cmd/compile: generic constant folding: Floor Ceil Trunc RoundToEven

Change-Id: I553a6d0bd3ae45e5bf62191411e71102b3f44cd8
Reviewed-on: https://go-review.googlesource.com/c/go/+/411215
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Joedian Reid <joedian@golang.org>
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Keith Randall <khr@google.com>

2 files changed, 73 insertions, 0 deletions

diff --git a/src/cmd/compile/internal/ssa/gen/generic.rules b/src/cmd/compile/internal/ssa/gen/generic.rules
index e56ee4a6f1..ac0b6eb8c1 100644
--- a/src/cmd/compile/internal/ssa/gen/generic.rules
+++ b/src/cmd/compile/internal/ssa/gen/generic.rules
@@ -163,6 +163,11 @@
 
 (Not (ConstBool [c])) => (ConstBool [!c])
 
+(Floor       (Const64F [c])) => (Const64F [math.Floor(c)])
+(Ceil        (Const64F [c])) => (Const64F [math.Ceil(c)])
+(Trunc       (Const64F [c])) => (Const64F [math.Trunc(c)])
+(RoundToEven (Const64F [c])) => (Const64F [math.RoundToEven(c)])
+
 // Convert x * 1 to x.
 (Mul(8|16|32|64)  (Const(8|16|32|64)  [1]) x) => x
 (Select0 (Mul(32|64)uover (Const(32|64) [1]) x)) => x
diff --git a/src/cmd/compile/internal/ssa/rewritegeneric.go b/src/cmd/compile/internal/ssa/rewritegeneric.go
index 971d369a09..19a4f47914 100644
--- a/src/cmd/compile/internal/ssa/rewritegeneric.go
+++ b/src/cmd/compile/internal/ssa/rewritegeneric.go
@@ -34,6 +34,8 @@ func rewriteValuegeneric(v *Value) bool {
 		return rewriteValuegeneric_OpAndB(v)
 	case OpArraySelect:
 		return rewriteValuegeneric_OpArraySelect(v)
+	case OpCeil:
+		return rewriteValuegeneric_OpCeil(v)
 	case OpCom16:
 		return rewriteValuegeneric_OpCom16(v)
 	case OpCom32:
@@ -120,6 +122,8 @@ func rewriteValuegeneric(v *Value) bool {
 		return rewriteValuegeneric_OpEqPtr(v)
 	case OpEqSlice:
 		return rewriteValuegeneric_OpEqSlice(v)
+	case OpFloor:
+		return rewriteValuegeneric_OpFloor(v)
 	case OpIMake:
 		return rewriteValuegeneric_OpIMake(v)
 	case OpInterLECall:
@@ -298,6 +302,8 @@ func rewriteValuegeneric(v *Value) bool {
 		return rewriteValuegeneric_OpRound32F(v)
 	case OpRound64F:
 		return rewriteValuegeneric_OpRound64F(v)
+	case OpRoundToEven:
+		return rewriteValuegeneric_OpRoundToEven(v)
 	case OpRsh16Ux16:
 		return rewriteValuegeneric_OpRsh16Ux16(v)
 	case OpRsh16Ux32:
@@ -412,6 +418,8 @@ func rewriteValuegeneric(v *Value) bool {
 		return rewriteValuegeneric_OpSub64F(v)
 	case OpSub8:
 		return rewriteValuegeneric_OpSub8(v)
+	case OpTrunc:
+		return rewriteValuegeneric_OpTrunc(v)
 	case OpTrunc16to8:
 		return rewriteValuegeneric_OpTrunc16to8(v)
 	case OpTrunc32to16:
@@ -5085,6 +5093,21 @@ func rewriteValuegeneric_OpArraySelect(v *Value) bool {
 	}
 	return false
 }
+func rewriteValuegeneric_OpCeil(v *Value) bool {
+	v_0 := v.Args[0]
+	// match: (Ceil (Const64F [c]))
+	// result: (Const64F [math.Ceil(c)])
+	for {
+		if v_0.Op != OpConst64F {
+			break
+		}
+		c := auxIntToFloat64(v_0.AuxInt)
+		v.reset(OpConst64F)
+		v.AuxInt = float64ToAuxInt(math.Ceil(c))
+		return true
+	}
+	return false
+}
 func rewriteValuegeneric_OpCom16(v *Value) bool {
 	v_0 := v.Args[0]
 	// match: (Com16 (Com16 x))
@@ -10145,6 +10168,21 @@ func rewriteValuegeneric_OpEqSlice(v *Value) bool {
 		return true
 	}
 }
+func rewriteValuegeneric_OpFloor(v *Value) bool {
+	v_0 := v.Args[0]
+	// match: (Floor (Const64F [c]))
+	// result: (Const64F [math.Floor(c)])
+	for {
+		if v_0.Op != OpConst64F {
+			break
+		}
+		c := auxIntToFloat64(v_0.AuxInt)
+		v.reset(OpConst64F)
+		v.AuxInt = float64ToAuxInt(math.Floor(c))
+		return true
+	}
+	return false
+}
 func rewriteValuegeneric_OpIMake(v *Value) bool {
 	v_1 := v.Args[1]
 	v_0 := v.Args[0]
@@ -23703,6 +23741,21 @@ func rewriteValuegeneric_OpRound64F(v *Value) bool {
 	}
 	return false
 }
+func rewriteValuegeneric_OpRoundToEven(v *Value) bool {
+	v_0 := v.Args[0]
+	// match: (RoundToEven (Const64F [c]))
+	// result: (Const64F [math.RoundToEven(c)])
+	for {
+		if v_0.Op != OpConst64F {
+			break
+		}
+		c := auxIntToFloat64(v_0.AuxInt)
+		v.reset(OpConst64F)
+		v.AuxInt = float64ToAuxInt(math.RoundToEven(c))
+		return true
+	}
+	return false
+}
 func rewriteValuegeneric_OpRsh16Ux16(v *Value) bool {
 	v_1 := v.Args[1]
 	v_0 := v.Args[0]
@@ -29016,6 +29069,21 @@ func rewriteValuegeneric_OpSub8(v *Value) bool {
 	}
 	return false
 }
+func rewriteValuegeneric_OpTrunc(v *Value) bool {
+	v_0 := v.Args[0]
+	// match: (Trunc (Const64F [c]))
+	// result: (Const64F [math.Trunc(c)])
+	for {
+		if v_0.Op != OpConst64F {
+			break
+		}
+		c := auxIntToFloat64(v_0.AuxInt)
+		v.reset(OpConst64F)
+		v.AuxInt = float64ToAuxInt(math.Trunc(c))
+		return true
+	}
+	return false
+}
 func rewriteValuegeneric_OpTrunc16to8(v *Value) bool {
 	v_0 := v.Args[0]
 	// match: (Trunc16to8 (Const16 [c]))