%highest(sym1 - sym2 + const) relocations. Remove "ABS_" from VK_Mips_HI
and VK_Mips_LO enums in MipsMCExpr, to be consistent with VK_Mips_HIGHER
and VK_Mips_HIGHEST.
This change also deletes test file test/MC/Mips/higher_highest.ll and moves
its CHECK's to the new test file test/MC/Mips/higher-highest-addressing.s.
The deleted file tests that R_MIPS_HIGHER and R_MIPS_HIGHEST relocations are
emitted in the .o file. Since it uses -force-mips-long-branch option, it was
created when MipsLongBranch's implementation was emitting R_MIPS_HIGHER and
R_MIPS_HIGHEST relocations in the .o file. It was disabled when MipsLongBranch
started to directly calculate offsets.
Differential Revision: http://llvm-reviews.chandlerc.com/D3230
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205522 91177308-0d34-0410-b5e6-96231b3b80d8
Adds the instructions ext/ext32/cins/cins32.
It also changes pop/dpop to accept the two operand version and
adds a simple pattern to generate baddu.
Tests for the two operand versions (including baddu/dmul/dpop/pop)
and the code generation pattern for baddu are included.
Reviewed by: Daniel.Sanders@imgtec.com
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205449 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
This should fix the issues the D3222 caused in lld. Testcase is based on
the one that failed in the buildbot.
Depends on D3233
Reviewers: matheusalmeida, vmedic
Reviewed By: matheusalmeida
Differential Revision: http://llvm-reviews.chandlerc.com/D3234
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205298 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
Highlights:
- Registers are resolved much later (by the render method).
Prior to that point, GPR32's/GPR64's are GPR's regardless of register
size. Similarly FGR32's/FGR64's/AFGR64's are FGR's regardless of register
size or FR mode. Numeric registers can be anything.
- All registers are parsed the same way everywhere (even when handling
symbol aliasing)
- One consequence is that all registers can be specified numerically
almost anywhere (e.g. $fccX, $wX). The exception is symbol aliasing
but that can be easily resolved.
- Removes the need for the hasConsumedDollar hack
- Parenthesis and Bracket suffixes are handled generically
- Micromips instructions are parsed directly instead of going through the
standard encodings first.
- rdhwr accepts all 32 registers, and the following instructions that previously
xfailed now work:
ddiv, ddivu, div, divu, cvt.l.[ds], se[bh], wsbh, floor.w.[ds], c.ngl.d,
c.sf.s, dsbh, dshd, madd.s, msub.s, nmadd.s, nmsub.s, swxc1
- Diagnostics involving registers point at the correct character (the $)
- There's only one kind of immediate in MipsOperand. LSA immediates are handled
by the predicate and renderer.
Lowlights:
- Hardcoded '$zero' in the div patterns is handled with a hack.
MipsOperand::isReg() will return true for a k_RegisterIndex token
with Index == 0 and getReg() will return ZERO for this case. Note that it
doesn't return ZERO_64 on isGP64() targets.
- I haven't cleaned up all of the now-unused functions.
Some more of the generic parser could be removed too (integers and relocs
for example).
- insve.df needed a custom decoder to handle the implicit fourth operand that
was needed to make it parse correctly. The difficulty was that the matcher
expected a Token<'0'> but gets an Imm<0>. Adding an implicit zero solved this.
Reviewers: matheusalmeida, vmedic
Reviewed By: matheusalmeida
Differential Revision: http://llvm-reviews.chandlerc.com/D3222
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205292 91177308-0d34-0410-b5e6-96231b3b80d8
This moves one case of raw text checking down into the MCStreamer
interfaces in the form of a virtual function, even if we ultimately end
up consolidating on the one-or-many line tables issue one day, this is
nicer in the interim. This just generally streamlines a bunch of use
cases into a common code path.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205287 91177308-0d34-0410-b5e6-96231b3b80d8
I don't think this is reachable by any frontend (why would you transform
asm to asm+debug info?) but it helps tidy up some of this code, avoid
the weird special case of "emit the first CU, store the label, then emit
the rest" in MCDwarfLineTable::Emit by instead having the
DWARF-for-assembly case use the same codepath as DwarfDebug.cpp, by
registering the label of the debug_line section, thus causing it to be
emitted. (with a special case in asm output to just emit the label since
asm output uses the .loc directives, etc, rather than the debug_loc
directly)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205286 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
Highlights:
- Registers are resolved much later (by the render method).
Prior to that point, GPR32's/GPR64's are GPR's regardless of register
size. Similarly FGR32's/FGR64's/AFGR64's are FGR's regardless of register
size or FR mode. Numeric registers can be anything.
- All registers are parsed the same way everywhere (even when handling
symbol aliasing)
- One consequence is that all registers can be specified numerically
almost anywhere (e.g. $fccX, $wX). The exception is symbol aliasing
but that can be easily resolved.
- Removes the need for the hasConsumedDollar hack
- Parenthesis and Bracket suffixes are handled generically
- Micromips instructions are parsed directly instead of going through the
standard encodings first.
- rdhwr accepts all 32 registers, and the following instructions that previously
xfailed now work:
ddiv, ddivu, div, divu, cvt.l.[ds], se[bh], wsbh, floor.w.[ds], c.ngl.d,
c.sf.s, dsbh, dshd, madd.s, msub.s, nmadd.s, nmsub.s, swxc1
- Diagnostics involving registers point at the correct character (the $)
- There's only one kind of immediate in MipsOperand. LSA immediates are handled
by the predicate and renderer.
Lowlights:
- Hardcoded '$zero' in the div patterns is handled with a hack.
MipsOperand::isReg() will return true for a k_RegisterIndex token
with Index == 0 and getReg() will return ZERO for this case. Note that it
doesn't return ZERO_64 on isGP64() targets.
- I haven't cleaned up all of the now-unused functions.
Some more of the generic parser could be removed too (integers and relocs
for example).
- insve.df needed a custom decoder to handle the implicit fourth operand that
was needed to make it parse correctly. The difficulty was that the matcher
expected a Token<'0'> but gets an Imm<0>. Adding an implicit zero solved this.
Reviewers: matheusalmeida, vmedic
Reviewed By: matheusalmeida
Differential Revision: http://llvm-reviews.chandlerc.com/D3222
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205229 91177308-0d34-0410-b5e6-96231b3b80d8
%got_hi, %got_lo, %call_hi, %call_lo, %higher, and %highest are now recognised
by MipsAsmParser::getVariantKind().
To prevent future issues with missing entries in this StringSwitch, I've added
an assertion to the default case.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205200 91177308-0d34-0410-b5e6-96231b3b80d8
Unlike my previous commit, don't try to remove the corresponding VK_Mips_GOT yet
even though it shares the same assembly text since that is used.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205196 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
Where those ISA's are not currently supported, the test is run with the smallest
superset of that ISA.
Some instructions are valid but don't pass yet. These have been placed in the
valid-xfail.s's which will XPASS if _any_ instruction starts working.
The valid.s's do not verify the encoding yet. There are also no tests checking that instructions from neighbouring ISA's are not accepted.
Reviewers: matheusalmeida
Reviewed By: matheusalmeida
Differential Revision: http://llvm-reviews.chandlerc.com/D3214
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205180 91177308-0d34-0410-b5e6-96231b3b80d8
When LLVM is not built with zlib, nocompression.s will test
for the error message. But this test case will cause breakage
because the exit code is non-zero. This commit fix this issue
by adding "not" to the command.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205102 91177308-0d34-0410-b5e6-96231b3b80d8
Issue subject: Crash using integrated assembler with immediate arithmetic
Fix description:
Expressions like 'cmp r0, #(l1 - l2) >> 3' could not be evaluated on asm parsing stage,
since it is impossible to resolve labels on this stage. In the end of stage we still have
expression (MCExpr).
Then, when we want to encode it, we expect it to be an immediate, but it still an expression.
Patch introduces a Fixup (MCFixup instance), that is processed after main encoding stage.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205094 91177308-0d34-0410-b5e6-96231b3b80d8
This adds a second implementation of the AArch64 architecture to LLVM,
accessible in parallel via the "arm64" triple. The plan over the
coming weeks & months is to merge the two into a single backend,
during which time thorough code review should naturally occur.
Everything will be easier with the target in-tree though, hence this
commit.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205090 91177308-0d34-0410-b5e6-96231b3b80d8
I started trying to fix a small issue, but this code has seen a small fix too
many.
The old code was fairly convoluted. Some of the issues it had:
* It failed to check if a symbol difference was in the some section when
converting a relocation to pcrel.
* It failed to check if the relocation was already pcrel.
* The pcrel value computation was wrong in some cases (relocation-pc.s)
* It was missing quiet a few cases where it should not convert symbol
relocations to section relocations, leaving the backends to patch it up.
* It would not propagate the fact that it had changed a relocation to pcrel,
requiring a quiet nasty work around in ARM.
* It was missing comments.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205076 91177308-0d34-0410-b5e6-96231b3b80d8
Turns out debug_frame does use multiple fragments, so it doesn't
compress correctly with the current approach. Disable compressing it for
now while I figure out what's the best solution for it.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205059 91177308-0d34-0410-b5e6-96231b3b80d8
This is a bit of a stab in the dark, since I have zlib on my machine.
Just going to bounce it off the bots & see if it sticks.
Do we have some convention for negative REQUIRES: checks? Or do I just
need to add a feature like I've done here?
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205050 91177308-0d34-0410-b5e6-96231b3b80d8
It was using "lc -filetype=obj" just to pass the result to
"llvm-objdupm -disassemble" and then filecheck assembly.
The CHECK-NOT would never match anyway since it was missing $.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205036 91177308-0d34-0410-b5e6-96231b3b80d8
1) When creating a .debug_* section and instead create a .zdebug_
section.
2) When creating a fragment in a .zdebug_* section, make it a compressed
fragment.
3) When computing the size of a compressed section, compress the data
and use the size of the compressed data.
4) Emit the compressed bytes.
Also, check that only if a section has a compressed fragment, then that
is the only fragment in the section.
Assert-fail if the fragment's data is modified after it is compressed.
Initial review on llvm-commits by Eric Christopher and Rafael Espindola.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204958 91177308-0d34-0410-b5e6-96231b3b80d8
Fix description:
Expressions like 'cmp r0, #(l1 - l2) >> 3' could not be evaluated on asm parsing stage,
since it is impossible to resolve labels on this stage. In the end of stage we still have
expression (MCExpr).
Then, when we want to encode it, we expect it to be an immediate, but it still an expression.
Patch introduces a Fixup (MCFixup instance), that is processed after main encoding stage.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204899 91177308-0d34-0410-b5e6-96231b3b80d8
This enables TableGen to generate an additional two operand matcher
for our ArithLogicR class of instructions (constituted by 3 register operands).
E.g.: and $1, $2 <=> and $1, $1, $2
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204826 91177308-0d34-0410-b5e6-96231b3b80d8
The '.dword' directive accepts a list of expressions and emits
them in 8-byte chunks in successive locations.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204822 91177308-0d34-0410-b5e6-96231b3b80d8
The '.set mips64' directive enables the feature Mips:FeatureMips64
from assembly. Note that it doesn't modify the ELF header as opposed
to the use of -mips64 from the command-line. The reason for this
is that we want to be as compatible as possible with existing assemblers
like GAS.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204817 91177308-0d34-0410-b5e6-96231b3b80d8
The '.set mips64r2' directive enables the feature Mips:FeatureMips64r2
from assembly. Note that it doesn't modify the ELF header as opposed
to the use of -mips64r2 from the command-line. The reason for this
is that we want to be as compatible as possible with existing assemblers
like GAS.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204815 91177308-0d34-0410-b5e6-96231b3b80d8
The directive '.option pic2' enables PIC from assembly source.
At the moment none of the macros/directives check the PIC bit
but that's going to be fixed relatively soon. For example, the
expansion of macros like 'la' depend on the relocation model.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204803 91177308-0d34-0410-b5e6-96231b3b80d8
These are aliases of t4-t7 and are provided for compatibility with both the
original ABI documentation (using t4-t7) and GNU As (using t0-t3)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204797 91177308-0d34-0410-b5e6-96231b3b80d8
This reveals a small mistake in mips-register-names.s ($sp is tested twice and
$s8 is not tested) which will be fixed in a follow-up commit.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204792 91177308-0d34-0410-b5e6-96231b3b80d8
The logic was incorrect for variables, causing them to end up in the wrong
section if the section had an index >= 0xff00.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204771 91177308-0d34-0410-b5e6-96231b3b80d8
We need .symtab_shndxr if and only if a symbol references a section with an
index >= 0xff00.
The old code was trying to figure out if the section was needed ahead of time,
making it a fairly dependent on the code actually writing the table. It was
also somewhat conservative and would create the section in cases where it was
not needed.
If I remember correctly, the old structure was there so that the sections were
created in the same order gas creates them. That was valuable when MC's support
for ELF was new and we tested with elf-dump.py.
This patch refactors the symbol table creation to another class and makes it
obvious that .symtab_shndxr is really only created when we are about to output
a reference to a section index >= 0xff00.
While here, also improve the tests to use macros. One file is one section
short of needing .symtab_shndxr, the second one has just the right number.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204769 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
Remove the XFAIL added in my previous commit and correct the test such that
it correctly tests the expansion of the assembler temporary.
Also added a test to check that $at is always $1 when written by the
user.
Corrected the new assembler temporary warnings so that they are emitted for
numeric registers too.
Differential Revision: http://llvm-reviews.chandlerc.com/D3169
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204711 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
The assembler temporary is normally $at ($1) but can be reassigned using
'.set at=$reg'. Regardless of which register is nominated as the assembler
temporary, $at remains $1 when written by the user.
Adds warnings under the following conditions:
* The register nominated as the assembler temporary is used by the user.
* '.set noat' is in effect and $at is used by the user.
Both of these only work for named registers. I have a follow up commit that makes it work for numeric registers as well.
XFAIL set-at-directive.s since it incorrectly tests that $at is redefined by
'.set at=$reg'. Testcases will follow in a separate commit.
Patch by David Chisnall
His work was sponsored by: DARPA, AFRL
Differential Revision: http://llvm-reviews.chandlerc.com/D3167
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204710 91177308-0d34-0410-b5e6-96231b3b80d8
As a first step towards real little-endian code generation, this patch
changes the PowerPC MC layer to actually generate little-endian object
files. This involves passing the little-endian flag through the various
layers, including down to createELFObjectWriter so we actually get basic
little-endian ELF objects, emitting instructions in little-endian order,
and handling fixups and relocations as appropriate for little-endian.
The bulk of the patch is to update most test cases in test/MC/PowerPC
to verify both big- and little-endian encodings. (The only test cases
*not* updated are those that create actual big-endian ABI code, like
the TLS tests.)
Note that while the object files are now little-endian, the generated
code itself is not yet updated, in particular, it still does not adhere
to the ELFv2 ABI.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204634 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
- If only two registers are passed to a three-register operation, then the
first argument is both source and destination register.
- If a non-register is passed as the last argument, generate the immediate
version of the instruction.
Also mark DADD commutative and add scheduling information (to the generic
scheduler), and implement DSUB.
Patch by David Chisnall
His work was sponsored by: DARPA, AFRL
CC: theraven
Differential Revision: http://llvm-reviews.chandlerc.com/D3148
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204605 91177308-0d34-0410-b5e6-96231b3b80d8
This is similar, but not identical to what gas does. The logic in MC is to just
compute the symbol table after parsing the entire file. GAS is mixed, given
.type b, @object
a = b
b:
.type b, @function
It will propagate the change and make 'a' a function. Given
.type b, @object
b:
a = b
.type b, @function
the type of 'a' is still object.
Since we do the computation in the end, we produce a function in both cases.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204555 91177308-0d34-0410-b5e6-96231b3b80d8
When a label is parsed, check if there is type information available for the
label. If so, check if the symbol is a function. If the symbol is a function
and we are in thumb mode and no explicit thumb_func has been emitted, adjust the
symbol data to indicate that the function definition is a thumb function.
The application of this inferencing is improved value handling in the object
file (the required thumb bit is set on symbols which are thumb functions). It
also helps improve compatibility with binutils.
The one complication that arises from this handling is the MCAsmStreamer. The
default implementation of getOrCreateSymbolData in MCStreamer does not support
tracking the symbol data. In order to support the semantics of thumb functions,
track symbol data in assembly streamer. Although O(n) in number of labels in
the TU, this is already done in various other streamers and as such the memory
overhead is not a practical concern in this scenario.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204544 91177308-0d34-0410-b5e6-96231b3b80d8
sym_a:
sym_d = sym_a + 1
This is the smallest fix I was able to extract from what got reverted in
r204203.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204527 91177308-0d34-0410-b5e6-96231b3b80d8
The commit r203762 introduced silent failure for complext SO expression, and it's even worse than compiler crash.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204427 91177308-0d34-0410-b5e6-96231b3b80d8
The Octeon cpu from Cavium Networks is mips64r2 based and has an extended
instruction set. In order to utilize this with LLVM, a new cpu feature "octeon"
and a subtarget feature "cnmips" is added. A small set of new instructions
(baddu, dmul, pop, dpop, seq, sne) is also added. LLVM generates dmul, pop and
dpop instructions with option -mcpu=octeon or -mattr=+cnmips.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204337 91177308-0d34-0410-b5e6-96231b3b80d8
Given
bar = foo + 4
.long bar
MC would eat the 4. GNU as includes it in the relocation. The rule seems to be
that a variable that defines a symbol is used in the relocation and one that
does not define a symbol is evaluated and the result included in the relocation.
Fixing this unfortunately required some other changes:
* Since the variable is now evaluated, it would prevent the ELF writer from
noticing the weakref marker the elf streamer uses. This patch then replaces
that with a VariantKind in MCSymbolRefExpr.
* Using VariantKind then requires us to look past other VariantKind to see
.weakref bar,foo
call bar@PLT
doing this also fixes
zed = foo +2
call zed@PLT
so that is a good thing.
* Looking past VariantKind means that the relocation selection has to use
the fixup instead of the target.
This is a reboot of the previous fixes for MC. I will watch the sanitizer
buildbot and wait for a build before adding back the previous fixes.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204294 91177308-0d34-0410-b5e6-96231b3b80d8
Allow object files to be tagged with a version-min load command for iOS
or MacOSX.
Teach macho-dump to understand the version-min load commands for
testcases.
rdar://11337778
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204190 91177308-0d34-0410-b5e6-96231b3b80d8
The revision I'm reverting breaks handling of transitive aliases. This blocks us
and breaks sanitizer bootstrap:
http://lab.llvm.org:8011/builders/sanitizer-x86_64-linux-bootstrap/builds/2651
(and checked locally by Alexey).
This revision is the result of:
svn merge -r204059:204058 -r204028:204027 -r203962:203961 .
+ the regression test added to test/MC/ELF/alias.s
Another way to reproduce the regression with clang:
$ cat q.c
void a1();
void a2() __attribute__((alias("a1")));
void a3() __attribute__((alias("a2")));
void a1() {}
$ ~/work/llvm-build/bin/clang-3.5-good -c q.c && mv q.o good.o && \
~/work/llvm-build/bin/clang-3.5-bad -c q.c && mv q.o bad.o && \
objdump -t good.o bad.o
good.o: file format elf64-x86-64
SYMBOL TABLE:
0000000000000000 l df *ABS* 0000000000000000 q.c
0000000000000000 l d .text 0000000000000000 .text
0000000000000000 l d .data 0000000000000000 .data
0000000000000000 l d .bss 0000000000000000 .bss
0000000000000000 l d .comment 0000000000000000 .comment
0000000000000000 l d .note.GNU-stack 0000000000000000 .note.GNU-stack
0000000000000000 l d .eh_frame 0000000000000000 .eh_frame
0000000000000000 g F .text 0000000000000006 a1
0000000000000000 g F .text 0000000000000006 a2
0000000000000000 g F .text 0000000000000006 a3
bad.o: file format elf64-x86-64
SYMBOL TABLE:
0000000000000000 l df *ABS* 0000000000000000 q.c
0000000000000000 l d .text 0000000000000000 .text
0000000000000000 l d .data 0000000000000000 .data
0000000000000000 l d .bss 0000000000000000 .bss
0000000000000000 l d .comment 0000000000000000 .comment
0000000000000000 l d .note.GNU-stack 0000000000000000 .note.GNU-stack
0000000000000000 l d .eh_frame 0000000000000000 .eh_frame
0000000000000000 g F .text 0000000000000006 a1
0000000000000000 g F .text 0000000000000006 a2
0000000000000000 g .text 0000000000000000 a3
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204137 91177308-0d34-0410-b5e6-96231b3b80d8
This performs the equivalent of a .set directive in that it creates a symbol
which is an alias for another symbol or value which may possibly be yet
undefined. This directive also has the added property in that it marks the
aliased symbol as being a thumb function entry point, in the same way that the
.thumb_func directive does.
The current implementation fails one test due to an unrelated issue. Functions
within .thumb sections are not marked as thumb_func. The result is that
the aliasee function is not valued correctly.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204059 91177308-0d34-0410-b5e6-96231b3b80d8
This is really a consistency fix. Since given
a = b
we propagate the information, we should propagate it too given
a = b + (1 - 1)
Fixes pr19145.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204028 91177308-0d34-0410-b5e6-96231b3b80d8
The previous deduping strategy was woefully inadequate - it only
considered the most recent file used and avoided emitting a duplicate in
that case - never considering the a/b/a scenario.
It was also lacking when it came to directory paths as the previous
filename would never match the current if the filename had been split
into file and directory components.
This change builds caching functionality into the line table at the
lowest level in an optional form (a file number of 0 indicates that one
should be chosen and returned) and will eventually be reused by the
normal source level debugging DWARF emission.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204027 91177308-0d34-0410-b5e6-96231b3b80d8
