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Commit Graph

9 Commits

Author SHA1 Message Date
Daniel Sanders
3f27cf24cf [globalisel] Add very brief docs summarizing the ISel part of the LLVMDev tutorial.
Also added links to the talks available.

llvm-svn: 316350
2017-10-23 17:18:44 +00:00
Quentin Colombet
ed9a033b66 [GlobalISel] Update the documentation and comment for G_[UN]MERGE_VALUES
In r296921, we added the G_[UN]MERGE_VALUES node, but did not update the
documentation. Fixing that.

NFC.

llvm-svn: 314168
2017-09-25 22:03:06 +00:00
Quentin Colombet
f124af2f5e [GlobalISel] Update the documentation for G_SEQUENCE
This instruction has been removed in r306120.

NFC.

llvm-svn: 314167
2017-09-25 22:03:05 +00:00
Quentin Colombet
2e2793f727 [GlobalISel] Update the documentation and comments for G_EXTRACT
In r297100, G_EXTRACT changed from a multiple results instruction to a
single result one. Update the documentation accordingly.

NFC.

llvm-svn: 314166
2017-09-25 22:03:01 +00:00
Quentin Colombet
862e639dc6 Reapply "[GlobalISel] Remove the GISelAccessor API."
This reverts commit r310425, thus reapplying r310335 with a fix for link
issue of the AArch64 unittests on Linux bots when BUILD_SHARED_LIBS is ON.

Original commit message:
[GlobalISel] Remove the GISelAccessor API.

Its sole purpose was to avoid spreading around ifdefs related to
building global-isel. Since r309990, GlobalISel is not optional anymore,
thus, we can get rid of this mechanism all together.

NFC.

----
The fix for the link issue consists in adding the GlobalISel library in
the list of dependencies for the AArch64 unittests. This dependency
comes from the use of AArch64Subtarget that needs to know how
to destruct the GISel related APIs when being detroyed.

Thanks to Bill Seurer and Ahmed Bougacha for helping me reproducing and
understand the problem.

llvm-svn: 310969
2017-08-15 22:31:51 +00:00
Quentin Colombet
3f63039f98 Revert "[GlobalISel] Remove the GISelAccessor API."
This reverts commit r310115.

It causes a linker failure for the one of the unittests of AArch64 on one
of the linux bot:
http://lab.llvm.org:8011/builders/clang-ppc64le-linux-multistage/builds/3429

: && /home/fedora/gcc/install/gcc-7.1.0/bin/g++   -fPIC
-fvisibility-inlines-hidden -Werror=date-time -std=c++11 -Wall -W
-Wno-unused-parameter -Wwrite-strings -Wcast-qual
-Wno-missing-field-initializers -pedantic -Wno-long-long
-Wno-maybe-uninitialized -Wdelete-non-virtual-dtor -Wno-comment
-ffunction-sections -fdata-sections -O2
-L/home/fedora/gcc/install/gcc-7.1.0/lib64 -Wl,-allow-shlib-undefined
-Wl,-O3 -Wl,--gc-sections
unittests/Target/AArch64/CMakeFiles/AArch64Tests.dir/InstSizes.cpp.o  -o
unittests/Target/AArch64/AArch64Tests
lib/libLLVMAArch64CodeGen.so.6.0.0svn lib/libLLVMAArch64Desc.so.6.0.0svn
lib/libLLVMAArch64Info.so.6.0.0svn lib/libLLVMCodeGen.so.6.0.0svn
lib/libLLVMCore.so.6.0.0svn lib/libLLVMMC.so.6.0.0svn
lib/libLLVMMIRParser.so.6.0.0svn lib/libLLVMSelectionDAG.so.6.0.0svn
lib/libLLVMTarget.so.6.0.0svn lib/libLLVMSupport.so.6.0.0svn -lpthread
lib/libgtest_main.so.6.0.0svn lib/libgtest.so.6.0.0svn -lpthread
-Wl,-rpath,/home/buildbots/ppc64le-clang-multistage-test/clang-ppc64le-multistage/stage1/lib
&& :
unittests/Target/AArch64/CMakeFiles/AArch64Tests.dir/InstSizes.cpp.o:(.toc+0x0):
undefined reference to `vtable for llvm::LegalizerInfo'
unittests/Target/AArch64/CMakeFiles/AArch64Tests.dir/InstSizes.cpp.o:(.toc+0x8):
undefined reference to `vtable for llvm::RegisterBankInfo'

The particularity of this bot is that it is built with
BUILD_SHARED_LIBS=ON

However, I was not able to reproduce the problem so far.
Reverting to unblock the bot.

llvm-svn: 310425
2017-08-08 22:22:30 +00:00
Quentin Colombet
0a7c56803e [GlobalISel] Remove the GISelAccessor API.
Its sole purpose was to avoid spreading around ifdefs related to
building global-isel. Since r309990, GlobalISel is not optional anymore,
thus, we can get rid of this mechanism all together.

NFC.

llvm-svn: 310115
2017-08-04 20:15:46 +00:00
Ahmed Bougacha
a84a7cf9e8 [AArch64][GlobalISel] Legalize narrow scalar ops again.
Since r279760, we've been marking as legal operations on narrow integer
types that have wider legal equivalents (for instance, G_ADD s8).
Compared to legalizing these operations, this reduced the amount of
extends/truncates required, but was always a weird legalization decision
made at selection time.

So far, we haven't been able to formalize it in a way that permits the
selector generated from SelectionDAG patterns to be sufficient.

Using a wide instruction (say, s64), when a narrower instruction exists
(s32) would introduce register class incompatibilities (when one narrow
generic instruction is selected to the wider variant, but another is
selected to the narrower variant).

It's also impractical to limit which narrow operations are matched for
which instruction, as restricting "narrow selection" to ranges of types
clashes with potentially incompatible instruction predicates.

Concerns were also raised regarding  MIPS64's sign-extended register
assumptions, as well as wrapping behavior.
See discussions in https://reviews.llvm.org/D26878.

Instead, legalize the operations.

Should we ever revert to selecting these narrow operations, we should
try to represent this more accurately: for instance, by separating
a "concrete" type on operations, and an "underlying" type on vregs, we
could move the "this narrow-looking op is really legal" decision to the
legalizer, and let the selector use the "underlying" vreg type only,
which would be guaranteed to map to a register class.

In any case, we eventually should mitigate:
- the performance impact by selecting no-op extract/truncates to COPYs
  (which we currently do), and the COPYs to register reuses (which we
  don't do yet).
- the compile-time impact by optimizing away extract/truncate sequences
  in the legalizer.

llvm-svn: 292827
2017-01-23 21:10:05 +00:00
Ahmed Bougacha
858b02ac78 [docs] Add initial Global ISel documentation.
This reflects the current state of Global ISel.  As progress is
made, we'll document our design decisions in it.
Comments very welcome!

llvm-svn: 286002
2016-11-04 17:57:34 +00:00