[dev.simd] cmd/compile: improve slicemask removal

this will be subsumed by pending changes in local slice
representation, however this was easy and works well.

Change-Id: I5b6eb10d257f04f906be7a8a6f2b6833992a39e8
Reviewed-on: https://go-review.googlesource.com/c/go/+/704876
Reviewed-by: Keith Randall <khr@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Keith Randall <khr@google.com>

diff --git a/src/cmd/compile/internal/ssa/prove.go b/src/cmd/compile/internal/ssa/prove.go
index 5ed5be47443d77fbc55a37d08b3de0050b4136e9..b4f91fd4fd12dcab9c12e73be5f127a284e223f4 100644 (file)
--- a/src/cmd/compile/internal/ssa/prove.go
+++ b/src/cmd/compile/internal/ssa/prove.go
@@ -2529,24 +2529,38 @@ func simplifyBlock(sdom SparseTree, ft *factsTable, b *Block) {
                switch v.Op {
                case OpSlicemask:
                        // Replace OpSlicemask operations in b with constants where possible.
-                       x, delta := isConstDelta(v.Args[0])
-                       if x == nil {
+                       cap := v.Args[0]
+                       x, delta := isConstDelta(cap)
+                       if x != nil {
+                               // slicemask(x + y)
+                               // if x is larger than -y (y is negative), then slicemask is -1.
+                               lim := ft.limits[x.ID]
+                               if lim.umin > uint64(-delta) {
+                                       if cap.Op == OpAdd64 {
+                                               v.reset(OpConst64)
+                                       } else {
+                                               v.reset(OpConst32)
+                                       }
+                                       if b.Func.pass.debug > 0 {
+                                               b.Func.Warnl(v.Pos, "Proved slicemask not needed")
+                                       }
+                                       v.AuxInt = -1
+                               }
                                break
                        }
-                       // slicemask(x + y)
-                       // if x is larger than -y (y is negative), then slicemask is -1.
-                       lim := ft.limits[x.ID]
-                       if lim.umin > uint64(-delta) {
-                               if v.Args[0].Op == OpAdd64 {
+                       lim := ft.limits[cap.ID]
+                       if lim.umin > 0 {
+                               if cap.Type.Size() == 8 {
                                        v.reset(OpConst64)
                                } else {
                                        v.reset(OpConst32)
                                }
                                if b.Func.pass.debug > 0 {
-                                       b.Func.Warnl(v.Pos, "Proved slicemask not needed")
+                                       b.Func.Warnl(v.Pos, "Proved slicemask not needed (by limit)")
                                }
                                v.AuxInt = -1
                        }
+
                case OpCtz8, OpCtz16, OpCtz32, OpCtz64:
                        // On some architectures, notably amd64, we can generate much better
                        // code for CtzNN if we know that the argument is non-zero.

