Chandler Carruth 77c1270033 Refactor the PartitionUse structure to actually use the Use* instead of ... a pair of instructions, one for the used pointer and the second for the user. This simplifies the representation and also makes it more dense. This was noticed because of the miscompile in PR13926. In that case, we were running up against a fundamental "bad idea" in the speculation of PHI and select instructions: the speculation and rewriting are interleaved, which requires phi speculation to also perform load rewriting! This is bad, and causes us to miss opportunities to do (for example) vector rewriting only exposed after PHI speculation, etc etc. It also, in the old system, required us to insert *new* load uses into the current partition's use list, which would then be ignored during rewriting because we had already extracted an end iterator for the use list. The appending behavior (and much of the other oddities) stem from the strange de-duplication strategy in the PartitionUse builder. Amusingly, all this went without notice for so long because it could only be triggered by having *different* GEPs into the same partition of the same alloca, where both different GEPs were operands of a single PHI, and where the GEP which was not encountered first also had multiple uses within that same PHI node... Hence the insane steps required to reproduce. So, step one in fixing this fundamental bad idea is to make the PartitionUse actually contain a Use*, and to make the builder do proper deduplication instead of funky de-duplication. This is enough to remove the appending behavior, and fix the miscompile in PR13926, but there is more work to be done here. Subsequent commits will lift the speculation into its own visitor. It'll be a useful step toward potentially extracting all of the speculation logic into a generic utility transform. The existing PHI test case for repeated operands has been made more extreme to catch even these issues. This test case, run through the old pass, will exactly reproduce the miscompile from PR13926. ;] We were so close here! git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@164925 91177308-0d34-0410-b5e6-96231b3b80d8		2012-10-01 01:49:22 +00:00
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Analysis	Ignore apparent buffer overruns on external or weak globals. This is a major	2012-09-30 07:30:10 +00:00
Archive	Mark checkSignature const, and in turn stop casting away const from	2012-09-05 22:09:23 +00:00
AsmParser	Don't use bit-wise operations to query for inclusion/exclusion of attributes.	2012-09-28 22:30:18 +00:00
Bitcode	Move remaining methods inside the Attributes class. Merge the 'Attribute' namespaces.	2012-09-25 20:57:48 +00:00
CodeGen	Use dyn_cast instead of isa and cast.	2012-09-30 21:24:57 +00:00
DebugInfo	Mark unimplemented copy constructors and copy assignment operators as LLVM_DELETED_FUNCTION.	2012-09-18 02:01:41 +00:00
ExecutionEngine	Removing dependency on third party library for Intel JIT event support.	2012-09-28 17:35:20 +00:00
Linker	Move the "findUsedStructTypes" functionality outside of the Module class.	2012-08-03 00:30:35 +00:00
MC	Revert 'Fix a typo 'iff' => 'if''. iff is an abreviation of if and only if. See: http://en.wikipedia.org/wiki/If_and_only_if Commit 164767	2012-09-27 10:14:43 +00:00
Object	Reverting r 160419.	2012-07-19 21:43:55 +00:00
Support	Replace the use of strncpy() and sprintf() with std::string and LLVM streams.	2012-09-28 14:15:28 +00:00
TableGen	De-nest if's and fix mix-up	2012-09-19 02:14:59 +00:00
Target	Change getX86SubSuperRegister to take an MVT::SimpleValueType rather than an EVT and add llvm_unreachable to the switches. Helps it compile to dramatically better code.	2012-09-30 19:49:56 +00:00
Transforms	Refactor the PartitionUse structure to actually use the Use* instead of	2012-10-01 01:49:22 +00:00
VMCore	Revert 'Fix a typo 'iff' => 'if''. iff is an abreviation of if and only if. See: http://en.wikipedia.org/wiki/If_and_only_if Commit 164767	2012-09-27 10:14:43 +00:00
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