Remove execute-only support.

With kernel support being removed for execute-only memory layouts,
remove support for XOM until there's kernel support again.

This allows us to gain the code-size improvements from
"-z noseparate-code".

Bug: 147300048
Test: Compiled binaries no longer marked XOM by default.
Change-Id: Ie84bdd2ca025e8b14867008291bf9ce143b5e999

Android.bp

@@ -195,7 +195,6 @@ bootstrap_go_package {
         "cc/vendor_snapshot.go",
         "cc/vndk.go",
         "cc/vndk_prebuilt.go",
-        "cc/xom.go",
 
         "cc/cflag_artifacts.go",
         "cc/cmakelists.go",

android/config.go

@@ -790,14 +790,6 @@ func (c *config) DisableScudo() bool {
 	return Bool(c.productVariables.DisableScudo)
 }
 
-func (c *config) EnableXOM() bool {
-	if c.productVariables.EnableXOM == nil {
-		return true
-	} else {
-		return Bool(c.productVariables.EnableXOM)
-	}
-}
-
 func (c *config) Android64() bool {
 	for _, t := range c.Targets[Android] {
 		if t.Arch.ArchType.Multilib == "lib64" {
@@ -1153,13 +1145,6 @@ func (c *config) CFIEnabledForPath(path string) bool {
 	return PrefixInList(path, c.productVariables.CFIIncludePaths)
 }
 
-func (c *config) XOMDisabledForPath(path string) bool {
-	if c.productVariables.XOMExcludePaths == nil {
-		return false
-	}
-	return PrefixInList(path, c.productVariables.XOMExcludePaths)
-}
-
 func (c *config) VendorConfig(name string) VendorConfig {
 	return soongconfig.Config(c.productVariables.VendorVars[name])
 }

android/variable.go

@@ -241,9 +241,6 @@ type productVariables struct {
 
 	DisableScudo *bool `json:",omitempty"`
 
-	EnableXOM       *bool    `json:",omitempty"`
-	XOMExcludePaths []string `json:",omitempty"`
-
 	Experimental_mte *bool `json:",omitempty"`
 
 	VendorPath    *string `json:",omitempty"`

cc/cc.go

@@ -450,7 +450,6 @@ type Module struct {
 	vndkdep   *vndkdep
 	lto       *lto
 	pgo       *pgo
-	xom       *xom
 
 	outputFile android.OptionalPath
 
@@ -734,9 +733,6 @@ func (c *Module) Init() android.Module {
 	if c.pgo != nil {
 		c.AddProperties(c.pgo.props()...)
 	}
-	if c.xom != nil {
-		c.AddProperties(c.xom.props()...)
-	}
 	for _, feature := range c.features {
 		c.AddProperties(feature.props()...)
 	}
@@ -1206,7 +1202,6 @@ func newModule(hod android.HostOrDeviceSupported, multilib android.Multilib) *Mo
 	module.vndkdep = &vndkdep{}
 	module.lto = &lto{}
 	module.pgo = &pgo{}
-	module.xom = &xom{}
 	return module
 }
 
@@ -1401,9 +1396,6 @@ func (c *Module) GenerateAndroidBuildActions(actx android.ModuleContext) {
 	if c.pgo != nil {
 		flags = c.pgo.flags(ctx, flags)
 	}
-	if c.xom != nil {
-		flags = c.xom.flags(ctx, flags)
-	}
 	for _, feature := range c.features {
 		flags = feature.flags(ctx, flags)
 	}
@@ -2683,7 +2675,6 @@ func DefaultsFactory(props ...interface{}) android.Module {
 		&VndkProperties{},
 		&LTOProperties{},
 		&PgoProperties{},
-		&XomProperties{},
 		&android.ProtoProperties{},
 	)
 

cc/xom.go

@@ -1,79 +0,0 @@
-// Copyright 2018 Google Inc. All rights reserved.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package cc
-
-import (
-	"android/soong/android"
-)
-
-type XomProperties struct {
-	Xom *bool
-}
-
-type xom struct {
-	Properties XomProperties
-}
-
-func (xom *xom) props() []interface{} {
-	return []interface{}{&xom.Properties}
-}
-
-func (xom *xom) begin(ctx BaseModuleContext) {}
-
-func (xom *xom) deps(ctx BaseModuleContext, deps Deps) Deps {
-	return deps
-}
-
-func (xom *xom) flags(ctx ModuleContext, flags Flags) Flags {
-	disableXom := false
-
-	if !ctx.Config().EnableXOM() || ctx.Config().XOMDisabledForPath(ctx.ModuleDir()) {
-		disableXom = true
-	}
-
-	if xom.Properties.Xom != nil && !*xom.Properties.Xom {
-		return flags
-	}
-
-	// If any static dependencies have XOM disabled, we should disable XOM in this module,
-	// the assumption being if it's been explicitly disabled then there's probably incompatible
-	// code in the library which may get pulled in.
-	if !disableXom {
-		ctx.VisitDirectDeps(func(m android.Module) {
-			cc, ok := m.(*Module)
-			if !ok || cc.xom == nil || !cc.static() {
-				return
-			}
-			if cc.xom.Properties.Xom != nil && !*cc.xom.Properties.Xom {
-				disableXom = true
-				return
-			}
-		})
-	}
-
-	// Enable execute-only if none of the dependencies disable it,
-	// also if it's explicitly set true (allows overriding dependencies disabling it).
-	if !disableXom || (xom.Properties.Xom != nil && *xom.Properties.Xom) {
-		// XOM is only supported on AArch64 when using lld.
-		if ctx.Arch().ArchType == android.Arm64 && ctx.useClangLld(ctx) {
-			flags.Local.LdFlags = append(flags.Local.LdFlags,
-				"-Wl,--execute-only",
-				"-Wl,-z,separate-code",
-			)
-		}
-	}
-
-	return flags
-}