Commit Graph

1140 Commits

Author SHA1 Message Date
Akira Hatanaka d8136f14f1 [CodeGen][ObjC] Emit a primitive store to store a __strong field in
ExpandTypeFromArgs

This fixes a bug in IRGen where a call to `llvm.objc.storeStrong` was
being emitted to initialize a __strong field of an uninitialized
temporary struct, which caused crashes at runtime.

rdar://problem/51807365
2019-12-03 23:44:30 -08:00
Akira Hatanaka f139ae3d93 [NFC] Pass a reference to CodeGenFunction to methods of LValue and
AggValueSlot

This reapplies 8a5b7c3570 after a null
dereference bug in CGOpenMPRuntime::emitUserDefinedMapper.

Original commit message:

This is needed for the pointer authentication work we plan to do in the
near future.

a63a81bd99/clang/docs/PointerAuthentication.rst
2019-12-03 15:22:13 -08:00
Akira Hatanaka 9f37c0e703 Revert "[NFC] Pass a reference to CodeGenFunction to methods of LValue and"
This reverts commit 8a5b7c3570. This seems
to have broken UBSan because of a null dereference.
2019-12-03 13:08:01 -08:00
Akira Hatanaka 8a5b7c3570 [NFC] Pass a reference to CodeGenFunction to methods of LValue and
AggValueSlot

This is needed for the pointer authentication work we plan to do in the
near future.

a63a81bd99/clang/docs/PointerAuthentication.rst
2019-12-03 11:30:09 -08:00
Peter Collingbourne 90b8bc003c IRGen: Call SetLLVMFunctionAttributes{,ForDefinition} on __cfi_check_fail.
This has the main effect of causing target-cpu and target-features to be set
on __cfi_check_fail, causing the function to become ABI-compatible with other
functions in the case where these attributes affect ABI (e.g. reserve-x18).

Technically we only need to call SetLLVMFunctionAttributes to get the target-*
attributes set, but since we're creating a definition we probably ought to
call the ForDefinition function as well.

Fixes PR44094.

Differential Revision: https://reviews.llvm.org/D70692
2019-11-25 15:16:43 -08:00
Tyker b0561b3346 [NFC] Refactor representation of materialized temporaries
Summary:
this patch refactor representation of materialized temporaries to prevent an issue raised by rsmith in https://reviews.llvm.org/D63640#inline-612718

Reviewers: rsmith, martong, shafik

Reviewed By: rsmith

Subscribers: thakis, sammccall, ilya-biryukov, rnkovacs, arphaman, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D69360
2019-11-19 18:20:45 +01:00
Nico Weber c9276fbfdf Revert "[NFC] Refactor representation of materialized temporaries"
This reverts commit 08ea1ee2db.
It broke ./ClangdTests/FindExplicitReferencesTest.All
on the bots, see comments on https://reviews.llvm.org/D69360
2019-11-17 02:09:25 -05:00
Tyker 08ea1ee2db [NFC] Refactor representation of materialized temporaries
Summary:
this patch refactor representation of materialized temporaries to prevent an issue raised by rsmith in https://reviews.llvm.org/D63640#inline-612718

Reviewers: rsmith, martong, shafik

Reviewed By: rsmith

Subscribers: rnkovacs, arphaman, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D69360
2019-11-16 17:56:09 +01:00
Yonghong Song dd16b3fe25 [BPF] Restrict preserve_access_index attribute to C only
This patch is a follow-up for commit 4e2ce228ae
  [BPF] Add preserve_access_index attribute for record definition
to restrict attribute for C only. A new test case is added
to check for this restriction.

Additional code polishing is done based on
Aaron Ballman's suggestion in https://reviews.llvm.org/D69759/new/.

Differential Revision: https://reviews.llvm.org/D70257
2019-11-14 14:14:59 -08:00
Yonghong Song 4e2ce228ae [BPF] Add preserve_access_index attribute for record definition
This is a resubmission for the previous reverted commit
9434360401 with the same subject. This commit fixed the
segfault issue and addressed additional review comments.

This patch introduced a new bpf specific attribute which can
be added to struct or union definition. For example,
  struct s { ... } __attribute__((preserve_access_index));
  union u { ... } __attribute__((preserve_access_index));
The goal is to simplify user codes for cases
where preserve access index happens for certain struct/union,
so user does not need to use clang __builtin_preserve_access_index
for every members.

The attribute has no effect if -g is not specified.

