From b7e0dfc437edf6d744dfdf9f4613bee26ea08e31 Mon Sep 17 00:00:00 2001
From: Lynn Boger <laboger@linux.vnet.ibm.com>
Date: Tue, 12 Sep 2023 09:34:43 -0500
Subject: [PATCH] cmd/compile: add rules to avoid unnecessary MOVDaddr for
 PPC64

This adds some rules to recognize MOVDaddr in those cases where
it is just adding 0 to a ptr value. Instead the ptr value can just
be used.

Change-Id: I95188defc9701165c86bbea70d14d037a9e54853
Reviewed-on: https://go-review.googlesource.com/c/go/+/527698
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Paul Murphy <murp@ibm.com>
Run-TryBot: Lynn Boger <laboger@linux.vnet.ibm.com>
Reviewed-by: Than McIntosh <thanm@google.com>
---
 src/cmd/compile/internal/ssa/_gen/PPC64.rules |  2 ++
 src/cmd/compile/internal/ssa/rewritePPC64.go  | 35 +++++++++++++++++++
 2 files changed, 37 insertions(+)

diff --git a/src/cmd/compile/internal/ssa/_gen/PPC64.rules b/src/cmd/compile/internal/ssa/_gen/PPC64.rules
index 4c4f7c8c17..c5309f16c6 100644
--- a/src/cmd/compile/internal/ssa/_gen/PPC64.rules
+++ b/src/cmd/compile/internal/ssa/_gen/PPC64.rules
@@ -238,6 +238,8 @@
 (LocalAddr <t> {sym} base mem) && t.Elem().HasPointers() => (MOVDaddr {sym} (SPanchored base mem))
 (LocalAddr <t> {sym} base _)  && !t.Elem().HasPointers() => (MOVDaddr {sym} base)
 (OffPtr [off] ptr) => (ADD (MOVDconst <typ.Int64> [off]) ptr)
+(MOVDaddr {sym} [n] p:(ADD x y)) && sym == nil && n == 0 => p
+(MOVDaddr {sym} [n] ptr) && sym == nil && n == 0 && (ptr.Op == OpArgIntReg || ptr.Op == OpPhi) => ptr
 
 // TODO: optimize these cases?
 (Ctz32NonZero ...) => (Ctz32 ...)
diff --git a/src/cmd/compile/internal/ssa/rewritePPC64.go b/src/cmd/compile/internal/ssa/rewritePPC64.go
index 2bcc27fbc8..089e4e614c 100644
--- a/src/cmd/compile/internal/ssa/rewritePPC64.go
+++ b/src/cmd/compile/internal/ssa/rewritePPC64.go
@@ -533,6 +533,8 @@ func rewriteValuePPC64(v *Value) bool {
 		return rewriteValuePPC64_OpPPC64MOVBstoreidx(v)
 	case OpPPC64MOVBstorezero:
 		return rewriteValuePPC64_OpPPC64MOVBstorezero(v)
+	case OpPPC64MOVDaddr:
+		return rewriteValuePPC64_OpPPC64MOVDaddr(v)
 	case OpPPC64MOVDload:
 		return rewriteValuePPC64_OpPPC64MOVDload(v)
 	case OpPPC64MOVDloadidx:
@@ -7778,6 +7780,39 @@ func rewriteValuePPC64_OpPPC64MOVBstorezero(v *Value) bool {
 	}
 	return false
 }
+func rewriteValuePPC64_OpPPC64MOVDaddr(v *Value) bool {
+	v_0 := v.Args[0]
+	// match: (MOVDaddr {sym} [n] p:(ADD x y))
+	// cond: sym == nil && n == 0
+	// result: p
+	for {
+		n := auxIntToInt32(v.AuxInt)
+		sym := auxToSym(v.Aux)
+		p := v_0
+		if p.Op != OpPPC64ADD {
+			break
+		}
+		if !(sym == nil && n == 0) {
+			break
+		}
+		v.copyOf(p)
+		return true
+	}
+	// match: (MOVDaddr {sym} [n] ptr)
+	// cond: sym == nil && n == 0 && (ptr.Op == OpArgIntReg || ptr.Op == OpPhi)
+	// result: ptr
+	for {
+		n := auxIntToInt32(v.AuxInt)
+		sym := auxToSym(v.Aux)
+		ptr := v_0
+		if !(sym == nil && n == 0 && (ptr.Op == OpArgIntReg || ptr.Op == OpPhi)) {
+			break
+		}
+		v.copyOf(ptr)
+		return true
+	}
+	return false
+}
 func rewriteValuePPC64_OpPPC64MOVDload(v *Value) bool {
 	v_1 := v.Args[1]
 	v_0 := v.Args[0]
-- 
2.50.0