diff options
| author | Keith Randall <khr@golang.org> | 2025-07-21 10:09:35 -0700 |
|---|---|---|
| committer | Keith Randall <khr@google.com> | 2025-07-21 11:08:57 -0700 |
| commit | f7cc61e7d7f77521e073137c6045ba73f66ef902 (patch) | |
| tree | 4cefcdbc824dc0cbcbf2a463d2cb1af46957fc76 | |
| parent | 5dac42363ba8281a3f4f08e03af2292b763adc38 (diff) | |
| download | go-f7cc61e7d7f77521e073137c6045ba73f66ef902.tar.xz | |
cmd/compile: for arm64 epilog, do SP increment with a single instruction
That way, the frame is atomically popped. Previously, for big frames
the SP was unwound in two steps (because arm64 can only add constants
up to 1<<12 in a single instruction).
Fixes #73259
Change-Id: I382c249194ad7bc9fc19607c27487c58d90d49e5
Reviewed-on: https://go-review.googlesource.com/c/go/+/689235
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
Reviewed-by: Keith Randall <khr@google.com>
| -rw-r--r-- | src/cmd/internal/obj/arm64/obj7.go | 55 |
1 files changed, 43 insertions, 12 deletions
diff --git a/src/cmd/internal/obj/arm64/obj7.go b/src/cmd/internal/obj/arm64/obj7.go index 368a631ff5..ea1a35b097 100644 --- a/src/cmd/internal/obj/arm64/obj7.go +++ b/src/cmd/internal/obj/arm64/obj7.go @@ -907,18 +907,49 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) { p.To.Reg = REGFP p.To.Offset = REGLINK - // ADD $aoffset, RSP, RSP - q = newprog() - q.As = AADD - q.From.Type = obj.TYPE_CONST - q.From.Offset = int64(aoffset) - q.To.Type = obj.TYPE_REG - q.To.Reg = REGSP - q.Spadj = -aoffset - q.Pos = p.Pos - q.Link = p.Link - p.Link = q - p = q + if aoffset < 1<<12 { + // ADD $aoffset, RSP, RSP + q = newprog() + q.As = AADD + q.From.Type = obj.TYPE_CONST + q.From.Offset = int64(aoffset) + q.To.Type = obj.TYPE_REG + q.To.Reg = REGSP + q.Spadj = -aoffset + q.Pos = p.Pos + q.Link = p.Link + p.Link = q + p = q + } else { + // Put frame size in a separate register and + // add it in with a single instruction, + // so we never have a partial frame during + // the epilog. See issue 73259. + + // MOVD $aoffset, REGTMP + q = newprog() + q.As = AMOVD + q.From.Type = obj.TYPE_CONST + q.From.Offset = int64(aoffset) + q.To.Type = obj.TYPE_REG + q.To.Reg = REGTMP + q.Pos = p.Pos + q.Link = p.Link + p.Link = q + p = q + // ADD REGTMP, RSP, RSP + q = newprog() + q.As = AADD + q.From.Type = obj.TYPE_REG + q.From.Reg = REGTMP + q.To.Type = obj.TYPE_REG + q.To.Reg = REGSP + q.Spadj = -aoffset + q.Pos = p.Pos + q.Link = p.Link + p.Link = q + p = q + } } // If enabled, this code emits 'MOV PC, R27' before every 'MOV LR, PC', |