cmd/compile: use MOV pseudo-instructions for sign/zero extension

Rather than handling sign and zero extension via rules, defer to the assembler
and use MOV pseudo-instructions. The instruction can also be omitted where the
type and size is already correct. This change results in more than 6,000
instructions being removed from the go binary (in part due to omitted
instructions, in part due to MOVBU having a more efficient implementation in
the assembler than what is used in the current ZeroExt8to{16,32,64} rules).

This will also allow for further rewriting to remove redundant sign/zero
extension.

Change-Id: I05e42fd9f09f40a69948be7de772cce8946c8744
Reviewed-on: https://go-review.googlesource.com/c/go/+/264658
Trust: Joel Sing <joel@sing.id.au>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

1 files changed, 24 insertions, 211 deletions

diff --git a/src/cmd/compile/internal/ssa/rewriteRISCV64.go b/src/cmd/compile/internal/ssa/rewriteRISCV64.go
index c178290343..174d48e7c4 100644
--- a/src/cmd/compile/internal/ssa/rewriteRISCV64.go
+++ b/src/cmd/compile/internal/ssa/rewriteRISCV64.go
@@ -543,17 +543,23 @@ func rewriteValueRISCV64(v *Value) bool {
 	case OpRsh8x8:
 		return rewriteValueRISCV64_OpRsh8x8(v)
 	case OpSignExt16to32:
-		return rewriteValueRISCV64_OpSignExt16to32(v)
+		v.Op = OpRISCV64MOVHreg
+		return true
 	case OpSignExt16to64:
-		return rewriteValueRISCV64_OpSignExt16to64(v)
+		v.Op = OpRISCV64MOVHreg
+		return true
 	case OpSignExt32to64:
-		return rewriteValueRISCV64_OpSignExt32to64(v)
+		v.Op = OpRISCV64MOVWreg
+		return true
 	case OpSignExt8to16:
-		return rewriteValueRISCV64_OpSignExt8to16(v)
+		v.Op = OpRISCV64MOVBreg
+		return true
 	case OpSignExt8to32:
-		return rewriteValueRISCV64_OpSignExt8to32(v)
+		v.Op = OpRISCV64MOVBreg
+		return true
 	case OpSignExt8to64:
-		return rewriteValueRISCV64_OpSignExt8to64(v)
+		v.Op = OpRISCV64MOVBreg
+		return true
 	case OpSlicemask:
 		return rewriteValueRISCV64_OpSlicemask(v)
 	case OpSqrt:
@@ -621,17 +627,23 @@ func rewriteValueRISCV64(v *Value) bool {
 	case OpZero:
 		return rewriteValueRISCV64_OpZero(v)
 	case OpZeroExt16to32:
-		return rewriteValueRISCV64_OpZeroExt16to32(v)
+		v.Op = OpRISCV64MOVHUreg
+		return true
 	case OpZeroExt16to64:
-		return rewriteValueRISCV64_OpZeroExt16to64(v)
+		v.Op = OpRISCV64MOVHUreg
+		return true
 	case OpZeroExt32to64:
-		return rewriteValueRISCV64_OpZeroExt32to64(v)
+		v.Op = OpRISCV64MOVWUreg
+		return true
 	case OpZeroExt8to16:
-		return rewriteValueRISCV64_OpZeroExt8to16(v)
+		v.Op = OpRISCV64MOVBUreg
+		return true
 	case OpZeroExt8to32:
