[llvm] [SME] Stop RA from coalescing COPY instructions that transcend beyond smstart/smstop. (PR #78294)

[David Sherwood via llvm-commits]

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@@ -249,11 +249,15 @@ define double @call_to_intrinsic_without_chain(double %x) nounwind "aarch64_psta
 ; CHECK-NEXT:    str x30, [sp, #80] // 8-byte Folded Spill
 ; CHECK-NEXT:    str d0, [sp, #8] // 8-byte Folded Spill
 ; CHECK-NEXT:    smstart sm
+; CHECK-NEXT:    ldr d0, [sp, #8] // 8-byte Folded Reload
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david-arm wrote:

I guess we might be able to improve these over time, but for now it's important to have functional correctness.

https://github.com/llvm/llvm-project/pull/78294