This is in preparation for my next change, which will introduce a relro
nobits section. That requires that relro sections appear at the end of the
progbits part of the r/w segment so that the relro nobits section can appear
contiguously.
Because of the amount of churn required in the test suite, I'm making this
change separately.
llvm-svn: 291523
The MipsGotSection::getPageEntryOffset calculates index of GOT entry
with a "page" address. Previously this method changes the state
of MipsGotSection because it modifies PageIndexMap field. That leads
to the unpredictable results if getPageEntryOffset called from multiple threads.
The patch makes getPageEntryOffset constant. To do so it calculates GOT
entry index but does not update PageIndexMap field. Later in the
MipsGotSection::writeTo method linker calculates "page" addresses and
writes them to the output.
llvm-svn: 288129
If output section which referenced by R_MIPS_GOT_PAGE or R_MIPS_GOT16
relocations is small (less that 0x10000 bytes) and occupies two adjacent
0xffff-bytes pages, current formula gives incorrect number of required "page"
GOT entries. The problem is that in time of calculation we do not know
the section address and so we cannot calculate number of 0xffff-bytes
pages exactly.
This patch fix the formula. Now it gives a correct number of pages in
the worst case when "small" section intersects 0xffff-bytes page
boundary. From the other side, sometimes it adds one more redundant GOT
entry for each output section. But usually number of output sections
referenced by GOT relocations is small.
llvm-svn: 288127
There are two motivations for this patch. The first one is a preparation
for support MIPS TLS relocations. It might sound like a joke but for GOT
entries related to TLS relocations MIPS ABI uses almost regular approach
with creation of dynamic relocations for each GOT enty etc. But we need
to separate these 'regular' TLS related entries from MIPS specific local
and global parts of GOT. ABI declare simple solution - all TLS related
entries allocated at the end of GOT after local/global parts. The second
motivation it to support GOT relocations for non-preemptible symbols
with addends. If we have more than one GOT relocations against symbol S
with different addends we need to create GOT entries for each unique
Symbol/Addend pairs.
So we store all MIPS GOT entries in separate containers. For non-preemptible
symbols we have to maintain two data structures. The first one is MipsLocal
vector. Each entry corresponds to the GOT entry from the 'local' part
of the GOT contains the symbol's address plus addend. The second one
is MipsLocalMap. It is a map from Symbol/Addend pair to the GOT index.
Differential Revision: http://reviews.llvm.org/D21297
llvm-svn: 273127
R_MIPS_GOT16 relocation against local symbol requires index of a local
GOT entry which contains page address corresponds to sum of the symbol
address and addend. The addend in that case is calculated using addends
from the R_MIPS_GOT16 and paired R_MIPS_LO16 relocations.
Differential Revision: http://reviews.llvm.org/D17610
llvm-svn: 261930
Some MIPS relocation (for now R_MIPS_GOT16) requires creation of GOT
entries for symbol not included in the dynamic symbol table. They are
local symbols and non-local symbols with 'local' visibility. Local GOT
entries occupy continuous block between GOT header and regular GOT
entries.
The patch adds initial support for handling local GOT entries. The main
problem is allocating local GOT entries for local symbols. Such entries
should be initialized by high 16-bit of the symbol value. In ideal world
there should be no duplicated entries with the same values. But at the
moment of the `Writer::scanRelocs` call we do not know a value of the
symbol. In this patch we create new local GOT entry for each relocation
against local symbol, though we can exhaust GOT quickly. That needs to
be optimized later. When we calculate relocation we know a final symbol
value and request local GOT entry index. To do that we maintain map
between addresses and local GOT entry indexes. If we start to calculate
relocations in parallel we will have to serialize access to this map.
Differential Revision: http://reviews.llvm.org/D16324
llvm-svn: 258388
Fangrui Song