonicalizationPatterns(fusionPatterns);
       memref::populateResolveRankedShapeTypeResultDimsPatterns(fusionPatterns);
 
+      GreedyRewriteConfig rewriteConfig;
+      rewriteConfig.maxIterations = GreedyRewriteConfig::kNoIterationLimit;
       if (failed(applyPatternsAndFoldGreedily(funcOp->getRegions(),
-                                              std::move(fusionPatterns)))) {
+                                              std::move(fusionPatterns),
+                                              rewriteConfig))) {
+        funcOp->emitError("failed to apply fusion patterns");
         return signalPassFailure();
       }
 
@@ -311,6 +315,7 @@
           collapsingReshapePatterns);
       if (failed(applyPatternsAndFoldGreedily(
               funcOp->getRegions(), std::move(collapsingReshapePatterns)))) {
+        funcOp->emitError("failed to apply collapsing reshape patterns");
         return signalPassFailure();
       }
 
@@ -330,7 +335,10 @@
         auto &dominanceInfo = getAnalysis<DominanceInfo>();
         FailureOr<unsigned> numOfFusableCandidates =
             fuseMultiUseProducers(funcOp, context, dominanceInfo);
-        if (failed(numOfFusableCandidates)) return signalPassFailure();
+        if (failed(numOfFusableCandidates)) {
+          funcOp->emitError("failed to fuse multi-use producers");
+          return signalPassFailure();
+        }
         if (numOfFusableCandidates.value() == 0) break;
       }
     }