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266 Commits

Author SHA1 Message Date
Chris Lattner 4fe01c42ca Three changes: 
1. Remove a bunch of ifdef'd code.
2. When a block just contains an uncond branch, change all blocks branching
   to it to jump to the destination instead.
3. If branch analysis tells us some edges in the machinecfg are not actually
   possible, remove them.

#2 triggers a suprisingly large number of times.

llvm-svn: 31094
 2006-10-21 05:08:28 +00:00
Chris Lattner 60c9d4dc76 Add an experimental cross-jumping implementation. 
This is currently disabled by default and limited in several ways, but does
have a positive effect.

llvm-svn: 31090
 2006-10-21 00:47:49 +00:00
Chris Lattner 73da320e50 Teach the branch folder to update debug info if it removes blocks with line 
# notes in it.

llvm-svn: 31026
 2006-10-17 23:17:27 +00:00
Chris Lattner bca3e297fe Enable deleting branches to successor blocks. With the previous patches, 
branch folding can now compile stuff like this:

void foo(int W, int X, int Y, int Z) {
  if (W & 1) {
    for (; X;--X) bar();
  } else if (W & 2) {
    for (; Y;--Y) bar();
  } else if (W & 4) {
    for (; Z;--Z) bar();
  } else if (W & 8) {
    for (; W;--W) bar();
  }

  if (W) {
    bar();
  }
}

contrived testcase where loops exits all end up merging together.  To have
the loop merges be:

...
        cmplw cr0, r30, r27
        bne cr0, LBB1_14        ;bb38
LBB1_16:        ;cond_next48.loopexit
        mr r27, r29
LBB1_20:        ;cond_next48
        cmplwi cr0, r27, 0
        beq cr0, LBB1_22        ;UnifiedReturnBlock
...

instead of:


...
        cmplw cr0, r30, r27
        bne cr0, LBB1_14        ;bb38
LBB1_16:        ;cond_next48.loopexit
        mr r27, r29
        b LBB1_20       ;cond_next48
LBB1_17:        ;cond_next48.loopexit1
        b LBB1_20       ;cond_next48
LBB1_18:        ;cond_next48.loopexit2
        b LBB1_20       ;cond_next48
LBB1_19:        ;cond_next48.loopexit3
LBB1_20:        ;cond_next48
        cmplwi cr0, r27, 0
        beq cr0, LBB1_22        ;UnifiedReturnBlock
...


This is CodeGen/PowerPC/branch-opt.ll

llvm-svn: 31006
 2006-10-17 18:16:40 +00:00
Chris Lattner 56c9d2597e Reenable this pass, fixing the bugs in it. 
It now correctly deletes unreachable blocks and blocks that are empty.

llvm-svn: 31000
 2006-10-17 17:13:52 +00:00
Chris Lattner 47db29a405 disable this pass for now, it's causing issues 
llvm-svn: 30951
 2006-10-14 00:30:06 +00:00
Chris Lattner 3218e0eed5 falling off the end of a function is ok with an unreachable instruction. 
llvm-svn: 30950
 2006-10-14 00:21:48 +00:00
Chris Lattner 3e8e57c771 disable some objectionable code, maybe we can bring this pass to life 
llvm-svn: 30939
 2006-10-13 20:43:10 +00:00
Misha Brukman 835702a094 Remove trailing whitespace 
llvm-svn: 21420
 2005-04-21 22:36:52 +00:00
Reid Spencer 7c16caa336 Changes For Bug 352 
Move include/Config and include/Support into include/llvm/Config,
include/llvm/ADT and include/llvm/Support. From here on out, all LLVM
public header files must be under include/llvm/.

llvm-svn: 16137
 2004-09-01 22:55:40 +00:00
Chris Lattner 356f5a13f5 Dereferencing end() is bad. 
llvm-svn: 15402
 2004-08-01 09:51:42 +00:00
Alkis Evlogimenos 62c979ba07 Make OptimizeBlock take a MachineFunction::iterator instead of a 
MachineBasicBlock* as a parameter so that nxext() and prior() helper
functions can work naturally on it.

llvm-svn: 15376
 2004-07-31 19:24:41 +00:00
Chris Lattner 0f1c2ed907 Next on a pointer increments the pointer, not an iterator 
llvm-svn: 15375
 2004-07-31 18:40:36 +00:00
Alkis Evlogimenos 2303d3f660 Use next() helper to make code more readable. Use 
MachineFunction::iterator instead of MachineBasicBlock* to avoid
dereferencing end iterators.

llvm-svn: 15373
 2004-07-31 15:14:29 +00:00
Alkis Evlogimenos 1e8d8fd81f Use MachineFunction::iterator instead of a MachineBasicBlock* because 
FallThrough maybe == to MF.end().

llvm-svn: 15372
 2004-07-31 15:03:52 +00:00
Chris Lattner 25e48dd2e0 Implement a simple target-independent CFG cleanup pass 
llvm-svn: 15368
 2004-07-31 10:01:27 +00:00