From: Lynn Boger <laboger@linux.vnet.ibm.com>
Date: Tue, 5 Oct 2021 15:22:47 +0000 (-0500)
Subject: cmd/compile: improve PPC64 rules for AtomicLoad{8,32}
X-Git-Tag: go1.18beta1~1027
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=ce72766a02a4be127a26e95fbd62c4b4bb906e91;p=gostls13.git

cmd/compile: improve PPC64 rules for AtomicLoad{8,32}

This adds a rule to avoid the zero extension after an AtomicLoad8
or AtomicLoad32 since the atomic load has already filled it with
zeros. This eliminates an instruction in a high use block in findObject
and the AtomicLoad8 appears many times within runtime.

Change-Id: I7e684bf73d3812110bd371e05b1aa44fa235fc9b
Reviewed-on: https://go-review.googlesource.com/c/go/+/354029
Run-TryBot: Lynn Boger <laboger@linux.vnet.ibm.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Trust: Lynn Boger <laboger@linux.vnet.ibm.com>
---

diff --git a/src/cmd/compile/internal/ssa/gen/PPC64.rules b/src/cmd/compile/internal/ssa/gen/PPC64.rules
index 4c766df4b3..8e42bae215 100644
--- a/src/cmd/compile/internal/ssa/gen/PPC64.rules
+++ b/src/cmd/compile/internal/ssa/gen/PPC64.rules
@@ -1019,6 +1019,8 @@
 (MOVWZreg x:(MOVWZloadidx _ _ _)) => x
 (MOVWreg x:(MOVWload _ _)) => x
 (MOVWreg x:(MOVWloadidx _ _ _)) => x
+(MOVBZreg x:(Select0 (LoweredAtomicLoad8 _ _))) => x
+(MOVWZreg x:(Select0 (LoweredAtomicLoad32 _ _))) => x
 
 // don't extend if argument is already extended
 (MOVBreg x:(Arg <t>)) && is8BitInt(t) && isSigned(t) => x
diff --git a/src/cmd/compile/internal/ssa/rewritePPC64.go b/src/cmd/compile/internal/ssa/rewritePPC64.go
index b278a4cb44..1e6624e906 100644
--- a/src/cmd/compile/internal/ssa/rewritePPC64.go
+++ b/src/cmd/compile/internal/ssa/rewritePPC64.go
@@ -7093,6 +7093,20 @@ func rewriteValuePPC64_OpPPC64MOVBZreg(v *Value) bool {
 		v.copyOf(x)
 		return true
 	}
+	// match: (MOVBZreg x:(Select0 (LoweredAtomicLoad8 _ _)))
+	// result: x
+	for {
+		x := v_0
+		if x.Op != OpSelect0 {
+			break
+		}
+		x_0 := x.Args[0]
+		if x_0.Op != OpPPC64LoweredAtomicLoad8 {
+			break
+		}
+		v.copyOf(x)
+		return true
+	}
 	// match: (MOVBZreg x:(Arg <t>))
 	// cond: is8BitInt(t) && !isSigned(t)
 	// result: x
@@ -10549,6 +10563,20 @@ func rewriteValuePPC64_OpPPC64MOVWZreg(v *Value) bool {
 		v.copyOf(x)
 		return true
 	}
+	// match: (MOVWZreg x:(Select0 (LoweredAtomicLoad32 _ _)))
+	// result: x
+	for {
+		x := v_0
+		if x.Op != OpSelect0 {
+			break
+		}
+		x_0 := x.Args[0]
+		if x_0.Op != OpPPC64LoweredAtomicLoad32 {
+			break
+		}
+		v.copyOf(x)
+		return true
+	}
 	// match: (MOVWZreg x:(Arg <t>))
 	// cond: (is8BitInt(t) || is16BitInt(t) || is32BitInt(t)) && !isSigned(t)
 	// result: x