Exploit distributive laws (eg: And distributes over Or, Mul over Add, etc) in a
fairly systematic way in instcombine. Some of these cases were already dealt
with, in which case I removed the existing code. The case of Add has a bunch of
funky logic which covers some of this plus a few variants (considers shifts to be
a form of multiplication), which I didn't touch. The simplification performed is:
A*B+A*C -> A*(B+C). The improvement is to do this in cases that were not already
handled [such as A*B-A*C -> A*(B-C), which was reported on the mailing list], and
also to do it more often by not checking for "only one use" if "B+C" simplifies.
llvm-svn: 120024
diff --git a/llvm/lib/Transforms/InstCombine/InstCombine.h b/llvm/lib/Transforms/InstCombine/InstCombine.h
index 05846d0..b492777 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombine.h
+++ b/llvm/lib/Transforms/InstCombine/InstCombine.h
@@ -290,6 +290,12 @@
/// operators which are associative or commutative.
bool SimplifyAssociativeOrCommutative(BinaryOperator &I);
+ /// SimplifyDistributed - This tries to simplify binary operations which some
+ /// other binary operation distributes over (eg "A*B+A*C" -> "A*(B+C)" since
+ /// addition is distributed over by multiplication). Returns the result of
+ /// the simplification, or null if no simplification was performed.
+ Instruction *SimplifyDistributed(BinaryOperator &I);
+
/// SimplifyDemandedUseBits - Attempts to replace V with a simpler value
/// based on the demanded bits.
Value *SimplifyDemandedUseBits(Value *V, APInt DemandedMask,