golang: backport an upstream fix for non-retpoline-compatible error

This fixes the following build error:
```
Building targets
runtime
<autogenerated>:1: non-retpoline-compatible: 00200 (/home/username/works/openwrt/staging_dir/hostpkg/lib/go-cross/src/runtime/time.go:915)       JMP     (R15)(R12*8)
<autogenerated>:1: non-retpoline-compatible: 00115 (/home/username/works/openwrt/staging_dir/hostpkg/lib/go-cross/src/runtime/type.go:614)       JMP     (AX)(SI*8)
<autogenerated>:1: non-retpoline-compatible: 00028 (/home/username/works/openwrt/staging_dir/hostpkg/lib/go-cross/src/runtime/time.go:452)       JMP     (R11)(R10*8)
<autogenerated>:1: non-retpoline-compatible: 00021 (/home/username/works/openwrt/staging_dir/hostpkg/lib/go-cross/src/runtime/error.go:261)      JMP     (DX)(CX*8)
<autogenerated>:1: non-retpoline-compatible: 00050 (/home/username/works/openwrt/staging_dir/hostpkg/lib/go-cross/src/runtime/time.go:691)       JMP     (CX)(R12*8)
<autogenerated>:1: non-retpoline-compatible: 00024 (/home/username/works/openwrt/staging_dir/hostpkg/lib/go-cross/src/runtime/debuglog.go:616)   JMP     (CX)(SI*8)
<autogenerated>:1: non-retpoline-compatible: 00079 (/home/username/works/openwrt/staging_dir/hostpkg/lib/go-cross/src/runtime/time.go:617)       JMP     (R9)(R8*8)
<autogenerated>:1: non-retpoline-compatible: 00025 (/home/username/works/openwrt/staging_dir/hostpkg/lib/go-cross/src/runtime/cgocall.go:453)    JMP     (R9)(DX*8)
<autogenerated>:1: non-retpoline-compatible: 00018 (/home/username/works/openwrt/staging_dir/hostpkg/lib/go-cross/src/runtime/type.go:66)        JMP     (DX)(CX*8)
<autogenerated>:1: non-retpoline-compatible: 00020 (/home/username/works/openwrt/staging_dir/hostpkg/lib/go-cross/src/runtime/alg.go:156)        JMP     (SI)(DX*8)
<autogenerated>:1: too many errors
```

Fixes: #20026
Signed-off-by: Tianling Shen <cnsztl@immortalwrt.org>
(cherry picked from commit 35f33c99b126cfa3ac51b9d7634340d43458b7db)

diff --git a/lang/golang/golang/patches/010-cmd-compile-turn-off-jump-tables-when-spectre-retpolines-.patch b/lang/golang/golang/patches/010-cmd-compile-turn-off-jump-tables-when-spectre-retpolines-.patch
new file mode 100644 (file)
index 0000000..1899571
--- /dev/null
+++ b/lang/golang/golang/patches/010-cmd-compile-turn-off-jump-tables-when-spectre-retpolines-.patch
@@ -0,0 +1,67 @@
+From 156578067111742b55718066c91b8ec66d35e03d Mon Sep 17 00:00:00 2001
+From: Keith Randall <khr@golang.org>
+Date: Mon, 5 Dec 2022 16:26:26 -0800
+Subject: [PATCH] [release-branch.go1.19] cmd/compile: turn off jump tables
+ when spectre retpolines are on
+
+Fixes #57100
+
+Change-Id: I6ab659abbca1ae0ac8710674d39aec116fab0baa
+Reviewed-on: https://go-review.googlesource.com/c/go/+/455336
+Reviewed-by: Keith Randall <khr@google.com>
+Reviewed-by: Cherry Mui <cherryyz@google.com>
+TryBot-Result: Gopher Robot <gobot@golang.org>
+Run-TryBot: Keith Randall <khr@golang.org>
+(cherry picked from commit 1eb0465fa596a2d6e9c1a632499989544f0d7e68)
+Reviewed-on: https://go-review.googlesource.com/c/go/+/455416
+Reviewed-by: Michael Pratt <mpratt@google.com>
+---
+ src/cmd/compile/internal/walk/switch.go |  2 +-
+ test/codegen/retpoline.go               | 28 +++++++++++++++++++++++++
+ 2 files changed, 29 insertions(+), 1 deletion(-)
+
+--- a/src/cmd/compile/internal/walk/switch.go
++++ b/src/cmd/compile/internal/walk/switch.go
+@@ -289,7 +289,7 @@ func (s *exprSwitch) tryJumpTable(cc []e
+       const minCases = 8   // have at least minCases cases in the switch
+       const minDensity = 4 // use at least 1 out of every minDensity entries
+ 
+-      if !go119UseJumpTables || base.Flag.N != 0 || !ssagen.Arch.LinkArch.CanJumpTable {
++      if !go119UseJumpTables || base.Flag.N != 0 || !ssagen.Arch.LinkArch.CanJumpTable || base.Ctxt.Retpoline {
+               return false
+       }
+       if len(cc) < minCases {
+--- a/test/codegen/retpoline.go
++++ b/test/codegen/retpoline.go
+@@ -12,3 +12,31 @@ func CallInterface(x interface{ M() }) {
+       // amd64:`CALL\truntime.retpoline`
+       x.M()
+ }
++
++// Check to make sure that jump tables are disabled
++// when retpoline is on. See issue 57097.
++func noJumpTables(x int) int {
++      switch x {
++      case 0:
++              return 0
++      case 1:
++              return 1
++      case 2:
++              return 2
++      case 3:
++              return 3
++      case 4:
++              return 4
++      case 5:
++              return 5
++      case 6:
++              return 6
++      case 7:
++              return 7
++      case 8:
++              return 8
++      case 9:
++              return 9
++      }
++      return 10
++}