[llvm] [SDAG] Ensure load is included in output chain of sincos expansion (PR #140525)

[Simon Pilgrim via llvm-commits]

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+; RUN: llc < %s | FileCheck %s
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RKSimon wrote:

(pedantic) please can you rename this pr140491-sincos-lifetimes.ll to match other tests.

https://github.com/llvm/llvm-project/pull/140525