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[ELF] LinkerScript: Don't assign zero to all regular symbols 

This fixes an assertion `Align != 0u && "Align can't be 0."'
in llvm::alignTo() when a linker script references a globally
defined variable in an ALIGN() context.

Patch by Alexander Richardson !

Differential revision: https://reviews.llvm.org/D31984

llvm-svn: 300315
This commit is contained in:
George Rimar 2017-04-14 09:23:26 +00:00
parent 4e7bcd5216
commit 01aa795f82
2 changed files with 40 additions and 2 deletions
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7
lld/ELF/LinkerScript.cpp
View File

@ -68,8 +68,13 @@ template <class ELFT> static SymbolBody *addRegular(SymbolAssignment *Cmd) {
Sym->Binding = STB_GLOBAL;
ExprValue Value = Cmd->Expression();
SectionBase *Sec = Value.isAbsolute() ? nullptr : Value.Sec;
// We want to set symbol values early if we can. This allows us to use symbols
// as variables in linker scripts. Doing so allows us to write expressions
// like this: `alignment = 16; . = ALIGN(., alignment)`
uint64_t SymValue = Value.isAbsolute() ? Value.getValue() : 0;
replaceBody<DefinedRegular>(Sym, Cmd->Name, /*IsLocal=*/false, Visibility,
STT_NOTYPE, 0, 0, Sec, nullptr);
STT_NOTYPE, SymValue, 0, Sec, nullptr);
return Sym->body();
}

35
lld/test/ELF/linkerscript/align.s
View File

@ -67,7 +67,40 @@
# RUN: } \
# RUN: }" > %t2.script
# RUN: ld.lld -o %t2 --script %t2.script %t
# RUN: llvm-objdump -section-headers %t1 | FileCheck %s
# RUN: llvm-objdump -section-headers %t2 | FileCheck %s
## Check use of variables in align expressions:
# RUN: echo " VAR = 0x1000; \
# RUN: __code_base__ = 0x10000; \
# RUN: SECTIONS { \
# RUN: . = __code_base__; \
# RUN: .aaa : \
# RUN: { \
# RUN: *(.aaa) \
# RUN: } \
# RUN: .bbb : ALIGN(VAR) \
# RUN: { \
# RUN: *(.bbb) \
# RUN: } \
# RUN: . = ALIGN(., VAR * 4); \
# RUN: .ccc : \
# RUN: { \
# RUN: *(.ccc) \
# RUN: } \
# RUN: __start_bbb = ADDR(.bbb); \
# RUN: __end_bbb = ALIGN(__start_bbb + SIZEOF(.bbb), VAR); \
# RUN: }" > %t3.script
# RUN: ld.lld -o %t3 --script %t3.script %t
# RUN: llvm-objdump -section-headers %t3 | FileCheck %s
# RUN: llvm-objdump -t %t3 | FileCheck -check-prefix SYMBOLS %s
# SYMBOLS-LABEL: SYMBOL TABLE:
# SYMBOLS-NEXT: 0000000000000000 *UND* 00000000
# SYMBOLS-NEXT: 0000000000014008 .text 00000000 _start
# SYMBOLS-NEXT: 0000000000010000 *ABS* 00000000 __code_base__
# SYMBOLS-NEXT: 0000000000001000 *ABS* 00000000 VAR
# SYMBOLS-NEXT: 0000000000011000 .bbb 00000000 __start_bbb
# SYMBOLS-NEXT: 0000000000012000 *ABS* 00000000 __end_bbb
.global _start
_start: