For background of BPF CO-RE project, please refer to
http://vger.kernel.org/bpfconf2019.html
In summary, BPF CO-RE intends to compile bpf programs
adjustable on struct/union layout change so the same
program can run on multiple kernels with adjustment
before loading based on native kernel structures.
In order to do this, we need keep track of GEP(getelementptr)
instruction base and result debuginfo types, so we
can adjust on the host based on kernel BTF info.
Capturing such information as an IR optimization is hard
as various optimization may have tweaked GEP and also
union is replaced by structure it is impossible to track
fieldindex for union member accesses.
Three intrinsic functions, preserve_{array,union,struct}_access_index,
are introducted.
addr = preserve_array_access_index(base, index, dimension)
addr = preserve_union_access_index(base, di_index)
addr = preserve_struct_access_index(base, gep_index, di_index)
here,
base: the base pointer for the array/union/struct access.
index: the last access index for array, the same for IR/DebugInfo layout.
dimension: the array dimension.
gep_index: the access index based on IR layout.
di_index: the access index based on user/debuginfo types.
For example, for the following example,
$ cat test.c
struct sk_buff {
int i;
int b1:1;
int b2:2;
union {
struct {
int o1;
int o2;
} o;
struct {
char flags;
char dev_id;
} dev;
int netid;
} u[10];
};
static int (*bpf_probe_read)(void *dst, int size, const void *unsafe_ptr)
= (void *) 4;
#define _(x) (__builtin_preserve_access_index(x))
int bpf_prog(struct sk_buff *ctx) {
char dev_id;
bpf_probe_read(&dev_id, sizeof(char), _(&ctx->u[5].dev.dev_id));
return dev_id;
}
$ clang -target bpf -O2 -g -emit-llvm -S -mllvm -print-before-all \
test.c >& log
The generated IR looks like below:
...
define dso_local i32 @bpf_prog(%struct.sk_buff*) #0 !dbg !15 {
%2 = alloca %struct.sk_buff*, align 8
%3 = alloca i8, align 1
store %struct.sk_buff* %0, %struct.sk_buff** %2, align 8, !tbaa !45
call void @llvm.dbg.declare(metadata %struct.sk_buff** %2, metadata !43, metadata !DIExpression()), !dbg !49
call void @llvm.lifetime.start.p0i8(i64 1, i8* %3) #4, !dbg !50
call void @llvm.dbg.declare(metadata i8* %3, metadata !44, metadata !DIExpression()), !dbg !51
%4 = load i32 (i8*, i32, i8*)*, i32 (i8*, i32, i8*)** @bpf_probe_read, align 8, !dbg !52, !tbaa !45
%5 = load %struct.sk_buff*, %struct.sk_buff** %2, align 8, !dbg !53, !tbaa !45
%6 = call [10 x %union.anon]* @llvm.preserve.struct.access.index.p0a10s_union.anons.p0s_struct.sk_buffs(
%struct.sk_buff* %5, i32 2, i32 3), !dbg !53, !llvm.preserve.access.index !19
%7 = call %union.anon* @llvm.preserve.array.access.index.p0s_union.anons.p0a10s_union.anons(
[10 x %union.anon]* %6, i32 1, i32 5), !dbg !53
%8 = call %union.anon* @llvm.preserve.union.access.index.p0s_union.anons.p0s_union.anons(
%union.anon* %7, i32 1), !dbg !53, !llvm.preserve.access.index !26
%9 = bitcast %union.anon* %8 to %struct.anon.0*, !dbg !53
%10 = call i8* @llvm.preserve.struct.access.index.p0i8.p0s_struct.anon.0s(
%struct.anon.0* %9, i32 1, i32 1), !dbg !53, !llvm.preserve.access.index !34
%11 = call i32 %4(i8* %3, i32 1, i8* %10), !dbg !52
%12 = load i8, i8* %3, align 1, !dbg !54, !tbaa !55
%13 = sext i8 %12 to i32, !dbg !54
call void @llvm.lifetime.end.p0i8(i64 1, i8* %3) #4, !dbg !56
ret i32 %13, !dbg !57
}
!19 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "sk_buff", file: !3, line: 1, size: 704, elements: !20)
!26 = distinct !DICompositeType(tag: DW_TAG_union_type, scope: !19, file: !3, line: 5, size: 64, elements: !27)
!34 = distinct !DICompositeType(tag: DW_TAG_structure_type, scope: !26, file: !3, line: 10, size: 16, elements: !35)
Note that @llvm.preserve.{struct,union}.access.index calls have metadata llvm.preserve.access.index
attached to instructions to provide struct/union debuginfo type information.
