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cmd/compile: fix Zero-to-Load forwarding rules

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Avoid using values that do not dominate the block the Zero op is in.
Should fix the SSA check builder.

The additional OffPtr ops inserted by these rules should always be
optimized away when the Load is replaced with a const zero.

Fixes #25288.

Change-Id: I4163b58e60364f77c8a206ba084073a58ca6320a
Reviewed-on: https://go-review.googlesource.com/112136
Run-TryBot: Michael Munday <mike.munday@ibm.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
This commit is contained in:
Michael Munday 2018-05-08 16:30:48 +01:00
parent 8af0c77df3
commit fbfbf03b28
2 changed files with 38 additions and 20 deletions
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12
src/cmd/compile/internal/ssa/gen/generic.rules
View File

@ -575,26 +575,29 @@
(Store {t2} p2 _
mem:(Zero [n] p3 _)))
&& o1 >= 0 && o1+t1.Size() <= n && isSamePtr(p1, p3)
&& fe.CanSSA(t1)
&& disjoint(op, t1.Size(), p2, sizeof(t2))
-> @mem.Block (Load <t1> op mem)
-> @mem.Block (Load <t1> (OffPtr <op.Type> [o1] p3) mem)
(Load <t1> op:(OffPtr [o1] p1)
(Store {t2} p2 _
(Store {t3} p3 _
mem:(Zero [n] p4 _))))
&& o1 >= 0 && o1+t1.Size() <= n && isSamePtr(p1, p4)
&& fe.CanSSA(t1)
&& disjoint(op, t1.Size(), p2, sizeof(t2))
&& disjoint(op, t1.Size(), p3, sizeof(t3))
-> @mem.Block (Load <t1> op mem)
-> @mem.Block (Load <t1> (OffPtr <op.Type> [o1] p4) mem)
(Load <t1> op:(OffPtr [o1] p1)
(Store {t2} p2 _
(Store {t3} p3 _
(Store {t4} p4 _
mem:(Zero [n] p5 _)))))
&& o1 >= 0 && o1+t1.Size() <= n && isSamePtr(p1, p5)
&& fe.CanSSA(t1)
&& disjoint(op, t1.Size(), p2, sizeof(t2))
&& disjoint(op, t1.Size(), p3, sizeof(t3))
&& disjoint(op, t1.Size(), p4, sizeof(t4))
-> @mem.Block (Load <t1> op mem)
-> @mem.Block (Load <t1> (OffPtr <op.Type> [o1] p5) mem)
(Load <t1> op:(OffPtr [o1] p1)
(Store {t2} p2 _
(Store {t3} p3 _
@ -602,11 +605,12 @@
(Store {t5} p5 _
mem:(Zero [n] p6 _))))))
&& o1 >= 0 && o1+t1.Size() <= n && isSamePtr(p1, p6)
&& fe.CanSSA(t1)
&& disjoint(op, t1.Size(), p2, sizeof(t2))
&& disjoint(op, t1.Size(), p3, sizeof(t3))
&& disjoint(op, t1.Size(), p4, sizeof(t4))
&& disjoint(op, t1.Size(), p5, sizeof(t5))
-> @mem.Block (Load <t1> op mem)
-> @mem.Block (Load <t1> (OffPtr <op.Type> [o1] p6) mem)
// Zero to Load forwarding.
(Load <t1> (OffPtr [o] p1) (Zero [n] p2 _))

