[llvm] 4905bca - [ConstantFolding] Check return value of ConstantFoldInstOperandsImpl()

[Nikita Popov via llvm-commits]

Author: Nikita Popov
Date: 2022-07-04T14:19:59+02:00
New Revision: 4905bcac00e6588bc82e51973dcac7b7a5361c94

URL: https://github.com/llvm/llvm-project/commit/4905bcac00e6588bc82e51973dcac7b7a5361c94
DIFF: https://github.com/llvm/llvm-project/commit/4905bcac00e6588bc82e51973dcac7b7a5361c94.diff

LOG: [ConstantFolding] Check return value of ConstantFoldInstOperandsImpl()

This operation is fallible, but ConstantFoldConstantImpl() is not.
If we fail to fold, we should simply return the original expression.

I don't think this can cause any issues right now, but it becomes
a problem if once make ConstantFoldInstOperandsImpl() not create a
constant expression for everything it possibly could.

Added: 
    

Modified: 
    llvm/lib/Analysis/ConstantFolding.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Analysis/ConstantFolding.cpp b/llvm/lib/Analysis/ConstantFolding.cpp
index a810418450520..b708b71192036 100644
--- a/llvm/lib/Analysis/ConstantFolding.cpp
+++ b/llvm/lib/Analysis/ConstantFolding.cpp
@@ -1142,8 +1142,12 @@ ConstantFoldConstantImpl(const Constant *C, const DataLayout &DL,
     Ops.push_back(NewC);
   }
 
-  if (auto *CE = dyn_cast<ConstantExpr>(C))
-    return ConstantFoldInstOperandsImpl(CE, CE->getOpcode(), Ops, DL, TLI);
+  if (auto *CE = dyn_cast<ConstantExpr>(C)) {
+    if (Constant *Res =
+            ConstantFoldInstOperandsImpl(CE, CE->getOpcode(), Ops, DL, TLI))
+      return Res;
+    return const_cast<Constant *>(C);
+  }
 
   assert(isa<ConstantVector>(C));
   return ConstantVector::get(Ops);