For &ctx->u[5].dev.dev_id,
. The "%6 = ..." represents struct member "u" with index 2 for IR layout and index 3 for DI layout.
. The "%7 = ..." represents array subscript "5".
. The "%8 = ..." represents union member "dev" with index 1 for DI layout.
. The "%10 = ..." represents struct member "dev_id" with index 1 for both IR and DI layout.
Basically, traversing the use-def chain recursively for the 3rd argument of bpf_probe_read() and
examining all preserve_*_access_index calls, the debuginfo struct/union/array access index
can be achieved.
The intrinsics also contain enough information to regenerate codes for IR layout.
For array and structure intrinsics, the proper GEP can be constructed.
For union intrinsics, replacing all uses of "addr" with "base" should be enough.
Signed-off-by: Yonghong Song <yhs@fb.com>
Differential Revision: https://reviews.llvm.org/D61810
llvm-svn: 365352
Summary:
Before, they were one category of operands which could cause
crashes in non-sensical combinations, e.g. "f32.const symbol".
Now these are forced to be an error.
Reviewers: dschuff
Subscribers: sbc100, jgravelle-google, aheejin, sunfish, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D64039
llvm-svn: 365351
This patch removes trivial-object-test.elf-i386,
trivial-object-test.elf-x86-64 and trivial-object-test2.elf-x86-64
precompiled objects from test/Object/Inputs folder.
I adjusted the existent test cases to use YAML instead.
Differential revision: https://reviews.llvm.org/D64206
llvm-svn: 365348
Summary of changes:
- added description of GFX10;
- added description of operands sccz, vccz, lds_direct, etc;
- minor bugfixing and improvements.
llvm-svn: 365347
We recognize a splat from element 0 in (VectorUtils) llvm::getSplatValue()
and also in ShuffleVectorInst::isZeroEltSplatMask(), so this converts
to that form for better matching.
The backend generically turns these patterns into build_vector,
so there should be no codegen difference.
llvm-svn: 365342
The IRBuilder has calls to create floating point instructions like fadd.
It does not have calls to create constrained versions of them. This patch
adds support for constrained creation of fadd, fsub, fmul, fdiv, and frem.
Reviewed by: John McCall, Sanjay Patel
Approved by: John McCall
Differential Revision: https://reviews.llvm.org/D53157
llvm-svn: 365339
This patch adds a function attribute, nofree, to indicate that a function does
not, directly or indirectly, call a memory-deallocation function (e.g., free,
C++'s operator delete).
Reviewers: jdoerfert
Differential Revision: https://reviews.llvm.org/D49165
llvm-svn: 365336
This matches isARM, isThumb, isAArch64 and similar helpers. Future commits
which clean-up code that currently checks for Triple::riscv32 ||
Triple::riscv64.
Differential Revision: https://reviews.llvm.org/D54215
Patch by Simon Cook.
Test case added by Alex Bradbury.
llvm-svn: 365327
Select gprb or fprb when loaded value is used by either:
copy to physical register or
instruction with only one mapping available for that use operand.
Load of integer s64 is handled with narrowScalar when mapping is applied,
produced artifacts are combined away. Manually set gprb to all register
operands of instructions created during narrowScalar.
Differential Revision: https://reviews.llvm.org/D64269
llvm-svn: 365323
Select gprb or fprb when stored value is defined by either:
copy from physical register or
instruction with only one mapping available for that def operand.
Store of integer s64 is handled with narrowScalar when mapping is applied,
produced artifacts are combined away. Manually set gprb to all register
operands of instructions created during narrowScalar.
Differential Revision: https://reviews.llvm.org/D64268
llvm-svn: 365322
Summary of changes:
- simplified handling of FLAT offset: offset_s13 and offset_u12 have been replaced with flat_offset;
- provided information about error position for pre-gfx9 targets;
- improved errors handling.
Reviewers: artem.tamazov, arsenm, rampitec
Differential Revision: https://reviews.llvm.org/D64244
llvm-svn: 365321
Fixes AMDGPU patterns for 32-bit address spaces always failing. Tests
will be included in future patches when additional issues are solved.
llvm-svn: 365319
Similar to `FILECHECK_OPTS` for FileCheck, `LIT_OPTS` makes it easy to
adjust lit behavior when running the test suite via ninja. For
example:
```
$ LIT_OPTS='--time-tests -vv --filter=threadprivate' \
ninja check-clang-openmp
```
Reviewed By: probinson
Differential Revision: https://reviews.llvm.org/D64135
llvm-svn: 365313
We briefly referred to being able to specify --target=binary without
explaining what binary input/output meant. This change adds a section on
this.
Reviewed by: MaskRay, abrachet
Differential Revision: https://reviews.llvm.org/D64245
llvm-svn: 365312
Don't do this locally, computeKnownBits does this better (and can handle non-constant cases as well).
A next step would be to actually simplify non-constant elements - building on what we already do in SimplifyDemandedVectorElts.
llvm-svn: 365309
Summary:
According to a recently updated Armv8-M spec
(https://static.docs.arm.com/ddi0553/bh/DDI0553B_h_armv8m_arm.pdf) the
32-bit width versions of the following instructions:
* VQDMLADH
* VQDMLADHX
* VQRDMLADH
* VQRDMLADHX
* VQDMLSDH
* VQDMLSDHX
* VQRDMLSDH
* VQRDMLSDHX
are no longer unpredictable when their output register is the same as
one of the input registers.
This patch updates the assembler parser and the corresponding tests
and also removes @earlyclobber from the instruction constraints.
Reviewers: simon_tatham, ostannard, dmgreen, SjoerdMeijer, samparker
Reviewed By: simon_tatham
Subscribers: javed.absar, kristof.beyls, hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D64250
llvm-svn: 365306
Defines RISCV registers for getExceptionPointerRegister() and
getExceptionSelectorRegister().
Differential Revision: https://reviews.llvm.org/D63411
Patch by Edward Jones.
Modified by Alex Bradbury to add CHECK lines to exception-pointer-register.ll.
llvm-svn: 365301
This mirrors the change made for X86 in rL336987. Without this patch,
update_llc_test_checks will completely skip functions with personality
functions.
llvm-svn: 365297
This can help avoid a copy or enable load folding.
On SSE4.1 targets we can commute it to blendi instead.
I had to make shufpd with a 0x02 immediate commutable as well
since we expect commuting to be reversible.
llvm-svn: 365292
This allows us to use the analyzer from unit tests.
* Refactor the interface to use proper error handling for most functions
after JF's work.
* Move everything into a BitstreamAnalyzer class.
* Move that to Bitcode/BitcodeAnalyzer.h.
Differential Revision: https://reviews.llvm.org/D64116
llvm-svn: 365286
This reverts commit r365260 which broke the following tests:
Clang :: CodeGenCXX/cfi-mfcall.cpp
Clang :: CodeGenObjC/ubsan-nullability.m
LLVM :: Transforms/LoopVectorize/AArch64/pr36032.ll
llvm-svn: 365284
Since these are in a custom list, `gn format` doesn't automatically sort
them.
Now their order matches the CMake build.
No additions or deletions, this just sorts the files that are there.
llvm-svn: 365277
Some out of tree backend require larger vector type. Since maintaining the changes out of tree is difficult due to the many manual changes needed when adding a new type we are adding it even if no backend currently use it.
Differential Revision: https://reviews.llvm.org/D64141
Patch by Thomas Raoux!
llvm-svn: 365274
