[llvm] [HLSL] Add support to lookup a ResourceBindingInfo from its use (PR #126556)

[Ashley Coleman via llvm-commits]

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@@ -782,9 +781,8 @@ DXILBindingMap::findByUse(const Value *Key) const {
   }
 
   const CallInst *CI = dyn_cast<CallInst>(Key);
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V-FEXrt wrote:

Happy to test it but it looks like `PHINode` isn't a subclass of `CallInst` right? https://llvm.org/doxygen/classllvm_1_1PHINode.html

Which means the base case would earily exit before the PHINode code had a chance to run.  Could maybe tuck it inside the `if (!CI)`  but that feels a bit messsy to me

https://github.com/llvm/llvm-project/pull/126556