InferAddressSpaces: Infer from just addrspacecasts

Eliminates some more cases where some subset of the addressing
computation remains flat. Some cases with addrspacecasts
in nested constant expressions are still left behind however.

llvm-svn: 301704

1 files changed, 12 insertions, 0 deletions

diff --git a/llvm/lib/Transforms/Scalar/InferAddressSpaces.cpp b/llvm/lib/Transforms/Scalar/InferAddressSpaces.cpp
index 9e2563879da..a9505a45eef 100644
--- a/llvm/lib/Transforms/Scalar/InferAddressSpaces.cpp
+++ b/llvm/lib/Transforms/Scalar/InferAddressSpaces.cpp
@@ -326,6 +326,9 @@ InferAddressSpaces::collectFlatAddressExpressions(Function &F) const {
         PushPtrOperand(Cmp->getOperand(0));
         PushPtrOperand(Cmp->getOperand(1));
       }
+    } else if (auto *ASC = dyn_cast<AddrSpaceCastInst>(&I)) {
+      if (!ASC->getType()->isVectorTy())
+        PushPtrOperand(ASC->getPointerOperand());
     }
   }
 
@@ -881,6 +884,15 @@ bool InferAddressSpaces::rewriteWithNewAddressSpaces(
           }
         }
 
+        if (AddrSpaceCastInst *ASC = dyn_cast<AddrSpaceCastInst>(CurUser)) {
+          unsigned NewAS = NewV->getType()->getPointerAddressSpace();
+          if (ASC->getDestAddressSpace() == NewAS) {
+            ASC->replaceAllUsesWith(NewV);
+            ASC->eraseFromParent();
+            continue;
+          }
+        }
+
         // Otherwise, replaces the use with flat(NewV).
         if (Instruction *I = dyn_cast<Instruction>(V)) {
           BasicBlock::iterator InsertPos = std::next(I->getIterator());