[CodeGen] guarantee templated static variables are initialized in the reverse instantiation order

Based on Richard's suggestion in D126341:
`If we can actually describe a rule that we provide for in

[CodeGen] guarantee templated static variables are initialized in the reverse instantiation order

Based on Richard's suggestion in D126341:
`If we can actually describe a rule that we provide for initialization
order of instantiated variables, and we can easily implement that rule
and be confident we won't want to substantially weaken it later, and we
can thereby assure our users that we will satisfy that rule, then I
think that could be interesting, but anything less than that doesn't
seem worthwhile to me.`

I'm giving it try here. IMHO the implementation is pretty simple and
does not change behavior for unrelated constructs like the timing when
instantiated variables are passed to CodeGen.

This is based on the same ordering guarantee needed for inline variables D127233.
To provide this guarantee, we also need to
emit DeferredDeclsToEmit in the DFS order. https://github.com/llvm/llvm-project/commit/e5df59ff78faebd897e81907606ce6074aac0df6
originally supported this but it is not exactly DFS order for cases like
the one in cwg362. For the example of Fib<5>, it triggers the instantiation
of Fib<4> and Fib<3>. However, due to the way GlobalEagerInstantiationScope
is implemented, Fib<4> does not actually trigger Fib<3> instantiation
since it is already triggered by Fib<5>. This breaks the guarantee.

This patch makes sure DeferredDeclsToEmit is emitted in DFS order by moving
DeferredDeclsToEmit storage from the call stack to an explicit stack-like
data structure. Then the DFS order could be enforced.

Differential Revision: https://reviews.llvm.org/D127259

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[CodeGenCXX] Convert some tests to opaque pointers (NFC)

Conversion done using the script at
https://gist.github.com/nikic/98357b71fd67756b0f064c9517b62a34.

These are tests where the conversion wor

[CodeGenCXX] Convert some tests to opaque pointers (NFC)

Conversion done using the script at
https://gist.github.com/nikic/98357b71fd67756b0f064c9517b62a34.

These are tests where the conversion worked out of the box and no
manual fixup was performed.

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[OpaquePtrs][Clang] Add -no-opaque-pointers to tests (NFC)

This adds -no-opaque-pointers to clang tests whose output will
change when opaque pointers are enabled by default. This is
intended to be p

[OpaquePtrs][Clang] Add -no-opaque-pointers to tests (NFC)

This adds -no-opaque-pointers to clang tests whose output will
change when opaque pointers are enabled by default. This is
intended to be part of the migration approach described in
https://discourse.llvm.org/t/enabling-opaque-pointers-by-default/61322/9.

The patch has been produced by replacing %clang_cc1 with
%clang_cc1 -no-opaque-pointers for tests that fail with opaque
pointers enabled. Worth noting that this doesn't cover all tests,
there's a remaining ~40 tests not using %clang_cc1 that will need
a followup change.

Differential Revision: https://reviews.llvm.org/D123115

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COFF/ELF: Place llvm.global_ctors elements in llvm.used if comdat is used

On ELF, an SHT_INIT_ARRAY outside a section group is a GC root. The current
codegen abuses SHT_INIT_ARRAY in a section group

COFF/ELF: Place llvm.global_ctors elements in llvm.used if comdat is used

On ELF, an SHT_INIT_ARRAY outside a section group is a GC root. The current
codegen abuses SHT_INIT_ARRAY in a section group to mean a GC root.

On PE/COFF, the dynamic initialization for `__declspec(selectany)` in a comdat
can be garbage collected by `-opt:ref`.

Call `addUsedGlobal` for the two cases to fix the abuse/bug.

Reviewed By: rnk

Differential Revision: https://reviews.llvm.org/D106925

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[test] Add {{.*}} to make tests immune to dso_local/dso_preemptable/(none) differences

For a definition (of most linkage types), dso_local is set for ELF -fno-pic/-fpie
and COFF, but not for Mach-O.

