!395 [sync] PR-394: backport: handle constant pointer offsets in dead store elimination
From: @openeuler-sync-bot Reviewed-by: @hcnbxx Signed-off-by: @hcnbxx
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@ -0,0 +1,143 @@
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From 131f773664fa2d0dbc870e11c388a3131a3a2029 Mon Sep 17 00:00:00 2001
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From: Keith Randall <khr@golang.org>
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Date: Sun, 29 Oct 2023 21:00:29 -0700
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Subject: cmd/compile: handle constant pointer offsets in dead store elimination
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Conflict:NA
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Reference:https://go-review.googlesource.com/c/go/+/538595
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Update #63657
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Update #45573
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Change-Id: I163c6038c13d974dc0ca9f02144472bc05331826
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Reviewed-on: https://go-review.googlesource.com/c/go/+/538595
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LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
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Reviewed-by: David Chase <drchase@google.com>
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Reviewed-by: Keith Randall <khr@google.com>
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---
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src/cmd/compile/internal/ssa/deadstore.go | 64 ++++++++++++++++++++---
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src/cmd/compile/internal/ssa/rewrite.go | 6 +++
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2 files changed, 62 insertions(+), 8 deletions(-)
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diff --git a/src/cmd/compile/internal/ssa/deadstore.go b/src/cmd/compile/internal/ssa/deadstore.go
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index 648b68af78b1..7656e45cb9d5 100644
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--- a/src/cmd/compile/internal/ssa/deadstore.go
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+++ b/src/cmd/compile/internal/ssa/deadstore.go
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@@ -73,9 +73,9 @@ func dse(f *Func) {
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}
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// Walk backwards looking for dead stores. Keep track of shadowed addresses.
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- // A "shadowed address" is a pointer and a size describing a memory region that
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- // is known to be written. We keep track of shadowed addresses in the shadowed
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- // map, mapping the ID of the address to the size of the shadowed region.
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+ // A "shadowed address" is a pointer, offset, and size describing a memory region that
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+ // is known to be written. We keep track of shadowed addresses in the shadowed map,
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+ // mapping the ID of the address to a shadowRange where future writes will happen.
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// Since we're walking backwards, writes to a shadowed region are useless,
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// as they will be immediately overwritten.
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shadowed.clear()
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@@ -88,13 +88,20 @@ func dse(f *Func) {
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shadowed.clear()
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}
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if v.Op == OpStore || v.Op == OpZero {
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+ ptr := v.Args[0]
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+ var off int64
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+ for ptr.Op == OpOffPtr { // Walk to base pointer
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+ off += ptr.AuxInt
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+ ptr = ptr.Args[0]
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+ }
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var sz int64
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if v.Op == OpStore {
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sz = v.Aux.(*types.Type).Size()
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} else { // OpZero
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sz = v.AuxInt
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}
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- if shadowedSize := int64(shadowed.get(v.Args[0].ID)); shadowedSize != -1 && shadowedSize >= sz {
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+ sr := shadowRange(shadowed.get(ptr.ID))
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+ if sr.contains(off, off+sz) {
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// Modify the store/zero into a copy of the memory state,
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// effectively eliding the store operation.
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if v.Op == OpStore {
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@@ -108,10 +115,8 @@ func dse(f *Func) {
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v.AuxInt = 0
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v.Op = OpCopy
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} else {
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- if sz > 0x7fffffff { // work around sparseMap's int32 value type
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- sz = 0x7fffffff
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- }
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- shadowed.set(v.Args[0].ID, int32(sz))
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+ // Extend shadowed region.
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+ shadowed.set(ptr.ID, int32(sr.merge(off, off+sz)))
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}
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}
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// walk to previous store
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@@ -131,6 +136,49 @@ func dse(f *Func) {
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}
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}
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+// A shadowRange encodes a set of byte offsets [lo():hi()] from
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+// a given pointer that will be written to later in the block.
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+// A zero shadowRange encodes an empty shadowed range (and so
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+// does a -1 shadowRange, which is what sparsemap.get returns
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+// on a failed lookup).
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+type shadowRange int32
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+
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+func (sr shadowRange) lo() int64 {
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+ return int64(sr & 0xffff)
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+}
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+func (sr shadowRange) hi() int64 {
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+ return int64((sr >> 16) & 0xffff)
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+}
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+
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+// contains reports whether [lo:hi] is completely within sr.
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+func (sr shadowRange) contains(lo, hi int64) bool {
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+ return lo >= sr.lo() && hi <= sr.hi()
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+}
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+
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+// merge returns the union of sr and [lo:hi].
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+// merge is allowed to return something smaller than the union.
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+func (sr shadowRange) merge(lo, hi int64) shadowRange {
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+ if lo < 0 || hi > 0xffff {
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+ // Ignore offsets that are too large or small.
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+ return sr
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+ }
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+ if sr.lo() == sr.hi() {
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+ // Old range is empty - use new one.
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+ return shadowRange(lo + hi<<16)
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+ }
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+ if hi < sr.lo() || lo > sr.hi() {
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+ // The two regions don't overlap or abut, so we would
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+ // have to keep track of multiple disjoint ranges.
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+ // Because we can only keep one, keep the larger one.
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+ if sr.hi()-sr.lo() >= hi-lo {
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+ return sr
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+ }
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+ return shadowRange(lo + hi<<16)
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+ }
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+ // Regions overlap or abut - compute the union.
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+ return shadowRange(min(lo, sr.lo()) + max(hi, sr.hi())<<16)
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+}
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+
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// elimDeadAutosGeneric deletes autos that are never accessed. To achieve this
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// we track the operations that the address of each auto reaches and if it only
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// reaches stores then we delete all the stores. The other operations will then
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diff --git a/src/cmd/compile/internal/ssa/rewrite.go b/src/cmd/compile/internal/ssa/rewrite.go
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index 43843bda5536..5c7ed16f12be 100644
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--- a/src/cmd/compile/internal/ssa/rewrite.go
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+++ b/src/cmd/compile/internal/ssa/rewrite.go
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@@ -1183,6 +1183,12 @@ func min(x, y int64) int64 {
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}
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return y
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}
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+func max(x, y int64) int64 {
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+ if x > y {
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+ return x
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+ }
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+ return y
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+}
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func isConstZero(v *Value) bool {
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switch v.Op {
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--
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2.33.0
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@ -66,7 +66,7 @@
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Name: golang
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Version: 1.21.4
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Release: 15
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Release: 16
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Summary: The Go Programming Language
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License: BSD and Public Domain
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URL: https://golang.org/
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@ -134,6 +134,7 @@ Patch6010: backport-0010-release-branch.go1.21-net-http-limit-chunked-data-ov.pa
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Patch6011: backport-0011-Backport-archive-zip-treat-truncated-EOCDR-comment-a.patch
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Patch6012: backport-0012-net-http-send-body-or-close-connection-on-expect-100.patch
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Patch6013: backport-0013-release-branch.go1.21-net-http-update-bundled-golang.patch
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Patch6014: backport-0014-cmd-compile-handle-constant-pointer-offsets-in-dead-.patch
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ExclusiveArch: %{golang_arches}
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@ -372,6 +373,9 @@ fi
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%files devel -f go-tests.list -f go-misc.list -f go-src.list
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%changelog
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* Mon Jul 30 2024 jingxiaolu <lujingxiao@huawei.com> - 1.21.4-16
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- cmd/compile: handle constant pointer offsets in dead store elimination
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* Mon Jul 29 2024 EulerOSWander <314264452@qq.com> - 1.21.4-15
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- fix send correct lastStreamID in stream-caused GOAWAY
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