46
src/cmd/compile/internal/ssa/rewritegeneric.go
View File

@ -13133,6 +13133,8 @@ func rewriteValuegeneric_OpLess8U_0(v *Value) bool {
func rewriteValuegeneric_OpLoad_0(v *Value) bool {
b := v.Block
_ = b
fe := b.Func.fe
_ = fe
// match: (Load <t1> p1 (Store {t2} p2 x _))
// cond: isSamePtr(p1, p2) && t1.Compare(x.Type) == types.CMPeq && t1.Size() == sizeof(t2)
// result: x
@ -13372,8 +13374,8 @@ func rewriteValuegeneric_OpLoad_0(v *Value) bool {
return true
}
// match: (Load <t1> op:(OffPtr [o1] p1) (Store {t2} p2 _ mem:(Zero [n] p3 _)))
// cond: o1 >= 0 && o1+t1.Size() <= n && isSamePtr(p1, p3) && disjoint(op, t1.Size(), p2, sizeof(t2))
// result: @mem.Block (Load <t1> op mem)
// cond: o1 >= 0 && o1+t1.Size() <= n && isSamePtr(p1, p3) && fe.CanSSA(t1) && disjoint(op, t1.Size(), p2, sizeof(t2))
// result: @mem.Block (Load <t1> (OffPtr <op.Type> [o1] p3) mem)
for {
t1 := v.Type
_ = v.Args[1]
@ -13397,20 +13399,23 @@ func rewriteValuegeneric_OpLoad_0(v *Value) bool {
n := mem.AuxInt
_ = mem.Args[1]
p3 := mem.Args[0]
if !(o1 >= 0 && o1+t1.Size() <= n && isSamePtr(p1, p3) && disjoint(op, t1.Size(), p2, sizeof(t2))) {
if !(o1 >= 0 && o1+t1.Size() <= n && isSamePtr(p1, p3) && fe.CanSSA(t1) && disjoint(op, t1.Size(), p2, sizeof(t2))) {
break
}
b = mem.Block
v0 := b.NewValue0(v.Pos, OpLoad, t1)
v.reset(OpCopy)
v.AddArg(v0)
v0.AddArg(op)
v1 := b.NewValue0(v.Pos, OpOffPtr, op.Type)
v1.AuxInt = o1
v1.AddArg(p3)
v0.AddArg(v1)
v0.AddArg(mem)
return true
}
// match: (Load <t1> op:(OffPtr [o1] p1) (Store {t2} p2 _ (Store {t3} p3 _ mem:(Zero [n] p4 _))))
// cond: o1 >= 0 && o1+t1.Size() <= n && isSamePtr(p1, p4) && disjoint(op, t1.Size(), p2, sizeof(t2)) && disjoint(op, t1.Size(), p3, sizeof(t3))
// result: @mem.Block (Load <t1> op mem)
// cond: o1 >= 0 && o1+t1.Size() <= n && isSamePtr(p1, p4) && fe.CanSSA(t1) && disjoint(op, t1.Size(), p2, sizeof(t2)) && disjoint(op, t1.Size(), p3, sizeof(t3))
// result: @mem.Block (Load <t1> (OffPtr <op.Type> [o1] p4) mem)
for {
t1 := v.Type
_ = v.Args[1]
@ -13441,14 +13446,17 @@ func rewriteValuegeneric_OpLoad_0(v *Value) bool {
n := mem.AuxInt
_ = mem.Args[1]
p4 := mem.Args[0]
if !(o1 >= 0 && o1+t1.Size() <= n && isSamePtr(p1, p4) && disjoint(op, t1.Size(), p2, sizeof(t2)) && disjoint(op, t1.Size(), p3, sizeof(t3))) {
if !(o1 >= 0 && o1+t1.Size() <= n && isSamePtr(p1, p4) && fe.CanSSA(t1) && disjoint(op, t1.Size(), p2, sizeof(t2)) && disjoint(op, t1.Size(), p3, sizeof(t3))) {
break
}
b = mem.Block
v0 := b.NewValue0(v.Pos, OpLoad, t1)
v.reset(OpCopy)
v.AddArg(v0)
v0.AddArg(op)
v1 := b.NewValue0(v.Pos, OpOffPtr, op.Type)
v1.AuxInt = o1
v1.AddArg(p4)
v0.AddArg(v1)
v0.AddArg(mem)
return true
}
@ -13460,8 +13468,8 @@ func rewriteValuegeneric_OpLoad_10(v *Value) bool {
fe := b.Func.fe
_ = fe
// match: (Load <t1> op:(OffPtr [o1] p1) (Store {t2} p2 _ (Store {t3} p3 _ (Store {t4} p4 _ mem:(Zero [n] p5 _)))))
// cond: o1 >= 0 && o1+t1.Size() <= n && isSamePtr(p1, p5) && disjoint(op, t1.Size(), p2, sizeof(t2)) && disjoint(op, t1.Size(), p3, sizeof(t3)) && disjoint(op, t1.Size(), p4, sizeof(t4))
// result: @mem.Block (Load <t1> op mem)
// cond: o1 >= 0 && o1+t1.Size() <= n && isSamePtr(p1, p5) && fe.CanSSA(t1) && disjoint(op, t1.Size(), p2, sizeof(t2)) && disjoint(op, t1.Size(), p3, sizeof(t3)) && disjoint(op, t1.Size(), p4, sizeof(t4))
// result: @mem.Block (Load <t1> (OffPtr <op.Type> [o1] p5) mem)
for {
t1 := v.Type
_ = v.Args[1]
@ -13499,20 +13507,23 @@ func rewriteValuegeneric_OpLoad_10(v *Value) bool {
n := mem.AuxInt
_ = mem.Args[1]
p5 := mem.Args[0]
if !(o1 >= 0 && o1+t1.Size() <= n && isSamePtr(p1, p5) && disjoint(op, t1.Size(), p2, sizeof(t2)) && disjoint(op, t1.Size(), p3, sizeof(t3)) && disjoint(op, t1.Size(), p4, sizeof(t4))) {
if !(o1 >= 0 && o1+t1.Size() <= n && isSamePtr(p1, p5) && fe.CanSSA(t1) && disjoint(op, t1.Size(), p2, sizeof(t2)) && disjoint(op, t1.Size(), p3, sizeof(t3)) && disjoint(op, t1.Size(), p4, sizeof(t4))) {
break
}
b = mem.Block
v0 := b.NewValue0(v.Pos, OpLoad, t1)
v.reset(OpCopy)
v.AddArg(v0)
v0.AddArg(op)
v1 := b.NewValue0(v.Pos, OpOffPtr, op.Type)
v1.AuxInt = o1
v1.AddArg(p5)
v0.AddArg(v1)
v0.AddArg(mem)
return true
}
// match: (Load <t1> op:(OffPtr [o1] p1) (Store {t2} p2 _ (Store {t3} p3 _ (Store {t4} p4 _ (Store {t5} p5 _ mem:(Zero [n] p6 _))))))
// cond: o1 >= 0 && o1+t1.Size() <= n && isSamePtr(p1, p6) && disjoint(op, t1.Size(), p2, sizeof(t2)) && disjoint(op, t1.Size(), p3, sizeof(t3)) && disjoint(op, t1.Size(), p4, sizeof(t4)) && disjoint(op, t1.Size(), p5, sizeof(t5))
// result: @mem.Block (Load <t1> op mem)
// cond: o1 >= 0 && o1+t1.Size() <= n && isSamePtr(p1, p6) && fe.CanSSA(t1) && disjoint(op, t1.Size(), p2, sizeof(t2)) && disjoint(op, t1.Size(), p3, sizeof(t3)) && disjoint(op, t1.Size(), p4, sizeof(t4)) && disjoint(op, t1.Size(), p5, sizeof(t5))
// result: @mem.Block (Load <t1> (OffPtr <op.Type> [o1] p6) mem)
for {
t1 := v.Type
_ = v.Args[1]
@ -13557,14 +13568,17 @@ func rewriteValuegeneric_OpLoad_10(v *Value) bool {
n := mem.AuxInt
_ = mem.Args[1]
p6 := mem.Args[0]
if !(o1 >= 0 && o1+t1.Size() <= n && isSamePtr(p1, p6) && disjoint(op, t1.Size(), p2, sizeof(t2)) && disjoint(op, t1.Size(), p3, sizeof(t3)) && disjoint(op, t1.Size(), p4, sizeof(t4)) && disjoint(op, t1.Size(), p5, sizeof(t5))) {
if !(o1 >= 0 && o1+t1.Size() <= n && isSamePtr(p1, p6) && fe.CanSSA(t1) && disjoint(op, t1.Size(), p2, sizeof(t2)) && disjoint(op, t1.Size(), p3, sizeof(t3)) && disjoint(op, t1.Size(), p4, sizeof(t4)) && disjoint(op, t1.Size(), p5, sizeof(t5))) {
break
}
b = mem.Block
v0 := b.NewValue0(v.Pos, OpLoad, t1)
v.reset(OpCopy)
v.AddArg(v0)
v0.AddArg(op)
v1 := b.NewValue0(v.Pos, OpOffPtr, op.Type)
v1.AuxInt = o1
v1.AddArg(p6)
v0.AddArg(v1)
v0.AddArg(mem)
return true
}