When the attribute is specified and -g is specified, any member
access defined by that structure or union, including array subscript
access and inner records, will be preserved through
  __builtin_preserve_{array,struct,union}_access_index()
IR intrinsics, which will enable relocation generation
in bpf backend.

The following is an example to illustrate the usage:
  -bash-4.4$ cat t.c
  #define __reloc__ __attribute__((preserve_access_index))
  struct s1 {
    int c;
  } __reloc__;

  struct s2 {
    union {
      struct s1 b[3];
    };
  } __reloc__;

  struct s3 {
    struct s2 a;
  } __reloc__;

  int test(struct s3 *arg) {
    return arg->a.b[2].c;
  }
  -bash-4.4$ clang -target bpf -g -S -O2 t.c

A relocation with access string "0:0:0:0:2:0" will be generated
representing access offset of arg->a.b[2].c.

forward declaration with attribute is also handled properly such
that the attribute is copied and populated in real record definition.

Differential Revision: https://reviews.llvm.org/D69759
2019-11-13 08:23:44 -08:00
Yonghong Song 9434360401 Revert "[BPF] Add preserve_access_index attribute for record definition"
This reverts commit 4a5aa1a7bf.

There are some other test failures. Investigate them first.
2019-11-09 08:32:44 -08:00
Yonghong Song 4a5aa1a7bf [BPF] Add preserve_access_index attribute for record definition
This patch introduced a new bpf specific attribute which can
be added to struct or union definition. For example,
  struct s { ... } __attribute__((preserve_access_index));
  union u { ... } __attribute__((preserve_access_index));
The goal is to simplify user codes for cases
where preserve access index happens for certain struct/union,
so user does not need to use clang __builtin_preserve_access_index
for every members.

The attribute has no effect if -g is not specified.

When the attribute is specified and -g is specified, any member
access defined by that structure or union, including array subscript
access and inner records, will be preserved through
  __builtin_preserve_{array,struct,union}_access_index()
IR intrinsics, which will enable relocation generation
in bpf backend.

The following is an example to illustrate the usage:
  -bash-4.4$ cat t.c
  #define __reloc__ __attribute__((preserve_access_index))
  struct s1 {
    int c;
  } __reloc__;

  struct s2 {
    union {
      struct s1 b[3];
    };
  } __reloc__;

  struct s3 {
    struct s2 a;
  } __reloc__;

  int test(struct s3 *arg) {
    return arg->a.b[2].c;
  }
  -bash-4.4$ clang -target bpf -g -S -O2 t.c

A relocation with access string "0:0:0:0:2:0" will be generated
representing access offset of arg->a.b[2].c.

forward declaration with attribute is also handled properly such
that the attribute is copied and populated in real record definition.

Differential Revision: https://reviews.llvm.org/D69759
2019-11-09 08:17:12 -08:00
Craig Topper 910718bd03 [opaque pointer types] Add element type argument to IRBuilder CreatePreserveStructAccessIndex and CreatePreserveArrayAccessIndex
Summary:
These were the only remaining users of the GetElementPtrInst::getGEPReturnType
method that gets the element type from the pointer type.

Remove that method since its now dead.

Reviewers: jyknight, t.p.northover, arsenm

Reviewed By: arsenm

Subscribers: wdng, arsenm, arphaman, cfe-commits, llvm-commits

Tags: #clang, #llvm

Differential Revision: https://reviews.llvm.org/D69756
2019-11-03 10:27:18 -08:00
Richard Smith 778dc0f1d4 [c++20] Add CXXRewrittenBinaryOperator to represent a comparison
operator that is rewritten as a call to multiple other operators.

No functionality change yet: nothing creates these expressions.

llvm-svn: 375305
2019-10-19 00:04:38 +00:00
Dmitry Mikulin 15984457a6 Revert Tag CFI-generated data structures with "#pragma clang section" attributes.
This reverts r375022 (git commit e2692b3bc0)

llvm-svn: 375069
2019-10-17 00:55:38 +00:00
Dmitry Mikulin e2692b3bc0 Tag CFI-generated data structures with "#pragma clang section" attributes.
Differential Revision: https://reviews.llvm.org/D68808

llvm-svn: 375022
2019-10-16 17:51:40 +00:00
Yonghong Song 05e46979d2 [BPF] do compile-once run-everywhere relocation for bitfields
A bpf specific clang intrinsic is introduced:
   u32 __builtin_preserve_field_info(member_access, info_kind)
Depending on info_kind, different information will
be returned to the program. A relocation is also
recorded for this builtin so that bpf loader can
patch the instruction on the target host.
This clang intrinsic is used to get certain information
to facilitate struct/union member relocations.

The offset relocation is extended by 4 bytes to
include relocation kind.
Currently supported relocation kinds are
 enum {
    FIELD_BYTE_OFFSET = 0,
    FIELD_BYTE_SIZE,
    FIELD_EXISTENCE,
    FIELD_SIGNEDNESS,
    FIELD_LSHIFT_U64,
    FIELD_RSHIFT_U64,
 };
for __builtin_preserve_field_info. The old
access offset relocation is covered by
    FIELD_BYTE_OFFSET = 0.

An example:
struct s {
    int a;
    int b1:9;
    int b2:4;
};
enum {
    FIELD_BYTE_OFFSET = 0,
    FIELD_BYTE_SIZE,
    FIELD_EXISTENCE,
    FIELD_SIGNEDNESS,
    FIELD_LSHIFT_U64,
    FIELD_RSHIFT_U64,
};

void bpf_probe_read(void *, unsigned, const void *);
int field_read(struct s *arg) {
  unsigned long long ull = 0;
  unsigned offset = __builtin_preserve_field_info(arg->b2, FIELD_BYTE_OFFSET);
  unsigned size = __builtin_preserve_field_info(arg->b2, FIELD_BYTE_SIZE);
 #ifdef USE_PROBE_READ
  bpf_probe_read(&ull, size, (const void *)arg + offset);
  unsigned lshift = __builtin_preserve_field_info(arg->b2, FIELD_LSHIFT_U64);
 #if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
  lshift = lshift + (size << 3) - 64;
 #endif
 #else
  switch(size) {
  case 1:
    ull = *(unsigned char *)((void *)arg + offset); break;
  case 2:
    ull = *(unsigned short *)((void *)arg + offset); break;
  case 4:
    ull = *(unsigned int *)((void *)arg + offset); break;
  case 8:
    ull = *(unsigned long long *)((void *)arg + offset); break;
  }
  unsigned lshift = __builtin_preserve_field_info(arg->b2, FIELD_LSHIFT_U64);
 #endif
  ull <<= lshift;
  if (__builtin_preserve_field_info(arg->b2, FIELD_SIGNEDNESS))
    return (long long)ull >> __builtin_preserve_field_info(arg->b2, FIELD_RSHIFT_U64);
  return ull >> __builtin_preserve_field_info(arg->b2, FIELD_RSHIFT_U64);
}

There is a minor overhead for bpf_probe_read() on big endian.

The code and relocation generated for field_read where bpf_probe_read() is
used to access argument data on little endian mode:
        r3 = r1
        r1 = 0
        r1 = 4  <=== relocation (FIELD_BYTE_OFFSET)
        r3 += r1
        r1 = r10
        r1 += -8
        r2 = 4  <=== relocation (FIELD_BYTE_SIZE)
        call bpf_probe_read
        r2 = 51 <=== relocation (FIELD_LSHIFT_U64)
        r1 = *(u64 *)(r10 - 8)
        r1 <<= r2
        r2 = 60 <=== relocation (FIELD_RSHIFT_U64)
        r0 = r1
        r0 >>= r2
        r3 = 1  <=== relocation (FIELD_SIGNEDNESS)
        if r3 == 0 goto LBB0_2
        r1 s>>= r2
        r0 = r1
LBB0_2:
        exit

Compare to the above code between relocations FIELD_LSHIFT_U64 and
FIELD_LSHIFT_U64, the code with big endian mode has four more
instructions.
        r1 = 41   <=== relocation (FIELD_LSHIFT_U64)
        r6 += r1
        r6 += -64
        r6 <<= 32
        r6 >>= 32
        r1 = *(u64 *)(r10 - 8)
        r1 <<= r6
        r2 = 60   <=== relocation (FIELD_RSHIFT_U64)

