Adrian Prantl 47833cff03 Teach LiveDebugValues about lexical scopes. ... This addresses PR26055 LiveDebugValues is very slow. Contrary to the old LiveDebugVariables pass LiveDebugValues currently doesn't look at the lexical scopes before inserting a DBG_VALUE intrinsic. This means that we often propagate DBG_VALUEs much further down than necessary. This is especially noticeable in large C++ functions with many inlined method calls that all use the same "this"-pointer. For example, in the following code it makes no sense to propagate the inlined variable a from the first inlined call to f() into any of the subsequent basic blocks, because the variable will always be out of scope: void sink(int a); void __attribute((always_inline)) f(int a) { sink(a); } void foo(int i) { f(i); if (i) f(i); f(i); } This patch reuses the LexicalScopes infrastructure we have for LiveDebugVariables to take this into account. The effect on compile time and memory consumption is quite noticeable: I tested a benchmark that is a large C++ source with an enormous amount of inlined "this"-pointers that would previously eat >24GiB (most of them for DBG_VALUE intrinsics) and whose compile time was dominated by LiveDebugValues. With this patch applied the memory consumption is 1GiB and 1.7% of the time is spent in LiveDebugValues. https://reviews.llvm.org/D24994 Thanks to Daniel Berlin and Keith Walker for reviewing! llvm-svn: 282611		2016-09-28 17:51:14 +00:00
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X86	Teach LiveDebugValues about lexical scopes.	2016-09-28 17:51:14 +00:00
lit.local.cfg	Recommit LiveDebugValues pass after fixing a couple of minor issues.	2015-12-16 11:09:48 +00:00