Finish and benchmark inline/mem2reg improvements. #1593

Job	Run time
cargo-deny	1m 24s
Test (ubuntu-latest)	11m 35s
Lint	5m 39s
Android (ubuntu-latest, aarch64-linux-android)	8m 21s
Test (windows-latest)	22m 21s
Compiletest (ubuntu-latest)	7m 38s
Compiletest (macOS-latest)	9m 48s
Compiletest (windows-latest)	17m 26s
Difftest (ubuntu-latest)	13m 3s
Difftest (macOS-latest)	15m 14s
Difftest (windows-latest)	22m 51s
Test (macOS-latest)	13m 37s
test_success	2s
	2h 28m 59s

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