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cmd/compile: fix no-op instruction used by s390x 

CL 152537 introduced a new use for ginsnop, the arch-dependent
routine that generates nops. The previous s390x nop clobbered flags.
It turns out the previous uses of this nop did not require flags
to be preserved, but the new use does.

Use a real nop: the 4-byte preferred nop.

Fixes #29453

Change-Id: I95310dfdd831932e26f5d5b6608324687f4c3162
Reviewed-on: https://go-review.googlesource.com/c/155926
Reviewed-by: Michael Munday <mike.munday@ibm.com>
This commit is contained in:
Keith Randall 2018-12-31 15:03:33 -08:00 committed by Keith Randall
parent 0175064e69
commit abd1dde1f7
1 changed files with 3 additions and 5 deletions
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8
src/cmd/compile/internal/s390x/ggen.go
View File

@ -105,10 +105,8 @@ func zeroAuto(pp *gc.Progs, n *gc.Node) {
}
func ginsnop(pp *gc.Progs) *obj.Prog {
p := pp.Prog(s390x.AOR)
p.From.Type = obj.TYPE_REG
p.From.Reg = int16(s390x.REG_R0)
p.To.Type = obj.TYPE_REG
p.To.Reg = int16(s390x.REG_R0)
p := pp.Prog(s390x.AWORD)
p.From.Type = obj.TYPE_CONST
p.From.Offset = 0x47000000 // nop 0
return p
}