This is a major change on how we represent nested name qualifications in
the AST.
* The nested name specifier itself and how it's stored is changed. The
prefixes for types are handled within the type hierarchy, which makes
canonicalization for them super cheap, no memory allocation required.
Also translating a type into nested name specifier form becomes a no-op.
An identifier is stored as a DependentNameType. The nested name
specifier gains a lightweight handle class, to be used instead of
passing around pointers, which is similar to what is implemented for
TemplateName. There is still one free bit available, and this handle can
be used within a PointerUnion and PointerIntPair, which should keep
bit-packing aficionados happy.
* The ElaboratedType node is removed, all type nodes in which it could
previously apply to can now store the elaborated keyword and name
qualifier, tail allocating when present.
* TagTypes can now point to the exact declaration found when producing
these, as opposed to the previous situation of there only existing one
TagType per entity. This increases the amount of type sugar retained,
and can have several applications, for example in tracking module
ownership, and other tools which care about source file origins, such as
IWYU. These TagTypes are lazily allocated, in order to limit the
increase in AST size.
This patch offers a great performance benefit.
It greatly improves compilation time for
[stdexec](https://github.com/NVIDIA/stdexec). For one datapoint, for
`test_on2.cpp` in that project, which is the slowest compiling test,
this patch improves `-c` compilation time by about 7.2%, with the
`-fsyntax-only` improvement being at ~12%.
This has great results on compile-time-tracker as well:
This patch also further enables other optimziations in the future, and
will reduce the performance impact of template specialization resugaring
when that lands.
It has some other miscelaneous drive-by fixes.
About the review: Yes the patch is huge, sorry about that. Part of the
reason is that I started by the nested name specifier part, before the
ElaboratedType part, but that had a huge performance downside, as
ElaboratedType is a big performance hog. I didn't have the steam to go
back and change the patch after the fact.
There is also a lot of internal API changes, and it made sense to remove
ElaboratedType in one go, versus removing it from one type at a time, as
that would present much more churn to the users. Also, the nested name
specifier having a different API avoids missing changes related to how
prefixes work now, which could make existing code compile but not work.
How to review: The important changes are all in
`clang/include/clang/AST` and `clang/lib/AST`, with also important
changes in `clang/lib/Sema/TreeTransform.h`.
The rest and bulk of the changes are mostly consequences of the changes
in API.
PS: TagType::getDecl is renamed to `getOriginalDecl` in this patch, just
for easier to rebasing. I plan to rename it back after this lands.
Fixes#136624
Fixes https://github.com/llvm/llvm-project/issues/43179
Fixes https://github.com/llvm/llvm-project/issues/68670
Fixes https://github.com/llvm/llvm-project/issues/92757
Enable _Float16 for LoongArch target. Additionally, this change fixes
incorrect ABI lowering of _Float16 in the case of structs containing
fp16 that are eligible for passing via GPR+FPR or FPR+FPR. Finally, it
also fixes int16 -> __fp16 conversion code gen, which uses generic LLVM
IR rather than llvm.convert.to.fp16 intrinsics.
`sret` arguments are always going to reside in the stack/`alloca`
address space, which makes the current formulation where their AS is
derived from the pointee somewhat quaint. This patch ensures that `sret`
ends up pointing to the `alloca` AS in IR function signatures, and also
guards agains trying to pass a casted `alloca`d pointer to a `sret` arg,
which can happen for most languages, when compiled for targets that have
a non-zero `alloca` AS (e.g. AMDGCN) / map `LangAS::default` to a
non-zero value (SPIR-V). A target could still choose to do something
different here, by e.g. overriding `classifyReturnType` behaviour.
In a broader sense, this patch extends non-aliased indirect args to also
carry an AS, which leads to changing the `getIndirect()` interface. At
the moment we're only using this for (indirect) returns, but it allows
for future handling of indirect args themselves. We default to using the
AllocaAS as that matches what Clang is currently doing, however if, in
the future, a target would opt for e.g. placing indirect returns in some
other storage, with another AS, this will require revisiting.
