cmd/compile/internal/ssa: generalize prove to all booleans

* Refacts a bit saving and restoring parents restrictions
* Shaves ~100k from pkg/tools/linux_amd64,
but most of the savings come from the rewrite rules.
* Improves on the following artificial test case:
func f1(a4 bool, a6 bool) bool {
  return a6 || (a6 || (a6 || a4)) || (a6 || (a4 || a6 || (false || a6)))
}

Change-Id: I714000f75a37a3a6617c6e6834c75bd23674215f
Reviewed-on: https://go-review.googlesource.com/20306Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Alexandru Moșoi <alexandru@mosoi.ro>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/cmd/compile/internal/ssa/gen/generic.rules

@@ -77,14 +77,19 @@
 (Rsh8x64   (Const8  [0]) _) -> (Const8  [0])
 (Rsh8Ux64  (Const8  [0]) _) -> (Const8  [0])
 
+(IsInBounds x x) -> (ConstBool [0])
 (IsInBounds (And32 (Const32 [c]) _) (Const32 [d])) && inBounds32(c, d) -> (ConstBool [1])
 (IsInBounds (And64 (Const64 [c]) _) (Const64 [d])) && inBounds64(c, d) -> (ConstBool [1])
 (IsInBounds (Const32 [c]) (Const32 [d])) -> (ConstBool [b2i(inBounds32(c,d))])
 (IsInBounds (Const64 [c]) (Const64 [d])) -> (ConstBool [b2i(inBounds64(c,d))])
+(IsSliceInBounds x x) -> (ConstBool [1])
 (IsSliceInBounds (And32 (Const32 [c]) _) (Const32 [d])) && sliceInBounds32(c, d) -> (ConstBool [1])
 (IsSliceInBounds (And64 (Const64 [c]) _) (Const64 [d])) && sliceInBounds64(c, d) -> (ConstBool [1])
+(IsSliceInBounds (Const32 [0]) _) -> (ConstBool [1])
+(IsSliceInBounds (Const64 [0]) _) -> (ConstBool [1])
 (IsSliceInBounds (Const32 [c]) (Const32 [d])) -> (ConstBool [b2i(sliceInBounds32(c,d))])
 (IsSliceInBounds (Const64 [c]) (Const64 [d])) -> (ConstBool [b2i(sliceInBounds64(c,d))])
+(IsSliceInBounds (SliceLen x) (SliceCap x)) -> (ConstBool [1])
 
 (Eq64 x x) -> (ConstBool [1])
 (Eq32 x x) -> (ConstBool [1])
@@ -547,6 +552,10 @@
 (SlicePtr (SliceMake (Const64 <t> [c]) _ _)) -> (Const64 <t> [c])
 (SliceLen (SliceMake _ (Const64 <t> [c]) _)) -> (Const64 <t> [c])
 (SliceCap (SliceMake _ _ (Const64 <t> [c]))) -> (Const64 <t> [c])
+(SlicePtr (SliceMake (SlicePtr x) _ _)) -> (SlicePtr x)
+(SliceLen (SliceMake _ (SliceLen x) _)) -> (SliceLen x)
+(SliceCap (SliceMake _ _ (SliceCap x))) -> (SliceCap x)
+
 (ConstSlice) && config.PtrSize == 4 ->
   (SliceMake
     (ConstNil <config.fe.TypeBytePtr()>)

