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[ELF] - Make ASSERT() return Dot instead of evaluated value. 

Previously ASSERT we implemented returned expression value.
Ex:
. = ASSERT(0x100);
would set Dot value to 0x100

Form of assert when it is assigned to Dot was implemented for 
compatibility with very old GNU ld which required it.
Some scripts in the wild, including linux kernel scripts 
use such ASSERTs at the end for doing different checks.

Currently we fail with "unable to move location counter backward"
for such scripts. Patch changes ASSERT to return location counter 
value to fix that.

Differential revision: https://reviews.llvm.org/D30171

llvm-svn: 295703
This commit is contained in:
George Rimar 2017-02-21 07:33:38 +00:00
parent 002549b8be
commit 60f1fe8438
3 changed files with 5 additions and 7 deletions
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5
lld/ELF/LinkerScript.cpp
View File

@ -1468,10 +1468,9 @@ Expr ScriptParser::readAssert() {
StringRef Msg = unquote(next());
expect(")");
return [=](uint64_t Dot) {
uint64_t V = E(Dot);
if (!V)
if (!E(Dot))
error(Msg);
return V;
return Dot;
};
}

4
lld/test/ELF/linkerscript/assert.s
View File

@ -5,10 +5,6 @@
# RUN: ld.lld -shared -o %t1 --script %t1.script %t1.o
# RUN: llvm-readobj %t1 > /dev/null
# RUN: echo "SECTIONS { ASSERT(ASSERT(42, fail) == 42, fail) }" > %t2.script
# RUN: ld.lld -shared -o %t2 --script %t2.script %t1.o
# RUN: llvm-readobj %t2 > /dev/null
# RUN: echo "SECTIONS { ASSERT(0, fail) }" > %t3.script
# RUN: not ld.lld -shared -o %t3 --script %t3.script %t1.o > %t.log 2>&1
# RUN: FileCheck %s -check-prefix=FAIL < %t.log

3
lld/test/ELF/linkerscript/locationcountererr2.s
View File

@ -3,3 +3,6 @@
# RUN: echo "SECTIONS { . = 0x20; . = 0x10; }" > %t.script
# RUN: not ld.lld %t.o --script %t.script -o %t -shared 2>&1 | FileCheck %s
# CHECK: unable to move location counter backward
# RUN: echo "SECTIONS { . = 0x20; . = ASSERT(0x1, "foo"); }" > %t2.script
# RUN: ld.lld %t.o --script %t2.script -o %t -shared