There are instances where clang codegen creates stores to
address space 4 in ctors, which causes a crash in llc.
This store was being optimized out at opt levels > 0.
For example:
pragma omp declare target
static const double log_smallx = log2(smallx);
pragma omp end declare target
This patch ensures that any global const that does not
have constant initialization stays in address space 1.
Note - a second patch is in the works where all global
constants are placed in address space 1 during
codegen and then the opt pass InferAdressSpaces
will promote to address space 4 where necessary.
Reviewed By: JonChesterfield
Differential Revision: https://reviews.llvm.org/D115661
For a default visibility external linkage definition, dso_local is set for ELF
-fno-pic/-fpie and COFF and Mach-O. Since default clang -cc1 for ELF is similar
to -fpic ("PIC Level" is not set), this nuance causes unneeded binary format differences.
To make emitted IR similar, ELF -cc1 -fpic will default to -fno-semantic-interposition,
which sets dso_local for default visibility external linkage definitions.
To make this flip smooth and enable future (dso_local as definition default),
this patch replaces (function) `define ` with `define{{.*}} `,
(variable/constant/alias) `= ` with `={{.*}} `, or inserts appropriate `{{.*}} `.
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
Sometimes a global var is replaced by a different llvm value. clang use GetAddrOfGlobalVar to get the original llvm global variable.
For most targets, GetAddrOfGlobalVar returns either the llvm global variable or a bitcast of the llvm global variable.
However, for AMDGPU target, GetAddrOfGlobalVar returns the addrspace cast or addrspace cast plus bitcast of the llvm global variable.
To get the llvm global variable, these casts need to be stripped, otherwise there is assertion.
This patch fixes that.
Differential Revision: https://reviews.llvm.org/D69129
llvm-svn: 375362
By exposing the constant initializer, the optimizer can fold many
of these constructs.
This is a recommit of r311857 that was reverted in r311898 because
an assert was hit when building Chromium.
We have to take into account that the GlobalVariable may be first
created with a different type than the initializer. This can
happen for example when the variable is a struct with tail padding
while the initializer does not have padding. In such case, the
variable needs to be destroyed an replaced with a new one with the
type of the initializer.
Differential Revision: https://reviews.llvm.org/D34992
llvm-svn: 312512
It caused PR759744.
> Emit static constexpr member as available_externally definition
>
> By exposing the constant initializer, the optimizer can fold many
> of these constructs.
>
> Differential Revision: https://reviews.llvm.org/D34992
llvm-svn: 311898
By exposing the constant initializer, the optimizer can fold many
of these constructs.
Differential Revision: https://reviews.llvm.org/D34992
llvm-svn: 311857
Ethan Stewart