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cmd/compile: remove AUNDEF opcode

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This opcode was only used to mark unreachable code for plive to use.
plive now uses the SSA representation, so it knows locations are
unreachable because they are ends of Exit blocks. It doesn't need
these opcodes any more.

These opcodes actually used space in the binary, 2 bytes per undef
on x86 and more for other archs.

Makes the amd64 go binary 0.2% smaller.

Change-Id: I64c84c35db7c7949617a3a5830f09c8e5fcd2620
Reviewed-on: https://go-review.googlesource.com/c/go/+/171058
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
This commit is contained in:
Keith Randall 2019-04-06 12:42:51 -07:00 • committed by Keith Randall
parent cb6646234c
commit ad6c691542
10 changed files with 7 additions and 9 deletions
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1
src/cmd/compile/internal/amd64/ssa.go
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@ -1208,7 +1208,6 @@ func ssaGenBlock(s *gc.SSAGenState, b, next *ssa.Block) {
s.Branches = append(s.Branches, gc.Branch{P: p, B: b.Succs[0].Block()})
}
case ssa.BlockExit:
s.Prog(obj.AUNDEF) // tell plive.go that we never reach here
case ssa.BlockRet:
s.Prog(obj.ARET)
case ssa.BlockRetJmp: