Commit Graph

8 Commits

Author SHA1 Message Date
Simon Atanasyan 11766558d7 [mips] Fix relocation record format and ELF header for N32 ABI
The N32 ABI uses RELA relocation format, do not use 3-in-1 relocation's
encoding, and uses ELFCLASS32. This change passes the `IsN32` flag
to the `MCAsmBackend` to distinguish usage of N32 ABI.

We still do not handle some cases like providing the `-target-abi=o32`
command line option with the `mips64` target triple. That's why
elf_header.s contains some "FIXME" strings. This case will be fixed in
a separate patch.

Differential revision: https://reviews.llvm.org/D37960

llvm-svn: 313873
2017-09-21 10:44:26 +00:00
Rafael Espindola 13a79bbfe5 Change how we handle section symbols on ELF.
On ELF every section can have a corresponding section symbol. When in
an assembly file we have

.quad .text

the '.text' refers to that symbol.

The way we used to handle them is to leave .text an undefined symbol
until the very end when the object writer would map them to the
actual section symbol.

The problem with that is that anything before the end would see an
undefined symbol. This could result in bad diagnostics
(test/MC/AArch64/label-arithmetic-diags-elf.s), or incorrect results
when using the asm streamer (est/MC/Mips/expansion-jal-sym-pic.s).

Fixing this will also allow using the section symbol earlier for
setting sh_link of SHF_METADATA sections.

This patch includes a few hacks to avoid changing our behaviour when
handling conflicts between section symbols and other symbols. I
reported pr31850 to track that.

llvm-svn: 293936
2017-02-02 21:26:06 +00:00
Simon Atanasyan 5048514c20 [mips] For PIC code convert unconditional jump to unconditional branch
Unconditional branch uses relative addressing which is the right choice
in case of position independent code.

This is a fix for the bug:
https://dmz-portal.mips.com/bugz/show_bug.cgi?id=2445

Differential revision: https://reviews.llvm.org/D27483

llvm-svn: 289448
2016-12-12 17:40:26 +00:00
Simon Dardis c08af6db5b [mips] Correct jal expansion for local symbols in .local directives.
This patch corrects the behaviour of code such as:

   .local foo
   jal foo
foo:
to use the correct jal expansion when writing ELF files.

Patch by: Daniel Sanders

Reviewers: zoran.jovanovic, seanbruno, vkalintiris

Differential Revision: https://reviews.llvm.org/D24722

llvm-svn: 287918
2016-11-25 11:06:43 +00:00
Daniel Sanders 6a73883c48 [mips] Correct label prefixes for N32 and N64.
Summary:
N32 and N64 follow the standard ELF conventions (.L) whereas O32 uses its own
($).

This fixes the majority of object differences between -fintegrated-as and
-fno-integrated-as.

Reviewers: sdardis

Subscribers: dsanders, sdardis, llvm-commits

Differential Revision: https://reviews.llvm.org/D22412

llvm-svn: 275967
2016-07-19 10:49:03 +00:00
Daniel Sanders 0d97270ae5 [mips] Use --check-prefixes where appropriate. NFC.
llvm-svn: 273669
2016-06-24 12:23:17 +00:00
Daniel Sanders fe98b2f54b [mips] Use MipsMCExpr instead of MCSymbolRefExpr for all relocations.
Summary:
This is much closer to the way MIPS relocation expressions work
(%hi(foo + 2) rather than %hi(foo) + 2) and removes the need for the
various bodges in MipsAsmParser::evaluateRelocExpr().

Removing those bodges ensures that the constant stored in MCValue is the
full 32 or 64-bit (depending on ABI) offset from the symbol. This will be used
to correct the %hi/%lo matching needed to sort the relocation table correctly.

As part of this:
* Gave MCExpr::print() the ability to omit parenthesis when emitting a
  symbol reference inside a MipsMCExpr operator like %hi(X). Without this
  we print things like %lo(($L1)).
* %hi(%neg(%gprel(X))) is now three MipsMCExpr's instead of one. Most of
  the related special cases have been removed or moved to MipsMCExpr. We
  can remove the rest as we gain support for the less common relocations
  when they are not part of this specific combination.
* Renamed MipsMCExpr::VariantKind and the enum prefix ('VK_') to avoid confusion
  with MCSymbolRefExpr::VariantKind and its prefix (also 'VK_').
* fixup_Mips_GOT_Local and fixup_Mips_GOT_Global were found to be identical
  and merged into fixup_Mips_GOT.
* MO_GOT16 and MO_GOT turned out to be identical and have been merged into
  MO_GOT.
* VK_Mips_GOT and VK_Mips_GOT16 turned out to be the same thing so they
  have been merged into MEK_GOT

Reviewers: sdardis

Subscribers: dsanders, sdardis, llvm-commits

Differential Revision: http://reviews.llvm.org/D19716

llvm-svn: 268379
2016-05-03 13:35:44 +00:00
Daniel Sanders 63f4a5dcad [mips] Expand JAL instructions when PIC is enabled.
Summary: This is the correct way to handle JAL instructions when PIC is enabled.

Patch by Toma Tabacu

Reviewers: seanbruno, tomatabacu

Subscribers: brooks, seanbruno, emaste, llvm-commits

Differential Revision: http://reviews.llvm.org/D6231

llvm-svn: 245305
2015-08-18 16:18:09 +00:00