[clang] [llvm] [IR] Add `fpmath` to keep list of dropUBImplyingAttrsAndMetadata (PR #179019)

[Yingwei Zheng via cfe-commits]

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@@ -576,7 +576,8 @@ void Instruction::dropUBImplyingAttrsAndMetadata(ArrayRef<unsigned> Keep) {
   // immediate undefined behavior.
   static const unsigned KnownIDs[] = {
       LLVMContext::MD_annotation, LLVMContext::MD_range,
-      LLVMContext::MD_nonnull, LLVMContext::MD_align, LLVMContext::MD_prof};
+      LLVMContext::MD_nonnull,    LLVMContext::MD_align,
+      LLVMContext::MD_fpmath,     LLVMContext::MD_prof};
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dtcxzyw wrote:

Can you add some comments above for fpmath?

https://github.com/llvm/llvm-project/pull/179019