-		return rewriteValueRISCV64_OpZeroExt8to32(v)
+		v.Op = OpRISCV64MOVBUreg
+		return true
 	case OpZeroExt8to64:
-		return rewriteValueRISCV64_OpZeroExt8to64(v)
+		v.Op = OpRISCV64MOVBUreg
+		return true
 	}
 	return false
 }
@@ -4719,103 +4731,6 @@ func rewriteValueRISCV64_OpRsh8x8(v *Value) bool {
 		return true
 	}
 }
-func rewriteValueRISCV64_OpSignExt16to32(v *Value) bool {
-	v_0 := v.Args[0]
-	b := v.Block
-	// match: (SignExt16to32 <t> x)
-	// result: (SRAI [48] (SLLI <t> [48] x))
-	for {
-		t := v.Type
-		x := v_0
-		v.reset(OpRISCV64SRAI)
-		v.AuxInt = int64ToAuxInt(48)
-		v0 := b.NewValue0(v.Pos, OpRISCV64SLLI, t)
-		v0.AuxInt = int64ToAuxInt(48)
-		v0.AddArg(x)
-		v.AddArg(v0)
-		return true
-	}
-}
-func rewriteValueRISCV64_OpSignExt16to64(v *Value) bool {
-	v_0 := v.Args[0]
-	b := v.Block
-	// match: (SignExt16to64 <t> x)
-	// result: (SRAI [48] (SLLI <t> [48] x))
-	for {
-		t := v.Type
-		x := v_0
-		v.reset(OpRISCV64SRAI)
-		v.AuxInt = int64ToAuxInt(48)
-		v0 := b.NewValue0(v.Pos, OpRISCV64SLLI, t)
-		v0.AuxInt = int64ToAuxInt(48)
-		v0.AddArg(x)
-		v.AddArg(v0)
-		return true
-	}
-}
-func rewriteValueRISCV64_OpSignExt32to64(v *Value) bool {
-	v_0 := v.Args[0]
-	// match: (SignExt32to64 <t> x)
-	// result: (ADDIW [0] x)
-	for {
-		x := v_0
-		v.reset(OpRISCV64ADDIW)
-		v.AuxInt = int64ToAuxInt(0)
-		v.AddArg(x)
-		return true
-	}
-}
-func rewriteValueRISCV64_OpSignExt8to16(v *Value) bool {
-	v_0 := v.Args[0]
-	b := v.Block
-	// match: (SignExt8to16 <t> x)
-	// result: (SRAI [56] (SLLI <t> [56] x))
-	for {
-		t := v.Type
-		x := v_0
-		v.reset(OpRISCV64SRAI)
-		v.AuxInt = int64ToAuxInt(56)
-		v0 := b.NewValue0(v.Pos, OpRISCV64SLLI, t)
-		v0.AuxInt = int64ToAuxInt(56)
-		v0.AddArg(x)
-		v.AddArg(v0)
-		return true
-	}
-}
-func rewriteValueRISCV64_OpSignExt8to32(v *Value) bool {
-	v_0 := v.Args[0]
-	b := v.Block
-	// match: (SignExt8to32 <t> x)
-	// result: (SRAI [56] (SLLI <t> [56] x))
-	for {
-		t := v.Type
-		x := v_0
-		v.reset(OpRISCV64SRAI)
-		v.AuxInt = int64ToAuxInt(56)
-		v0 := b.NewValue0(v.Pos, OpRISCV64SLLI, t)
-		v0.AuxInt = int64ToAuxInt(56)
-		v0.AddArg(x)
-		v.AddArg(v0)
-		return true
-	}
-}
-func rewriteValueRISCV64_OpSignExt8to64(v *Value) bool {
-	v_0 := v.Args[0]
-	b := v.Block
-	// match: (SignExt8to64 <t> x)
-	// result: (SRAI [56] (SLLI <t> [56] x))
-	for {
-		t := v.Type
-		x := v_0
-		v.reset(OpRISCV64SRAI)
-		v.AuxInt = int64ToAuxInt(56)
-		v0 := b.NewValue0(v.Pos, OpRISCV64SLLI, t)
-		v0.AuxInt = int64ToAuxInt(56)
-		v0.AddArg(x)
-		v.AddArg(v0)
-		return true
-	}
-}
 func rewriteValueRISCV64_OpSlicemask(v *Value) bool {
