[dev.ssa] cmd/compile: decompose 64-bit integer on ARM
Introduce dec64 rules to (generically) decompose 64-bit integer on 32-bit architectures. 64-bit integer is composed/decomposed with Int64Make/Hi/Lo ops, as for complex types. The idea of dealing with Add64 is the following: (Add64 (Int64Make xh xl) (Int64Make yh yl)) -> (Int64Make (Add32withcarry xh yh (Select0 (Add32carry xl yl))) (Select1 (Add32carry xl yl))) where Add32carry returns a tuple (flags,uint32). Select0 and Select1 read the first and the second component of the tuple, respectively. The two Add32carry will be CSE'd. Similarly for multiplication, Mul32uhilo returns a tuple (hi, lo). Also add support of KeepAlive, to fix build after merge. Tests addressed_ssa.go, array_ssa.go, break_ssa.go, chan_ssa.go, cmp_ssa.go, ctl_ssa.go, map_ssa.go, and string_ssa.go in cmd/compile/internal/gc/testdata passed. Progress on SSA for ARM. Still not complete. Updates #15365. Change-Id: I7867c76785a456312de5d8398a6b3f7ca5a4f7ec Reviewed-on: https://go-review.googlesource.com/23213Reviewed-by:Keith Randall <khr@golang.org>
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