[PATCH] D81433: AMDGPU: Restrict the number of instructions to scan for getPointerDependencyFrom

[Changpeng Fang via Phabricator via llvm-commits]

cfang created this revision.
cfang added reviewers: arsen, rampitec.
Herald added subscribers: kerbowa, hiraditya, t-tye, tpr, dstuttard, yaxunl, nhaehnle, wdng, jvesely, kzhuravl.
Herald added a project: LLVM.

This is for getPointerDependencyFrom in  AMDGPUAnnotateUniformValues.
With the default scan limit of 100 instruction per block, we can reduce the compile time
of a special kernel from longer than 2 hours to 7 minutes.


https://reviews.llvm.org/D81433

Files:
  llvm/lib/Target/AMDGPU/AMDGPUAnnotateUniformValues.cpp


Index: llvm/lib/Target/AMDGPU/AMDGPUAnnotateUniformValues.cpp
===================================================================
--- llvm/lib/Target/AMDGPU/AMDGPUAnnotateUniformValues.cpp
+++ llvm/lib/Target/AMDGPU/AMDGPUAnnotateUniformValues.cpp
@@ -105,11 +105,13 @@
   }
 
   DFS(Start, Checklist);
+  // Maximum number of instructions to search in a block (default 100).
+  auto Limit = MDR->getDefaultBlockScanLimit();
   for (auto &BB : Checklist) {
     BasicBlock::iterator StartIt = (!L && (BB == Load->getParent())) ?
       BasicBlock::iterator(Load) : BB->end();
     auto Q = MDR->getPointerDependencyFrom(MemoryLocation(Ptr), true,
-                                           StartIt, BB, Load);
+                                           StartIt, BB, Load, &Limit);
     if (Q.isClobber() || Q.isUnknown())
       return true;
   }


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