diff --git a/test/loopbce.go b/test/loopbce.go
index 8bc44ece9455a0c87c41ada47fe8119f7234bc93..8a58d942361221738b4bca9e03614ade8eddda10 100644 (file)
--- a/test/loopbce.go
+++ b/test/loopbce.go
@@ -9,7 +9,7 @@ import "math"
 func f0a(a []int) int {
        x := 0
        for i := range a { // ERROR "Induction variable: limits \[0,\?\), increment 1$"
-               x += a[i] // ERROR "(\([0-9]+\) )?Proved IsInBounds$"
+               x += a[i] // ERROR "Proved IsInBounds$"
        }
        return x
 }
@@ -17,7 +17,7 @@ func f0a(a []int) int {
 func f0b(a []int) int {
        x := 0
        for i := range a { // ERROR "Induction variable: limits \[0,\?\), increment 1$"
-               b := a[i:] // ERROR "(\([0-9]+\) )?Proved IsSliceInBounds$"
+               b := a[i:] // ERROR "Proved IsSliceInBounds$"
                x += b[0]
        }
        return x
@@ -26,8 +26,8 @@ func f0b(a []int) int {
 func f0c(a []int) int {
        x := 0
        for i := range a { // ERROR "Induction variable: limits \[0,\?\), increment 1$"
-               b := a[:i+1] // ERROR "(\([0-9]+\) )?Proved IsSliceInBounds$"
-               x += b[0]    // ERROR "(\([0-9]+\) )?Proved IsInBounds$"
+               b := a[:i+1] // ERROR "Proved IsSliceInBounds$"
+               x += b[0]    // ERROR "Proved IsInBounds$"
        }
        return x
 }
@@ -43,7 +43,7 @@ func f1(a []int) int {
 func f2(a []int) int {
        x := 0
        for i := 1; i < len(a); i++ { // ERROR "Induction variable: limits \[1,\?\), increment 1$"
-               x += a[i] // ERROR "(\([0-9]+\) )?Proved IsInBounds$"
+               x += a[i] // ERROR "Proved IsInBounds$"
        }
        return x
 }
@@ -51,7 +51,7 @@ func f2(a []int) int {
 func f4(a [10]int) int {
        x := 0
        for i := 0; i < len(a); i += 2 { // ERROR "Induction variable: limits \[0,8\], increment 2$"
-               x += a[i] // ERROR "(\([0-9]+\) )?Proved IsInBounds$"
+               x += a[i] // ERROR "Proved IsInBounds$"
        }
        return x
 }
@@ -91,7 +91,7 @@ func f5_int8(a [10]int) int {
 //go:noinline
 func f6(a []int) {
        for i := range a { // ERROR "Induction variable: limits \[0,\?\), increment 1$"
-               b := a[0:i] // ERROR "(\([0-9]+\) )?Proved IsSliceInBounds$"
+               b := a[0:i] // ERROR "Proved IsSliceInBounds$"
                f6(b)
        }
 }
@@ -99,7 +99,7 @@ func f6(a []int) {
 func g0a(a string) int {
        x := 0
        for i := 0; i < len(a); i++ { // ERROR "Induction variable: limits \[0,\?\), increment 1$"
-               x += int(a[i]) // ERROR "(\([0-9]+\) )?Proved IsInBounds$"
+               x += int(a[i]) // ERROR "Proved IsInBounds$"
        }
        return x
 }
@@ -107,7 +107,7 @@ func g0a(a string) int {
 func g0b(a string) int {
        x := 0
        for i := 0; len(a) > i; i++ { // ERROR "Induction variable: limits \[0,\?\), increment 1$"
-               x += int(a[i]) // ERROR "(\([0-9]+\) )?Proved IsInBounds$"
