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cmd/compile: don't rewrite (CMP (AND x y) 0) to TEST if AND has other uses
If the AND has other uses, we end up saving an argument to the AND in another register, so we can use it for the TEST. No point in doing that. Change-Id: I73444a6aeddd6f55e2328ce04d77c3e6cf4a83e0 Reviewed-on: https://go-review.googlesource.com/c/go/+/241280 Run-TryBot: Keith Randall <khr@golang.org> Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com> TryBot-Result: Gobot Gobot <gobot@golang.org>
This commit is contained in:
Keith Randall
parent
8b8f926fc3
commit
ef9c8a38ad
3 changed files with 128 additions and 40 deletions
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@ -1463,14 +1463,14 @@
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(MULQconst [c] (NEGQ x)) && c != -(1<<31) -> (MULQconst [-c] x)
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// checking AND against 0.
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(CMPQconst (ANDQ x y) [0]) -> (TESTQ x y)
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(CMPLconst (ANDL x y) [0]) -> (TESTL x y)
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(CMPWconst (ANDL x y) [0]) -> (TESTW x y)
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(CMPBconst (ANDL x y) [0]) -> (TESTB x y)
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(CMPQconst (ANDQconst [c] x) [0]) -> (TESTQconst [c] x)
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(CMPLconst (ANDLconst [c] x) [0]) -> (TESTLconst [c] x)
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(CMPWconst (ANDLconst [c] x) [0]) -> (TESTWconst [int64(int16(c))] x)
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(CMPBconst (ANDLconst [c] x) [0]) -> (TESTBconst [int64(int8(c))] x)
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(CMPQconst a:(ANDQ x y) [0]) && a.Uses == 1 -> (TESTQ x y)
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(CMPLconst a:(ANDL x y) [0]) && a.Uses == 1 -> (TESTL x y)
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(CMPWconst a:(ANDL x y) [0]) && a.Uses == 1 -> (TESTW x y)
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(CMPBconst a:(ANDL x y) [0]) && a.Uses == 1 -> (TESTB x y)
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(CMPQconst a:(ANDQconst [c] x) [0]) && a.Uses == 1 -> (TESTQconst [c] x)
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(CMPLconst a:(ANDLconst [c] x) [0]) && a.Uses == 1 -> (TESTLconst [c] x)
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(CMPWconst a:(ANDLconst [c] x) [0]) && a.Uses == 1 -> (TESTWconst [int64(int16(c))] x)
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(CMPBconst a:(ANDLconst [c] x) [0]) && a.Uses == 1 -> (TESTBconst [int64(int8(c))] x)
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// Convert TESTx to TESTxconst if possible.
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(TESTQ (MOVQconst [c]) x) && is32Bit(c) -> (TESTQconst [c] x)
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@ -6924,26 +6924,42 @@ func rewriteValueAMD64_OpAMD64CMPBconst(v *Value) bool {
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v.reset(OpAMD64FlagLT_ULT)
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return true
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}
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// match: (CMPBconst (ANDL x y) [0])
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// match: (CMPBconst a:(ANDL x y) [0])
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// cond: a.Uses == 1
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// result: (TESTB x y)
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for {
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if v.AuxInt != 0 || v_0.Op != OpAMD64ANDL {
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if v.AuxInt != 0 {
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break
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}
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a := v_0
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if a.Op != OpAMD64ANDL {
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break
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}
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y := a.Args[1]
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x := a.Args[0]
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if !(a.Uses == 1) {
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break
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}
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y := v_0.Args[1]
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x := v_0.Args[0]
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v.reset(OpAMD64TESTB)
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v.AddArg2(x, y)
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return true
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}
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// match: (CMPBconst (ANDLconst [c] x) [0])
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// match: (CMPBconst a:(ANDLconst [c] x) [0])
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// cond: a.Uses == 1
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// result: (TESTBconst [int64(int8(c))] x)
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for {
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if v.AuxInt != 0 || v_0.Op != OpAMD64ANDLconst {
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if v.AuxInt != 0 {
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break
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}
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a := v_0
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if a.Op != OpAMD64ANDLconst {
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break
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}
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c := a.AuxInt
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x := a.Args[0]
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if !(a.Uses == 1) {
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break
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}
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c := v_0.AuxInt
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x := v_0.Args[0]
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v.reset(OpAMD64TESTBconst)
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v.AuxInt = int64(int8(c))
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v.AddArg(x)
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@ -7309,26 +7325,42 @@ func rewriteValueAMD64_OpAMD64CMPLconst(v *Value) bool {
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v.reset(OpAMD64FlagLT_ULT)
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return true
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}
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// match: (CMPLconst (ANDL x y) [0])
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// match: (CMPLconst a:(ANDL x y) [0])
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// cond: a.Uses == 1
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// result: (TESTL x y)
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for {
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if v.AuxInt != 0 || v_0.Op != OpAMD64ANDL {
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if v.AuxInt != 0 {
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break
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}
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a := v_0
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if a.Op != OpAMD64ANDL {
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break
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}
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y := a.Args[1]
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x := a.Args[0]
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if !(a.Uses == 1) {
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break
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}
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y := v_0.Args[1]
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x := v_0.Args[0]
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v.reset(OpAMD64TESTL)
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v.AddArg2(x, y)
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return true
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}
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// match: (CMPLconst (ANDLconst [c] x) [0])
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// match: (CMPLconst a:(ANDLconst [c] x) [0])
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// cond: a.Uses == 1
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// result: (TESTLconst [c] x)
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for {
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if v.AuxInt != 0 || v_0.Op != OpAMD64ANDLconst {
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if v.AuxInt != 0 {
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break
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}
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a := v_0
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if a.Op != OpAMD64ANDLconst {
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break
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}
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c := a.AuxInt
