From: Xiaolin Zhao <zhaoxiaolin@loongson.cn>
Date: Mon, 8 Sep 2025 10:00:52 +0000 (+0800)
Subject: cmd/compile: fold constant in ADDshift op on loong64
X-Git-Tag: go1.26rc1~939
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=6447ff409ac7e2a621bc8ca5c44b2eaed751fbaa;p=gostls13.git

cmd/compile: fold constant in ADDshift op on loong64

Removes 918 instructions from the go binary on loong64.

        file        before      after       Δ
        go          1633120     1632948    -172
        gofmt       323470      323334     -136
        asm         568024      568024     -0
        cgo         488030      487890     -140
        compile     2501050     2500728    -322
        cover       530124      530124     -0
        link        723532      723520     -12
        preprofile  240568      240568     -0
        vet         819392      819256     -136

Change-Id: Id4015c66b2073323b7ad257b3ed05bb99f81e9a1
Reviewed-on: https://go-review.googlesource.com/c/go/+/701655
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Keith Randall <khr@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
Auto-Submit: Keith Randall <khr@golang.org>
Reviewed-by: Mark Freeman <markfreeman@google.com>
---

diff --git a/src/cmd/compile/internal/ssa/_gen/LOONG64.rules b/src/cmd/compile/internal/ssa/_gen/LOONG64.rules
index a3dd050d14..d0a64364d6 100644
--- a/src/cmd/compile/internal/ssa/_gen/LOONG64.rules
+++ b/src/cmd/compile/internal/ssa/_gen/LOONG64.rules
@@ -730,6 +730,9 @@
 
 (ADDV x0 x1:(SLLVconst [c] y)) && x1.Uses == 1 && c > 0 && c <= 4 => (ADDshiftLLV x0 y [c])
 
+// fold constant in ADDshift op
+(ADDshiftLLV x (MOVVconst [c]) [d]) && is12Bit(c<<d) => (ADDVconst x [c<<d])
+
 // div by constant
 (DIVVU x (MOVVconst [1])) => x
 (DIVVU x (MOVVconst [c])) && isPowerOfTwo(c) => (SRLVconst [log64(c)] x)
diff --git a/src/cmd/compile/internal/ssa/rewriteLOONG64.go b/src/cmd/compile/internal/ssa/rewriteLOONG64.go
index 036d70a15f..6a9b723c8c 100644
--- a/src/cmd/compile/internal/ssa/rewriteLOONG64.go
+++ b/src/cmd/compile/internal/ssa/rewriteLOONG64.go
@@ -324,6 +324,8 @@ func rewriteValueLOONG64(v *Value) bool {
 		return rewriteValueLOONG64_OpLOONG64ADDV(v)
 	case OpLOONG64ADDVconst:
 		return rewriteValueLOONG64_OpLOONG64ADDVconst(v)
+	case OpLOONG64ADDshiftLLV:
+		return rewriteValueLOONG64_OpLOONG64ADDshiftLLV(v)
 	case OpLOONG64AND:
 		return rewriteValueLOONG64_OpLOONG64AND(v)
 	case OpLOONG64ANDconst:
@@ -2024,6 +2026,29 @@ func rewriteValueLOONG64_OpLOONG64ADDVconst(v *Value) bool {
 	}
 	return false
 }
+func rewriteValueLOONG64_OpLOONG64ADDshiftLLV(v *Value) bool {
+	v_1 := v.Args[1]
+	v_0 := v.Args[0]
+	// match: (ADDshiftLLV x (MOVVconst [c]) [d])
+	// cond: is12Bit(c<<d)
+	// result: (ADDVconst x [c<<d])
+	for {
+		d := auxIntToInt64(v.AuxInt)
+		x := v_0
+		if v_1.Op != OpLOONG64MOVVconst {
+			break
+		}
+		c := auxIntToInt64(v_1.AuxInt)
+		if !(is12Bit(c << d)) {
+			break
+		}
+		v.reset(OpLOONG64ADDVconst)
+		v.AuxInt = int64ToAuxInt(c << d)
+		v.AddArg(x)
+		return true
+	}
+	return false
+}
 func rewriteValueLOONG64_OpLOONG64AND(v *Value) bool {
 	v_1 := v.Args[1]
 	v_0 := v.Args[0]