+               x += int(a[i]) // ERROR "Proved IsInBounds$"
        }
        return x
 }
@@ -115,7 +115,7 @@ func g0b(a string) int {
 func g0c(a string) int {
        x := 0
        for i := len(a); i > 0; i-- { // ERROR "Induction variable: limits \(0,\?\], increment 1$"
-               x += int(a[i-1]) // ERROR "(\([0-9]+\) )?Proved IsInBounds$"
+               x += int(a[i-1]) // ERROR "Proved IsInBounds$"
        }
        return x
 }
@@ -123,7 +123,7 @@ func g0c(a string) int {
 func g0d(a string) int {
        x := 0
        for i := len(a); 0 < i; i-- { // ERROR "Induction variable: limits \(0,\?\], increment 1$"
-               x += int(a[i-1]) // ERROR "(\([0-9]+\) )?Proved IsInBounds$"
+               x += int(a[i-1]) // ERROR "Proved IsInBounds$"
        }
        return x
 }
@@ -131,7 +131,7 @@ func g0d(a string) int {
 func g0e(a string) int {
        x := 0
        for i := len(a) - 1; i >= 0; i-- { // ERROR "Induction variable: limits \[0,\?\], increment 1$"
-               x += int(a[i]) // ERROR "(\([0-9]+\) )?Proved IsInBounds$"
+               x += int(a[i]) // ERROR "Proved IsInBounds$"
        }
        return x
 }
@@ -139,7 +139,7 @@ func g0e(a string) int {
 func g0f(a string) int {
        x := 0
        for i := len(a) - 1; 0 <= i; i-- { // ERROR "Induction variable: limits \[0,\?\], increment 1$"
-               x += int(a[i]) // ERROR "(\([0-9]+\) )?Proved IsInBounds$"
+               x += int(a[i]) // ERROR "Proved IsInBounds$"
        }
        return x
 }
@@ -148,7 +148,7 @@ func g1() int {
        a := "evenlength"
        x := 0
        for i := 0; i < len(a); i += 2 { // ERROR "Induction variable: limits \[0,8\], increment 2$"
-               x += int(a[i]) // ERROR "(\([0-9]+\) )?Proved IsInBounds$"
+               x += int(a[i]) // ERROR "Proved IsInBounds$"
        }
        return x
 }
@@ -158,7 +158,7 @@ func g2() int {
        x := 0
        for i := 0; i < len(a); i += 2 { // ERROR "Induction variable: limits \[0,8\], increment 2$"
                j := i
-               if a[i] == 'e' { // ERROR "(\([0-9]+\) )?Proved IsInBounds$"
+               if a[i] == 'e' { // ERROR "Proved IsInBounds$"
                        j = j + 1
                }
                x += int(a[j])
@@ -169,29 +169,29 @@ func g2() int {
 func g3a() {
        a := "this string has length 25"
        for i := 0; i < len(a); i += 5 { // ERROR "Induction variable: limits \[0,20\], increment 5$"
-               useString(a[i:])   // ERROR "(\([0-9]+\) )?Proved IsSliceInBounds$"
-               useString(a[:i+3]) // ERROR "(\([0-9]+\) )?Proved IsSliceInBounds$"
-               useString(a[:i+5]) // ERROR "(\([0-9]+\) )?Proved IsSliceInBounds$"
+               useString(a[i:])   // ERROR "Proved IsSliceInBounds$" "Proved slicemask not needed \(by limit\)$"
+               useString(a[:i+3]) // ERROR "Proved IsSliceInBounds$"
+               useString(a[:i+5]) // ERROR "Proved IsSliceInBounds$"
                useString(a[:i+6])
        }
 }
 
