[dev.ssa] cmd/compile: fix constant subtraction rules

(SUBQconst [x] y) computes y-x, not x-y.

Fixes #12137

Change-Id: Idbd0554eee051102f562240d1756647843666ee6
Reviewed-on: https://go-review.googlesource.com/13631
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>

diff --git a/src/cmd/compile/internal/gc/testdata/arith_ssa.go b/src/cmd/compile/internal/gc/testdata/arith_ssa.go
index 0dbf9451ab053c0da0f05bfc9b96a9da07790b1b..ca96988113bda18322482e509a3e2dfd82030338 100644 (file)
--- a/src/cmd/compile/internal/gc/testdata/arith_ssa.go
+++ b/src/cmd/compile/internal/gc/testdata/arith_ssa.go
@@ -222,6 +222,36 @@ func testLrot() {
 
 }
 
+func sub1_ssa() uint64 {
+       switch {
+       } // prevent inlining
+       v1 := uint64(3) // uint64
+       return v1*v1 - (v1&v1)&v1
+}
+func sub2_ssa() uint8 {
+       switch {
+       }
+       v1 := uint8(0)
+       v3 := v1 + v1 + v1 ^ v1 | 3 + v1 ^ v1 | v1 ^ v1
+       v1-- // dev.ssa doesn't see this one
+       return v1 ^ v1*v1 - v3
+}
+
+func testSubConst() {
+       x1 := sub1_ssa()
+       want1 := uint64(6)
+       if x1 != want1 {
+               println("sub1_ssa()=", want1, ", got", x1)
+               failed = true
+       }
+       x2 := sub2_ssa()
+       want2 := uint8(251)
+       if x2 != want2 {
+               println("sub2_ssa()=", want2, ", got", x2)
+               failed = true
+       }
+}
+
 var failed = false
 
 func main() {
@@ -233,6 +263,7 @@ func main() {
        testBitwiseLogic()
        testOcom()
        testLrot()
+       testSubConst()
 
        if failed {
                panic("failed")

diff --git a/src/cmd/compile/internal/ssa/gen/AMD64.rules b/src/cmd/compile/internal/ssa/gen/AMD64.rules
index ab8e44a4442d4911bc5115a0b2f3e9b0748012a4..ec142d801e7c3e8437e3f9c72da5329adaada6ea 100644 (file)
--- a/src/cmd/compile/internal/ssa/gen/AMD64.rules
+++ b/src/cmd/compile/internal/ssa/gen/AMD64.rules
@@ -483,14 +483,14 @@
 (ADDLconst [c] (ADDLconst [d] x)) -> (ADDLconst [c+d] x)
 (ADDWconst [c] (ADDWconst [d] x)) -> (ADDWconst [c+d] x)
 (ADDBconst [c] (ADDBconst [d] x)) -> (ADDBconst [c+d] x)
-(SUBQconst [c] (MOVQconst [d])) -> (MOVQconst [c-d])
-(SUBLconst [c] (MOVLconst [d])) -> (MOVLconst [c-d])
-(SUBWconst [c] (MOVWconst [d])) -> (MOVWconst [c-d])
-(SUBBconst [c] (MOVBconst [d])) -> (MOVBconst [c-d])
-(SUBQconst [c] (SUBQconst [d] x)) -> (ADDQconst [c-d] x)
-(SUBLconst [c] (SUBLconst [d] x)) -> (ADDLconst [c-d] x)
-(SUBWconst [c] (SUBWconst [d] x)) -> (ADDWconst [c-d] x)
-(SUBBconst [c] (SUBBconst [d] x)) -> (ADDBconst [c-d] x)
+(SUBQconst [c] (MOVQconst [d])) -> (MOVQconst [d-c])
+(SUBLconst [c] (MOVLconst [d])) -> (MOVLconst [d-c])
+(SUBWconst [c] (MOVWconst [d])) -> (MOVWconst [d-c])
+(SUBBconst [c] (MOVBconst [d])) -> (MOVBconst [d-c])
+(SUBQconst [c] (SUBQconst [d] x)) -> (ADDQconst [-c-d] x)
+(SUBLconst [c] (SUBLconst [d] x)) -> (ADDLconst [-c-d] x)
+(SUBWconst [c] (SUBWconst [d] x)) -> (ADDWconst [-c-d] x)
+(SUBBconst [c] (SUBBconst [d] x)) -> (ADDBconst [-c-d] x)
 (NEGQ (MOVQconst [c])) -> (MOVQconst [-c])
 (NEGL (MOVLconst [c])) -> (MOVLconst [-c])
 (NEGW (MOVWconst [c])) -> (MOVWconst [-c])

