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cmd/compile: turn off jump tables when spectre retpolines are on

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Fixes #57097

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>
This commit is contained in:
Keith Randall 2022-12-05 16:26:26 -08:00 committed by Keith Randall
parent 9dde2de454
commit 1eb0465fa5
2 changed files with 29 additions and 1 deletions
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2
src/cmd/compile/internal/walk/switch.go
View File

@ -290,7 +290,7 @@ func (s *exprSwitch) tryJumpTable(cc []exprClause, out *ir.Nodes) bool {
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 {

28
test/codegen/retpoline.go
View File

@ -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
}