There are two optimizations here:
1. Consider the following code:
FCMPSrr %0, %1, implicit-def $nzcv
%sel1:gpr32 = CSELWr %_, %_, 12, implicit $nzcv
%sub:gpr32 = SUBSWrr %_, %_, implicit-def $nzcv
FCMPSrr %0, %1, implicit-def $nzcv
%sel2:gpr32 = CSELWr %_, %_, 12, implicit $nzcv
This kind of code where we have 2 FCMPs each feeding a CSEL can happen
when we have a single IR fcmp being used by two selects. During selection,
to ensure that there can be no clobbering of nzcv between the fcmp and the
csel, we have to generate an fcmp immediately before each csel is
selected.
However, often we can essentially CSE these together later in MachineCSE.
This doesn't work though if there are unrelated flag-setting instructions
in between the two FCMPs. In this case, the SUBS defines NZCV
but it doesn't have any users, being overwritten by the second FCMP.
Our solution here is to try to convert flag setting operations between
a interval of identical FCMPs, so that CSE will be able to eliminate one.
2. SelectionDAG imported patterns for arithmetic ops currently select the
flag-setting ops for CSE reasons, and add the implicit-def $nzcv operand
to those instructions. However if those impdef operands are not marked as
dead, the peephole optimizations are not able to optimize them into non-flag
setting variants. The optimization here is to find these dead imp-defs and
mark them as such.
This pass is only enabled when optimizations are enabled.
Differential Revision: https://reviews.llvm.org/D89415
This reverts commit b3ca53e14274642274be8fe7db8b43dc3c146366.
This reverts commit 8b7dac81d378c339d3e55f6f51cd0c42803903ad.
This reverts commit 37c030f81a9fdd7a7e1b6fa5407b277c1ab1afa1.
Fixes
$ ninja obj/build/rel/gen/clang-tools-extra/clangd/CompletionModel.CompletionModel.obj
Some tablegen include files from clang/include/clang/AST and
clang/include/clang/Sema need to be generated before CompletionModel is
compiled.
Reviewed By: thakis
Differential Revision: https://reviews.llvm.org/D89657
37c030f81a9fdd made it so that depending on //libcxx/include
automatically added the copied header dir to the include search path.
For some reason, clang can't build against the copied libcxx headers
(it complains about ldiv_t not being a type). I don't have a mac
to debug right now, but for the clang target this change was
unintentional anyways -- only depend on the copies target, instead
of on the target that also adjusts the include path.
Apparenlty I added these in https://reviews.llvm.org/rL350628 but
I'm not sure why. They never existed in the CMake build, and now
they're causing trouble.
It's built with just-built clang, like all other compiler-rt parts
in the GN build.
This requires adding some cross build support to the mac toolchain.
Also add explicit mmacosx-version-min and miphoneos-version-min
flags to the build.
ios.a is only built with the arm64 slice, iossim.a only with the
x86_64 slice for now. (The latter should maybe become host_cpu
when Arm Macs become a common iOS development platform.)
With this, it's possible to build chromium/iOS with a GN-built LLVM.
Differential Revision: https://reviews.llvm.org/D89260
