[clang] [llvm] [IR] Add fast-math support to {u,s}itofp (PR #198470)

[via cfe-commits]

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@@ -1815,6 +1815,13 @@ static uint64_t getOptimizationFlags(const Value *V) {
       Flags |= bitc::AllowContract;
     if (FPMO->hasApproxFunc())
       Flags |= bitc::ApproxFunc;
+
+    // Handle uitofp.
+    if (const auto *NNI = dyn_cast<PossiblyNonNegInst>(V)) {
+      Flags <<= 1;
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paperchalice wrote:

Unfortunately, it offends bitcode compatibility policy, from LLVM Developer Policy:
> - The textual format is not backwards compatible. We don’t change it too often, but there are no specific promises.
> - The current LLVM version supports loading any bitcode since version 3.0.

https://github.com/llvm/llvm-project/pull/198470