Changes

Summary

1. [InstSimplify] Add test case to show bad sign bit handling for integer abs idiom in computeKnownBits. computeKnownBits will indicate the sign bit of abs is 0 if the the RHS operand returned by matchSelectPattern has the nsw flag set. For abs idioms like (X >= 0) ? X : -X, the RHS returns -X. But we can also match ((X-Y) >= 0 ? X-Y : Y-X as abs. In this case RHS will be the Y-X operand. According to Alive, the sign bit for this is only 0 if both the X-Y and Y-X operands have the nsw flag. But we're only checking the Y-X operand.
2. MCRegister/Register: DenseMapInfo should take `const T &`

Revision 367747 by ctopper: [InstSimplify] Add test case to show bad sign bit handling for integer abs idiom in computeKnownBits. computeKnownBits will indicate the sign bit of abs is 0 if the the RHS operand returned by matchSelectPattern has the nsw flag set. For abs idioms like (X >= 0) ? X : -X, the RHS returns -X. But we can also match ((X-Y) >= 0 ? X-Y : Y-X as abs. In this case RHS will be the Y-X operand. According to Alive, the sign bit for this is only 0 if both the X-Y and Y-X operands have the nsw flag. But we're only checking the Y-X operand.
Change Type	Path in Repository	Path in Workspace
	/llvm/trunk/test/Transforms/InstSimplify/icmp-abs-nabs.ll	llvm.src/test/Transforms/InstSimplify/icmp-abs-nabs.ll
Revision 367744 by dsanders: MCRegister/Register: DenseMapInfo should take `const T &`
Change Type	Path in Repository	Path in Workspace
	/llvm/trunk/include/llvm/CodeGen/Register.h	llvm.src/include/llvm/CodeGen/Register.h
	/llvm/trunk/include/llvm/MC/MCRegister.h	llvm.src/include/llvm/MC/MCRegister.h