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cmd/compile: fix unaligned loads/stores to global variables on s390x
Load/store-merging and move optimizations can result in unaligned memory accesses. This is fine so long as the load/store instruction used does not take a relative offset. In the SSA rules this means we must not merge (MOVDaddr (SB)) ops into loads/stores unless we can guarantee the alignment of the target. Fixes golang#21048. Change-Id: I70f13a62a148d5f0a56e704e8f76e36b4a4226d9 Reviewed-on: https://go-review.googlesource.com/49250 Run-TryBot: Michael Munday <[email protected]> TryBot-Result: Gobot Gobot <[email protected]> Reviewed-by: Cherry Zhang <[email protected]>
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,72 @@ | ||
| // run | ||
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| // Copyright 2017 The Go Authors. All rights reserved. | ||
| // Use of this source code is governed by a BSD-style | ||
| // license that can be found in the LICENSE file. | ||
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| // Issue 21048: s390x merged address generation into stores | ||
| // to unaligned global variables. This resulted in an illegal | ||
| // instruction. | ||
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| package main | ||
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| type T struct { | ||
| _ [1]byte | ||
| a [2]byte // offset: 1 | ||
| _ [3]byte | ||
| b [2]uint16 // offset: 6 | ||
| _ [2]byte | ||
| c [2]uint32 // offset: 12 | ||
| _ [2]byte | ||
| d [2]int16 // offset: 22 | ||
| _ [2]byte | ||
| e [2]int32 // offset: 28 | ||
| } | ||
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| var Source, Sink T | ||
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| func newT() T { | ||
| return T{ | ||
| a: [2]byte{1, 2}, | ||
| b: [2]uint16{1, 2}, | ||
| c: [2]uint32{1, 2}, | ||
| d: [2]int16{1, 2}, | ||
| e: [2]int32{1, 2}, | ||
| } | ||
| } | ||
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| //go:noinline | ||
| func moves() { | ||
| Sink.a = Source.a | ||
| Sink.b = Source.b | ||
| Sink.c = Source.c | ||
| Sink.d = Source.d | ||
| Sink.e = Source.e | ||
| } | ||
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| //go:noinline | ||
| func loads() *T { | ||
| t := newT() | ||
| t.a = Source.a | ||
| t.b = Source.b | ||
| t.c = Source.c | ||
| t.d = Source.d | ||
| t.e = Source.e | ||
| return &t | ||
| } | ||
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| //go:noinline | ||
| func stores() { | ||
| t := newT() | ||
| Sink.a = t.a | ||
| Sink.b = t.b | ||
| Sink.c = t.c | ||
| Sink.d = t.d | ||
| Sink.e = t.e | ||
| } | ||
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| func main() { | ||
| moves() | ||
| loads() | ||
| stores() | ||
| } |