The code and relocation generated when using direct load.
        r2 = 0
        r3 = 4
        r4 = 4
        if r4 s> 3 goto LBB0_3
        if r4 == 1 goto LBB0_5
        if r4 == 2 goto LBB0_6
        goto LBB0_9
LBB0_6:                                 # %sw.bb1
        r1 += r3
        r2 = *(u16 *)(r1 + 0)
        goto LBB0_9
LBB0_3:                                 # %entry
        if r4 == 4 goto LBB0_7
        if r4 == 8 goto LBB0_8
        goto LBB0_9
LBB0_8:                                 # %sw.bb9
        r1 += r3
        r2 = *(u64 *)(r1 + 0)
        goto LBB0_9
LBB0_5:                                 # %sw.bb
        r1 += r3
        r2 = *(u8 *)(r1 + 0)
        goto LBB0_9
LBB0_7:                                 # %sw.bb5
        r1 += r3
        r2 = *(u32 *)(r1 + 0)
LBB0_9:                                 # %sw.epilog
        r1 = 51
        r2 <<= r1
        r1 = 60
        r0 = r2
        r0 >>= r1
        r3 = 1
        if r3 == 0 goto LBB0_11
        r2 s>>= r1
        r0 = r2
LBB0_11:                                # %sw.epilog
        exit

Considering verifier is able to do limited constant
propogation following branches. The following is the
code actually traversed.
        r2 = 0
        r3 = 4   <=== relocation
        r4 = 4   <=== relocation
        if r4 s> 3 goto LBB0_3
LBB0_3:                                 # %entry
        if r4 == 4 goto LBB0_7
LBB0_7:                                 # %sw.bb5
        r1 += r3
        r2 = *(u32 *)(r1 + 0)
LBB0_9:                                 # %sw.epilog
        r1 = 51   <=== relocation
        r2 <<= r1
        r1 = 60   <=== relocation
        r0 = r2
        r0 >>= r1
        r3 = 1
        if r3 == 0 goto LBB0_11
        r2 s>>= r1
        r0 = r2
LBB0_11:                                # %sw.epilog
        exit

For native load case, the load size is calculated to be the
same as the size of load width LLVM otherwise used to load
the value which is then used to extract the bitfield value.

Differential Revision: https://reviews.llvm.org/D67980

llvm-svn: 374099
2019-10-08 18:23:17 +00:00
Simon Pilgrim 7e38f0c408 Codegen - silence static analyzer getAs<> null dereference warnings. NFCI.
The static analyzer is warning about potential null dereferences, but in these cases we should be able to use castAs<> directly and if not assert will fire for us.

llvm-svn: 373918
2019-10-07 16:42:25 +00:00
Guillaume Chatelet c79099e0f4 [Alignment][Clang][NFC] Add CharUnits::getAsAlign
Summary:
This is a prerequisite to removing `llvm::GlobalObject::setAlignment(unsigned)`.
This is patch is part of a series to introduce an Alignment type.
See this thread for context: http://lists.llvm.org/pipermail/llvm-dev/2019-July/133851.html
See this patch for the introduction of the type: https://reviews.llvm.org/D64790

Reviewers: courbet

Subscribers: jholewinski, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D68274

llvm-svn: 373592
2019-10-03 13:00:29 +00:00
Guillaume Chatelet ab11b9188d [Alignment][NFC] Remove AllocaInst::setAlignment(unsigned)
Summary:
This is patch is part of a series to introduce an Alignment type.
See this thread for context: http://lists.llvm.org/pipermail/llvm-dev/2019-July/133851.html
See this patch for the introduction of the type: https://reviews.llvm.org/D64790

Reviewers: courbet

Subscribers: jholewinski, arsenm, jvesely, nhaehnle, eraman, hiraditya, cfe-commits, llvm-commits

Tags: #clang, #llvm

Differential Revision: https://reviews.llvm.org/D68141

llvm-svn: 373207
2019-09-30 13:34:44 +00:00
Richard Smith 00223827a9 Improve code generation for thread_local variables:
Summary:
 * Don't bother using a thread wrapper when the variable is known to
   have constant initialization.
 * Emit the thread wrapper as discardable-if-unused in TUs that don't
   contain a definition of the thread_local variable.
 * Don't emit the thread wrapper at all if the thread_local variable
   is unused and discardable; it will be emitted by all TUs that need
   it.

Reviewers: rjmccall, jdoerfert

Subscribers: cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D67429

llvm-svn: 371767
2019-09-12 20:00:24 +00:00
Alexey Bataev b5890a329a Fix for PR43175: compiler crash when trying to emit noncapturable
constant.