src/cmd/compile/internal/ssa/rewritegeneric.go

@@ -2487,6 +2487,18 @@ func rewriteValuegeneric_OpITab(v *Value, config *Config) bool {
 func rewriteValuegeneric_OpIsInBounds(v *Value, config *Config) bool {
 	b := v.Block
 	_ = b
+	// match: (IsInBounds x x)
+	// cond:
+	// result: (ConstBool [0])
+	for {
+		x := v.Args[0]
+		if v.Args[1] != x {
+			break
+		}
+		v.reset(OpConstBool)
+		v.AuxInt = 0
+		return true
+	}
 	// match: (IsInBounds (And32 (Const32 [c]) _) (Const32 [d]))
 	// cond: inBounds32(c, d)
 	// result: (ConstBool [1])
@@ -2568,6 +2580,18 @@ func rewriteValuegeneric_OpIsInBounds(v *Value, config *Config) bool {
 func rewriteValuegeneric_OpIsSliceInBounds(v *Value, config *Config) bool {
 	b := v.Block
 	_ = b
+	// match: (IsSliceInBounds x x)
+	// cond:
+	// result: (ConstBool [1])
+	for {
+		x := v.Args[0]
+		if v.Args[1] != x {
+			break
+		}
+		v.reset(OpConstBool)
+		v.AuxInt = 1
+		return true
+	}
 	// match: (IsSliceInBounds (And32 (Const32 [c]) _) (Const32 [d]))
 	// cond: sliceInBounds32(c, d)
 	// result: (ConstBool [1])
@@ -2612,6 +2636,34 @@ func rewriteValuegeneric_OpIsSliceInBounds(v *Value, config *Config) bool {
 		v.AuxInt = 1
 		return true
 	}
+	// match: (IsSliceInBounds (Const32 [0]) _)
+	// cond:
+	// result: (ConstBool [1])
+	for {
+		if v.Args[0].Op != OpConst32 {
+			break
+		}
+		if v.Args[0].AuxInt != 0 {
+			break
+		}
+		v.reset(OpConstBool)
+		v.AuxInt = 1
+		return true
+	}
+	// match: (IsSliceInBounds (Const64 [0]) _)
+	// cond:
+	// result: (ConstBool [1])
+	for {
+		if v.Args[0].Op != OpConst64 {
+			break
+		}
+		if v.Args[0].AuxInt != 0 {
+			break
+		}
+		v.reset(OpConstBool)
+		v.AuxInt = 1
+		return true
+	}
 	// match: (IsSliceInBounds (Const32 [c]) (Const32 [d]))
 	// cond:
 	// result: (ConstBool [b2i(sliceInBounds32(c,d))])
@@ -2644,6 +2696,24 @@ func rewriteValuegeneric_OpIsSliceInBounds(v *Value, config *Config) bool {
 		v.AuxInt = b2i(sliceInBounds64(c, d))
 		return true
 	}
+	// match: (IsSliceInBounds (SliceLen x) (SliceCap x))
+	// cond:
+	// result: (ConstBool [1])
+	for {
+		if v.Args[0].Op != OpSliceLen {
+			break
+		}
+		x := v.Args[0].Args[0]
+		if v.Args[1].Op != OpSliceCap {
+			break
+		}
+		if v.Args[1].Args[0] != x {
+			break
+		}
+		v.reset(OpConstBool)
+		v.AuxInt = 1
+		return true
+	}
 	return false
 }
 func rewriteValuegeneric_OpLeq16(v *Value, config *Config) bool {
@@ -6709,6 +6779,21 @@ func rewriteValuegeneric_OpSliceCap(v *Value, config *Config) bool {
 		v.AuxInt = c
 		return true
 	}
+	// match: (SliceCap (SliceMake _ _ (SliceCap x)))
+	// cond:
+	// result: (SliceCap x)
+	for {
+		if v.Args[0].Op != OpSliceMake {
+			break
+		}
+		if v.Args[0].Args[2].Op != OpSliceCap {
+			break
+		}
+		x := v.Args[0].Args[2].Args[0]
+		v.reset(OpSliceCap)
+		v.AddArg(x)
+		return true
+	}
 	return false
 }
 func rewriteValuegeneric_OpSliceLen(v *Value, config *Config) bool {
@@ -6731,6 +6816,21 @@ func rewriteValuegeneric_OpSliceLen(v *Value, config *Config) bool {
 		v.AuxInt = c
 		return true
 	}
+	// match: (SliceLen (SliceMake _ (SliceLen x) _))
+	// cond:
+	// result: (SliceLen x)
+	for {
+		if v.Args[0].Op != OpSliceMake {
+			break
+		}
+		if v.Args[0].Args[1].Op != OpSliceLen {
+			break
+		}
+		x := v.Args[0].Args[1].Args[0]
+		v.reset(OpSliceLen)
+		v.AddArg(x)
+		return true
+	}
 	return false
 }
 func rewriteValuegeneric_OpSlicePtr(v *Value, config *Config) bool {
@@ -6753,6 +6853,21 @@ func rewriteValuegeneric_OpSlicePtr(v *Value, config *Config) bool {
 		v.AuxInt = c
 		return true
 	}
+	// match: (SlicePtr (SliceMake (SlicePtr x) _ _))
+	// cond:
+	// result: (SlicePtr x)
+	for {
+		if v.Args[0].Op != OpSliceMake {
+			break
+		}
+		if v.Args[0].Args[0].Op != OpSlicePtr {
+			break
+		}
+		x := v.Args[0].Args[0].Args[0]
+		v.reset(OpSlicePtr)
+		v.AddArg(x)
+		return true
+	}
 	return false
 }
 func rewriteValuegeneric_OpStore(v *Value, config *Config) bool {

test/prove.go

@@ -5,11 +5,11 @@ package main
 
 func f0(a []int) int {
 	a[0] = 1
-	a[0] = 1 // ERROR "Proved IsInBounds$"
+	a[0] = 1 // ERROR "Proved boolean IsInBounds$"
 	a[6] = 1
-	a[6] = 1 // ERROR "Proved IsInBounds$"
+	a[6] = 1 // ERROR "Proved boolean IsInBounds$"
 	a[5] = 1
-	a[5] = 1 // ERROR "Proved IsInBounds$"
+	a[5] = 1 // ERROR "Proved boolean IsInBounds$"
 	return 13
 }
 
@@ -18,18 +18,18 @@ func f1(a []int) int {
 		return 18
 	}
 	a[0] = 1
-	a[0] = 1 // ERROR "Proved IsInBounds$"
+	a[0] = 1 // ERROR "Proved boolean IsInBounds$"
 	a[6] = 1
-	a[6] = 1 // ERROR "Proved IsInBounds$"
-	a[5] = 1 // ERROR "Proved constant IsInBounds$"
-	a[5] = 1 // ERROR "Proved IsInBounds$"
+	a[6] = 1 // ERROR "Proved boolean IsInBounds$"
+	a[5] = 1 // ERROR "Proved non-negative bounds IsInBounds$"
+	a[5] = 1 // ERROR "Proved boolean IsInBounds$"
 	return 26
 }
 
 func f2(a []int) int {
 	for i := range a {
 		a[i] = i
-		a[i] = i // ERROR "Proved IsInBounds$"
+		a[i] = i // ERROR "Proved boolean IsInBounds$"
 	}
 	return 34
 }
@@ -49,13 +49,13 @@ func f4a(a, b, c int) int {
 		if a > b { // ERROR "Disproved Greater64$"
 			return 50
 		}
-		if a < b { // ERROR "Proved Less64$"
+		if a < b { // ERROR "Proved boolean Less64$"
 			return 53
 		}
-		if a == b { // ERROR "Disproved Eq64$"
+		if a == b { // ERROR "Disproved boolean Eq64$"
 			return 56
 		}
-		if a > b {
+		if a > b { // ERROR "Disproved boolean Greater64$"
 			return 59
 		}
 		return 61
@@ -92,8 +92,8 @@ func f4c(a, b, c int) int {
 func f4d(a, b, c int) int {
 	if a < b {
 		if a < c {
-			if a < b { // ERROR "Proved Less64$"
-				if a < c { // ERROR "Proved Less64$"
+			if a < b { // ERROR "Proved boolean Less64$"
+				if a < c { // ERROR "Proved boolean Less64$"
 					return 87
 				}
 				return 89
@@ -183,8 +183,8 @@ func f6e(a uint8) int {
 func f7(a []int, b int) int {
 	if b < len(a) {
 		a[b] = 3
-		if b < len(a) { // ERROR "Proved Less64$"
-			a[b] = 5 // ERROR "Proved IsInBounds$"
+		if b < len(a) { // ERROR "Proved boolean Less64$"
+			a[b] = 5 // ERROR "Proved boolean IsInBounds$"
 		}
 	}
 	return 161
@@ -203,5 +203,55 @@ func f8(a, b uint) int {
 	return 174
 }
 
+func f9(a, b bool) int {
+	if a {
+		return 1
+	}
+	if a || b { // ERROR "Disproved boolean Arg$"
+		return 2
+	}
+	return 3
+}
+
+func f10(a string) int {
+	n := len(a)
+	if a[:n>>1] == "aaa" {
+		return 0
+	}
+	return 1
+}
+
+func f11a(a []int, i int) {
+	useInt(a[i])
+	useInt(a[i]) // ERROR "Proved boolean IsInBounds$"
+}
+
+func f11b(a []int, i int) {
+	useSlice(a[i:])
+	useSlice(a[i:]) // ERROR "Proved boolean IsSliceInBounds$"
+}
+
+func f11c(a []int, i int) {
+	useSlice(a[:i])
+	useSlice(a[:i]) // ERROR "Proved boolean IsSliceInBounds$"
+}
+
+func f11d(a []int, i int) {
+	useInt(a[2*i+7])
+	useInt(a[2*i+7])
+}
+
+func f12(a []int, b int) {
+	useSlice(a[:b])
+}
+
+//go:noinline
+func useInt(a int) {
+}
+
+//go:noinline
+func useSlice(a []int) {
+}
+
 func main() {
 }