[PATCH] D51969: [AMDGPU] Add an AMDGPU specific atomic optimizer.

[Nicolai Hähnle via Phabricator via llvm-commits]

nhaehnle added inline comments.


================
Comment at: lib/Target/AMDGPU/AMDGPUAtomicOptimizer.cpp:243-244
+  Value *const ExtractHi = B.CreateExtractElement(BitCast, B.getInt32(1));
+  Function *const MbcntLoIntrinsic =
+      Intrinsic::getDeclaration(I.getModule(), Intrinsic::amdgcn_mbcnt_lo);
+  Function *const MbcntHiIntrinsic =
----------------
sheredom wrote:
> arsenm wrote:
> > CreateIntrinsic
> I can't use the IRBuilder's CreateIntrinsic because it will then try and mangle the amdgcn_mbcnt_lo like llvm.amdgcn.mbcnt.lo.i32, whereas we expect the name to be sans-type-suffix.
Ugh, this is a bug in CreateIntrinsic. It does:
```
  Function *Fn = Intrinsic::getDeclaration(M, ID, { Args.front()->getType() });
```
... when in this particular case, the type vector should be empty.

There aren't that many users of CreateIntrinsic -- can you just fix CreateIntrinsic so that it takes an `ArrayRef<Type*>` like Intrinsic::getDeclaration? (As a separate preparatory patch obviously.)


https://reviews.llvm.org/D51969