cmd/compile: fold negation into addition/subtraction on mips64x

Fold negation into addition/subtraction and avoid double negation.

file      before    after     Δ       %
addr2line 4007310   4007470   +160    +0.004%
asm       7007636   7007436   -200    -0.003%
buildid   3839268   3838972   -296    -0.008%
cgo       6353466   6352738   -728    -0.011%
compile   30426920  30426896  -24     -0.000%
cover     7005408   7004744   -664    -0.009%
dist      4651192   4650872   -320    -0.007%
doc       10606050  10606034  -16     -0.000%
fix       4446414   4446390   -24     -0.001%
link      9237736   9237024   -712    -0.008%
nm        3999107   3999323   +216    +0.005%
objdump   6762424   6762144   -280    -0.004%
pack      3270757   3270493   -264    -0.008%
pprof     19428299  19361939  -66360  -0.342%
test2json 3717345   3717217   -128    -0.003%
trace     17382273  17381657  -616    -0.004%
vet       10689481  10688985  -496    -0.005%
go        19118769  19118609  -160    -0.001%
total     171949855 171878943 -70912  -0.041%

Change-Id: I35c1f264d216c214ea3f56252a9ddab8ea850fa6
Reviewed-on: https://go-review.googlesource.com/c/go/+/673555
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Keith Randall <khr@google.com>
Auto-Submit: Keith Randall <khr@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>

diff --git a/src/cmd/compile/internal/ssa/_gen/MIPS64.rules b/src/cmd/compile/internal/ssa/_gen/MIPS64.rules
index 5b55c3bef75e9c0075bef43f680ec4ec5eec28c9..cd82655ff3fa99f170f882f6f0b572cd6108262a 100644 (file)
--- a/src/cmd/compile/internal/ssa/_gen/MIPS64.rules
+++ b/src/cmd/compile/internal/ssa/_gen/MIPS64.rules
@@ -719,11 +719,14 @@
 
 // generic simplifications
 (ADDV x (NEGV y)) => (SUBV x y)
+(SUBV x (NEGV y)) => (ADDV x y)
 (SUBV x x) => (MOVVconst [0])
 (SUBV (MOVVconst [0]) x) => (NEGV x)
 (AND x x) => x
 (OR  x x) => x
 (XOR x x) => (MOVVconst [0])
+(NEGV (SUBV x y)) => (SUBV y x)
+(NEGV (NEGV x)) => x
 
 // remove redundant *const ops
 (ADDVconst [0]  x) => x

diff --git a/src/cmd/compile/internal/ssa/rewriteMIPS64.go b/src/cmd/compile/internal/ssa/rewriteMIPS64.go
index 10281e7e70905acd5729247c24c275e9f1664524..14b273f9aa0db1c8c8cee071555d227db6c4345a 100644 (file)
--- a/src/cmd/compile/internal/ssa/rewriteMIPS64.go
+++ b/src/cmd/compile/internal/ssa/rewriteMIPS64.go
@@ -4673,6 +4673,28 @@ func rewriteValueMIPS64_OpMIPS64MOVWstorezero(v *Value) bool {
 }
 func rewriteValueMIPS64_OpMIPS64NEGV(v *Value) bool {
        v_0 := v.Args[0]
+       // match: (NEGV (SUBV x y))
+       // result: (SUBV y x)
+       for {
+               if v_0.Op != OpMIPS64SUBV {
+                       break
+               }
+               y := v_0.Args[1]
+               x := v_0.Args[0]
+               v.reset(OpMIPS64SUBV)
+               v.AddArg2(y, x)
+               return true
+       }
+       // match: (NEGV (NEGV x))
+       // result: x
+       for {
+               if v_0.Op != OpMIPS64NEGV {
+                       break
+               }
+               x := v_0.Args[0]
+               v.copyOf(x)
+               return true
+       }
        // match: (NEGV (MOVVconst [c]))
        // result: (MOVVconst [-c])
        for {
@@ -5319,6 +5341,18 @@ func rewriteValueMIPS64_OpMIPS64SUBV(v *Value) bool {
                v.AddArg(x)
                return true
        }
+       // match: (SUBV x (NEGV y))
+       // result: (ADDV x y)
+       for {
+               x := v_0
+               if v_1.Op != OpMIPS64NEGV {
+                       break
+               }
+               y := v_1.Args[0]
+               v.reset(OpMIPS64ADDV)
+               v.AddArg2(x, y)
+               return true
+       }
        // match: (SUBV x x)
        // result: (MOVVconst [0])
        for {

