Chandler Carruth b3dca3f50e Revert the business end of r164636 and try again. I'll come in again. ;] ... This should really, really fix PR13916. For real this time. The underlying bug is... a bit more subtle than I had imagined. The setup is a code pattern that leads to an @llvm.memcpy call with two equal pointers to an alloca in the source and dest. Now, not any pattern will do. The alloca needs to be formed just so, and both pointers should be wrapped in different bitcasts etc. When this precise pattern hits, a funny sequence of events transpires. First, we correctly detect the potential for overlap, and correctly optimize the memcpy. The first time. However, we do simplify the set of users of the alloca, and that causes us to run the alloca back through the SROA pass in case there are knock-on simplifications. At this point, a curious thing has happened. If we happen to have an i8 alloca, we have direct i8 pointer values. So we don't bother creating a cast, we rewrite the arguments to the memcpy to dircetly refer to the alloca. Now, in an unrelated area of the pass, we have clever logic which ensures that when visiting each User of a particular pointer derived from an alloca, we only visit that User once, and directly inspect all of its operands which refer to that particular pointer value. However, the mechanism used to detect memcpy's with the potential to overlap relied upon getting visited once per *Use*, not once per *User*. This is always true *unless* the same exact value is both source and dest. It turns out that almost nothing actually produces that pattern though. We can hand craft test cases that more directly test this behavior of course, and those are included. Also, note that there is a significant missed optimization here -- we prove in many cases that there is a non-volatile memcpy call with identical source and dest addresses. We shouldn't prevent splitting the alloca in that case, and in fact we should just remove such memcpy calls eagerly. I'll address that in a subsequent commit. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@164669 91177308-0d34-0410-b5e6-96231b3b80d8		2012-09-26 07:41:40 +00:00
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Analysis	Change the way the lint sanity checking pass detects misaligned memory accesses.	2012-09-25 10:00:49 +00:00
Archive	Mark checkSignature const, and in turn stop casting away const from	2012-09-05 22:09:23 +00:00
AsmParser	Encapsulate the "construct*AlignmentFromInt" functions.	2012-09-21 16:07:28 +00:00
Bitcode	Move remaining methods inside the Attributes class. Merge the 'Attribute' namespaces.	2012-09-25 20:57:48 +00:00
CodeGen	Rename virtual table anchors from Anchor() to anchor() for consistency with the rest of the tree.	2012-09-26 06:36:36 +00:00
DebugInfo	Mark unimplemented copy constructors and copy assignment operators as LLVM_DELETED_FUNCTION.	2012-09-18 02:01:41 +00:00
ExecutionEngine	Mark unimplemented copy constructors and copy assignment operators as LLVM_DELETED_FUNCTION.	2012-09-18 02:01:41 +00:00
Linker
MC	Rename virtual table anchors from Anchor() to anchor() for consistency with the rest of the tree.	2012-09-26 06:36:36 +00:00
Object
Support	Fix a -Wparentheses warning in the mingw build	2012-09-25 05:24:16 +00:00
TableGen	De-nest if's and fix mix-up	2012-09-19 02:14:59 +00:00
Target	Remove hasNoAVX method. Can just invert hasAVX instead.	2012-09-26 06:29:37 +00:00
Transforms	Revert the business end of r164636 and try again. I'll come in again. ;]	2012-09-26 07:41:40 +00:00
VMCore	Replace calls to getSizeInBits with getExtendedSizeInBits since its already known its an extended type.	2012-09-26 07:11:42 +00:00
CMakeLists.txt
LLVMBuild.txt
Makefile