llvm-project/llvm
Simon Cook a26bd4ec16 [TableGen] Support combining AssemblerPredicates with ORs
For context, the proposed RISC-V bit manipulation extension has a subset
of instructions which require one of two SubtargetFeatures to be
enabled, 'zbb' or 'zbp', and there is no defined feature which both of
these can imply to use as a constraint either (see comments in D65649).

AssemblerPredicates allow multiple SubtargetFeatures to be declared in
the "AssemblerCondString" field, separated by commas, and this means
that the two features must both be enabled. There is no equivalent to
say that _either_ feature X or feature Y must be enabled, short of
creating a dummy SubtargetFeature for this purpose and having features X
and Y imply the new feature.

To solve the case where X or Y is needed without adding a new feature,
and to better match a typical TableGen style, this replaces the existing
"AssemblerCondString" with a dag "AssemblerCondDag" which represents the
same information. Two operators are defined for use with
AssemblerCondDag, "all_of", which matches the current behaviour, and
"any_of", which adds the new proposed ORing features functionality.

This was originally proposed in the RFC at
http://lists.llvm.org/pipermail/llvm-dev/2020-February/139138.html

Changes to all current backends are mechanical to support the replaced
functionality, and are NFCI.

At this stage, it is illegal to combine features with ands and ors in a
single AssemblerCondDag. I suspect this case is sufficiently rare that
adding more complex changes to support it are unnecessary.

Differential Revision: https://reviews.llvm.org/D74338
2020-03-13 17:13:51 +00:00
..
benchmarks
bindings Add an SDK attribute to DICompileUnit 2020-03-11 14:14:06 -07:00
cmake [clang][cmake] Include generated rst files in html built by docs-clang-html target 2020-03-05 21:30:37 -08:00
docs Add support for SHA256 source file checksums in debug info 2020-03-12 16:32:05 -07:00
examples Add missing "llvm/Support/Host.h" header to LLVM example after recent header trimming (NFC) 2020-03-12 00:12:03 +00:00
include [TableGen] Support combining AssemblerPredicates with ORs 2020-03-13 17:13:51 +00:00
lib [TableGen] Support combining AssemblerPredicates with ORs 2020-03-13 17:13:51 +00:00
projects
resources
runtimes [runtimes] When COMPILER_RT is enabled, consider SANITIZER prefixes 2020-03-11 14:22:20 -07:00
test [TableGen] Support combining AssemblerPredicates with ORs 2020-03-13 17:13:51 +00:00
tools [llvm-objdump] --syms: print 'u' for STB_GNU_UNIQUE 2020-03-13 08:04:09 -07:00
unittests [AssumeBundles] filter usefull attriutes to preserve 2020-03-13 17:35:47 +01:00
utils [TableGen] Support combining AssemblerPredicates with ORs 2020-03-13 17:13:51 +00:00
.clang-format
.clang-tidy
.gitattributes
.gitignore
CMakeLists.txt [AVR] Include AVR by default in LLVM builds 2020-03-13 17:40:30 +13:00
CODE_OWNERS.TXT Remove myself from CODE_OWNERS. 2020-02-25 11:59:29 +00:00
CREDITS.TXT
LICENSE.TXT
LLVMBuild.txt
README.txt
RELEASE_TESTERS.TXT
configure
llvm.spec.in

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