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[release-branch.go1.9] cmd/compile: fix sign-extension merging rules
If we have y = <int16> (MOVBQSX x) z = <int32> (MOVWQSX y) We used to use this rewrite rule: (MOVWQSX x:(MOVBQSX _)) -> x But that resulted in replacing z with a value whose type is only int16. Then if z is spilled and restored, it gets zero extended instead of sign extended. Instead use the rule (MOVWQSX (MOVBQSX x)) -> (MOVBQSX x) The result is has the correct type, so it can be spilled and restored correctly. It might mean that a few more extension ops might not be eliminated, but that's the price for correctness. Fixes #21963 Change-Id: I6ec82c3d2dbe43cc1fee6fb2bd6b3a72fca3af00 Reviewed-on: https://go-review.googlesource.com/65290 Reviewed-by: Cherry Zhang <cherryyz@google.com> Run-TryBot: Cherry Zhang <cherryyz@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-on: https://go-review.googlesource.com/70986 Run-TryBot: Russ Cox <rsc@golang.org> Reviewed-by: Keith Randall <khr@golang.org>
This commit is contained in:
Keith Randall
Russ Cox
parent
79996e4a1d
commit
78952c06c5
@ -2405,15 +2405,17 @@
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(BSFQ (ORQconst <t> [1<<16] (MOVWQZX x))) -> (BSFQ (ORQconst <t> [1<<16] x))
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// Redundant sign/zero extensions
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(MOVLQSX x:(MOVLQSX _)) -> x
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(MOVLQSX x:(MOVWQSX _)) -> x
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(MOVLQSX x:(MOVBQSX _)) -> x
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(MOVWQSX x:(MOVWQSX _)) -> x
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(MOVWQSX x:(MOVBQSX _)) -> x
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(MOVBQSX x:(MOVBQSX _)) -> x
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(MOVLQZX x:(MOVLQZX _)) -> x
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(MOVLQZX x:(MOVWQZX _)) -> x
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(MOVLQZX x:(MOVBQZX _)) -> x
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(MOVWQZX x:(MOVWQZX _)) -> x
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(MOVWQZX x:(MOVBQZX _)) -> x
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(MOVBQZX x:(MOVBQZX _)) -> x
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// Note: see issue 21963. We have to make sure we use the right type on
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// the resulting extension (the outer type, not the inner type).
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(MOVLQSX (MOVLQSX x)) -> (MOVLQSX x)
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(MOVLQSX (MOVWQSX x)) -> (MOVWQSX x)
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(MOVLQSX (MOVBQSX x)) -> (MOVBQSX x)
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(MOVWQSX (MOVWQSX x)) -> (MOVWQSX x)
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(MOVWQSX (MOVBQSX x)) -> (MOVBQSX x)
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(MOVBQSX (MOVBQSX x)) -> (MOVBQSX x)
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(MOVLQZX (MOVLQZX x)) -> (MOVLQZX x)
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(MOVLQZX (MOVWQZX x)) -> (MOVWQZX x)
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(MOVLQZX (MOVBQZX x)) -> (MOVBQZX x)
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(MOVWQZX (MOVWQZX x)) -> (MOVWQZX x)
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(MOVWQZX (MOVBQZX x)) -> (MOVBQZX x)
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(MOVBQZX (MOVBQZX x)) -> (MOVBQZX x)
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@ -4319,16 +4319,16 @@ func rewriteValueAMD64_OpAMD64MOVBQSX_0(v *Value) bool {
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v.AddArg(x)
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return true
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}
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// match: (MOVBQSX x:(MOVBQSX _))
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// match: (MOVBQSX (MOVBQSX x))
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// cond:
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// result: x
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// result: (MOVBQSX x)
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for {
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x := v.Args[0]
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if x.Op != OpAMD64MOVBQSX {
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v_0 := v.Args[0]
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if v_0.Op != OpAMD64MOVBQSX {
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break
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}
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v.reset(OpCopy)
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v.Type = x.Type
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x := v_0.Args[0]
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v.reset(OpAMD64MOVBQSX)
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v.AddArg(x)
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return true
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}
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@ -4536,16 +4536,16 @@ func rewriteValueAMD64_OpAMD64MOVBQZX_0(v *Value) bool {
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v.AddArg(x)
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return true
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}
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// match: (MOVBQZX x:(MOVBQZX _))
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// match: (MOVBQZX (MOVBQZX x))
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// cond:
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// result: x
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// result: (MOVBQZX x)
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for {
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x := v.Args[0]
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if x.Op != OpAMD64MOVBQZX {
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v_0 := v.Args[0]
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if v_0.Op != OpAMD64MOVBQZX {
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break
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}
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v.reset(OpCopy)
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v.Type = x.Type
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x := v_0.Args[0]
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v.reset(OpAMD64MOVBQZX)
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v.AddArg(x)
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return true
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}
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@ -6392,42 +6392,42 @@ func rewriteValueAMD64_OpAMD64MOVLQSX_0(v *Value) bool {
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v.AddArg(x)
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return true
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}
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// match: (MOVLQSX x:(MOVLQSX _))
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// match: (MOVLQSX (MOVLQSX x))
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// cond:
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// result: x
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// result: (MOVLQSX x)
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for {