[test] Add {{.*}} to make tests immune to dso_local/dso_preemptable/(none) differences

For a definition (of most linkage types), dso_local is set for ELF -fno-pic/-fpie
and COFF, but not for Mach-O. This nuance causes unneeded binary format differences.

This patch replaces (function) `define ` with `define{{.*}} `,
(variable/constant/alias) `= ` with `={{.*}} `, or inserts appropriate `{{.*}} `
if there is an explicit linkage.

* Clang will set dso_local for Mach-O, which is currently implied by TargetMachine.cpp. This will make COFF/Mach-O and executable ELF similar.
* Eventually I hope we can make dso_local the textual LLVM IR default (write explicit "dso_preemptable" when applicable) and -fpic ELF will be similar to everything else. This patch helps move toward that goal.

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Revert "[CodeGenModule] Assume dso_local for -fpic -fno-semantic-interposition"

This reverts commit 789a46f2d742e11edaade28cb59a0f4d2a1d770e.

Accidentally committed.

[CodeGenModule] Assume dso_local for -fpic -fno-semantic-interposition

Summary:
Clang -fpic defaults to -fno-semantic-interposition (GCC -fpic defaults
to -fsemantic-interposition).
Users need to sp

[CodeGenModule] Assume dso_local for -fpic -fno-semantic-interposition

Summary:
Clang -fpic defaults to -fno-semantic-interposition (GCC -fpic defaults
to -fsemantic-interposition).
Users need to specify -fsemantic-interposition to get semantic
interposition behavior.

Semantic interposition is currently a best-effort feature. There may
still be some cases where it is not handled well.

Reviewers: peter.smith, rnk, serge-sans-paille, sfertile, jfb, jdoerfert

Subscribers: dschuff, jyknight, dylanmckay, nemanjai, jvesely, kbarton, fedor.sergeev, asb, rbar, johnrusso, simoncook, sabuasal, niosHD, jrtc27, zzheng, edward-jones, atanasyan, rogfer01, MartinMosbeck, brucehoult, the_o, arphaman, PkmX, jocewei, jsji, Jim, lenary, s.egerton, pzheng, sameer.abuasal, apazos, luismarques, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D73865

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Make this test a bit stricter.

The first function is named __cxx_global_var_init, which is a substring of
the following functions @__cxx_global_var_init(1,2,3,etc).

llvm-svn: 225191

Don't use a global_ctors comdat for globals that aren't externally visible

In particular, if you have two identical templates in different TUs in
anonymous namespaces, we would use the same global_c

Don't use a global_ctors comdat for globals that aren't externally visible

In particular, if you have two identical templates in different TUs in
anonymous namespaces, we would use the same global_ctors comdat key for
both. As a result, only one would be run.

llvm-svn: 219806

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Revert "Don't use comdats for initializers on platforms that don't support it"

On further investigation, COMDATs should work with .ctors, and the issue
I was hitting probably reproduces with .init_a

Revert "Don't use comdats for initializers on platforms that don't support it"

On further investigation, COMDATs should work with .ctors, and the issue
I was hitting probably reproduces with .init_array.

This reverts commit r218287.

llvm-svn: 218313

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Don't use comdats for initializers on platforms that don't support it

In particular, pre-.init_array ELF uses the .ctors section mechanism.
MinGW COFF also uses .ctors, now that I think about it. Th

Don't use comdats for initializers on platforms that don't support it

In particular, pre-.init_array ELF uses the .ctors section mechanism.
MinGW COFF also uses .ctors, now that I think about it. Therefore,
restrict this optimization to the two platforms that are currently known
to work: ELF with .init_array and COFF with .CRT$XCU.

llvm-svn: 218287

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Don't use the third field of llvm.global_ctors for MachO.

The field is defined as:

If the third field is present, non-null, and points to a global variable or function, the initializer function wil

Don't use the third field of llvm.global_ctors for MachO.

