[lld] cb03ac0 - [ELF] Move Symbol::needsTlsLd to config->needsTlsLd
Fangrui Song via llvm-commits
llvm-commits at lists.llvm.org
Mon Feb 7 10:26:21 PST 2022
Author: Fangrui Song
Date: 2022-02-07T10:26:16-08:00
New Revision: cb03ac0b5d6f5c46d453762b2f6e234c24eabe1e
URL: https://github.com/llvm/llvm-project/commit/cb03ac0b5d6f5c46d453762b2f6e234c24eabe1e
DIFF: https://github.com/llvm/llvm-project/commit/cb03ac0b5d6f5c46d453762b2f6e234c24eabe1e.diff
LOG: [ELF] Move Symbol::needsTlsLd to config->needsTlsLd
to decrease sizeof(SymbolUnion) from 72 to 64 on ELF64 platforms.
Use a dummy `Undefined` to prevent null pointer dereference (though unused)
`*rel.sym` in InputSectionBase::relocateAlloc.
The relocation order may shuffle a bit, but otherwise there is no behavior
difference.
Added:
Modified:
lld/ELF/Config.h
lld/ELF/Relocations.cpp
lld/ELF/Symbols.h
lld/test/ELF/i386-tls-dynamic.s
lld/test/ELF/ppc64-tls-missing-gdld.s
Removed:
################################################################################
diff --git a/lld/ELF/Config.h b/lld/ELF/Config.h
index 72b7be8165e05..6d5c4cb592878 100644
--- a/lld/ELF/Config.h
+++ b/lld/ELF/Config.h
@@ -312,6 +312,9 @@ struct Configuration {
// if that's true.)
bool isMips64EL;
+ // True if we need to reserve two .got entries for local-dynamic TLS model.
+ bool needsTlsLd = false;
+
// True if we need to set the DF_STATIC_TLS flag to an output file, which
// works as a hint to the dynamic loader that the shared object contains code
// compiled with the initial-exec TLS model.
diff --git a/lld/ELF/Relocations.cpp b/lld/ELF/Relocations.cpp
index 58a61b4154dc4..f2b312c7729c3 100644
--- a/lld/ELF/Relocations.cpp
+++ b/lld/ELF/Relocations.cpp
@@ -1238,7 +1238,7 @@ static unsigned handleTlsRelocation(RelType type, Symbol &sym,
}
if (expr == R_TLSLD_HINT)
return 1;
- sym.needsTlsLd = true;
+ config->needsTlsLd = true;
c.relocations.push_back({expr, type, offset, addend, &sym});
return 1;
}
@@ -1681,15 +1681,6 @@ void elf::postScanRelocations() {
mainPart->relaDyn->addSymbolReloc(target->tlsGotRel, *in.got,
sym.getGotOffset(), sym);
}
-
- if (sym.needsTlsLd && in.got->addTlsIndex()) {
- if (isLocalInExecutable)
- in.got->relocations.push_back(
- {R_ADDEND, target->symbolicRel, in.got->getTlsIndexOff(), 1, &sym});
- else
