Hal Finkel 7463a12ef9 Add scoped-noalias metadata ... This commit adds scoped noalias metadata. The primary motivations for this feature are: 1. To preserve noalias function attribute information when inlining 2. To provide the ability to model block-scope C99 restrict pointers Neither of these two abilities are added here, only the necessary infrastructure. In fact, there should be no change to existing functionality, only the addition of new features. The logic that converts noalias function parameters into this metadata during inlining will come in a follow-up commit. What is added here is the ability to generally specify noalias memory-access sets. Regarding the metadata, alias-analysis scopes are defined similar to TBAA nodes: !scope0 = metadata !{ metadata !"scope of foo()" } !scope1 = metadata !{ metadata !"scope 1", metadata !scope0 } !scope2 = metadata !{ metadata !"scope 2", metadata !scope0 } !scope3 = metadata !{ metadata !"scope 2.1", metadata !scope2 } !scope4 = metadata !{ metadata !"scope 2.2", metadata !scope2 } Loads and stores can be tagged with an alias-analysis scope, and also, with a noalias tag for a specific scope: ... = load %ptr1, !alias.scope !{ !scope1 } ... = load %ptr2, !alias.scope !{ !scope1, !scope2 }, !noalias !{ !scope1 } When evaluating an aliasing query, if one of the instructions is associated with an alias.scope id that is identical to the noalias scope associated with the other instruction, or is a descendant (in the scope hierarchy) of the noalias scope associated with the other instruction, then the two memory accesses are assumed not to alias. Note that is the first element of the scope metadata is a string, then it can be combined accross functions and translation units. The string can be replaced by a self-reference to create globally unqiue scope identifiers. [Note: This overview is slightly stylized, since the metadata nodes really need to just be numbers (!0 instead of !scope0), and the scope lists are also global unnamed metadata.] Existing noalias metadata in a callee is "cloned" for use by the inlined code. This is necessary because the aliasing scopes are unique to each call site (because of possible control dependencies on the aliasing properties). For example, consider a function: foo(noalias a, noalias b) { *a = *b; } that gets inlined into bar() { ... if (...) foo(a1, b1); ... if (...) foo(a2, b2); } -- now just because we know that a1 does not alias with b1 at the first call site, and a2 does not alias with b2 at the second call site, we cannot let inlining these functons have the metadata imply that a1 does not alias with b2. llvm-svn: 213864		2014-07-24 14:25:39 +00:00
..
Transforms	Add scoped-noalias metadata	2014-07-24 14:25:39 +00:00
Analysis.h
BitReader.h	include/llvm-c: Whitespace.	2013-10-23 17:56:29 +00:00
BitWriter.h	include/llvm-c: Whitespace.	2013-10-23 17:56:29 +00:00
Core.h	Add a dereferenceable attribute	2014-07-18 15:51:28 +00:00
Disassembler.h	ARM64: initial backend import	2014-03-29 10:18:08 +00:00
ExecutionEngine.h	Add target analysis passes to the codegen pipeline for MCJIT.	2014-01-23 19:23:28 +00:00
Initialization.h	Extracted ObjCARC.cpp into its own library libLLVMObjCARCOpts in preparation for refactoring the ARC Optimizer.	2013-01-28 01:35:51 +00:00
IRReader.h	Fix known typos	2014-01-24 17:20:08 +00:00
Linker.h	Supply a C interface to the "LinkModules" method.	2012-05-09 08:55:40 +00:00
LinkTimeOptimizer.h	include/llvm-c: Whitespace.	2013-10-23 17:56:29 +00:00
lto.h	Move LTOModule and LTOCodeGenerator to the llvm namespace.	2014-05-03 14:59:52 +00:00
module.modulemap	[modules] The LLVM C API does not require C++!	2014-06-12 22:09:39 +00:00
Object.h	Convert getFileOffset to getOffset and move it to its only user.	2014-04-21 13:45:32 +00:00
Support.h	[Modules] Fix a layering issue that is actually impacting the modules	2014-03-06 04:13:12 +00:00
Target.h	[llvm-c] Remove dead typedef	2013-11-11 14:47:01 +00:00
TargetMachine.h	Add target analysis passes to the codegen pipeline for MCJIT.	2014-01-23 19:23:28 +00:00