If the constexpr variable is partially initialized, the initializer can
be emitted as the structure, not as an array, because of some early
optimizations. The llvm variable gets the type from this constant and,
thus, gets the type which is pointer to struct rather than pointer to an
array. We need to convert this type to be truely array, otherwise it may
lead to the compiler crash when trying to emit array subscript
expression.

llvm-svn: 371548
2019-09-10 19:16:56 +00:00
Aaron Ballman 0299dbd2ae Implement codegen for MSVC unions with reference members.
Currently, clang accepts a union with a reference member when given the -fms-extensions flag. This change fixes the codegen for this case.

Patch by Dominic Ferreira.

llvm-svn: 370052
2019-08-27 12:42:45 +00:00
Vitaly Buka 669d111c52 hwasan, codegen: Keep more lifetime markers used for hwasan
Reviewers: eugenis

Subscribers: cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D66697

llvm-svn: 369980
2019-08-26 22:16:05 +00:00
Vitaly Buka aeca56964f msan, codegen, instcombine: Keep more lifetime markers used for msan
Reviewers: eugenis

Subscribers: hiraditya, cfe-commits, #sanitizers, llvm-commits

Tags: #clang, #sanitizers, #llvm

Differential Revision: https://reviews.llvm.org/D66695

llvm-svn: 369979
2019-08-26 22:15:50 +00:00
Peter Collingbourne 2452d7030b IR. Change strip* family of functions to not look through aliases.
I noticed another instance of the issue where references to aliases were
being replaced with aliasees, this time in InstCombine. In the instance that
I saw it turned out to be only a QoI issue (a symbol ended up being missing
from the symbol table due to the last reference to the alias being removed,
preventing HWASAN from symbolizing a global reference), but it could easily
have manifested as incorrect behaviour.

Since this is the third such issue encountered (previously: D65118, D65314)
it seems to be time to address this common error/QoI issue once and for all
and make the strip* family of functions not look through aliases.

Includes a test for the specific issue that I saw, but no doubt there are
other similar bugs fixed here.

As with D65118 this has been tested to make sure that the optimization isn't
load bearing. I built Clang, Chromium for Linux, Android and Windows as well
as the test-suite and there were no size regressions.

Differential Revision: https://reviews.llvm.org/D66606

llvm-svn: 369697
2019-08-22 19:56:14 +00:00
Yonghong Song d0ea05d5ef [BPF] annotate DIType metadata for builtin preseve_array_access_index()
Previously, debuginfo types are annotated to
IR builtin preserve_struct_access_index() and
preserve_union_access_index(), but not
preserve_array_access_index(). The debug info
is useful to identify the root type name which
later will be used for type comparison.

For user access without explicit type conversions,
the previous scheme works as we can ignore intermediate
compiler generated type conversions (e.g., from union types to
union members) and still generate correct access index string.

The issue comes with user explicit type conversions, e.g.,
converting an array to a structure like below:
  struct t { int a; char b[40]; };
  struct p { int c; int d; };
  struct t *var = ...;
  ... __builtin_preserve_access_index(&(((struct p *)&(var->b[0]))->d)) ...
Although BPF backend can derive the type of &(var->b[0]),
explicit type annotation make checking more consistent
and less error prone.

Another benefit is for multiple dimension array handling.
For example,
  struct p { int c; int d; } g[8][9][10];
  ... __builtin_preserve_access_index(&g[2][3][4].d) ...
It would be possible to calculate the number of "struct p"'s
before accessing its member "d" if array debug info is
available as it contains each dimension range.

This patch enables to annotate IR builtin preserve_array_access_index()
with proper debuginfo type. The unit test case and language reference
is updated as well.

Signed-off-by: Yonghong Song <yhs@fb.com>

Differential Revision: https://reviews.llvm.org/D65664

llvm-svn: 367724
2019-08-02 21:28:28 +00:00
Yonghong Song 4754814c5a fix unnamed fiefield issue and add tests for __builtin_preserve_access_index intrinsic
The original commit is r366076. It is temporarily reverted (r366155)
due to test failure. This resubmit makes test more robust by accepting
regex instead of hardcoded names/references in several places.

This is a followup patch for https://reviews.llvm.org/D61809.
Handle unnamed bitfield properly and add more test cases.

Fixed the unnamed bitfield issue. The unnamed bitfield is ignored
by debug info, so we need to ignore such a struct/union member
when we try to get the member index in the debug info.

D61809 contains two test cases but not enough as it does
not checking generated IRs in the fine grain level, and also
it does not have semantics checking tests.
This patch added unit tests for both code gen and semantics checking for
the new intrinsic.