- mainPart->relaDyn->addReloc({target->tlsModuleIndexRel, in.got.get(),
- in.got->getTlsIndexOff()});
- }
if (sym.needsGotDtprel) {
in.got->addEntry(sym);
in.got->relocations.push_back(
@@ -1700,6 +1691,16 @@ void elf::postScanRelocations() {
addTpOffsetGotEntry(sym);
};
+ if (config->needsTlsLd && in.got->addTlsIndex()) {
+ static Undefined dummy(nullptr, "", STB_LOCAL, 0, 0);
+ if (config->shared)
+ mainPart->relaDyn->addReloc(
+ {target->tlsModuleIndexRel, in.got.get(), in.got->getTlsIndexOff()});
+ else
+ in.got->relocations.push_back(
+ {R_ADDEND, target->symbolicRel, in.got->getTlsIndexOff(), 1, &dummy});
+ }
+
assert(symAux.empty());
for (Symbol *sym : symtab->symbols())
fn(*sym);
diff --git a/lld/ELF/Symbols.h b/lld/ELF/Symbols.h
index b682601667990..271b0fadae23c 100644
--- a/lld/ELF/Symbols.h
+++ b/lld/ELF/Symbols.h
@@ -247,8 +247,8 @@ class Symbol {
isInIplt(false), gotInIgot(false), folded(false),
needsTocRestore(false), scriptDefined(false), needsCopy(false),
needsGot(false), needsPlt(false), needsTlsDesc(false),
- needsTlsGd(false), needsTlsGdToIe(false), needsTlsLd(false),
- needsGotDtprel(false), needsTlsIe(false), hasDirectReloc(false) {}
+ needsTlsGd(false), needsTlsGdToIe(false), needsGotDtprel(false),
+ needsTlsIe(false), hasDirectReloc(false) {}
public:
// True if this symbol is in the Iplt sub-section of the Plt and the Igot
@@ -283,7 +283,6 @@ class Symbol {
uint8_t needsTlsDesc : 1;
uint8_t needsTlsGd : 1;
uint8_t needsTlsGdToIe : 1;
- uint8_t needsTlsLd : 1;
uint8_t needsGotDtprel : 1;
uint8_t needsTlsIe : 1;
uint8_t hasDirectReloc : 1;
@@ -301,7 +300,7 @@ class Symbol {
bool needsDynReloc() const {
return needsCopy || needsGot || needsPlt || needsTlsDesc || needsTlsGd ||
- needsTlsGdToIe || needsTlsLd || needsGotDtprel || needsTlsIe;
+ needsTlsGdToIe || needsGotDtprel || needsTlsIe;
}
void allocateAux() {
assert(auxIdx == uint32_t(-1));
@@ -513,9 +512,9 @@ union SymbolUnion {
};
// It is important to keep the size of SymbolUnion small for performance and
-// memory usage reasons. 72 bytes is a soft limit based on the size of Defined
+// memory usage reasons. 64 bytes is a soft limit based on the size of Defined
// on a 64-bit system.
-static_assert(sizeof(SymbolUnion) <= 72, "SymbolUnion too large");
+static_assert(sizeof(SymbolUnion) <= 64, "SymbolUnion too large");
