This is in the context of the automatic padding work for the jcc erratum mitigation. These are example cases we need to *not* pad for correctness. Exact mechanism to suppress is still TBD, but saving the tests which have come up.
Summary:
This is documented as the appropriate template modifier for call operands.
Fixes PR44272, and adds a regression test.
Also adds support for operand modifiers in Intel-style inline assembly.
Reviewers: rnk
Reviewed By: rnk
Subscribers: merge_guards_bot, hiraditya, cfe-commits, llvm-commits
Tags: #clang, #llvm
Differential Revision: https://reviews.llvm.org/D71677
This is another potential regression exposed by D63815.
Here we peek through a bitcast to find an extract subvector and
scale the splat offset based on that:
splat (bitcast (extract X, C)), LaneC --> duplane (bitcast X), LaneC'
Differential Revision: https://reviews.llvm.org/D71672
This now defines HAVE_VCS_VERSION_INC for all files in Basic,
but now the BUILD.gn file has only a single "sources" field again,
and the automerger requires that. Having the automerger work for
clang/lib/Basic is a very nice to have, and the downside seems tiny.
As discussed in PR44330:
https://bugs.llvm.org/show_bug.cgi?id=44330
...the transform from pow(X, -0.5) libcall/intrinsic to
reciprocal square root can result in small deviations from
the expected result due to differences in the pow()
implementation and/or the extra rounding step from the division.
This patch proposes to allow that difference with either the
'approximate functions' or 'reassociate' FMF:
http://llvm.org/docs/LangRef.html#fast-math-flags
In practice, this likely means that the code is compiled with
all of 'fast' (-ffast-math), but I have preserved the existing
specializations for -0.0/-INF that enable generating safe code
if those special values are allowed simultaneously with
allowing approximation/reassociation.
The question about whether a similar restriction is needed for
the non-reciprocal case -- pow(X, 0.5) -- is deferred. That
transform is allowed without FMF currently, and this patch does
not change that behavior.
Differential Revision: https://reviews.llvm.org/D71706
This seems to have been relying on extra spills being inserted in
these blocks to increase the code size to trigger branch
relaxation. This broke when these spills were avoided. Add some asm to
pad the size of the blocks to make it not matter.
Confusingly, the intrinsic operands do not match the
instruction/custom node. The order is shuffled, and the 3rd operand is
an immediate to select operands.
I'm not 100% sure I did this right, but fdiv still doesn't select end
to end and it will be easier to tell when it does. This at least
avoids an assertion in RegBankSelect and allows hitting the fallback
on selection.
Having this function be recursive could use up way too much stack space.
Rewrite it as an iterative traversal in the tree instead to prevent this.
Fixes PR44344.
It isn't necessary to create DIEs for all of the declaration subprograms
in a CU's retainedTypes list. We can defer creating these subprograms
until we need to prepare a call site tag that refers to one.
This cleanup was mentioned in passing in D70350.
This allows a call site tag in CU A to reference a callee DIE in CU B
without resorting to creating an incomplete duplicate DIE for the callee
inside of CU A.
We already allow cross-CU references of subprogram declarations, so it
doesn't seem like definitions ought to be special.
This improves entry value evaluation and tail call frame synthesis in
the LTO setting. During LTO, it's common for cross-module inlining to
produce a call in some CU A where the callee resides in a different CU,
and there is no declaration subprogram for the callee anywhere. In this
case llvm would (unnecessarily, I think) emit an empty DW_TAG_subprogram
in order to fill in the call site tag. That empty 'definition' defeats
entry value evaluation etc., because the debugger can't figure out what
it means.
As a follow-up, maybe we could add a DWARF verifier check that a
DW_TAG_subprogram at least has a DW_AT_name attribute.
Update:
Reland with a fix to create a declaration DIE when the declaration is
missing from the CU's retainedTypes list. The declaration is left out
of the retainedTypes list in two cases:
1) Re-compiling pre-r266445 bitcode (in which declarations weren't added
to the retainedTypes list), and
2) Doing LTO function importing (which doesn't update the retainedTypes
list).
It's possible to handle (1) and (2) by modifying the retainedTypes list
(in AutoUpgrade, or in the LTO importing logic resp.), but I don't see
an advantage to doing it this way, as it would cause more DWARF to be
emitted compared to creating the declaration DIEs lazily.
Tested with a stage2 ThinLTO+RelWithDebInfo build of clang, and with a
ReleaseLTO-g build of the test suite.
rdar://46577651, rdar://57855316, rdar://57840415
Differential Revision: https://reviews.llvm.org/D70350
Summary:
llvm-objdump will commonly error out when disassembling a Mach-O binary with
stab symbols, or when printing a Mach-O symbol table that includesstab symbols.
That is because the Mach-O N_OSO symbol has been modified to include the
bottom 8-bit value of the Mach-O's cpusubtype value in the section field. In
general, one cannot blindly assume a stab symbol's section field is valid
unless one has actually consulted the specification for the specific stab.
Since objdump mostly just walks the symbol table to get mnemonics for code
disassembly it's best for objdump to just ignore stab symbols. llvm-nm will
do a more complete and correct job of displaying Mach-O symbol table contents.
Reviewers: pete, lhames, ab, thegameg, jhenderson, MaskRay
Reviewed By: thegameg, MaskRay
Subscribers: MaskRay, rupprecht, seiya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D71394
Extends DWARF expression language to express locals/globals locations. (via
target-index operands atm) (possible variants are: non-virtual registers
or address spaces)
The WebAssemblyExplicitLocals can replace virtual registers to targertindex
operand type at the time when WebAssembly backend introduces
{get,set,tee}_local instead of corresponding virtual registers.
Reviewed By: aprantl, dschuff
Tags: #debug-info, #llvm
Differential Revision: https://reviews.llvm.org/D52634
Summary:
This patch limits the default number of iterations performed by InstCombine. It also exposes a new option that allows to specify how many iterations is considered getting stuck in an infinite loop.
Based on experiments performed on real-world C++ programs, InstCombine seems to perform at most ~8-20 iterations, so treating 1000 iterations as an infinite loop seems like a safe choice. See D71145 for details.
The two limits can be specified via command line options.
Reviewers: spatel, lebedev.ri, nikic, xbolva00, grosser
Reviewed By: spatel
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D71673
This is a purely cosmetic change that is NFC in terms of the binary
output. I bugs me that I called the attribute DW_AT_LLVM_isysroot
since the "i" is an artifact of GCC command line option syntax
(-isysroot is in the category of -i options) and doesn't carry any
useful information otherwise.
This attribute only appears in Clang module debug info.
Differential Revision: https://reviews.llvm.org/D71722
llvm-symbolizer is used by sanitizers to symbolize errors discovered by
sanitizer, but there's no way to pass options to llvm-symbolizer since
the tool is invoked directly by the sanitizer runtime. Therefore, we
don't have a way to pass options needed to find debug symbols such as
-dsym-hint or -debug-file-directory. This change enables reading options
from the LLVM_SYMBOLIZER_OPTS in addition to command line which can be
used to pass those additional options to llvm-symbolizer invocations
made by sanitizer runtime.
Differential Revision: https://reviews.llvm.org/D71668
Demote member functions to static functions where possible
Use early continue/early return to reduce nesting
Clarify comments slightly.
Reuse previously define expression in one case.
Should have caught this in review, but only noticed when addressing post commit style items. We were creating a new instance of the X86MCInstrInfo class, and then never reclaiming the memory. This wasn't even conditional on the new off by default flags, so it was an unconditional leak.
WARNING: If you're looking at this patch because you're looking for a full
performace mitigation of the Intel JCC Erratum, this is not it!
This is a preliminary patch on the patch towards mitigating the performance
regressions caused by Intel's microcode update for Jump Conditional Code
Erratum. For context, see:
https://www.intel.com/content/www/us/en/support/articles/000055650.html
The patch adds the required assembler infrastructure and command line options
needed to exercise the logic for INTERNAL TESTING. These are NOT public flags,
and should not be used for anything other than LLVM's own testing/debugging
purposes. They are likely to change both in spelling and meaning.
WARNING: This patch is knowingly incorrect in some cornercases. We need, and
do not yet provide, a mechanism to selective enable/disable the padding.
Conversation on this will continue in parellel with work on extending this
infrastructure to support prefix padding.
The goal here is to have the assembler align specific instructions such that
they neither cross or end at a 32 byte boundary. The impacted instructions are:
a. Conditional jump.
b. Fused conditional jump.
c. Unconditional jump.
d. Indirect jump.
e. Ret.
f. Call.
The new options for llvm-mc are:
-x86-align-branch-boundary=NUM aligns branches within NUM byte boundary.
-x86-align-branch=TYPE[+TYPE...] specifies types of branches to align.
A new MCFragment type, MCBoundaryAlignFragment, is added, which may emit
NOP to align the fused/unfused branch.
alignBranchesBegin inserts MCBoundaryAlignFragment before instructions,
alignBranchesEnd marks the end of the branch to be aligned,
relaxBoundaryAlign grows or shrinks sizes of NOP to align the target branch.
Nop padding is disabled when the instruction may be rewritten by the linker,
such as TLS Call.
Process Note: I am landing a patch by skan as it has been LGTMed, and
continuing to iterate on the review is simply slowing us down at this point.
We can and will continue to iterate in tree.
Patch By: skan
Differential Revision: https://reviews.llvm.org/D70157
static void *ifunc(void) __attribute__((ifunc("resolver")));
void foo() { ifunc(); }
The relocation produced by the ifunc() call:
1. gcc -msecure-plt -fPIC => R_PPC_PLTREL24 r_addend=0x8000
2. gcc -msecure-plt -PIE => R_PPC_PLTREL24 r_addend=0x8000
3. clang -msecure-plt -fPIC => R_PPC_PLTREL24 r_addend=0x8000
4. clang -msecure-plt -fPIE => R_PPC_REL24
4 is incorrect. The R_PPC_REL24 needs a call stub due to ifunc. If this
relocation is mixed with other R_PPC_PLTREL24(r_addend=0x8000) in a
function, both GNU ld and lld (after D71621 fix) may produce a wrong
result.
This patch fixes 4 to use R_PPC_PLTREL24, which matches GCC.
Both GNU ld and lld (after D71621) will be happy.
Reviewed By: sfertile
Differential Revision: https://reviews.llvm.org/D71649
The setcc operands are copied into LHS and RHS variables at the top of the function. We also capture the condition code.
A later piece of code swaps the operands and changing the CC variable as part of a canonicalization to make some other checks simpler. But we might not make the transform we canonicalized for. So we continue on through the function where we can use the swapped LHS/RHS variables and access the original condition code operand instead of the modified CC variable. This leads to a setcc being created with the original condition code, but with swapped operands.
To mitigate this, this patch does a couple things. The LHS/RHS/CC variables are made const to keep them from being modified like this again. The transform that needs the swap now uses temporary copies of the variables. And the transform that used the original condition code operand has been altered to use the CC variable we cached originally. Either of these changes are enough to fix the issue, but doing both to make this code very safe.
I also considered rewriting the swap code in some way to check both permutations without explicitly swapping or needing temporary variables, but held off on that.
Differential Revision: https://reviews.llvm.org/D71736
Summary: Replace the integer immediate intrisics with splat vector variants so they can be applied as optimizations for the C/C++ intrinsics.
Reviewers: sdesmalen, huntergr, rengolin, efriedma, c-rhodes, mgudim, kmclaughlin
Subscribers: tschuett, kristof.beyls, hiraditya, rkruppe, psnobl, llvm-commits, amehsan
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D71614
The SELR(Mux) instructions can be converted to two-address form as LOCR(Mux)
instructions whenever one of the sources are the same reg as dest. By adding
this mapping in getTwoOperandOpcode(), we get:
- Two-address hints in getRegAllocationHints() for select register
instructions.
- No need anymore for special handling in SystemZShortenInst.cpp -
shortenSelect() removed.
The two-address hints are now added before the GRX32 hints, which should be
preferred.
Review: Ulrich Weigand
https://reviews.llvm.org/D68870
Summary:
With -gdwarf-5 local variable locations are emitted as DW_FORM_loclistx
form instead of the regular DW_FORM_sec_offset. Teach
DWARFDie::getLocations to understand the new format and use it in
llvm-symbolizer "FRAME" command.
Reviewers: pcc, jdoerfert
Subscribers: srhines, aprantl, hiraditya, rupprecht, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D70756
This reverts commits 7e18aeba5062cd4324a9efb7bc25c9dbc4a34c2c (D70376) 21fbd5587cdfa11dabb3aeb0ead2d3d5fd0b490d (D69914) due to increased memory usage.
It was recently discovered that the handling of CC values was actually broken
since overflow was not properly handled ('nsw' flag not checked for).
Add and sub instructions now have a new target specific instruction flag
named SystemZII::CCIfNoSignedWrap. It means that the CC result can be used
instead of a compare with 0, but only if the instruction has the 'nsw' flag
set.
This patch also adds the improvements of conversion to logical instructions
and the analyzing of add with immediates, to be able to eliminate more
compares.
Review: Ulrich Weigand
https://reviews.llvm.org/D66868