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x := v.Args[0]
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if x.Op != OpAMD64MOVLQSX {
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v_0 := v.Args[0]
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if v_0.Op != OpAMD64MOVLQSX {
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break
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}
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v.reset(OpCopy)
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v.Type = x.Type
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x := v_0.Args[0]
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v.reset(OpAMD64MOVLQSX)
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v.AddArg(x)
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return true
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}
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// match: (MOVLQSX x:(MOVWQSX _))
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// match: (MOVLQSX (MOVWQSX x))
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// cond:
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// result: x
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// result: (MOVWQSX x)
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for {
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x := v.Args[0]
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if x.Op != OpAMD64MOVWQSX {
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v_0 := v.Args[0]
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if v_0.Op != OpAMD64MOVWQSX {
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break
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}
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v.reset(OpCopy)
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v.Type = x.Type
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x := v_0.Args[0]
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v.reset(OpAMD64MOVWQSX)
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v.AddArg(x)
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return true
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}
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// match: (MOVLQSX x:(MOVBQSX _))
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// match: (MOVLQSX (MOVBQSX x))
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// cond:
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// result: x
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// result: (MOVBQSX x)
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for {
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x := v.Args[0]
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if x.Op != OpAMD64MOVBQSX {
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v_0 := v.Args[0]
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if v_0.Op != OpAMD64MOVBQSX {
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break
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}
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v.reset(OpCopy)
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v.Type = x.Type
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x := v_0.Args[0]
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v.reset(OpAMD64MOVBQSX)
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v.AddArg(x)
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return true
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}
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@ -6611,42 +6611,42 @@ func rewriteValueAMD64_OpAMD64MOVLQZX_0(v *Value) bool {
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v.AddArg(x)
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return true
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}
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// match: (MOVLQZX x:(MOVLQZX _))
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// match: (MOVLQZX (MOVLQZX x))
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// cond:
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// result: x
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// result: (MOVLQZX x)
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for {
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x := v.Args[0]
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if x.Op != OpAMD64MOVLQZX {
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v_0 := v.Args[0]
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if v_0.Op != OpAMD64MOVLQZX {
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break
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}
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v.reset(OpCopy)
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v.Type = x.Type
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x := v_0.Args[0]
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v.reset(OpAMD64MOVLQZX)
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v.AddArg(x)
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return true
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}
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// match: (MOVLQZX x:(MOVWQZX _))
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// match: (MOVLQZX (MOVWQZX x))
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// cond:
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// result: x
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// result: (MOVWQZX x)
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for {
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x := v.Args[0]
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if x.Op != OpAMD64MOVWQZX {
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v_0 := v.Args[0]
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if v_0.Op != OpAMD64MOVWQZX {
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break
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}
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v.reset(OpCopy)
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v.Type = x.Type
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x := v_0.Args[0]
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v.reset(OpAMD64MOVWQZX)
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v.AddArg(x)
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return true
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}
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// match: (MOVLQZX x:(MOVBQZX _))
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// match: (MOVLQZX (MOVBQZX x))
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// cond:
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// result: x
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// result: (MOVBQZX x)
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for {
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x := v.Args[0]
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if x.Op != OpAMD64MOVBQZX {
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v_0 := v.Args[0]
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if v_0.Op != OpAMD64MOVBQZX {
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break
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}
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v.reset(OpCopy)
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v.Type = x.Type
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x := v_0.Args[0]
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v.reset(OpAMD64MOVBQZX)
