[lld] 5bdc5e7 - [lld-link] Add safe icf mode to lld-link, which does safe icf for all sections.
Zequan Wu via llvm-commits
llvm-commits at lists.llvm.org
Wed Mar 3 14:52:54 PST 2021
Author: Zequan Wu
Date: 2021-03-03T14:52:33-08:00
New Revision: 5bdc5e7efda4100c4d11085c2da8f1fb932ccce4
URL: https://github.com/llvm/llvm-project/commit/5bdc5e7efda4100c4d11085c2da8f1fb932ccce4
DIFF: https://github.com/llvm/llvm-project/commit/5bdc5e7efda4100c4d11085c2da8f1fb932ccce4.diff
LOG: [lld-link] Add safe icf mode to lld-link, which does safe icf for all sections.
Differential Revision: https://reviews.llvm.org/D97436
Added:
Modified:
lld/COFF/Config.h
lld/COFF/Driver.cpp
lld/COFF/ICF.cpp
lld/COFF/ICF.h
lld/test/COFF/icf-safe.s
Removed:
################################################################################
diff --git a/lld/COFF/Config.h b/lld/COFF/Config.h
index 65ddc326ba78..ba1a5793ed5b 100644
--- a/lld/COFF/Config.h
+++ b/lld/COFF/Config.h
@@ -80,6 +80,13 @@ enum class GuardCFLevel {
Full, // Enable all protections.
};
+enum class ICFLevel {
+ None,
+ Safe, // Safe ICF for all sections.
+ All, // Aggressive ICF for code, but safe ICF for data, similar to MSVC's
+ // behavior.
+};
+
// Global configuration.
struct Configuration {
enum ManifestKind { SideBySide, Embed, No };
@@ -95,7 +102,7 @@ struct Configuration {
std::string importName;
bool demangle = true;
bool doGC = true;
- bool doICF = true;
+ ICFLevel doICF = ICFLevel::None;
bool tailMerge;
bool relocatable = true;
bool forceMultiple = false;
diff --git a/lld/COFF/Driver.cpp b/lld/COFF/Driver.cpp
index 69ed2922309e..9c13d4a078ec 100644
--- a/lld/COFF/Driver.cpp
+++ b/lld/COFF/Driver.cpp
@@ -1552,8 +1552,9 @@ void LinkerDriver::linkerMain(ArrayRef<const char *> argsArr) {
// Handle /opt.
bool doGC = debug == DebugKind::None || args.hasArg(OPT_profile);
- unsigned icfLevel =
- args.hasArg(OPT_profile) ? 0 : 1; // 0: off, 1: limited, 2: on
+ Optional<ICFLevel> icfLevel = None;
+ if (args.hasArg(OPT_profile))
+ icfLevel = ICFLevel::None;
unsigned tailMerge = 1;
bool ltoNewPM = LLVM_ENABLE_NEW_PASS_MANAGER;
bool ltoDebugPM = false;
@@ -1567,9 +1568,11 @@ void LinkerDriver::linkerMain(ArrayRef<const char *> argsArr) {
} else if (s == "noref") {
doGC = false;
} else if (s == "icf" || s.startswith("icf=")) {
- icfLevel = 2;
+ icfLevel = ICFLevel::All;
+ } else if (s == "safeicf") {
+ icfLevel = ICFLevel::Safe;
} else if (s == "noicf") {
- icfLevel = 0;
+ icfLevel = ICFLevel::None;
} else if (s == "lldtailmerge") {
tailMerge = 2;
} else if (s == "nolldtailmerge") {
@@ -1601,16 +1604,12 @@ void LinkerDriver::linkerMain(ArrayRef<const char *> argsArr) {
}
}
- // Limited ICF is enabled if GC is enabled and ICF was never mentioned
- // explicitly.
- // FIXME: LLD only implements "limited" ICF, i.e. it only merges identical
- // code. If the user passes /OPT:ICF explicitly, LLD should merge identical
- // comdat readonly data.
- if (icfLevel == 1 && !doGC)
- icfLevel = 0;
+ if (!icfLevel)
+ icfLevel = doGC ? ICFLevel::All : ICFLevel::None;
config->doGC = doGC;
- config->doICF = icfLevel > 0;
- config->tailMerge = (tailMerge == 1 && config->doICF) || tailMerge == 2;
+ config->doICF = icfLevel.getValue();
+ config->tailMerge =
+ (tailMerge == 1 && config->doICF != ICFLevel::None) || tailMerge == 2;
config->ltoNewPassManager = ltoNewPM;
config->ltoDebugPassManager = ltoDebugPM;
@@ -1719,8 +1718,8 @@ void LinkerDriver::linkerMain(ArrayRef<const char *> argsArr) {
args.hasFlag(OPT_allowisolation, OPT_allowisolation_no, true);
config->incremental =
args.hasFlag(OPT_incremental, OPT_incremental_no,
- !config->doGC && !config->doICF && !args.hasArg(OPT_order) &&
- !args.hasArg(OPT_profile));
+ !config->doGC && config->doICF == ICFLevel::None &&
+ !args.hasArg(OPT_order) && !args.hasArg(OPT_profile));
config->integrityCheck =
args.hasFlag(OPT_integritycheck, OPT_integritycheck_no, false);
config->cetCompat = args.hasFlag(OPT_cetcompat, OPT_cetcompat_no, false);
@@ -1769,7 +1768,7 @@ void LinkerDriver::linkerMain(ArrayRef<const char *> argsArr) {
config->incremental = false;
}
- if (config->incremental && config->doICF) {
+ if (config->incremental && config->doICF != ICFLevel::None) {
warn("ignoring '/incremental' because ICF is enabled; use '/opt:noicf' to "
"disable");
config->incremental = false;
@@ -2212,9 +2211,9 @@ void LinkerDriver::linkerMain(ArrayRef<const char *> argsArr) {
convertResources();
// Identify identical COMDAT sections to merge them.
