[llvm] [RISCV] Remove unneeded zext.h instructions (PR #225960)

[Craig Topper via llvm-commits]

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@@ -1016,7 +1021,7 @@ bool TypePromotionImpl::run(Function &F, const TargetMachine *TM,
                             << "register for ZExt type\n");
           continue;
         }
-        MadeChange |= TryToPromote(Phi, PromoteWidth, LI);
+        MadeChange |= TryToPromote(Phi, PromoteWidth, LI, UseSExt);
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topperc wrote:

The traversal inside of TryToPromote does things that are only valid for zero extend like checking NoUnsignedWrap, or only handling the unsigned forms of div, rem, and shift.

https://github.com/llvm/llvm-project/pull/225960