[clang] [llvm] [Mips] Add r5900 (PlayStation 2 Emotion Engine) CPU support (PR #176666)

[Rick Gaiser via cfe-commits]

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@@ -278,6 +280,65 @@ static bool hasUnoccupiedSlot(const MachineInstr *MI) {
   return MI->hasDelaySlot() && !MI->isBundledWithSucc();
 }
 
+/// Check if a branch is a short backward loop that triggers the R5900 erratum.
+/// The erratum occurs when:
+/// - A loop has 6 or fewer instructions (including branch + delay slot)
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rickgaiser wrote:

No, as far as I know the error wil only trigger when all conditions have been met:
 - A loop has 6 or fewer instructions (including branch + delay slot)
 - The branch is a conditional backward branch
 - The delay slot is not NOP
 - No other branches exist in the loop body

@frno7 can you confirm?

https://github.com/llvm/llvm-project/pull/176666