diff --git a/test/codegen/arithmetic.go b/test/codegen/arithmetic.go
index d02154bd3cb4c07a10d198e08d1051cf5ca2751c..1023a62beee944389cd5e84221367f53b6050061 100644 (file)
--- a/test/codegen/arithmetic.go
+++ b/test/codegen/arithmetic.go
@@ -92,6 +92,7 @@ func SubFromConst(a int) int {
 
 func SubFromConstNeg(a int) int {
        // loong64: "ADDV[U]\t\\$40"
+       // mips64: "ADDV[U]\t\\$40"
        // ppc64x: `ADD\t[$]40,\sR[0-9]+,\sR`
        // riscv64: "ADDI\t\\$40",-"NEG"
        c := 40 - (-a)
@@ -100,6 +101,7 @@ func SubFromConstNeg(a int) int {
 
 func SubSubFromConst(a int) int {
        // loong64: "ADDV[U]\t\\$20"
+       // mips64: "ADDV[U]\t\\$20"
        // ppc64x: `ADD\t[$]20,\sR[0-9]+,\sR`
        // riscv64: "ADDI\t\\$20",-"NEG"
        c := 40 - (20 - a)
@@ -115,6 +117,7 @@ func AddSubFromConst(a int) int {
 
 func NegSubFromConst(a int) int {
        // loong64: "ADDV[U]\t\\$-20"
+       // mips64: "ADDV[U]\t\\$-20"
        // ppc64x: `ADD\t[$]-20,\sR[0-9]+,\sR`
        // riscv64: "ADDI\t\\$-20"
        c := -(20 - a)
@@ -123,6 +126,7 @@ func NegSubFromConst(a int) int {
 
 func NegAddFromConstNeg(a int) int {
        // loong64: "ADDV[U]\t\\$-40","SUBV"
+       // mips64: "ADDV[U]\t\\$-40","SUBV"
        // ppc64x: `SUBC\tR[0-9]+,\s[$]40,\sR`
        // riscv64: "ADDI\t\\$-40","NEG"
        c := -(-40 + a)
@@ -132,6 +136,7 @@ func NegAddFromConstNeg(a int) int {
 func SubSubNegSimplify(a, b int) int {
        // amd64:"NEGQ"
        // loong64:"SUBV"
+       // mips64:"SUBV"
        // ppc64x:"NEG"
        // riscv64:"NEG",-"SUB"
        r := (a - b) - a
@@ -141,6 +146,7 @@ func SubSubNegSimplify(a, b int) int {
 func SubAddSimplify(a, b int) int {
        // amd64:-"SUBQ",-"ADDQ"
        // loong64:-"SUBV",-"ADDV"
+       // mips64:-"SUBV",-"ADDV"
        // ppc64x:-"SUB",-"ADD"
        // riscv64:-"SUB",-"ADD"
        r := a + (b - a)
@@ -149,6 +155,7 @@ func SubAddSimplify(a, b int) int {
 
 func SubAddSimplify2(a, b, c int) (int, int, int, int, int, int) {
        // amd64:-"ADDQ"
+       // mips64:"SUBV",-"ADDV"
        // loong64:"SUBV",-"ADDV"
        r := (a + b) - (a + c)
        // amd64:-"ADDQ"
@@ -158,6 +165,7 @@ func SubAddSimplify2(a, b, c int) (int, int, int, int, int, int) {
        // amd64:-"ADDQ"
        r3 := (b + a) - (c + a)
        // amd64:-"SUBQ"
+       // mips64:"ADDV",-"SUBV"
        // loong64:"ADDV",-"SUBV"
        r4 := (a - c) + (c + b)
        // amd64:-"SUBQ"
@@ -168,6 +176,7 @@ func SubAddSimplify2(a, b, c int) (int, int, int, int, int, int) {
 func SubAddNegSimplify(a, b int) int {
        // amd64:"NEGQ",-"ADDQ",-"SUBQ"
        // loong64:"SUBV",-"ADDV"
+       // mips64:"SUBV",-"ADDV"
        // ppc64x:"NEG",-"ADD",-"SUB"
        // riscv64:"NEG",-"ADD",-"SUB"
        r := a - (b + a)
@@ -177,6 +186,7 @@ func SubAddNegSimplify(a, b int) int {
 func AddAddSubSimplify(a, b, c int) int {
        // amd64:-"SUBQ"
        // loong64:"ADDV",-"SUBV"
+       // mips64:"ADDV",-"SUBV"
        // ppc64x:-"SUB"
        // riscv64:"ADD","ADD",-"SUB"
        r := a + (b + (c - a))