- if (config->doICF) {
+ if (config->doICF != ICFLevel::None) {
findKeepUniqueSections();
- doICF(symtab->getChunks());
+ doICF(symtab->getChunks(), config->doICF);
}
// Write the result.
diff --git a/lld/COFF/ICF.cpp b/lld/COFF/ICF.cpp
index 386f861fb27f..732646967296 100644
--- a/lld/COFF/ICF.cpp
+++ b/lld/COFF/ICF.cpp
@@ -40,6 +40,7 @@ static Timer icfTimer("ICF", Timer::root());
class ICF {
public:
+ ICF(ICFLevel icfLevel) : icfLevel(icfLevel){};
void run(ArrayRef<Chunk *> v);
private:
@@ -62,6 +63,7 @@ class ICF {
std::vector<SectionChunk *> chunks;
int cnt = 0;
std::atomic<bool> repeat = {false};
+ ICFLevel icfLevel = ICFLevel::All;
};
// Returns true if section S is subject of ICF.
@@ -81,8 +83,9 @@ bool ICF::isEligible(SectionChunk *c) {
if (!c->isCOMDAT() || !c->live || writable)
return false;
- // Code sections are eligible.
- if (c->getOutputCharacteristics() & llvm::COFF::IMAGE_SCN_MEM_EXECUTE)
+ // Under regular (not safe) ICF, all code sections are eligible.
+ if ((icfLevel == ICFLevel::All) &&
+ c->getOutputCharacteristics() & llvm::COFF::IMAGE_SCN_MEM_EXECUTE)
return true;
// .pdata and .xdata unwind info sections are eligible.
@@ -314,7 +317,9 @@ void ICF::run(ArrayRef<Chunk *> vec) {
}
// Entry point to ICF.
-void doICF(ArrayRef<Chunk *> chunks) { ICF().run(chunks); }
+void doICF(ArrayRef<Chunk *> chunks, ICFLevel icfLevel) {
+ ICF(icfLevel).run(chunks);
+}
} // namespace coff
} // namespace lld
diff --git a/lld/COFF/ICF.h b/lld/COFF/ICF.h
index 0b3c8fa2ff2e..f8cc8071f9eb 100644
--- a/lld/COFF/ICF.h
+++ b/lld/COFF/ICF.h
@@ -9,6 +9,7 @@
#ifndef LLD_COFF_ICF_H
#define LLD_COFF_ICF_H
+#include "Config.h"
#include "lld/Common/LLVM.h"
#include "llvm/ADT/ArrayRef.h"
@@ -17,7 +18,7 @@ namespace coff {
class Chunk;
-void doICF(ArrayRef<Chunk *> chunks);
+void doICF(ArrayRef<Chunk *> chunks, ICFLevel);
} // namespace coff
} // namespace lld
diff --git a/lld/test/COFF/icf-safe.s b/lld/test/COFF/icf-safe.s
index d16f21f458fc..e3a20edecc8a 100644
--- a/lld/test/COFF/icf-safe.s
+++ b/lld/test/COFF/icf-safe.s
@@ -3,14 +3,28 @@
# RUN: llvm-mc -filetype=obj -triple=x86_64-pc-win32 %S/Inputs/icf-safe.s -o %t2.obj
# RUN: lld-link /dll /noentry /out:%t.dll /verbose /opt:noref,icf %t1.obj %t2.obj 2>&1 | FileCheck %s
# RUN: lld-link /dll /noentry /out:%t.dll /verbose /opt:noref,icf /export:g3 /export:g4 %t1.obj %t2.obj 2>&1 | FileCheck --check-prefix=EXPORT %s
+# RUN: lld-link /dll /noentry /out:%t.dll /verbose /opt:noref,safeicf %t1.obj %t2.obj 2>&1 | FileCheck %s --check-prefix=SAFEICF
# CHECK-NOT: Selected
# CHECK: Selected g3
# CHECK-NEXT: Removed g4
+# CHECK: Selected f1
+# CHECK-NEXT: Removed f2
+# CHECK-NEXT: Removed f3
+# CHECK-NEXT: Removed f4
# CHECK-NOT: Removed
# CHECK-NOT: Selected
-# EXPORT-NOT: Selected
+# EXPORT-NOT: Selected g3
+# EXPORT-NOT: Selected g4
+
+# SAFEICF-NOT: Selected
+# SAFEICF: Selected g3
+# SAFEICF-NEXT: Removed g4
+# SAFEICF: Selected f3
+# SAFEICF-NEXT: Removed f4
+# SAFEICF-NOT: Removed
+# SAFEICF-NOT: Selected
.section .rdata,"dr",one_only,g1
.globl g1
@@ -32,6 +46,28 @@ g3:
g4:
.byte 2
+.section .text,"xr",one_only,f1
+.globl f1
+f1:
+ nop
+
+.section .text,"xr",one_only,f2
+.globl f2
+f2:
+ nop
+
+.section .text,"xr",one_only,f3
+.globl f3
+f3:
+ nop
+
+.section .text,"xr",one_only,f4
+.globl f4
+f4:
+ nop
+
.addrsig
.addrsig_sym g1
.addrsig_sym g2
+.addrsig_sym f1
+.addrsig_sym f2
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