 func g3b(a string) {
        for i := 0; i < len(a); i++ { // ERROR "Induction variable: limits \[0,\?\), increment 1$"
-               useString(a[i+1:]) // ERROR "(\([0-9]+\) )?Proved IsSliceInBounds$"
+               useString(a[i+1:]) // ERROR "Proved IsSliceInBounds$"
        }
 }
 
 func g3c(a string) {
        for i := 0; i < len(a); i++ { // ERROR "Induction variable: limits \[0,\?\), increment 1$"
-               useString(a[:i+1]) // ERROR "(\([0-9]+\) )?Proved IsSliceInBounds$"
+               useString(a[:i+1]) // ERROR "Proved IsSliceInBounds$"
        }
 }
 
 func h1(a []byte) {
        c := a[:128]
        for i := range c { // ERROR "Induction variable: limits \[0,128\), increment 1$"
-               c[i] = byte(i) // ERROR "(\([0-9]+\) )?Proved IsInBounds$"
+               c[i] = byte(i) // ERROR "Proved IsInBounds$"
        }
 }
 
@@ -208,11 +208,11 @@ func k0(a [100]int) [100]int {
                        continue
                }
                a[i-11] = i
-               a[i-10] = i // ERROR "(\([0-9]+\) )?Proved IsInBounds$"
-               a[i-5] = i  // ERROR "(\([0-9]+\) )?Proved IsInBounds$"
-               a[i] = i    // ERROR "(\([0-9]+\) )?Proved IsInBounds$"
-               a[i+5] = i  // ERROR "(\([0-9]+\) )?Proved IsInBounds$"
-               a[i+10] = i // ERROR "(\([0-9]+\) )?Proved IsInBounds$"
+               a[i-10] = i // ERROR "Proved IsInBounds$"
+               a[i-5] = i  // ERROR "Proved IsInBounds$"
+               a[i] = i    // ERROR "Proved IsInBounds$"
+               a[i+5] = i  // ERROR "Proved IsInBounds$"
+               a[i+10] = i // ERROR "Proved IsInBounds$"
                a[i+11] = i
        }
        return a
@@ -225,12 +225,12 @@ func k1(a [100]int) [100]int {
                        continue
                }
                useSlice(a[:i-11])
-               useSlice(a[:i-10]) // ERROR "(\([0-9]+\) )?Proved IsSliceInBounds$"
-               useSlice(a[:i-5])  // ERROR "(\([0-9]+\) )?Proved IsSliceInBounds$"
-               useSlice(a[:i])    // ERROR "(\([0-9]+\) )?Proved IsSliceInBounds$"
-               useSlice(a[:i+5])  // ERROR "(\([0-9]+\) )?Proved IsSliceInBounds$"
-               useSlice(a[:i+10]) // ERROR "(\([0-9]+\) )?Proved IsSliceInBounds$"
-               useSlice(a[:i+11]) // ERROR "(\([0-9]+\) )?Proved IsSliceInBounds$"
+               useSlice(a[:i-10]) // ERROR "Proved IsSliceInBounds$"
+               useSlice(a[:i-5])  // ERROR "Proved IsSliceInBounds$"
+               useSlice(a[:i])    // ERROR "Proved IsSliceInBounds$"
+               useSlice(a[:i+5])  // ERROR "Proved IsSliceInBounds$"
+               useSlice(a[:i+10]) // ERROR "Proved IsSliceInBounds$"
+               useSlice(a[:i+11]) // ERROR "Proved IsSliceInBounds$"
                useSlice(a[:i+12])
 
