[PATCH] D138496: [OpenMP][OMPContext] Move SIMD alignment calculation to LLVM Frontend

[Dominik Adamski via Phabricator via llvm-commits]

domada added inline comments.


================
Comment at: llvm/lib/Frontend/OpenMP/OMPContext.cpp:587
+  if (!TargetsIter->getValue())
+    return 0;
+
----------------
jdoerfert wrote:
> You lookup Key in Targets 3 times. Maybe we can reduce that a little. Can the pointer ever be nullptr (the one returned by `createTargetMachine`?
`createTargetMachine` can return nullptr. Test scenario:
  # build clang without support of one target arch (for example build only x86 target: `cmake "-DLLVM_TARGETS_TO_BUILD="X86;")
  # try to generate LLVM IR and specify target which hasn't been mentioned in cmake configuration: (for example: clang  --target=arm -S -emit-llvm -fopenmp test.c)

We can reduce number of lookups in the best scenario (given Key has been inserted earlier):

```
// find the corresponding target
 auto  TargetsIter = Targets.find(Key);
//if not found - insert it and update TargetsIter 
if (TargetsIter==Targets.end()) {
    // some initialization code
   Targets[Key] = TheTarget->createTargetMachine(..);
   TargetsIter = Targets.find(Key);
}
//check if TargetMachine is not nullptr:
if (!TargetsIter->getValue())
   return 0;
```




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  https://reviews.llvm.org/D138496/new/

https://reviews.llvm.org/D138496