for mul and div.

Instead of generating this:

test_divr:
        fld QWORD PTR [%ESP + 4]
        fld QWORD PTR [.CPItest_divr_0]
        fdivrp %ST(1)
        ret

We now generate this:

test_divr:
        fld QWORD PTR [%ESP + 4]
        fdivr QWORD PTR [.CPItest_divr_0]
        ret

This code desperately needs refactoring, which will come in the next
patch.

llvm-svn: 12841

instructions use.  This doesn't change any functionality except that long
constant expressions of these operations will now magically start working.

llvm-svn: 12840

        fld QWORD PTR [%ESP + 4]
        fadd QWORD PTR [.CPItest_add_0]

instead of:

        fld QWORD PTR [%ESP + 4]
        fld QWORD PTR [.CPItest_add_0]
        faddp %ST(1)

I also intend to do this for mul & div, but it appears that I have to
refactor a bit of code before I can do so.

This is tested by: test/Regression/CodeGen/X86/fp_constant_op.llx

llvm-svn: 12839

llvm-svn: 12838

llvm-svn: 12837

llvm-svn: 12836

  1. If an incoming argument is dead, don't load it from the stack
  2. Do not code gen noop copies at all (ie, cast int -> uint), not even to
     a move.  This should reduce register pressure for allocators that are
     unable to coallesce away these copies in some cases.

llvm-svn: 12835

llvm-svn: 12834

llvm-svn: 12833

llvm-svn: 12832

llvm-svn: 12831

llvm-svn: 12830

llvm-svn: 12829

llvm-svn: 12826

llvm-svn: 12825

llvm-svn: 12824

llvm-svn: 12823

llvm-svn: 12822

llvm-svn: 12821

llvm-svn: 12820

Canonicalize add of sign bit constant into a xor

llvm-svn: 12819

llvm-svn: 12818

and a bit more powerful

llvm-svn: 12817

llvm-svn: 12816

llvm-svn: 12815

llvm-svn: 12814

llvm-svn: 12813

llvm-svn: 12811

llvm-svn: 12810

llvm-svn: 12809

don't write to memory

llvm-svn: 12808

call and invoke instructions that are known to not write to memory.

llvm-svn: 12807

llvm-svn: 12806

llvm-svn: 12805

llvm-svn: 12804

llvm-svn: 12803

llvm-svn: 12802

eliminating the shifts

llvm-svn: 12801

This transforms code like this:

   %C = or %A, %B
   %D = select %cond, %C, %A
into:
   %C = select %cond, %B, 0
   %D = or %A, %C

Since B is often a constant, the select can often be eliminated.  In any case,
this reduces the usage count of A, allowing subsequent optimizations to happen.

This xform applies when the operator is any of:
  add, sub, mul, or, xor, and, shl, shr

llvm-svn: 12800

llvm-svn: 12799