template <typename T> struct AssertSymbol {
static_assert(std::is_trivially_destructible<T>(),
diff --git a/lld/test/ELF/i386-tls-dynamic.s b/lld/test/ELF/i386-tls-dynamic.s
index d61ee5526bb11..cff442e8ead39 100644
--- a/lld/test/ELF/i386-tls-dynamic.s
+++ b/lld/test/ELF/i386-tls-dynamic.s
@@ -66,13 +66,13 @@ addl tls1 at gotntpoff(%ebx),%eax
# CHECK: Relocations [
# CHECK: Section ({{.+}}) .rel.dyn {
-# CHECK-NEXT: 0x2370 R_386_TLS_DTPMOD32 -
-# CHECK-NEXT: 0x2358 R_386_TLS_DTPMOD32 tls0
-# CHECK-NEXT: 0x235C R_386_TLS_DTPOFF32 tls0
-# CHECK-NEXT: 0x2360 R_386_TLS_TPOFF tls0
-# CHECK-NEXT: 0x2364 R_386_TLS_DTPMOD32 tls1
-# CHECK-NEXT: 0x2368 R_386_TLS_DTPOFF32 tls1
-# CHECK-NEXT: 0x236C R_386_TLS_TPOFF tls1
+# CHECK-NEXT: 0x2358 R_386_TLS_DTPMOD32 -
+# CHECK-NEXT: 0x2360 R_386_TLS_DTPMOD32 tls0
+# CHECK-NEXT: 0x2364 R_386_TLS_DTPOFF32 tls0
+# CHECK-NEXT: 0x2368 R_386_TLS_TPOFF tls0
+# CHECK-NEXT: 0x236C R_386_TLS_DTPMOD32 tls1
+# CHECK-NEXT: 0x2370 R_386_TLS_DTPOFF32 tls1
+# CHECK-NEXT: 0x2374 R_386_TLS_TPOFF tls1
# CHECK-NEXT: }
# DIS: Disassembly of section .text:
@@ -81,20 +81,20 @@ addl tls1 at gotntpoff(%ebx),%eax
## General dynamic model:
## -4128 and -4116 are first and second GOT entries offsets.
## Each one is a pair of records.
-# DIS-NEXT: 1260: leal -4128(,%ebx), %eax
+# DIS-NEXT: 1260: leal -4120(,%ebx), %eax
# DIS-NEXT: 1267: calll 0x12d0
-# DIS-NEXT: 126c: leal -4116(,%ebx), %eax
+# DIS-NEXT: 126c: leal -4108(,%ebx), %eax
# DIS-NEXT: 1273: calll 0x12d0
## Local dynamic model:
## -16 is a local module tls index offset.
-# DIS-NEXT: 1278: leal -4104(%ebx), %eax
+# DIS-NEXT: 1278: leal -4128(%ebx), %eax
# DIS-NEXT: 127e: calll 0x12d0
# DIS-NEXT: 1283: leal 8(%eax), %edx
-# DIS-NEXT: 1289: leal -4104(%ebx), %eax
+# DIS-NEXT: 1289: leal -4128(%ebx), %eax
# DIS-NEXT: 128f: calll 0x12d0
# DIS-NEXT: 1294: leal 12(%eax), %edx
## Initial exec model:
# DIS-NEXT: 129a: movl %gs:0, %eax
-# DIS-NEXT: 12a0: addl -4120(%ebx), %eax
+# DIS-NEXT: 12a0: addl -4112(%ebx), %eax
# DIS-NEXT: 12a6: movl %gs:0, %eax
-# DIS-NEXT: 12ac: addl -4108(%ebx), %eax
+# DIS-NEXT: 12ac: addl -4100(%ebx), %eax
diff --git a/lld/test/ELF/ppc64-tls-missing-gdld.s b/lld/test/ELF/ppc64-tls-missing-gdld.s
index 2d1954e95b191..16a3085872c07 100644
--- a/lld/test/ELF/ppc64-tls-missing-gdld.s
+++ b/lld/test/ELF/ppc64-tls-missing-gdld.s
@@ -25,28 +25,28 @@
## .got+32: TPOFFSET for x = st_value-0x7000
# HEX: section '.got':
# HEX-NEXT: [[#%x,IGNORE:]] 50820210 00000000 01000000 00000000
-# HEX-NEXT: [[#%x,IGNORE:]] 0080ffff ffffffff 01000000 00000000
-# HEX-NEXT: [[#%x,IGNORE:]] 00000000 00000000 0090ffff ffffffff
+# HEX-NEXT: [[#%x,IGNORE:]] 00000000 00000000 01000000 00000000
+# HEX-NEXT: [[#%x,IGNORE:]] 0080ffff ffffffff 0090ffff ffffffff
## .TOC.-32768 = (.got+0x8000)-32768 = .got
# DIS-LABEL: <GeneralDynamic>:
# DIS-NEXT: addis 3, 2, 0
-# DIS-NEXT: addi 3, 3, -32760
+# DIS-NEXT: addi 3, 3, -32744
# DIS-NEXT: bl [[#%x,TGA:]]
# DIS-LABEL: <GeneralDynamic_NOTOC>:
# DIS-NEXT: addis 3, 2, 0
-# DIS-NEXT: addi 3, 3, -32760
+# DIS-NEXT: addi 3, 3, -32744
# DIS-NEXT: bl [[#TGA]]
## LocalDynamic references _TLS_MODULE_BASE_.
## .TOC.-32752 = (.got+0x8000)-32752 = .got+16
# DIS-LABEL: <LocalDynamic>:
# DIS-NEXT: addis 3, 2, 0
-# DIS-NEXT: addi 3, 3, -32744
+# DIS-NEXT: addi 3, 3, -32760
# DIS-NEXT: bl [[#TGA]]
# DIS-LABEL: <LocalDynamic_NOTOC>:
# DIS-NEXT: addis 3, 2, 0
-# DIS-NEXT: addi 3, 3, -32744
+# DIS-NEXT: addi 3, 3, -32760
# DIS-NEXT: bl [[#TGA]]
## Technically we don't have to disable IE to LE relaxation,
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