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[ELF] Linkerscript: symbol assignments with indentifiers on the right side of expression. 

In symbol assignments symbol may appear on the right-hand side of the expression:
(https://svnweb.freebsd.org/base/head/sys/conf/ldscript.amd64?revision=284870&view=markup#l8)

kernphys = CONSTANT (MAXPAGESIZE);
 . = kernbase + kernphys + SIZEOF_HEADERS;

Patch implements that.

Differential revision: https://reviews.llvm.org/D22759

llvm-svn: 276784
This commit is contained in:
George Rimar 2016-07-26 18:18:58 +00:00
parent f17d48e58a
commit a9c5a52846
2 changed files with 61 additions and 3 deletions
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32
lld/ELF/LinkerScript.cpp
View File

@ -756,6 +756,29 @@ SymbolAssignment *ScriptParser::readAssignment(StringRef Name) {
// script expression.
Expr ScriptParser::readExpr() { return readExpr1(readPrimary(), 0); }
static uint64_t getSymbolValue(StringRef S) {
switch (Config->EKind) {
case ELF32LEKind:
if (SymbolBody *B = Symtab<ELF32LE>::X->find(S))
return B->getVA<ELF32LE>();
break;
case ELF32BEKind:
if (SymbolBody *B = Symtab<ELF32BE>::X->find(S))
return B->getVA<ELF32BE>();
break;
case ELF64LEKind:
if (SymbolBody *B = Symtab<ELF64LE>::X->find(S))
return B->getVA<ELF64LE>();
break;
case ELF64BEKind:
if (SymbolBody *B = Symtab<ELF64BE>::X->find(S))
return B->getVA<ELF64BE>();
break;
}
error("symbol not found: " + S);
return 0;
}
// This is a part of the operator-precedence parser. This function
// assumes that the remaining token stream starts with an operator.
Expr ScriptParser::readExpr1(Expr Lhs, int MinPrec) {
@ -844,10 +867,13 @@ Expr ScriptParser::readPrimary() {
return [](uint64_t Dot) { return alignTo(Dot, Target->PageSize); };
}
// Parse a number literal
// Parse a symbol name or a number literal.
uint64_t V = 0;
if (Tok.getAsInteger(0, V))
setError("malformed number: " + Tok);
if (Tok.getAsInteger(0, V)) {
if (!isValidCIdentifier(Tok))
setError("malformed number: " + Tok);
return [=](uint64_t Dot) { return getSymbolValue(Tok); };
}
return [=](uint64_t Dot) { return V; };
}

32
lld/test/ELF/linkerscript/linkerscript-symbol-assignexpr.s Normal file
View File

@ -0,0 +1,32 @@
# REQUIRES: x86
# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t
# RUN: echo "SECTIONS { \
# RUN: symbol = CONSTANT(MAXPAGESIZE); \
# RUN: symbol2 = symbol + 0x1234; \
# RUN: symbol3 = symbol2; \
# RUN: }" > %t.script
# RUN: ld.lld -o %t1 --script %t.script %t
# RUN: llvm-objdump -t %t1 | FileCheck %s
# CHECK: SYMBOL TABLE:
# CHECK-NEXT: 0000000000000000 *UND* 00000000
# CHECK-NEXT: 0000000000000120 .text 00000000 _start
# CHECK-NEXT: 0000000000000121 .text 00000000 foo
# CHECK-NEXT: 0000000000001000 *ABS* 00000000 symbol
# CHECK-NEXT: 0000000000002234 *ABS* 00000000 symbol2
# CHECK-NEXT: 0000000000002234 *ABS* 00000000 symbol3
# RUN: echo "SECTIONS { \
# RUN: symbol2 = symbol; \
# RUN: }" > %t2.script
# RUN: not ld.lld -o %t2 --script %t2.script %t 2>&1 \
# RUN: | FileCheck -check-prefix=ERR %s
# ERR: symbol not found: symbol
.global _start
_start:
nop
.global foo
foo: