[llvm] r327459 - [LTO/gold] Support --wrap
Teresa Johnson via llvm-commits
llvm-commits at lists.llvm.org
Tue Mar 13 16:06:19 PDT 2018
Author: tejohnson
Date: Tue Mar 13 16:06:19 2018
New Revision: 327459
URL: http://llvm.org/viewvc/llvm-project?rev=327459&view=rev
Log:
[LTO/gold] Support --wrap
Summary:
Utilize new gold plugin api interface for obtaining --wrap option
arguments, and LTO API handling (added for --wrap support in lld LTO),
to mark symbols so that LTO does not optimize them inappropriately.
Note the test cases will be in a new gold test subdirectory that
is dependent on the next release of gold which will contain the new
interfaces.
Reviewers: pcc, tmsriram
Subscribers: mehdi_amini, llvm-commits, inglorion
Differential Revision: https://reviews.llvm.org/D44235
Added:
llvm/trunk/test/tools/gold/X86/v1.16/
llvm/trunk/test/tools/gold/X86/v1.16/Inputs/
llvm/trunk/test/tools/gold/X86/v1.16/Inputs/wrap-bar.ll
llvm/trunk/test/tools/gold/X86/v1.16/lit.local.cfg
llvm/trunk/test/tools/gold/X86/v1.16/wrap-1.ll
llvm/trunk/test/tools/gold/X86/v1.16/wrap-2.ll
Modified:
llvm/trunk/tools/gold/gold-plugin.cpp
Added: llvm/trunk/test/tools/gold/X86/v1.16/Inputs/wrap-bar.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/tools/gold/X86/v1.16/Inputs/wrap-bar.ll?rev=327459&view=auto
==============================================================================
--- llvm/trunk/test/tools/gold/X86/v1.16/Inputs/wrap-bar.ll (added)
+++ llvm/trunk/test/tools/gold/X86/v1.16/Inputs/wrap-bar.ll Tue Mar 13 16:06:19 2018
@@ -0,0 +1,14 @@
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+define hidden void @bar() {
+ ret void
+}
+
+define hidden void @__real_bar() {
+ ret void
+}
+
+define hidden void @__wrap_bar() {
+ ret void
+}
Added: llvm/trunk/test/tools/gold/X86/v1.16/lit.local.cfg
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/tools/gold/X86/v1.16/lit.local.cfg?rev=327459&view=auto
==============================================================================
--- llvm/trunk/test/tools/gold/X86/v1.16/lit.local.cfg (added)
+++ llvm/trunk/test/tools/gold/X86/v1.16/lit.local.cfg Tue Mar 13 16:06:19 2018
@@ -0,0 +1,28 @@
+import re
+import subprocess
+
+def is_gold_v1_16_linker_available():
+
+ if not config.gold_executable:
+ return False
+ try:
+ ld_cmd = subprocess.Popen([config.gold_executable, '-v'],
+ stdout = subprocess.PIPE,
+ stderr = subprocess.PIPE)
+ ld_out, _ = ld_cmd.communicate()
+ ld_out = ld_out.decode()
+ except:
+ return False
+
+ match = re.search(r'GNU gold \(.*\) (\d+)\.(\d+)', ld_out)
+ if not match:
+ return False
+ major = int(match.group(1))
+ minor = int(match.group(2))
+ if major < 1 or (major == 1 and minor < 16):
+ return False
+
+ return True
+
+if not is_gold_v1_16_linker_available():
+ config.unsupported = True
Added: llvm/trunk/test/tools/gold/X86/v1.16/wrap-1.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/tools/gold/X86/v1.16/wrap-1.ll?rev=327459&view=auto
==============================================================================
--- llvm/trunk/test/tools/gold/X86/v1.16/wrap-1.ll (added)
+++ llvm/trunk/test/tools/gold/X86/v1.16/wrap-1.ll Tue Mar 13 16:06:19 2018
@@ -0,0 +1,42 @@
+; LTO
+; RUN: llvm-as %s -o %t.o
+; RUN: %gold -plugin %llvmshlibdir/LLVMgold%shlibext %t.o -o %t.out -wrap=bar -plugin-opt=save-temps
+; RUN: llvm-readobj -t %t.out | FileCheck %s
+; RUN: cat %t.out.resolution.txt | FileCheck -check-prefix=RESOLS %s
+
+; ThinLTO
+; RUN: opt -module-summary %s -o %t.o
+; RUN: %gold -plugin %llvmshlibdir/LLVMgold%shlibext %t.o -o %t.out -wrap=bar -plugin-opt=save-temps
+; RUN: llvm-readobj -t %t.out | FileCheck %s
+; RUN: cat %t.out.resolution.txt | FileCheck -check-prefix=RESOLS %s
+
+; CHECK: Name: __wrap_bar
+; CHECK-NEXT: Value:
+; CHECK-NEXT: Size:
+; CHECK-NEXT: Binding: Global
+; CHECK-NEXT: Type: Function
+
+; Make sure that the 'r' (linker redefined) bit is set for bar and __real_bar
+; in the resolutions file, and that the 'x' (visible to regular obj) bit is set
+; for bar and __wrap_bar.
+; RESOLS: ,bar,lxr
+; RESOLS: ,__wrap_bar,plx
+; RESOLS: ,__real_bar,plr
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+declare void @bar()
+
+define void @_start() {
+ call void @bar()
+ ret void
+}
+
+define void @__wrap_bar() {
+ ret void
+}
+
+define void @__real_bar() {
+ ret void
+}
Added: llvm/trunk/test/tools/gold/X86/v1.16/wrap-2.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/tools/gold/X86/v1.16/wrap-2.ll?rev=327459&view=auto
==============================================================================
--- llvm/trunk/test/tools/gold/X86/v1.16/wrap-2.ll (added)
+++ llvm/trunk/test/tools/gold/X86/v1.16/wrap-2.ll Tue Mar 13 16:06:19 2018
@@ -0,0 +1,55 @@
+; LTO
+; This doesn't currently work with gold, because it does not apply defsym
+; renaming to symbols in the same module (apparently by design for consistency
+; with GNU ld). Because regular LTO hands back a single object file to gold,
+; it doesn't perform the desired defsym renaming. This isn't an issue with
+; ThinLTO which hands back multiple native objects to gold. For regular
+; LTO defsym handling, gold will need a fix (not the gold plugin).
+; RUN-TODO: llvm-as %s -o %t.o
+; RUN-TODO: llvm-as %S/Inputs/wrap-bar.ll -o %t1.o
+; RUN-TODO: %gold -plugin %llvmshlibdir/LLVMgold%shlibext %t.o %t1.o -shared -o %t.so -wrap=bar
+; RUN-TODO: llvm-objdump -d %t.so | FileCheck %s
+; RUN-TODO: llvm-readobj -t %t.so | FileCheck -check-prefix=BIND %s
+
+; ThinLTO
+; RUN: opt -module-summary %s -o %t.o
+; RUN: opt -module-summary %S/Inputs/wrap-bar.ll -o %t1.o
+; RUN: %gold -plugin %llvmshlibdir/LLVMgold%shlibext %t.o %t1.o -shared -o %t.so -wrap=bar
+; RUN: llvm-objdump -d %t.so | FileCheck %s -check-prefix=THIN
+; RUN: llvm-readobj -t %t.so | FileCheck -check-prefix=BIND %s
+
+; Make sure that calls in foo() are not eliminated and that bar is
+; routed to __wrap_bar and __real_bar is routed to bar.
+
+; CHECK: foo:
+; CHECK-NEXT: pushq %rax
+; CHECK-NEXT: callq{{.*}}<__wrap_bar>
+; CHECK-NEXT: callq{{.*}}<bar>
+
+; THIN: foo:
+; THIN-NEXT: pushq %rax
+; THIN-NEXT: callq{{.*}}<__wrap_bar>
+; THIN-NEXT: popq %rax
+; THIN-NEXT: jmp{{.*}}<bar>
+
+; Check that bar and __wrap_bar retain their original binding.
+; BIND: Name: bar
+; BIND-NEXT: Value:
+; BIND-NEXT: Size:
+; BIND-NEXT: Binding: Local
+; BIND: Name: __wrap_bar
+; BIND-NEXT: Value:
+; BIND-NEXT: Size:
+; BIND-NEXT: Binding: Local
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+declare void @bar()
+declare void @__real_bar()
+
+define void @foo() {
+ call void @bar()
+ call void @__real_bar()
+ ret void
+}
Modified: llvm/trunk/tools/gold/gold-plugin.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/gold/gold-plugin.cpp?rev=327459&r1=327458&r2=327459&view=diff
==============================================================================
--- llvm/trunk/tools/gold/gold-plugin.cpp (original)
+++ llvm/trunk/tools/gold/gold-plugin.cpp Tue Mar 13 16:06:19 2018
@@ -56,6 +56,7 @@ static ld_plugin_status discard_message(
static ld_plugin_release_input_file release_input_file = nullptr;
static ld_plugin_get_input_file get_input_file = nullptr;
static ld_plugin_message message = discard_message;
+static ld_plugin_get_wrap_symbols get_wrap_symbols = nullptr;
namespace {
struct claimed_file {
@@ -93,6 +94,8 @@ struct PluginInputFile {
struct ResolutionInfo {
bool CanOmitFromDynSym = true;
bool DefaultVisibility = true;
+ bool CanInline = true;
+ bool IsUsedInRegularObj = false;
};
}
@@ -367,6 +370,9 @@ ld_plugin_status onload(ld_plugin_tv *tv
case LDPT_MESSAGE:
message = tv->tv_u.tv_message;
break;
+ case LDPT_GET_WRAP_SYMBOLS:
+ get_wrap_symbols = tv->tv_u.tv_get_wrap_symbols;
+ break;
default:
break;
}
@@ -563,6 +569,29 @@ static ld_plugin_status claim_file_hook(
}
}
+ // Handle any --wrap options passed to gold, which are than passed
+ // along to the plugin.
+ if (get_wrap_symbols) {
+ const char **wrap_symbols;
+ uint64_t count = 0;
+ if (get_wrap_symbols(&count, &wrap_symbols) != LDPS_OK) {
+ message(LDPL_ERROR, "Unable to get wrap symbols!");
+ return LDPS_ERR;
+ }
+ for (uint64_t i = 0; i < count; i++) {
+ StringRef Name = wrap_symbols[i];
+ ResolutionInfo &Res = ResInfo[Name];
+ ResolutionInfo &WrapRes = ResInfo["__wrap_" + Name.str()];
+ ResolutionInfo &RealRes = ResInfo["__real_" + Name.str()];
+ // Tell LTO not to inline symbols that will be overwritten.
+ Res.CanInline = false;
+ RealRes.CanInline = false;
+ // Tell LTO not to eliminate symbols that will be used after renaming.
+ Res.IsUsedInRegularObj = true;
+ WrapRes.IsUsedInRegularObj = true;
+ }
+ }
+
return LDPS_OK;
}
@@ -686,6 +715,12 @@ static void addModule(LTO &Lto, claimed_
(IsExecutable || !Res.DefaultVisibility))
R.FinalDefinitionInLinkageUnit = true;
+ if (!Res.CanInline)
+ R.LinkerRedefined = true;
+
+ if (Res.IsUsedInRegularObj)
+ R.VisibleToRegularObj = true;
+
freeSymName(Sym);
}
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