Signed-off-by: Yonghong Song <yhs@fb.com>
llvm-svn: 366231
2019-07-16 17:24:33 +00:00
Stephan Bergmann e215996a29 Finish "Adapt -fsanitize=function to SANITIZER_NON_UNIQUE_TYPEINFO"
i.e., recent 5745eccef54ddd3caca278d1d292a88b2281528b:

* Bump the function_type_mismatch handler version, as its signature has changed.

* The function_type_mismatch handler can return successfully now, so
  SanitizerKind::Function must be AlwaysRecoverable (like for
  SanitizerKind::Vptr).

* But the minimal runtime would still unconditionally treat a call to the
  function_type_mismatch handler as failure, so disallow -fsanitize=function in
  combination with -fsanitize-minimal-runtime (like it was already done for
  -fsanitize=vptr).

* Add tests.

Differential Revision: https://reviews.llvm.org/D61479

llvm-svn: 366186
2019-07-16 06:23:27 +00:00
Rui Ueyama 49a3ad21d6 Fix parameter name comments using clang-tidy. NFC.
This patch applies clang-tidy's bugprone-argument-comment tool
to LLVM, clang and lld source trees. Here is how I created this
patch:

$ git clone https://github.com/llvm/llvm-project.git
$ cd llvm-project
$ mkdir build
$ cd build
$ cmake -GNinja -DCMAKE_BUILD_TYPE=Debug \
    -DLLVM_ENABLE_PROJECTS='clang;lld;clang-tools-extra' \
    -DCMAKE_EXPORT_COMPILE_COMMANDS=On -DLLVM_ENABLE_LLD=On \
    -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++ ../llvm
$ ninja
$ parallel clang-tidy -checks='-*,bugprone-argument-comment' \
    -config='{CheckOptions: [{key: StrictMode, value: 1}]}' -fix \
    ::: ../llvm/lib/**/*.{cpp,h} ../clang/lib/**/*.{cpp,h} ../lld/**/*.{cpp,h}

llvm-svn: 366177
2019-07-16 04:46:31 +00:00
Eric Christopher fdcbd5fa48 Temporarily Revert "fix unnamed fiefield issue and add tests for __builtin_preserve_access_index intrinsic"
The commit had tests that would only work with names in the IR.

This reverts commit r366076.

llvm-svn: 366155
2019-07-15 23:49:31 +00:00
Yonghong Song e5086481b6 fix unnamed fiefield issue and add tests for __builtin_preserve_access_index intrinsic
This is a followup patch for https://reviews.llvm.org/D61809.
Handle unnamed bitfield properly and add more test cases.

Fixed the unnamed bitfield issue. The unnamed bitfield is ignored
by debug info, so we need to ignore such a struct/union member
when we try to get the member index in the debug info.

D61809 contains two test cases but not enough as it does
not checking generated IRs in the fine grain level, and also
it does not have semantics checking tests.
This patch added unit tests for both code gen and semantics checking for
the new intrinsic.

Signed-off-by: Yonghong Song <yhs@fb.com>
llvm-svn: 366076
2019-07-15 15:42:41 +00:00
Yonghong Song 048493f882 [BPF] Preserve debuginfo array/union/struct type/access index
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.

If using these intrinsics blindly, i.e., transforming all GEPs
to these intrinsics and later on reducing them to GEPs, we have
seen up to 7% more instructions generated. To avoid such an overhead,
a clang builtin is proposed:
  base = __builtin_preserve_access_index(base)
such that user wraps to-be-relocated GEPs in this builtin
and preserve_*_access_index intrinsics only apply to
those GEPs. Such a buyin will prevent performance degradation
if people do not use CO-RE, even for programs which use
bpf_probe_read().

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/D61809

llvm-svn: 365438
2019-07-09 04:21:50 +00:00
Yonghong Song e085b40e9c Revert "[BPF] Preserve debuginfo array/union/struct type/access index"
This reverts commit r365435.

Forgot adding the Differential Revision link. Will add to the
commit message and resubmit.

llvm-svn: 365436
2019-07-09 04:15:12 +00:00
Yonghong Song f21eeafcd9 [BPF] Preserve debuginfo array/union/struct type/access index
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.