        }
@@ -243,13 +243,13 @@ func k2(a [100]int) [100]int {
                        // This is a trick to prohibit sccp to optimize out the following out of bound check
                        continue
                }
-               useSlice(a[i-11:])
-               useSlice(a[i-10:]) // ERROR "(\([0-9]+\) )?Proved IsSliceInBounds$"
-               useSlice(a[i-5:])  // ERROR "(\([0-9]+\) )?Proved IsSliceInBounds$"
-               useSlice(a[i:])    // ERROR "(\([0-9]+\) )?Proved IsSliceInBounds$"
-               useSlice(a[i+5:])  // ERROR "(\([0-9]+\) )?Proved IsSliceInBounds$"
-               useSlice(a[i+10:]) // ERROR "(\([0-9]+\) )?Proved IsSliceInBounds$"
-               useSlice(a[i+11:]) // ERROR "(\([0-9]+\) )?Proved IsSliceInBounds$"
+               useSlice(a[i-11:]) // ERROR "Proved slicemask not needed \(by limit\)$"
+               useSlice(a[i-10:]) // ERROR "Proved IsSliceInBounds$" "Proved slicemask not needed \(by limit\)$"
+               useSlice(a[i-5:])  // ERROR "Proved IsSliceInBounds$" "Proved slicemask not needed \(by limit\)$"
+               useSlice(a[i:])    // ERROR "Proved IsSliceInBounds$" "Proved slicemask not needed \(by limit\)$"
+               useSlice(a[i+5:])  // ERROR "Proved IsSliceInBounds$" "Proved slicemask not needed \(by limit\)$"
+               useSlice(a[i+10:]) // ERROR "Proved IsSliceInBounds$" "Proved slicemask not needed \(by limit\)$"
+               useSlice(a[i+11:]) // ERROR "Proved IsSliceInBounds$"
                useSlice(a[i+12:])
        }
        return a
@@ -262,7 +262,7 @@ func k3(a [100]int) [100]int {
                        continue
                }
                a[i+9] = i
-               a[i+10] = i // ERROR "(\([0-9]+\) )?Proved IsInBounds$"
+               a[i+10] = i // ERROR "Proved IsInBounds$"
                a[i+11] = i
        }
        return a
@@ -275,7 +275,7 @@ func k3neg(a [100]int) [100]int {
                        continue
                }
                a[i+9] = i
-               a[i+10] = i // ERROR "(\([0-9]+\) )?Proved IsInBounds$"
+               a[i+10] = i // ERROR "Proved IsInBounds$"
                a[i+11] = i
        }
        return a
@@ -288,7 +288,7 @@ func k3neg2(a [100]int) [100]int {
                        continue
                }
                a[i+9] = i
-               a[i+10] = i // ERROR "(\([0-9]+\) )?Proved IsInBounds$"
+               a[i+10] = i // ERROR "Proved IsInBounds$"
                a[i+11] = i
        }
        return a
@@ -299,7 +299,7 @@ func k4(a [100]int) [100]int {
        // and it isn't worth adding that special case to prove.
        min := (-1)<<63 + 1
        for i := min; i < min+50; i++ { // ERROR "Induction variable: limits \[-9223372036854775807,-9223372036854775757\), increment 1$"
-               a[i-min] = i // ERROR "(\([0-9]+\) )?Proved IsInBounds$"
+               a[i-min] = i // ERROR "Proved IsInBounds$"
        }
        return a
 }
@@ -307,8 +307,8 @@ func k4(a [100]int) [100]int {
 func k5(a [100]int) [100]int {
        max := (1 << 63) - 1
        for i := max - 50; i < max; i++ { // ERROR "Induction variable: limits \[9223372036854775757,9223372036854775807\), increment 1$"
-               a[i-max+50] = i   // ERROR "(\([0-9]+\) )?Proved IsInBounds$"
-               a[i-(max-70)] = i // ERROR "(\([0-9]+\) )?Proved IsInBounds$"
+               a[i-max+50] = i   // ERROR "Proved IsInBounds$"
+               a[i-(max-70)] = i // ERROR "Proved IsInBounds$"
        }
        return a
 }
@@ -374,22 +374,22 @@ func d4() {
 }
 
 func d5() {
-       for i := int64(math.MinInt64 + 9); i > math.MinInt64+2; i -= 4 { // ERROR "Induction variable: limits \[-9223372036854775803,-9223372036854775799\], increment 4"
+       for i := int64(math.MinInt64 + 9); i > math.MinInt64+2; i -= 4 { // ERROR "Induction variable: limits \[-9223372036854775803,-9223372036854775799\], increment 4$"
                useString("foo")
        }
-       for i := int64(math.MinInt64 + 8); i > math.MinInt64+2; i -= 4 { // ERROR "Induction variable: limits \[-9223372036854775804,-9223372036854775800\], increment 4"
+       for i := int64(math.MinInt64 + 8); i > math.MinInt64+2; i -= 4 { // ERROR "Induction variable: limits \[-9223372036854775804,-9223372036854775800\], increment 4$"
                useString("foo")
        }
        for i := int64(math.MinInt64 + 7); i > math.MinInt64+2; i -= 4 {
                useString("foo")
        }
-       for i := int64(math.MinInt64 + 6); i > math.MinInt64+2; i -= 4 { // ERROR "Induction variable: limits \[-9223372036854775802,-9223372036854775802\], increment 4"
+       for i := int64(math.MinInt64 + 6); i > math.MinInt64+2; i -= 4 { // ERROR "Induction variable: limits \[-9223372036854775802,-9223372036854775802\], increment 4$"
                useString("foo")
        }
-       for i := int64(math.MinInt64 + 9); i >= math.MinInt64+2; i -= 4 { // ERROR "Induction variable: limits \[-9223372036854775803,-9223372036854775799\], increment 4"
+       for i := int64(math.MinInt64 + 9); i >= math.MinInt64+2; i -= 4 { // ERROR "Induction variable: limits \[-9223372036854775803,-9223372036854775799\], increment 4$"
                useString("foo")
        }
-       for i := int64(math.MinInt64 + 8); i >= math.MinInt64+2; i -= 4 { // ERROR "Induction variable: limits \[-9223372036854775804,-9223372036854775800\], increment 4"
+       for i := int64(math.MinInt64 + 8); i >= math.MinInt64+2; i -= 4 { // ERROR "Induction variable: limits \[-9223372036854775804,-9223372036854775800\], increment 4$"
                useString("foo")
        }
        for i := int64(math.MinInt64 + 7); i >= math.MinInt64+2; i -= 4 {
@@ -410,23 +410,23 @@ func bce1() {
                panic("invalid test: modulos should differ")
        }
 
