General clean up of teh dwarf writer.

1. Most significant is the folding of debug information entries.  This
reduced self hosted -g SelectionDAGISel.s from 120M to 13M and pretty
close to matching .o file sizes with gcc.

2. Debug information entry printing for debugging the dwarf code.

3. Bring all the code closer to llvm standards.

4. Misc. fixes and doc clean ups.

llvm-svn: 31379

remove unused variables from lowerCall

llvm-svn: 31378

llvm-svn: 31377

llvm-svn: 31376

llvm-svn: 31375

llvm-svn: 31374

llvm-svn: 31373

llvm-svn: 31372

llvm-svn: 31371

llvm-svn: 31370

Replace the REM instruction with UREM, SREM and FREM.

llvm-svn: 31369

llvm-svn: 31368

sdisel changes, this eliminates a ton of copies around common inline asms.
For example:

int test2(int Y, int X) {
  asm("foo %0, %1" : "=r"(X): "r"(X));
  return X;
}

now compiles to:

_test2:
        foo r3, r4
        blr

instead of:

_test2:
        mr r2, r4
        foo r2, r2
        mr r3, r2
        blr

GCC produces:

_test2:
        foo r4, r4
        mr r3,r4
        blr

llvm-svn: 31367

no fixes physreg.  Treat this as permission to use any register in the register
class.  When this happens and it is safe, allow the llvm register allcoator to
allocate the register instead of doing it at isel time.  This eliminates a ton
of copies around common inline asms.  For example:

int test2(int Y, int X) {
  asm("foo %0, %1" : "=r"(X): "r"(X));
  return X;
}

now compiles to:

_test2:
        foo r3, r4
        blr

instead of:

_test2:
        mr r2, r4
        foo r2, r2
        mr r3, r2
        blr

GCC produces:

_test2:
        foo r4, r4
        mr r3,r4
        blr

llvm-svn: 31366

llvm-svn: 31365

llvm-svn: 31364

Two-address instructions no longer have to be A := A op C. Now any pair of dest / src operands can be tied together.

llvm-svn: 31363

llvm-svn: 31362

llvm-svn: 31361

llvm-svn: 31360

llvm-svn: 31359

This fixes http://llvm.org/bugs/show_bug.cgi?id=979

llvm-svn: 31358

llvm-svn: 31357

llvm-svn: 31356

having SCZeroExtendExpr be equivalent to SCTruncate

llvm-svn: 31355

it inserts an uncond branch where it is less likely to cause a problem.  This
fixes some perf issues on ppc.

llvm-svn: 31354

llvm-svn: 31353

llvm-svn: 31352

llvm-svn: 31351

llvm-svn: 31350

llvm-svn: 31349

llvm-svn: 31348

llvm-svn: 31347

llvm-svn: 31346

llvm-svn: 31345

result.  This can significantly shrink code and exposes identities more
aggressively.

llvm-svn: 31344

llvm-svn: 31343

llvm-svn: 31342

This triggers thousands of times on multisource.

llvm-svn: 31341

llvm-svn: 31340