---------
Co-authored-by: Matt Arsenault <arsenm2@gmail.com>
Co-authored-by: Matt Arsenault <Matthew.Arsenault@amd.com>
This reverts commit 81fc3add1e627c23b7270fe2739cdacc09063e54.
This breaks some LLDB tests, e.g.
SymbolFile/DWARF/x86/no_unique_address-with-bitfields.cpp:
lldb: ../llvm-project/clang/lib/AST/Decl.cpp:4604: unsigned int clang::FieldDecl::getBitWidthValue() const: Assertion `isa<ConstantExpr>(getBitWidth())' failed.
Save the bitwidth value as a `ConstantExpr` with the value set. Remove
the `ASTContext` parameter from `getBitWidthValue()`, so the latter
simply returns the value from the `ConstantExpr` instead of
constant-evaluating the bitwidth expression every time it is called.
In PR #79382, I need to add a new type that derives from
ConstantArrayType. This means that ConstantArrayType can no longer use
`llvm::TrailingObjects` to store the trailing optional Expr*.
This change refactors ConstantArrayType to store a 60-bit integer and
4-bits for the integer size in bytes. This replaces the APInt field
previously in the type but preserves enough information to recreate it
where needed.
To reduce the number of places where the APInt is re-constructed I've
also added some helper methods to the ConstantArrayType to allow some
common use cases that operate on either the stored small integer or the
APInt as appropriate.
Resolves#85124.
In g++, empty unions are not ignored like empty structs when flattening
structs to examine whether the structs can be passed via FARs in C++.
This patch aligns clang++ with g++.
Fix https://github.com/llvm/llvm-project/issues/70890.
How empty structs (not as fields of container struct) are passed in C++
is not explicitly documented in psABI. However, this patch fixes the
mismatch with g++.
Note that the unnamed bitfield case `struct { int : 1; }` in C is also
fixed. Previously clang regards it as an empty struct and then ignores
it when passing. Now size of the struct is counted; since it's size is
not 0, clang will not ignore it even in C.
While https://reviews.llvm.org/D156116 fixed the handling of empty
struct when considering eligibility of the container struct for the FP
calling convention ('flattening'), this patch fixes the handling of
passing the empty struct itself.
Fix https://github.com/llvm/llvm-project/issues/70319
GCC doesn't ignore non-zero-length array of empty structures in C++
while clang does. What this patch did is to match GCC's behaviour
although this rule is not documented in psABI.
Similar to D142327 for RISCV.
Reviewed By: xry111, xen0n
Differential Revision: https://reviews.llvm.org/D156116
GCC doesn't ignore non-zero-length array of empty structures in C++
while clang does. What this patch did is to match GCC's behaviour
although this rule is not documented in psABI.
Similar to D142327 for RISCV.
Reviewed By: xry111, xen0n
Differential Revision: https://reviews.llvm.org/D156116
Partial progress towards replacing `CreateElementBitCast`, as it no
longer does what its name suggests. Either replace its uses with
`Address::withElementType()`, or remove them if no longer needed.
Reviewed By: barannikov88, nikic
Differential Revision: https://reviews.llvm.org/D153314
This commit breaks up CodeGen/TargetInfo.cpp into a set of *.cpp files,
one file per target. There are no functional changes, mostly just code moving.
Non-code-moving changes are:
* A virtual destructor has been added to DefaultABIInfo to pin the vtable to a cpp file.
* A few methods of ABIInfo and DefaultABIInfo were split into declaration + definition
in order to reduce the number of transitive includes.
* Several functions that used to be static have been placed in clang::CodeGen
namespace so that they can be accessed from other cpp files.
RFC: https://discourse.llvm.org/t/rfc-splitting-clangs-targetinfo-cpp/69883
Reviewed By: efriedma
Differential Revision: https://reviews.llvm.org/D148094
