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[ELF] Simplify handling of AT section attribute.

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This also makes the behavior close to GNU ld's.

Differential Revision: https://reviews.llvm.org/D43284

llvm-svn: 325213
This commit is contained in:
Igor Kudrin
2018-02-15 06:13:52 +00:00
parent 5ffda0cc1f
commit 25f917341e
3 changed files with 40 additions and 9 deletions
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8
lld/ELF/Writer.cpp
View File

@@ -821,8 +821,6 @@ void PhdrEntry::add(OutputSection *Sec) {
p_align = std::max(p_align, Sec->Alignment);
if (p_type == PT_LOAD)
Sec->PtLoad = this;
if (Sec->LMAExpr)
ASectionHasLMA = true;
}
// The beginning and the ending of .rel[a].plt section are marked
@@ -1697,9 +1695,11 @@ template <class ELFT> std::vector<PhdrEntry *> Writer<ELFT>::createPhdrs() {
// (e.g. executable or writable). There is one phdr for each segment.
// Therefore, we need to create a new phdr when the next section has
// different flags or is loaded at a discontiguous address using AT linker
// script command.
// script command. At the same time, we don't want to create a separate
// load segment for the headers, even if the first output section has
// an AT attribute.
uint64_t NewFlags = computeFlags(Sec->getPhdrFlags());
if ((Sec->LMAExpr && Load->ASectionHasLMA) ||
if ((Sec->LMAExpr && Load->LastSec != Out::ProgramHeaders) ||
Sec->MemRegion != Load->FirstSec->MemRegion || Flags != NewFlags) {
Load = AddHdr(PT_LOAD, NewFlags);

5
lld/ELF/Writer.h
View File

@@ -45,11 +45,6 @@ struct PhdrEntry {
OutputSection *LastSec = nullptr;
bool HasLMA = false;
// True if one of the sections in this program header has a LMA specified via
// linker script: AT(addr). We never allow 2 or more sections with LMA in the
// same program header.
bool ASectionHasLMA = false;
uint64_t LMAOffset = 0;
};

36
lld/test/ELF/linkerscript/at4.s Normal file
View File

@@ -0,0 +1,36 @@
# REQUIRES: x86
# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t
# RUN: echo "SECTIONS { \
# RUN: . = 0x1000; \
# RUN: .aaa : { *(.aaa) } \
# RUN: .bbb : AT(0x2008) { *(.bbb) } \
# RUN: .ccc : { *(.ccc) } \
# RUN: }" > %t.script
# RUN: ld.lld %t --script %t.script -o %t2
# RUN: llvm-readobj -program-headers %t2 | FileCheck %s
# CHECK: Type: PT_LOAD
# CHECK-NEXT: Offset: 0x1000
# CHECK-NEXT: VirtualAddress: 0x1000
# CHECK-NEXT: PhysicalAddress: 0x1000
# CHECK-NEXT: FileSize: 8
# CHECK-NEXT: MemSize: 8
# CHECK: Type: PT_LOAD
# CHECK-NEXT: Offset: 0x1008
# CHECK-NEXT: VirtualAddress: 0x1008
# CHECK-NEXT: PhysicalAddress: 0x2008
# CHECK-NEXT: FileSize: 17
# CHECK-NEXT: MemSize: 17
.global _start
_start:
nop
.section .aaa, "a"
.quad 0
.section .bbb, "a"
.quad 0
.section .ccc, "a"
.quad 0