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v.AddArg(x)
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return true
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}
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@ -10767,29 +10767,29 @@ func rewriteValueAMD64_OpAMD64MOVWQSX_0(v *Value) bool {
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v.AddArg(x)
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return true
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}
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// match: (MOVWQSX x:(MOVWQSX _))
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// match: (MOVWQSX (MOVWQSX x))
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// cond:
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// result: x
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// result: (MOVWQSX x)
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for {
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x := v.Args[0]
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if x.Op != OpAMD64MOVWQSX {
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v_0 := v.Args[0]
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if v_0.Op != OpAMD64MOVWQSX {
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break
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}
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v.reset(OpCopy)
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v.Type = x.Type
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x := v_0.Args[0]
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v.reset(OpAMD64MOVWQSX)
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v.AddArg(x)
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return true
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}
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// match: (MOVWQSX x:(MOVBQSX _))
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// match: (MOVWQSX (MOVBQSX x))
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// cond:
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// result: x
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// result: (MOVBQSX x)
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for {
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x := v.Args[0]
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if x.Op != OpAMD64MOVBQSX {
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v_0 := v.Args[0]
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if v_0.Op != OpAMD64MOVBQSX {
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break
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}
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v.reset(OpCopy)
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v.Type = x.Type
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x := v_0.Args[0]
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v.reset(OpAMD64MOVBQSX)
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v.AddArg(x)
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return true
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}
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@ -10999,29 +10999,29 @@ func rewriteValueAMD64_OpAMD64MOVWQZX_0(v *Value) bool {
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v.AddArg(x)
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return true
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}
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// match: (MOVWQZX x:(MOVWQZX _))
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// match: (MOVWQZX (MOVWQZX x))
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// cond:
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// result: x
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// result: (MOVWQZX x)
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for {
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x := v.Args[0]
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if x.Op != OpAMD64MOVWQZX {
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v_0 := v.Args[0]
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if v_0.Op != OpAMD64MOVWQZX {
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break
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}
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v.reset(OpCopy)
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v.Type = x.Type
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x := v_0.Args[0]
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v.reset(OpAMD64MOVWQZX)
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v.AddArg(x)
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return true
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}
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// match: (MOVWQZX x:(MOVBQZX _))
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// match: (MOVWQZX (MOVBQZX x))
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// cond:
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// result: x
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// result: (MOVBQZX x)
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for {
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x := v.Args[0]
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if x.Op != OpAMD64MOVBQZX {
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v_0 := v.Args[0]
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if v_0.Op != OpAMD64MOVBQZX {
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break
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}
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v.reset(OpCopy)
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v.Type = x.Type
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x := v_0.Args[0]
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v.reset(OpAMD64MOVBQZX)
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v.AddArg(x)
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return true
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}
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27
test/fixedbugs/issue21963.go
Normal file
27
test/fixedbugs/issue21963.go
Normal file
@ -0,0 +1,27 @@
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// run
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// Copyright 2017 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package main
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import (
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"fmt"
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"runtime"
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)
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//go:noinline
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func f(x []int32, y *int8) int32 {
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c := int32(int16(*y))
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runtime.GC()
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return x[0] * c
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}
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func main() {
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var x = [1]int32{5}
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var y int8 = -1
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if got, want := f(x[:], &y), int32(-5); got != want {
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panic(fmt.Sprintf("wanted %d, got %d", want, got))
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}
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}
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