From: Keith Randall <khr@golang.org>
Date: Fri, 22 Nov 2024 23:24:54 +0000 (-0800)
Subject: cmd/internal/sys: allow unaligned loads on big-endian ppc64
X-Git-Tag: go1.25rc1~1178
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=3981b446ddba60108572606a74bc27bff1936d9e;p=gostls13.git

cmd/internal/sys: allow unaligned loads on big-endian ppc64

According to https://go.dev/wiki/MinimumRequirements, we've required
power8 since Go 1.9.

Before that, we supported power5 which couldn't do unaligned loads.
But power8 should be able to (it does for ppc64le).

In fact, I think we already support unaligned loads in some cases,
for instance cmd/compile/internal/ssa/config.go lists big-endian ppc64
as having unaligned loads.

Change-Id: I4a75f09d4b5199a889e0e8db0b3b7a1fa23145f3
Reviewed-on: https://go-review.googlesource.com/c/go/+/631318
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Keith Randall <khr@google.com>
Reviewed-by: Jayanth Krishnamurthy <jayanth.krishnamurthy@ibm.com>
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
---

diff --git a/src/cmd/internal/sys/arch.go b/src/cmd/internal/sys/arch.go
index 2e35284137..ee7089b544 100644
--- a/src/cmd/internal/sys/arch.go
+++ b/src/cmd/internal/sys/arch.go
@@ -208,7 +208,7 @@ var ArchPPC64 = &Arch{
 	RegSize:       8,
 	MinLC:         4,
 	Alignment:     1,
-	CanMergeLoads: false,
+	CanMergeLoads: true,
 	HasLR:         true,
 	// PIC code on ppc64le requires 32 bytes of stack, and it's
 	// easier to just use that much stack always.