Enhance analysis of srem.

Remove dead code analyzing urem. 'urem' of power-of-2 is canonicalized to an
'and' instruction.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@53506 91177308-0d34-0410-b5e6-96231b3b80d8

test/Transforms/InstCombine/2008-07-11-RemAnd.ll

@@ -0,0 +1,9 @@
+; RUN: llvm-as < %s | opt -instcombine | llvm-dis | not grep rem
+; PR2330
+
+define i32 @a(i32 %b) nounwind  {
+entry:
+	srem i32 %b, 8		; <i32>:0 [#uses=1]
+	and i32 %0, 1		; <i32>:1 [#uses=1]
+	ret i32 %1
+}