-       for i := b; i < a; i += z { // ERROR "Induction variable: limits \[-1547,9223372036854772720\], increment 1337"
+       for i := b; i < a; i += z { // ERROR "Induction variable: limits \[-1547,9223372036854772720\], increment 1337$"
                useString("foobar")
        }
 }
 
 func nobce2(a string) {
        for i := int64(0); i < int64(len(a)); i++ { // ERROR "Induction variable: limits \[0,\?\), increment 1$"
-               useString(a[i:]) // ERROR "(\([0-9]+\) )?Proved IsSliceInBounds$"
+               useString(a[i:]) // ERROR "Proved IsSliceInBounds$"
        }
        for i := int64(0); i < int64(len(a))-31337; i++ { // ERROR "Induction variable: limits \[0,\?\), increment 1$"
-               useString(a[i:]) // ERROR "(\([0-9]+\) )?Proved IsSliceInBounds$"
+               useString(a[i:]) // ERROR "Proved IsSliceInBounds$"
        }
-       for i := int64(0); i < int64(len(a))+int64(-1<<63); i++ { // ERROR "Induction variable: limits \[0,\?\), increment 1$" "Disproved Less64"
+       for i := int64(0); i < int64(len(a))+int64(-1<<63); i++ { // ERROR "Disproved Less64$" "Induction variable: limits \[0,\?\), increment 1$"
                useString(a[i:])
        }
        j := int64(len(a)) - 123
-       for i := int64(0); i < j+123+int64(-1<<63); i++ { // ERROR "Induction variable: limits \[0,\?\), increment 1$" "Disproved Less64"
+       for i := int64(0); i < j+123+int64(-1<<63); i++ { // ERROR "Disproved Less64$" "Induction variable: limits \[0,\?\), increment 1$"
                useString(a[i:])
        }
        for i := int64(0); i < j+122+int64(-1<<63); i++ { // ERROR "Induction variable: limits \[0,\?\), increment 1$"
@@ -455,16 +455,16 @@ func issue26116a(a []int) {
 
 func stride1(x *[7]int) int {
        s := 0
-       for i := 0; i <= 8; i += 3 { // ERROR "Induction variable: limits \[0,6\], increment 3"
-               s += x[i] // ERROR "Proved IsInBounds"
+       for i := 0; i <= 8; i += 3 { // ERROR "Induction variable: limits \[0,6\], increment 3$"
+               s += x[i] // ERROR "Proved IsInBounds$"
        }
        return s
 }
 
 func stride2(x *[7]int) int {
        s := 0
-       for i := 0; i < 9; i += 3 { // ERROR "Induction variable: limits \[0,6\], increment 3"
-               s += x[i] // ERROR "Proved IsInBounds"
+       for i := 0; i < 9; i += 3 { // ERROR "Induction variable: limits \[0,6\], increment 3$"
+               s += x[i] // ERROR "Proved IsInBounds$"
        }
        return s
 }