 	v_0 := v.Args[0]
 	b := v.Block
@@ -5016,108 +4931,6 @@ func rewriteValueRISCV64_OpZero(v *Value) bool {
 		return true
 	}
 }
-func rewriteValueRISCV64_OpZeroExt16to32(v *Value) bool {
-	v_0 := v.Args[0]
-	b := v.Block
-	// match: (ZeroExt16to32 <t> x)
-	// result: (SRLI [48] (SLLI <t> [48] x))
-	for {
-		t := v.Type
-		x := v_0
-		v.reset(OpRISCV64SRLI)
-		v.AuxInt = int64ToAuxInt(48)
-		v0 := b.NewValue0(v.Pos, OpRISCV64SLLI, t)
-		v0.AuxInt = int64ToAuxInt(48)
-		v0.AddArg(x)
-		v.AddArg(v0)
-		return true
-	}
-}
-func rewriteValueRISCV64_OpZeroExt16to64(v *Value) bool {
-	v_0 := v.Args[0]
-	b := v.Block
-	// match: (ZeroExt16to64 <t> x)
-	// result: (SRLI [48] (SLLI <t> [48] x))
-	for {
-		t := v.Type
-		x := v_0
-		v.reset(OpRISCV64SRLI)
-		v.AuxInt = int64ToAuxInt(48)
-		v0 := b.NewValue0(v.Pos, OpRISCV64SLLI, t)
-		v0.AuxInt = int64ToAuxInt(48)
-		v0.AddArg(x)
-		v.AddArg(v0)
-		return true
-	}
-}
-func rewriteValueRISCV64_OpZeroExt32to64(v *Value) bool {
-	v_0 := v.Args[0]
-	b := v.Block
-	// match: (ZeroExt32to64 <t> x)
-	// result: (SRLI [32] (SLLI <t> [32] x))
-	for {
-		t := v.Type
-		x := v_0
-		v.reset(OpRISCV64SRLI)
-		v.AuxInt = int64ToAuxInt(32)
-		v0 := b.NewValue0(v.Pos, OpRISCV64SLLI, t)
-		v0.AuxInt = int64ToAuxInt(32)
-		v0.AddArg(x)
-		v.AddArg(v0)
-		return true
-	}
-}
-func rewriteValueRISCV64_OpZeroExt8to16(v *Value) bool {
-	v_0 := v.Args[0]
-	b := v.Block
-	// match: (ZeroExt8to16 <t> x)
-	// result: (SRLI [56] (SLLI <t> [56] x))
-	for {
-		t := v.Type
-		x := v_0
-		v.reset(OpRISCV64SRLI)
-		v.AuxInt = int64ToAuxInt(56)
-		v0 := b.NewValue0(v.Pos, OpRISCV64SLLI, t)
-		v0.AuxInt = int64ToAuxInt(56)
-		v0.AddArg(x)
-		v.AddArg(v0)
-		return true
-	}
-}
-func rewriteValueRISCV64_OpZeroExt8to32(v *Value) bool {
-	v_0 := v.Args[0]
-	b := v.Block
-	// match: (ZeroExt8to32 <t> x)
-	// result: (SRLI [56] (SLLI <t> [56] x))
-	for {
-		t := v.Type
-		x := v_0
-		v.reset(OpRISCV64SRLI)
-		v.AuxInt = int64ToAuxInt(56)
-		v0 := b.NewValue0(v.Pos, OpRISCV64SLLI, t)
-		v0.AuxInt = int64ToAuxInt(56)
-		v0.AddArg(x)
-		v.AddArg(v0)
-		return true
-	}
-}
-func rewriteValueRISCV64_OpZeroExt8to64(v *Value) bool {
-	v_0 := v.Args[0]
-	b := v.Block
-	// match: (ZeroExt8to64 <t> x)
-	// result: (SRLI [56] (SLLI <t> [56] x))
-	for {
-		t := v.Type
-		x := v_0
-		v.reset(OpRISCV64SRLI)
-		v.AuxInt = int64ToAuxInt(56)
-		v0 := b.NewValue0(v.Pos, OpRISCV64SLLI, t)
-		v0.AuxInt = int64ToAuxInt(56)
-		v0.AddArg(x)
-		v.AddArg(v0)
-		return true
-	}
-}
 func rewriteBlockRISCV64(b *Block) bool {
 	switch b.Kind {
 	case BlockRISCV64BEQ: