[PATCH] D74140: AMDGPU: Add compile time hack for hasCFUser

[Matt Arsenault via Phabricator via llvm-commits]

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

Assume the control flow intrinsic results are never casted, and early
exit based on the type.


https://reviews.llvm.org/D74140

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


Index: llvm/lib/Target/AMDGPU/SIISelLowering.cpp
===================================================================
--- llvm/lib/Target/AMDGPU/SIISelLowering.cpp
+++ llvm/lib/Target/AMDGPU/SIISelLowering.cpp
@@ -10872,7 +10872,15 @@
 // uniform values (as produced by the mask results of control flow intrinsics)
 // used outside of divergent blocks. The phi users need to also be treated as
 // always uniform.
-static bool hasCFUser(const Value *V, SmallPtrSet<const Value *, 16> &Visited) {
+static bool hasCFUser(const Value *V, SmallPtrSet<const Value *, 16> &Visited,
+                      unsigned WaveSize) {
+  // FIXME: We asssume we never cast the mask results of a control flow
+  // intrinsic.
+  // Early exit if the type won't be consistent as a compile time hack.
+  IntegerType *IT = dyn_cast<IntegerType>(V->getType());
+  if (!IT || IT->getBitWidth() != WaveSize)
+    return false;
+
   if (!isa<Instruction>(V))
     return false;
   if (!Visited.insert(V).second)
@@ -10904,7 +10912,7 @@
         }
       }
     } else {
-      Result = hasCFUser(U, Visited);
+      Result = hasCFUser(U, Visited, WaveSize);
     }
     if (Result)
       break;
@@ -10944,5 +10952,5 @@
     }
   }
   SmallPtrSet<const Value *, 16> Visited;
-  return hasCFUser(V, Visited);
+  return hasCFUser(V, Visited, Subtarget->getWavefrontSize());
 }


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