The field is defined as:

If the third field is present, non-null, and points to a global variable or function, the initializer function will only run if the associated data from the current module is not discarded.

And without COMDATs we can't implement that.

llvm-svn: 218097

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Use comdats to avoid double initialization of weak data

Initializers of global data that can appear multiple TUs (static data
members of class templates or __declspec(selectany) data) are now in a
c

Use comdats to avoid double initialization of weak data

Initializers of global data that can appear multiple TUs (static data
members of class templates or __declspec(selectany) data) are now in a
comdat group keyed on the global variable being initialized. On
non-Windows platforms, this is a code size and startup time
optimization. On Windows, this is necessary for ABI compatibility with
MSVC.

Fixes PR16959.

Reviewers: rsmith

Differential Revision: http://reviews.llvm.org/D3811

llvm-svn: 209555

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Include translation unit filename in global ctor symbol names.

This makes it easier to see where a global ctor comes from, and it also makes
ASan's init order analyzer output easier to understand.

Include translation unit filename in global ctor symbol names.

This makes it easier to see where a global ctor comes from, and it also makes
ASan's init order analyzer output easier to understand. gcc does this too,
but only in -fPIC mode for some reason. Don't do this for constructors with
explicit init priority.

Also prepend "sub_" before the 'I', that way regular constructors stay
lexicographically after symbols with init priority (because
ord('s') > ord('I')). gold seems to ignore the name of constructor symbols,
and ld only looks at the symbol if it includes an init priority, which this
patch doesn't change.

Before: __GLOBAL_I_a
Now: __GLOBAL_sub_I_myfile.cc
llvm-svn: 208128

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Implement restriction that a partial specialization must actually specialize
something, for variable templates.

llvm-svn: 191278

Do not emit duplicate global initializers for template static data members inside namespaces

A quirk of AST representation leads to class template static data member
definitions being visited twice

Do not emit duplicate global initializers for template static data members inside namespaces

A quirk of AST representation leads to class template static data member
definitions being visited twice during Clang IRGen resulting in
duplicate (benign) initializers.

Discovered while investigating a possibly-related debug info bug tickled
by the duplicate emission of these members & their associated debug
info.

With thanks to Richard Smith for help investigating, understanding, and
helping with the fix.

llvm-svn: 189996

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Order initializers of static data members of explicit specializations

I tried to implement this properly in r189051, but I didn't have enough
test coverage. Richard kindly provided more test cases

Order initializers of static data members of explicit specializations

I tried to implement this properly in r189051, but I didn't have enough
test coverage. Richard kindly provided more test cases than I could
possibly imagine and now we should have the correct condition.

llvm-svn: 189898

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Add a separate llvm.global_ctors entry for linkonce_odr data initializers

Summary:
These typically come from static data members of class template
specializations. This accomplishes two things:

1.

Add a separate llvm.global_ctors entry for linkonce_odr data initializers

Summary:
These typically come from static data members of class template
specializations. This accomplishes two things:

1. May expose GlobalOpt optimizations for Itanium C++ ABI code.
2. Works toward fixing double initialization in the Microsoft C++ ABI.

CC: cfe-commits

Differential Revision: http://llvm-reviews.chandlerc.com/D1475

llvm-svn: 189051

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Update tests to use %clang_cc1 instead of 'clang-cc' or 'clang -cc1'.
- This is designed to make it obvious that %clang_cc1 is a "test variable"
which is substituted. It is '%clang_cc1' instead o

Update tests to use %clang_cc1 instead of 'clang-cc' or 'clang -cc1'.
- This is designed to make it obvious that %clang_cc1 is a "test variable"
which is substituted. It is '%clang_cc1' instead of '%clang -cc1' because it
can be useful to redefine what gets run as 'clang -cc1' (for example, to set
a default target).

llvm-svn: 91446

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Don't emit explicit specializations of static member variable declarations.

llvm-svn: 90624