If using these intrinsics blindly, i.e., transforming all GEPs
to these intrinsics and later on reducing them to GEPs, we have
seen up to 7% more instructions generated. To avoid such an overhead,
a clang builtin is proposed:
  base = __builtin_preserve_access_index(base)
such that user wraps to-be-relocated GEPs in this builtin
and preserve_*_access_index intrinsics only apply to
those GEPs. Such a buyin will prevent performance degradation
if people do not use CO-RE, even for programs which use
bpf_probe_read().

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>
llvm-svn: 365435
2019-07-09 04:04:21 +00:00
Erik Pilkington eee944e7f9 [C++2a] Add __builtin_bit_cast, used to implement std::bit_cast
This commit adds a new builtin, __builtin_bit_cast(T, v), which performs a
bit_cast from a value v to a type T. This expression can be evaluated at
compile time under specific circumstances.

The compile time evaluation currently doesn't support bit-fields, but I'm
planning on fixing this in a follow up (some of the logic for figuring this out
is in CodeGen). I'm also planning follow-ups for supporting some more esoteric
types that the constexpr evaluator supports, as well as extending
__builtin_memcpy constexpr evaluation to use the same infrastructure.

rdar://44987528

Differential revision: https://reviews.llvm.org/D62825

llvm-svn: 364954
2019-07-02 18:28:13 +00:00
Djordje Todorovic 0f65168566 [clang] Add DISuprogram and DIE for a func decl
Attach a unique DISubprogram to a function declaration that will be
used for call site debug info.

([7/13] Introduce the debug entry values.)

Co-authored-by: Ananth Sowda <asowda@cisco.com>
Co-authored-by: Nikola Prica <nikola.prica@rt-rk.com>
Co-authored-by: Ivan Baev <ibaev@cisco.com>

Differential Revision: https://reviews.llvm.org/D60714

llvm-svn: 364502
2019-06-27 06:44:44 +00:00
Erich Keane 36176249d1 Ensure Target Features always_inline error happens in C++ cases.
A handful of C++ cases as reported in PR42352 didn't actually give an
error when always_inlining with a different target feature list. This
resulted in broken IR.

llvm-svn: 364109
2019-06-21 22:29:32 +00:00
Richard Smith 78b239ea67 P0840R2: support for [[no_unique_address]] attribute
Summary:
Add support for the C++2a [[no_unique_address]] attribute for targets using the Itanium C++ ABI.

This depends on D63371.

Reviewers: rjmccall, aaron.ballman

Subscribers: dschuff, aheejin, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D63451

llvm-svn: 363976
2019-06-20 20:44:45 +00:00
Gheorghe-Teodor Bercea 0034e84aa5 [OpenMP] Add support for handling declare target to clause when unified memory is required
Summary:
This patch adds support for the handling of the variables under the declare target to clause.

The variables in this case are handled like link variables are. A pointer is created on the host and then mapped to the device. The runtime will then copy the address of the host variable in the device pointer.

Reviewers: ABataev, AlexEichenberger, caomhin

Reviewed By: ABataev

Subscribers: guansong, jdoerfert, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D63108

llvm-svn: 363959
2019-06-20 18:04:47 +00:00
Richard Smith 24cdcadcc5 C++ DR712 and others: handle non-odr-use resulting from an lvalue-to-rvalue conversion applied to a member access or similar not-quite-trivial lvalue expression.
Summary:
When a variable is named in a context where we can't directly emit a
reference to it (because we don't know for sure that it's going to be
defined, or it's from an enclosing function and not captured, or the
reference might not "work" for some reason), we emit a copy of the
variable as a global and use that for the known-to-be-read-only access.

This reinstates r363295, reverted in r363352, with a fix for PR42276:
we now produce a proper name for a non-odr-use reference to a static
constexpr data member. The name <mangled-name>.const is used in that
case; such names are reserved to the implementation for cases such as
this and should demangle nicely.

Reviewers: rjmccall

Subscribers: jdoerfert, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D63157

llvm-svn: 363428
2019-06-14 17:46:37 +00:00
Nico Weber 3d02b895ed Revert 363295, it caused PR42276. Also revert follow-ups 363337, 363340.
Revert 363340 "Remove unused SK_LValueToRValue initialization step."
Revert 363337 "PR23833, DR2140: an lvalue-to-rvalue conversion on a glvalue of type"
Revert 363295 "C++ DR712 and others: handle non-odr-use resulting from an lvalue-to-rvalue conversion applied to a member access or similar not-quite-trivial lvalue expression."

llvm-svn: 363352
2019-06-14 04:05:17 +00:00
Richard Smith 17965d42f4 C++ DR712 and others: handle non-odr-use resulting from an lvalue-to-rvalue conversion applied to a member access or similar not-quite-trivial lvalue expression.
Summary:
When a variable is named in a context where we can't directly emit a
reference to it (because we don't know for sure that it's going to be
defined, or it's from an enclosing function and not captured, or the
reference might not "work" for some reason), we emit a copy of the
variable as a global and use that for the known-to-be-read-only access.

