[llvm] 5067f4b - [LV] Check opt-for-size before expanding runtime checks.

[Florian Hahn via llvm-commits]

Author: Florian Hahn
Date: 2020-08-29T20:35:14+01:00
New Revision: 5067f4b6261c07d5df94bf18407235d83ce33861

URL: https://github.com/llvm/llvm-project/commit/5067f4b6261c07d5df94bf18407235d83ce33861
DIFF: https://github.com/llvm/llvm-project/commit/5067f4b6261c07d5df94bf18407235d83ce33861.diff

LOG: [LV] Check opt-for-size before expanding runtime checks.

Move bail out when optimizing for size before runtime check generation.
In that case, we do not use the result of the expansion, the expanded
instruction will be dead and cleaned up later.

By doing the check before expanding the runtime-checks, we can save a
bit of unnecessary work.

Added: 
    

Modified: 
    llvm/lib/Transforms/Vectorize/LoopVectorize.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
index 1f82995588b0..16c2215aabe1 100644
--- a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -2935,13 +2935,6 @@ void InnerLoopVectorizer::emitMemRuntimeChecks(Loop *L, BasicBlock *Bypass) {
   const auto &RtPtrChecking = *LAI->getRuntimePointerChecking();
   if (!RtPtrChecking.Need)
     return;
-  Instruction *FirstCheckInst;
-  Instruction *MemRuntimeCheck;
-  std::tie(FirstCheckInst, MemRuntimeCheck) =
-      addRuntimeChecks(MemCheckBlock->getTerminator(), OrigLoop,
-                       RtPtrChecking.getChecks(), RtPtrChecking.getSE());
-  assert(MemRuntimeCheck && "no RT checks generated although RtPtrChecking "
-                            "claimed checks are required");
 
   if (MemCheckBlock->getParent()->hasOptSize() || OptForSizeBasedOnProfile) {
     assert(Cost->Hints->getForce() == LoopVectorizeHints::FK_Enabled &&
@@ -2957,6 +2950,14 @@ void InnerLoopVectorizer::emitMemRuntimeChecks(Loop *L, BasicBlock *Bypass) {
     });
   }
 
+  Instruction *FirstCheckInst;
+  Instruction *MemRuntimeCheck;
+  std::tie(FirstCheckInst, MemRuntimeCheck) =
+      addRuntimeChecks(MemCheckBlock->getTerminator(), OrigLoop,
+                       RtPtrChecking.getChecks(), RtPtrChecking.getSE());
+  assert(MemRuntimeCheck && "no RT checks generated although RtPtrChecking "
+                            "claimed checks are required");
+
   MemCheckBlock->setName("vector.memcheck");
   // Create new preheader for vector loop.
   LoopVectorPreHeader =