Be more careful when updating Phi nodes after eliminating dead switch cases.  Fix
proposed by Chris.

llvm-svn: 28947

of LCSSA.  This results several times the number of unswitchings occurring on
tests such and timberwolfmc, unix-tbl, and ldecod.

llvm-svn: 28912

bug exposed by the recent lcssa work.

llvm-svn: 28779

llvm-svn: 28759

Back out Owen's 6/9 changes. They broke MultiSource/Benchmarks/Prolangs-C/bison (and perhaps others).

llvm-svn: 28747

LCSSA.

llvm-svn: 28739

llvm-svn: 27051

caused SPASS to fail building last night.

We can't trivially unswitch a loop if the exit block has phi nodes in it,
because we don't know which predecessor to use.

llvm-svn: 26320

to rewrite with the wrong value.

llvm-svn: 26311

llvm-svn: 26289

llvm-svn: 26285

Thanks to nate for pointing this out :)

llvm-svn: 26280

llvm-svn: 26279

the right loop.

llvm-svn: 26277

llvm-svn: 26258

risk :)

llvm-svn: 26248

Change SplitBlock to increment a BasicBlock::iterator, not an Instruction*.  Apparently they do different things :)

This fixes a testcase that nate reduced from spass.

Also included are a couple minor code changes that don't affect the generated
code at all.

llvm-svn: 26235

llvm-svn: 26228

llvm-svn: 26225

unswitch this loop on 2 before sweating to unswitch on 1/3.

void test4(int N, int i, int C, int*P, int*Q) {
  int j;
  for (j = 0; j < N; ++j) {
    switch (C) {                // general unswitching.
    default: P[i+j] = 0; break;
    case 1: Q[i+j] = 0; break;
    case 3: P[i+j] = Q[i+j]; break;
    case 2: break;              //  TRIVIAL UNSWITCH on C==2
    }
  }
}

llvm-svn: 26223

this for example:

  for (j = 0; j < N; ++j) {     // trivial unswitch
    if (C)
      P[i+j] = 0;
  }

turning it into the obvious code without bothering to duplicate an empty loop.

llvm-svn: 26220

Y = seteq bool X, true
instead of just using X :)

llvm-svn: 26215

llvm-svn: 26194

llvm-svn: 26191

llvm-svn: 26157

llvm-svn: 26114

llvm-svn: 26113

llvm-svn: 26112

phi's in the successors

llvm-svn: 26108

with branches on partially invariant computations.

llvm-svn: 26104

llvm-svn: 26103

llvm-svn: 26102

branches in their entry block that control whether or not the loop is a noop or not.

llvm-svn: 26101

llvm-svn: 26098

llvm-svn: 26093

uses of loop values outside the loop.  We need loop-closed SSA form to do
this right, or to use SSA rewriting if we really care.

llvm-svn: 26089

llvm-svn: 25514

llvm-svn: 21427

llvm-svn: 19306

Patch contributed by Paolo Invernizzi!

llvm-svn: 16152