llvm-svn: 71211

Optimize code placement in loop to eliminate unconditional branches or move unconditional branch to the outside of the loop. e.g.

///       A:                                                                                                                                                                 
///       ...                                                                                                                                                                
///       <fallthrough to B>                                                                                                                                                 
///                                                                                                                                                                          
///       B:  --> loop header                                                                                                                                                
///       ...                                                                                                                                                                
///       jcc <cond> C, [exit]                                                                                                                                               
///                                                                                                                                                                          
///       C:                                                                                                                                                                 
///       ...                                                                                                                                                                
///       jmp B                                                                                                                                                              
///                                                                                                                                                                          
/// ==>                                                                                                                                                                      
///                                                                                                                                                                          
///       A:                                                                                                                                                                 
///       ...                                                                                                                                                                
///       jmp B                                                                                                                                                              
///                                                                                                                                                                          
///       C:  --> new loop header                                                                                                                                            
///       ...                                                                                                                                                                
///       <fallthough to B>                                                                                                                                                  
///                                                                                                                                                                          
///       B:                                                                                                                                                                 
///       ...                                                                                                                                                                
///       jcc <cond> C, [exit] 

llvm-svn: 71209

scavenger gets confused about register liveness if it doesn't see them.
I'm not thrilled with this solution, but it only comes up when there are dead
copies in the code, which is something that hopefully doesn't happen much.

Here is what happens in pr4100: As shown in the following excerpt from the
debug output of llc, the source of a move gets reloaded from the stack,
inserting a new load instruction before the move.  Since that source operand
is a kill, the physical register is free to be reused for the destination
of the move.  The move ends up being a no-op, copying R3 to R3, so it is
deleted.  But, it leaves behind the load to reload %reg1028 into R3, and
that load is not updated to show that it's destination operand (R3) is dead.
The scavenger gets confused by that load because it thinks that R3 is live.

Starting RegAlloc of: %reg1025<def,dead> = MOVr %reg1028<kill>, 14, %reg0, %reg0
  Regs have values: 
  Reloading %reg1028 into R3
  Last use of R3[%reg1028], removing it from live set
  Assigning R3 to %reg1025
  Register R3 [%reg1025] is never used, removing it from live set

Alternative solutions might be either marking the load as dead, or zapping
the load along with the no-op copy.  I couldn't see an easy way to do
either of those, though.

llvm-svn: 71196

llvm-svn: 71180

llvm-svn: 71179

several regressions. The problem due to 71158 is now fixed.

llvm-svn: 71176

checking for bcopy... no
checking for getc_unlocked... Assertion failed: (0 && "Unknown SCEV kind!"), function operator(), file /Volumes/Sandbox/Buildbot/llvm/full-llvm/build/llvmCore.roots/llvmCore~obj/src/lib/Analysis/ScalarEvolution.cpp, line 511.
/Volumes/Sandbox/Buildbot/llvm/full-llvm/build/llvmgcc42.roots/llvmgcc42~obj/src/libdecnumber/decUtility.c:360: internal compiler error: Abort trap
Please submit a full bug report,
with preprocessed source if appropriate.
See <URL:http://developer.apple.com/bugreporter> for instructions.
make[4]: *** [decUtility.o] Error 1
make[4]: *** Waiting for unfinished jobs....
Assertion failed: (0 && "Unknown SCEV kind!"), function operator(), file /Volumes/Sandbox/Buildbot/llvm/full-llvm/build/llvmCore.roots/llvmCore~obj/src/lib/Analysis/ScalarEvolution.cpp, line 511.
/Volumes/Sandbox/Buildbot/llvm/full-llvm/build/llvmgcc42.roots/llvmgcc42~obj/src/libdecnumber/decNumber.c:5591: internal compiler error: Abort trap
Please submit a full bug report,
with preprocessed source if appropriate.
See <URL:http://developer.apple.com/bugreporter> for instructions.
make[4]: *** [decNumber.o] Error 1
make[3]: *** [all-stage2-libdecnumber] Error 2
make[3]: *** Waiting for unfinished jobs....

llvm-svn: 71165

No functionality change.

llvm-svn: 71156

llvm-svn: 71151

llvm-svn: 71150

llvm-svn: 71140

llvm-svn: 71138

-Have it return a label ID
-Remove the unused Instruction parameter

No functionality change.

llvm-svn: 71132

  change.
- Reformatting.

llvm-svn: 71118

llvm-svn: 71098

llvm-svn: 71085

are legal.  Based on a patch by Micah Villmow.

llvm-svn: 71078

llvm-svn: 71057

allow it to have multiple CFG edges to that block. This is needed
to allow MachineBasicBlock::isOnlyReachableByFallthrough to work
correctly. This fixes PR4126.

llvm-svn: 71018

llvm-svn: 71010

For implicit decls like "self" and "_cmd" in ObjC, these decls
should not have a location.

llvm-svn: 70964

llvm-svn: 70953

llvm-svn: 70950

llvm-svn: 70937

shows up in -print-machineinstrs.  This doesn't appear to affect anything, but it was
weird for some DBG_LABELs to have DebugLocs but not all of them.

llvm-svn: 70921

llvm-svn: 70900

-Depend on DebugLocs for source line info.

(Comes with Regression-Be-Gone(tm))

llvm-svn: 70871

llvm-svn: 70821

The stack slots which share the same stack slot after coloring can, but do not have to, use the same register. In fact, they each may have different register class requirements.

llvm-svn: 70815

llvm-svn: 70811

-Depend on DebugLocs for source line info.

llvm-svn: 70803

llvm-svn: 70792

In some rare cases, the register allocator can spill registers but end up not utilizing registers at all. The fundamental problem is linearscan's backtracking can end up freeing more than one allocated registers. However,  reloads and restores might be folded into uses / defs and freed registers might not be used at all.

VirtRegMap keeps track of allocations so it knows what's not used. As a horrible hack, the stack coloring can color spill slots with *free* registers. That is, it replace reload and spills with copies from and to the free register. It unfold instructions that load and store the spill slot and replace them with register using variants.

Not yet enabled. This is part 1. More coming.

llvm-svn: 70787

llvm-svn: 70770

llvm-svn: 70764

llvm-svn: 70750

llvm-svn: 70749

-Create DebugLocs without the need to have a DwarfWriter around

llvm-svn: 70682

Changes to take advantage of this will come later.

llvm-svn: 70560

llvm-svn: 70539