diff --git a/src/cmd/compile/internal/ssa/rewriteAMD64.go b/src/cmd/compile/internal/ssa/rewriteAMD64.go
index a18097f91e1ffc1ac70296eed61ad8816b168760..a9f3ad79ab042c6c3990b799e93c0e71879d3a53 100644 (file)
--- a/src/cmd/compile/internal/ssa/rewriteAMD64.go
+++ b/src/cmd/compile/internal/ssa/rewriteAMD64.go
@@ -6801,30 +6801,30 @@ func rewriteValueAMD64(v *Value, config *Config) bool {
        case OpAMD64SUBBconst:
                // match: (SUBBconst [c] (MOVBconst [d]))
                // cond:
-               // result: (MOVBconst [c-d])
+               // result: (MOVBconst [d-c])
                {
                        c := v.AuxInt
                        if v.Args[0].Op != OpAMD64MOVBconst {
-                               goto end0e2d5c3e3c02001a20d5433daa9e8317
+                               goto enddc5383558e2f3eae507afcb94eada964
                        }
                        d := v.Args[0].AuxInt
                        v.Op = OpAMD64MOVBconst
                        v.AuxInt = 0
                        v.Aux = nil
                        v.resetArgs()
-                       v.AuxInt = c - d
+                       v.AuxInt = d - c
                        return true
                }
-               goto end0e2d5c3e3c02001a20d5433daa9e8317
-       end0e2d5c3e3c02001a20d5433daa9e8317:
+               goto enddc5383558e2f3eae507afcb94eada964
+       enddc5383558e2f3eae507afcb94eada964:
                ;
                // match: (SUBBconst [c] (SUBBconst [d] x))
                // cond:
-               // result: (ADDBconst [c-d] x)
+               // result: (ADDBconst [-c-d] x)
                {
                        c := v.AuxInt
                        if v.Args[0].Op != OpAMD64SUBBconst {
-                               goto end48eccb421dfe0c678ea9c47113521d5a
+                               goto end035c57413a46eb347ecb3736d1510915
                        }
                        d := v.Args[0].AuxInt
                        x := v.Args[0].Args[0]
@@ -6832,12 +6832,12 @@ func rewriteValueAMD64(v *Value, config *Config) bool {
                        v.AuxInt = 0
                        v.Aux = nil
                        v.resetArgs()
-                       v.AuxInt = c - d
+                       v.AuxInt = -c - d
                        v.AddArg(x)
                        return true
                }
-               goto end48eccb421dfe0c678ea9c47113521d5a
-       end48eccb421dfe0c678ea9c47113521d5a:
+               goto end035c57413a46eb347ecb3736d1510915
+       end035c57413a46eb347ecb3736d1510915:
                ;
        case OpAMD64SUBL:
                // match: (SUBL x (MOVLconst [c]))
@@ -6904,30 +6904,30 @@ func rewriteValueAMD64(v *Value, config *Config) bool {
        case OpAMD64SUBLconst:
                // match: (SUBLconst [c] (MOVLconst [d]))
                // cond:
-               // result: (MOVLconst [c-d])
+               // result: (MOVLconst [d-c])
                {
                        c := v.AuxInt
                        if v.Args[0].Op != OpAMD64MOVLconst {
-                               goto endbe7466f3c09d9645544bdfc44c37c922
+                               goto end6c5c6d58d4bdd0a5c2f7bf10b343b41e
                        }
                        d := v.Args[0].AuxInt
                        v.Op = OpAMD64MOVLconst
                        v.AuxInt = 0
                        v.Aux = nil
                        v.resetArgs()
-                       v.AuxInt = c - d
+                       v.AuxInt = d - c
                        return true
                }
-               goto endbe7466f3c09d9645544bdfc44c37c922
-       endbe7466f3c09d9645544bdfc44c37c922:
+               goto end6c5c6d58d4bdd0a5c2f7bf10b343b41e
+       end6c5c6d58d4bdd0a5c2f7bf10b343b41e:
                ;
                // match: (SUBLconst [c] (SUBLconst [d] x))
                // cond:
-               // result: (ADDLconst [c-d] x)
+               // result: (ADDLconst [-c-d] x)
                {
                        c := v.AuxInt
                        if v.Args[0].Op != OpAMD64SUBLconst {
-                               goto endb5106962a865bc4654b170c2e29a72c4
+                               goto end0c9ffb11e8a56ced1b14dbf6bf9a6737
                        }
                        d := v.Args[0].AuxInt
                        x := v.Args[0].Args[0]
@@ -6935,12 +6935,12 @@ func rewriteValueAMD64(v *Value, config *Config) bool {
                        v.AuxInt = 0
                        v.Aux = nil
                        v.resetArgs()
-                       v.AuxInt = c - d
+                       v.AuxInt = -c - d
                        v.AddArg(x)
                        return true
                }
-               goto endb5106962a865bc4654b170c2e29a72c4
-       endb5106962a865bc4654b170c2e29a72c4:
+               goto end0c9ffb11e8a56ced1b14dbf6bf9a6737