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x := a.Args[0]
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if !(a.Uses == 1) {
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break
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}
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c := v_0.AuxInt
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x := v_0.Args[0]
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v.reset(OpAMD64TESTLconst)
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v.AuxInt = c
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v.AddArg(x)
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@ -7874,26 +7906,42 @@ func rewriteValueAMD64_OpAMD64CMPQconst(v *Value) bool {
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v.reset(OpAMD64FlagLT_ULT)
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return true
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}
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// match: (CMPQconst (ANDQ x y) [0])
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// match: (CMPQconst a:(ANDQ x y) [0])
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// cond: a.Uses == 1
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// result: (TESTQ x y)
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for {
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if v.AuxInt != 0 || v_0.Op != OpAMD64ANDQ {
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if v.AuxInt != 0 {
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break
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}
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a := v_0
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if a.Op != OpAMD64ANDQ {
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break
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}
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y := a.Args[1]
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x := a.Args[0]
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if !(a.Uses == 1) {
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break
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}
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y := v_0.Args[1]
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x := v_0.Args[0]
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v.reset(OpAMD64TESTQ)
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v.AddArg2(x, y)
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return true
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}
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// match: (CMPQconst (ANDQconst [c] x) [0])
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// match: (CMPQconst a:(ANDQconst [c] x) [0])
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// cond: a.Uses == 1
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// result: (TESTQconst [c] x)
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for {
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if v.AuxInt != 0 || v_0.Op != OpAMD64ANDQconst {
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if v.AuxInt != 0 {
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break
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}
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a := v_0
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if a.Op != OpAMD64ANDQconst {
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break
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}
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c := a.AuxInt
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x := a.Args[0]
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if !(a.Uses == 1) {
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break
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}
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c := v_0.AuxInt
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x := v_0.Args[0]
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v.reset(OpAMD64TESTQconst)
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v.AuxInt = c
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v.AddArg(x)
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@ -8244,26 +8292,42 @@ func rewriteValueAMD64_OpAMD64CMPWconst(v *Value) bool {
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v.reset(OpAMD64FlagLT_ULT)
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return true
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}
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// match: (CMPWconst (ANDL x y) [0])
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// match: (CMPWconst a:(ANDL x y) [0])
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// cond: a.Uses == 1
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// result: (TESTW x y)
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for {
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if v.AuxInt != 0 || v_0.Op != OpAMD64ANDL {
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if v.AuxInt != 0 {
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break
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}
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a := v_0
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if a.Op != OpAMD64ANDL {
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break
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}
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y := a.Args[1]
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x := a.Args[0]
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if !(a.Uses == 1) {
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break
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}
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y := v_0.Args[1]
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x := v_0.Args[0]
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v.reset(OpAMD64TESTW)
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v.AddArg2(x, y)
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return true
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}
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// match: (CMPWconst (ANDLconst [c] x) [0])
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// match: (CMPWconst a:(ANDLconst [c] x) [0])
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// cond: a.Uses == 1
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// result: (TESTWconst [int64(int16(c))] x)
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for {
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if v.AuxInt != 0 || v_0.Op != OpAMD64ANDLconst {
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if v.AuxInt != 0 {
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break
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}
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a := v_0
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if a.Op != OpAMD64ANDLconst {
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break
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}
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c := a.AuxInt
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x := a.Args[0]
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if !(a.Uses == 1) {
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break
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}
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c := v_0.AuxInt
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x := v_0.Args[0]
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v.reset(OpAMD64TESTWconst)
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v.AuxInt = int64(int16(c))
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v.AddArg(x)
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24
test/codegen/logic.go
Normal file
24
test/codegen/logic.go
Normal file
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@ -0,0 +1,24 @@
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// asmcheck
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// Copyright 2018 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 codegen
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var gx, gy int
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// Test to make sure that (CMPQ (ANDQ x y) [0]) does not get rewritten to
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// (TESTQ x y) if the ANDQ has other uses. If that rewrite happens, then one
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// of the args of the ANDQ needs to be saved so it can be used as the arg to TESTQ.
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func andWithUse(x, y int) int {
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// Load x,y into registers, so those MOVQ will not appear at the z := x&y line.
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gx, gy = x, y
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// amd64:-"MOVQ"
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z := x & y
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if z == 0 {
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return 77
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}
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// use z by returning it
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return z
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}
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