From 37d4532867b9c49f936cb8e394dec44d8985fe29 Mon Sep 17 00:00:00 2001
From: Ben Shi <powerman1st@163.com>
Date: Thu, 2 Sep 2021 00:06:42 +0000
Subject: cmd/internal/obj/riscv: simplify addition with constant

This CL simplifies riscv addition (add r, imm) to
(ADDI (ADDI r, imm/2), imm-imm/2) if imm is in specific ranges.
(-4096 <= imm <= -2049 or 2048 <= imm <= 4094)

There is little impact to the go1 benchmark, while the total
size of pkg/linux_riscv64 decreased by about 11KB.

Change-Id: I236eb8af3b83bb35ce9c0b318fc1d235e8ab9a4e
GitHub-Last-Rev: a2f56a07635344a40d6b8a9571f236743122be34
GitHub-Pull-Request: golang/go#48110
Reviewed-on: https://go-review.googlesource.com/c/go/+/346689
Run-TryBot: Ben Shi <powerman1st@163.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Joel Sing <joel@sing.id.au>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
Trust: Michael Munday <mike.munday@lowrisc.org>
---
 test/codegen/arithmetic.go | 8 ++++++++
 1 file changed, 8 insertions(+)

(limited to 'test/codegen')

diff --git a/test/codegen/arithmetic.go b/test/codegen/arithmetic.go
index eb95416b6a..754c5c9bc9 100644
--- a/test/codegen/arithmetic.go
+++ b/test/codegen/arithmetic.go
@@ -575,3 +575,11 @@ func constantFold3(i, j int) int {
 	r := (5 * i) * (6 * j)
 	return r
 }
+
+func addConst(i int64) (int64, int64) {
+	// riscv64:`ADDI`,-`LUI`
+	a := i + 3001
+	// riscv64:`LUI`,`ADDIW`
+	b := i + 5009
+	return a, b
+}
-- 
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