Reviewers: rjmccall

Subscribers: jdoerfert, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D63157

llvm-svn: 363295
2019-06-13 19:00:16 +00:00
Richard Smith 36bd1c90d0 Remove redundant check for whether a DeclRefExpr that names a capture
constitutes an odr-use.

We now track this accurately on the DeclRefExpr.

llvm-svn: 363088
2019-06-11 17:50:37 +00:00
Richard Smith 1bbad59379 For DR712: store on a MemberExpr whether it constitutes an odr-use.
llvm-svn: 363087
2019-06-11 17:50:36 +00:00
Richard Smith 715f7a1bd0 For DR712: store on a DeclRefExpr whether it constitutes an odr-use.
Begin restructuring to support the forms of non-odr-use reference
permitted by DR712.

llvm-svn: 363086
2019-06-11 17:50:32 +00:00
Eric Fiselier 708afb56c1 Implement __builtin_LINE() et. al. to support source location capture.
Summary:
This patch implements the source location builtins `__builtin_LINE(), `__builtin_FUNCTION()`, `__builtin_FILE()` and `__builtin_COLUMN()`. These builtins are needed to implement [`std::experimental::source_location`](https://rawgit.com/cplusplus/fundamentals-ts/v2/main.html#reflection.src_loc.creation).

With the exception of `__builtin_COLUMN`, GCC also implements these builtins, and Clangs behavior is intended to match as closely as possible. 

Reviewers: rsmith, joerg, aaron.ballman, bogner, majnemer, shafik, martong

Reviewed By: rsmith

Subscribers: rnkovacs, loskutov, riccibruno, mgorny, kunitoki, alexr, majnemer, hfinkel, cfe-commits

Differential Revision: https://reviews.llvm.org/D37035

llvm-svn: 360937
2019-05-16 21:04:15 +00:00
Stephan Bergmann 5745eccef5 Adapt -fsanitize=function to SANITIZER_NON_UNIQUE_TYPEINFO
This follows up after b7692bc3e9 "[UBSan] Fix
isDerivedFromAtOffset on iOS ARM64" fixed the RTTI comparison in
isDerivedFromAtOffset on just one platform and then
a25a2c7c9a "Always compare C++ typeinfo (based on
libstdc++ implementation)" extended that fix to more platforms.

But there is another RTTI comparison for -fsanitize=function generated in
clang's CodeGenFunction::EmitCall as just a pointer comparison.  For
SANITIZER_NON_UNIQUE_TYPEINFO platforms this needs to be extended to also do
string comparison.  For that, __ubsan_handle_function_type_mismatch[_abort]
takes the two std::type_info pointers as additional parameters now, checks them
internally for potential equivalence, and returns without reporting failure if
they turn out to be equivalent after all.  (NORETURN needed to be dropped from
the _abort variant for that.)  Also these functions depend on ABI-specific RTTI
now, so needed to be moved from plain UBSAN_SOURCES (ubsan_handlers.h/cc) to
UBSAN_CXXABI_SOURCES (ubsan_handlers_cxx.h/cc), but as -fsanitize=function is
only supported in C++ mode that's not a problem.

Differential Revision: https://reviews.llvm.org/D60760

llvm-svn: 359759
2019-05-02 06:40:33 +00:00
Erik Pilkington 3299ead8e9 [CodeGen] Fix a regression by emitting lambda expressions in EmitLValue
This ability was removed in r351487, but it's needed when a lambda appears as an
OpaqueValueExpr subexpression of a PseudoObjectExpr.

rdar://49030379

Differential revision: https://reviews.llvm.org/D60099

llvm-svn: 357515
2019-04-02 19:48:07 +00:00
Peter Collingbourne d1c5b28c2a IRGen: Remove StructorType; thread GlobalDecl through more code. NFCI.
This should make it easier to add more structor variants.

Differential Revision: https://reviews.llvm.org/D59724

llvm-svn: 356822
2019-03-22 23:05:10 +00:00