From 0f0bc0f0160baa04086135fb0e41252311054c33 Mon Sep 17 00:00:00 2001 From: Russ Cox Date: Fri, 24 Apr 2015 10:50:18 -0400 Subject: [PATCH] cmd/internal/gc: use MOV R0, R1 instead of LEA 0(R0), R1 in Agen MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Minor code generation optimization I've been meaning to do for a while and noticed while working on the emitted write barrier code. Using MOV lets the compiler and maybe the processor do copy propagation. name old new delta BenchmarkBinaryTree17 17.9s × (0.99,1.01) 18.0s × (0.99,1.01) ~ BenchmarkFannkuch11 4.42s × (1.00,1.00) 4.36s × (1.00,1.00) -1.39% BenchmarkFmtFprintfEmpty 118ns × (0.96,1.02) 120ns × (0.99,1.06) ~ BenchmarkFmtFprintfString 486ns × (0.99,1.01) 480ns × (0.99,1.01) -1.34% BenchmarkFmtFprintfInt 457ns × (0.99,1.01) 451ns × (0.99,1.01) -1.31% BenchmarkFmtFprintfIntInt 768ns × (1.00,1.01) 766ns × (0.99,1.01) ~ BenchmarkFmtFprintfPrefixedInt 584ns × (0.99,1.03) 569ns × (0.99,1.01) -2.57% BenchmarkFmtFprintfFloat 739ns × (0.99,1.00) 728ns × (1.00,1.01) -1.49% BenchmarkFmtManyArgs 2.77µs × (1.00,1.00) 2.81µs × (1.00,1.01) +1.53% BenchmarkGobDecode 39.3ms × (0.99,1.01) 39.4ms × (0.99,1.01) ~ BenchmarkGobEncode 39.4ms × (0.99,1.00) 39.4ms × (0.99,1.00) ~ BenchmarkGzip 661ms × (0.99,1.01) 660ms × (1.00,1.01) ~ BenchmarkGunzip 142ms × (1.00,1.00) 143ms × (1.00,1.00) +0.20% BenchmarkHTTPClientServer 133µs × (0.98,1.01) 132µs × (0.99,1.01) ~ BenchmarkJSONEncode 56.5ms × (0.99,1.01) 57.1ms × (0.99,1.01) +0.94% BenchmarkJSONDecode 143ms × (1.00,1.00) 138ms × (1.00,1.01) -3.22% BenchmarkMandelbrot200 6.01ms × (1.00,1.00) 6.02ms × (1.00,1.00) ~ BenchmarkGoParse 9.63ms × (0.94,1.07) 9.79ms × (0.92,1.07) ~ BenchmarkRegexpMatchEasy0_32 210ns × (1.00,1.00) 210ns × (1.00,1.01) ~ BenchmarkRegexpMatchEasy0_1K 596ns × (0.99,1.01) 593ns × (0.99,1.01) ~ BenchmarkRegexpMatchEasy1_32 184ns × (0.99,1.01) 182ns × (0.99,1.01) ~ BenchmarkRegexpMatchEasy1_1K 1.01µs × (0.99,1.01) 1.01µs × (1.00,1.01) ~ BenchmarkRegexpMatchMedium_32 327ns × (1.00,1.01) 331ns × (1.00,1.00) +1.22% BenchmarkRegexpMatchMedium_1K 93.0µs × (1.00,1.02) 92.6µs × (1.00,1.01) ~ BenchmarkRegexpMatchHard_32 4.76µs × (0.95,1.01) 4.58µs × (0.99,1.05) ~ BenchmarkRegexpMatchHard_1K 136µs × (1.00,1.01) 136µs × (1.00,1.01) ~ BenchmarkRevcomp 892ms × (1.00,1.01) 900ms × (0.99,1.06) ~ BenchmarkTemplate 175ms × (0.99,1.00) 171ms × (1.00,1.01) -2.36% BenchmarkTimeParse 638ns × (1.00,1.00) 637ns × (1.00,1.00) ~ BenchmarkTimeFormat 772ns × (1.00,1.00) 742ns × (1.00,1.00) -3.95% Change-Id: I6504e310cb9cf48a73d539c478b4dbcacde208b2 Reviewed-on: https://go-review.googlesource.com/9308 Reviewed-by: Austin Clements --- src/cmd/internal/gc/cgen.go | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/src/cmd/internal/gc/cgen.go b/src/cmd/internal/gc/cgen.go index c996be72fd..427c671947 100644 --- a/src/cmd/internal/gc/cgen.go +++ b/src/cmd/internal/gc/cgen.go @@ -1512,6 +1512,17 @@ func Agen(n *Node, res *Node) { return } + if n.Op == OINDREG && n.Xoffset == 0 { + // Generate MOVW R0, R1 instead of MOVW $0(R0), R1. + // This allows better move propagation in the back ends + // (and maybe it helps the processor). + n1 := *n + n1.Op = OREGISTER + n1.Type = res.Type + Thearch.Gmove(&n1, res) + return + } + if n.Addable { if n.Op == OREGISTER { Fatal("agen OREGISTER") -- 2.48.1