Shuxin Yang 1bc7315c02 GVN proceeds in the presence of dead code. ... This is how it ignores the dead code: 1) When a dead branch target, say block B, is identified, all the blocks dominated by B is dead as well. 2) The PHIs of those blocks in dominance-frontier(B) is updated such that the operands corresponding to dead predecessors are replaced by "UndefVal". Using lattice's jargon, the "UndefVal" is the "Top" in essence. Phi node like this "phi(v1 bb1, undef xx)" will be optimized into "v1" if v1 is constant, or v1 is an instruction which dominate this PHI node. 3) When analyzing the availability of a load L, all dead mem-ops which L depends on disguise as a load which evaluate exactly same value as L. 4) The dead mem-ops will be materialized as "UndefVal" during code motion. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@191017 91177308-0d34-0410-b5e6-96231b3b80d8		2013-09-19 17:22:51 +00:00
..
Hello
InstCombine	Revert the load slicing done in r190870.	2013-09-17 22:01:26 +00:00
Instrumentation	[msan] Wrap indirect functions.	2013-09-19 15:22:35 +00:00
IPO	Bugfix for PR17099:	2013-09-17 09:36:11 +00:00
ObjCARC	Revert "Give internal classes hidden visibility."	2013-09-11 18:05:11 +00:00
Scalar	GVN proceeds in the presence of dead code.	2013-09-19 17:22:51 +00:00
Utils	Replace some unnecessary vector copies with references.	2013-09-15 22:04:42 +00:00
Vectorize	Prevent LoopVectorizer and SLPVectorizer running if the target has no vector registers.	2013-09-18 12:43:35 +00:00
CMakeLists.txt
LLVMBuild.txt
Makefile