[llvm] a5d6851 - LoopReroll::isLoopControlIV - use cast<> instead of dyn_cast<> to avoid dereference of nullptr

[Simon Pilgrim via llvm-commits]

Author: Simon Pilgrim
Date: 2022-02-11T10:19:25Z
New Revision: a5d6851489c7a4bfa3422a2fb3de40b9ea958833

URL: https://github.com/llvm/llvm-project/commit/a5d6851489c7a4bfa3422a2fb3de40b9ea958833
DIFF: https://github.com/llvm/llvm-project/commit/a5d6851489c7a4bfa3422a2fb3de40b9ea958833.diff

LOG: LoopReroll::isLoopControlIV - use cast<> instead of dyn_cast<> to avoid dereference of nullptr

The pointer is always dereferenced by isCompareUsedByBranch, so assert the cast is correct instead of returning nullptr

Added: 
    

Modified: 
    llvm/lib/Transforms/Scalar/LoopRerollPass.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/Scalar/LoopRerollPass.cpp b/llvm/lib/Transforms/Scalar/LoopRerollPass.cpp
index 9d22eceb987f6..0fc3b94d9f6a4 100644
--- a/llvm/lib/Transforms/Scalar/LoopRerollPass.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopRerollPass.cpp
@@ -559,12 +559,12 @@ bool LoopReroll::isLoopControlIV(Loop *L, Instruction *IV) {
           }
           // Must be a CMP or an ext (of a value with nsw) then CMP
           else {
-            Instruction *UUser = dyn_cast<Instruction>(UU);
+            auto *UUser = cast<Instruction>(UU);
             // Skip SExt if we are extending an nsw value
             // TODO: Allow ZExt too
-            if (BO->hasNoSignedWrap() && UUser && UUser->hasOneUse() &&
+            if (BO->hasNoSignedWrap() && UUser->hasOneUse() &&
                 isa<SExtInst>(UUser))
-              UUser = dyn_cast<Instruction>(*(UUser->user_begin()));
+              UUser = cast<Instruction>(*(UUser->user_begin()));
             if (!isCompareUsedByBranch(UUser))
               return false;
           }