[llvm] b1fbf43 - [OpenMPOpt] deduplicateRuntimeCalls(): avoid traditional map lookup pitfall

[Roman Lebedev via llvm-commits]

Author: Roman Lebedev
Date: 2020-04-16T19:54:02+03:00
New Revision: b1fbf438f647f3e8cf03baf7e0479359373241cd

URL: https://github.com/llvm/llvm-project/commit/b1fbf438f647f3e8cf03baf7e0479359373241cd
DIFF: https://github.com/llvm/llvm-project/commit/b1fbf438f647f3e8cf03baf7e0479359373241cd.diff

LOG: [OpenMPOpt] deduplicateRuntimeCalls(): avoid traditional map lookup pitfall

Summary:
This roughly halves time spent in that pass,
while unsurprisingly significantly reducing total memory usage.

This makes sense because most functions won't use any openmp functions..

old
```
   0.2329 (  0.5%)   0.0409 (  0.9%)   0.2738 (  0.5%)   0.2736 (  0.5%)  OpenMP specific optimizations
```
```
total runtime: 63.32s.
bytes allocated in total (ignoring deallocations): 8.34GB (131.70MB/s)
calls to allocation functions: 14526259 (229410/s)
temporary memory allocations: 3335760 (52680/s)
peak heap memory consumption: 324.36MB
peak RSS (including heaptrack overhead): 5.39GB
total memory leaked: 289.93MB
```

new
```
   0.1457 (  0.3%)   0.0276 (  0.6%)   0.1732 (  0.3%)   0.1731 (  0.3%)  OpenMP specific optimizations
```
```
total runtime: 55.01s.
bytes allocated in total (ignoring deallocations): 6.70GB (121.89MB/s)
calls to allocation functions: 14268205 (259398/s)
temporary memory allocations: 3225355 (58637/s)
peak heap memory consumption: 324.09MB
peak RSS (including heaptrack overhead): 5.39GB
total memory leaked: 289.87MB
```

diff
```
total runtime: -8.31s.
bytes allocated in total (ignoring deallocations): -1.63GB (196.58MB/s)
calls to allocation functions: -258054 (31034/s)
temporary memory allocations: -110405 (13277/s)
peak heap memory consumption: -262.36KB
peak RSS (including heaptrack overhead): 0B
total memory leaked: -61.45KB
```

Reviewers: jdoerfert, hfinkel

Reviewed By: jdoerfert

Subscribers: yaxunl, hiraditya, guansong, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D78299

Added: 
    

Modified: 
    llvm/lib/Transforms/IPO/OpenMPOpt.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/IPO/OpenMPOpt.cpp b/llvm/lib/Transforms/IPO/OpenMPOpt.cpp
index 8b45350ce44c..d0e0dde5a782 100644
--- a/llvm/lib/Transforms/IPO/OpenMPOpt.cpp
+++ b/llvm/lib/Transforms/IPO/OpenMPOpt.cpp
@@ -248,7 +248,11 @@ struct OpenMPOpt {
   /// \p ReplVal if given.
   bool deduplicateRuntimeCalls(Function &F, RuntimeFunctionInfo &RFI,
                                Value *ReplVal = nullptr) {
-    auto &Uses = RFI.UsesMap[&F];
+    auto UsesIt = RFI.UsesMap.find(&F);
+    if (UsesIt == RFI.UsesMap.end())
+      return false;
+
+    auto &Uses = UsesIt->getSecond();
     if (Uses.size() + (ReplVal != nullptr) < 2)
       return false;