llvm/lib/AsmParser
David Majnemer 2dacece9e2 [IR] Add token types
This introduces the basic functionality to support "token types".
The motivation stems from the need to perform operations on a Value
whose provenance cannot be obscured.

There are several applications for such a type but my immediate
motivation stems from WinEH.  Our personality routine enforces a
single-entry - single-exit regime for cleanups.  After several rounds of
optimizations, we may be left with a terminator whose "cleanup-entry
block" is not entirely clear because control flow has merged two
cleanups together.  We have experimented with using labels as operands
inside of instructions which are not terminators to indicate where we
came from but found that LLVM does not expect such exotic uses of
BasicBlocks.

Instead, we can use this new type to clearly associate the "entry point"
and "exit point" of our cleanup.  This is done by having the cleanuppad
yield a Token and consuming it at the cleanupret.
The token type makes it impossible to obscure or otherwise hide the
Value, making it trivial to track the relationship between the two
points.

What is the burden to the optimizer?  Well, it turns out we have already
paid down this cost by accepting that there are certain calls that we
are not permitted to duplicate, optimizations have to watch out for
such instructions anyway.  There are additional places in the optimizer
that we will probably have to update but early examination has given me
the impression that this will not be heroic.

Differential Revision: http://reviews.llvm.org/D11861

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@245029 91177308-0d34-0410-b5e6-96231b3b80d8
2015-08-14 05:09:07 +00:00
..
CMakeLists.txt modules: Add explicit dependency on intrinsics_gen 2015-06-16 00:44:12 +00:00
LLLexer.cpp [IR] Add token types 2015-08-14 05:09:07 +00:00
LLLexer.h Remove empty non-virtual destructors or mark them =default when non-public 2015-04-11 15:32:26 +00:00
LLParser.cpp Fix with a bit more care. (but only a bit) 2015-08-03 20:55:00 +00:00
LLParser.h Try to fix the build for C++ standard libraries missing std::map::emplace 2015-08-03 20:30:53 +00:00
LLToken.h New EH representation for MSVC compatibility 2015-07-31 17:58:14 +00:00
LLVMBuild.txt
Makefile
module.modulemap [modules] Add module maps for LLVM. These are not quite ready for prime-time 2014-05-21 02:46:14 +00:00
Parser.cpp AsmParser: Add a function to parse a standalone constant value. 2015-07-17 22:07:03 +00:00