+       end0c9ffb11e8a56ced1b14dbf6bf9a6737:
                ;
        case OpAMD64SUBQ:
                // match: (SUBQ x (MOVQconst [c]))
@@ -7013,30 +7013,30 @@ func rewriteValueAMD64(v *Value, config *Config) bool {
        case OpAMD64SUBQconst:
                // match: (SUBQconst [c] (MOVQconst [d]))
                // cond:
-               // result: (MOVQconst [c-d])
+               // result: (MOVQconst [d-c])
                {
                        c := v.AuxInt
                        if v.Args[0].Op != OpAMD64MOVQconst {
-                               goto end96c09479fb3c043e875d89d3eb92f1d8
+                               goto endb0daebe6831cf381377c3e4248070f25
                        }
                        d := v.Args[0].AuxInt
                        v.Op = OpAMD64MOVQconst
                        v.AuxInt = 0
                        v.Aux = nil
                        v.resetArgs()
-                       v.AuxInt = c - d
+                       v.AuxInt = d - c
                        return true
                }
-               goto end96c09479fb3c043e875d89d3eb92f1d8
-       end96c09479fb3c043e875d89d3eb92f1d8:
+               goto endb0daebe6831cf381377c3e4248070f25
+       endb0daebe6831cf381377c3e4248070f25:
                ;
                // match: (SUBQconst [c] (SUBQconst [d] x))
                // cond:
-               // result: (ADDQconst [c-d] x)
+               // result: (ADDQconst [-c-d] x)
                {
                        c := v.AuxInt
                        if v.Args[0].Op != OpAMD64SUBQconst {
-                               goto enddd9d61b404480adb40cfd7fedd7e5ec4
+                               goto end2d40ddb5ae9e90679456254c61858d9d
                        }
                        d := v.Args[0].AuxInt
                        x := v.Args[0].Args[0]
@@ -7044,12 +7044,12 @@ func rewriteValueAMD64(v *Value, config *Config) bool {
                        v.AuxInt = 0
                        v.Aux = nil
                        v.resetArgs()
-                       v.AuxInt = c - d
+                       v.AuxInt = -c - d
                        v.AddArg(x)
                        return true
                }
-               goto enddd9d61b404480adb40cfd7fedd7e5ec4
-       enddd9d61b404480adb40cfd7fedd7e5ec4:
+               goto end2d40ddb5ae9e90679456254c61858d9d
+       end2d40ddb5ae9e90679456254c61858d9d:
                ;
        case OpAMD64SUBW:
                // match: (SUBW x (MOVWconst [c]))
@@ -7116,30 +7116,30 @@ func rewriteValueAMD64(v *Value, config *Config) bool {
        case OpAMD64SUBWconst:
                // match: (SUBWconst [c] (MOVWconst [d]))
                // cond:
-               // result: (MOVWconst [c-d])
+               // result: (MOVWconst [d-c])
                {
                        c := v.AuxInt
                        if v.Args[0].Op != OpAMD64MOVWconst {
-                               goto end0e5079577fcf00f5925291dbd68306aa
+                               goto endae629a229c399eaed7dbb95b1b0e6f8a
                        }
                        d := v.Args[0].AuxInt
                        v.Op = OpAMD64MOVWconst
                        v.AuxInt = 0
                        v.Aux = nil
                        v.resetArgs()
-                       v.AuxInt = c - d
+                       v.AuxInt = d - c
                        return true
                }
-               goto end0e5079577fcf00f5925291dbd68306aa
-       end0e5079577fcf00f5925291dbd68306aa:
+               goto endae629a229c399eaed7dbb95b1b0e6f8a
+       endae629a229c399eaed7dbb95b1b0e6f8a:
                ;
                // match: (SUBWconst [c] (SUBWconst [d] x))
                // cond:
-               // result: (ADDWconst [c-d] x)
+               // result: (ADDWconst [-c-d] x)
                {
                        c := v.AuxInt
                        if v.Args[0].Op != OpAMD64SUBWconst {
-                               goto endb628696cf5b329d03782b8093093269b
+                               goto enda59f08d12aa08717b0443b7bb1b71374
                        }
                        d := v.Args[0].AuxInt
                        x := v.Args[0].Args[0]
@@ -7147,12 +7147,12 @@ func rewriteValueAMD64(v *Value, config *Config) bool {
                        v.AuxInt = 0
                        v.Aux = nil
                        v.resetArgs()
-                       v.AuxInt = c - d
+                       v.AuxInt = -c - d
                        v.AddArg(x)
                        return true
                }
-               goto endb628696cf5b329d03782b8093093269b
-       endb628696cf5b329d03782b8093093269b:
+               goto enda59f08d12aa08717b0443b7bb1b71374
+       enda59f08d12aa08717b0443b7bb1b71374:
                ;
        case OpSignExt16to32:
                // match: (SignExt16to32 x)