[llvm-commits] [llvm] r100062 - /llvm/trunk/lib/CodeGen/MachineBasicBlock.cpp

[Bob Wilson]

Are you sure?  I think that's the same test that's been failing intermittently.  Daniel tried to fix it (see http://llvm.org/bugs/show_bug.cgi?id=6753) but I think I also saw a comment from him that it wasn't really fixed.

On Mar 31, 2010, at 4:26 PM, Bill Wendling wrote:

> Author: void
> Date: Wed Mar 31 18:26:26 2010
> New Revision: 100062
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=100062&view=rev
> Log:
> Revert r100056. It was causing a failure on MSVC.
> 
> Modified:
>    llvm/trunk/lib/CodeGen/MachineBasicBlock.cpp
> 
> Modified: llvm/trunk/lib/CodeGen/MachineBasicBlock.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/MachineBasicBlock.cpp?rev=100062&r1=100061&r2=100062&view=diff
> ==============================================================================
> --- llvm/trunk/lib/CodeGen/MachineBasicBlock.cpp (original)
> +++ llvm/trunk/lib/CodeGen/MachineBasicBlock.cpp Wed Mar 31 18:26:26 2010
> @@ -23,7 +23,6 @@
> #include "llvm/Target/TargetMachine.h"
> #include "llvm/Assembly/Writer.h"
> #include "llvm/ADT/SmallString.h"
> -#include "llvm/ADT/SmallPtrSet.h"
> #include "llvm/Support/Debug.h"
> #include "llvm/Support/LeakDetector.h"
> #include "llvm/Support/raw_ostream.h"
> @@ -460,41 +459,54 @@
>   //    conditional branch followed by an unconditional branch. DestA is the
>   //    'true' destination and DestB is the 'false' destination.
> 
> -  bool Changed = false;
> +  bool MadeChange = false;
> +  bool AddedFallThrough = false;
> 
>   MachineFunction::iterator FallThru =
>     llvm::next(MachineFunction::iterator(this));
> -
> -  if (DestA == 0 && DestB == 0) {
> -    // Block falls through to successor.
> -    DestA = FallThru;
> -    DestB = FallThru;
> -  } else if (DestA != 0 && DestB == 0) {
> -    if (isCond)
> -      // Block ends in conditional jump that falls through to successor.
> +  
> +  if (isCond) {
> +    // If this block ends with a conditional branch that falls through to its
> +    // successor, set DestB as the successor.
> +    if (DestB == 0 && FallThru != getParent()->end()) {
>       DestB = FallThru;
> +      AddedFallThrough = true;
> +    }
>   } else {
> -    assert(DestA && DestB && isCond &&
> -           "CFG in a bad state. Cannot correct CFG edges");
> +    // If this is an unconditional branch with no explicit dest, it must just be
> +    // a fallthrough into DestA.
> +    if (DestA == 0 && FallThru != getParent()->end()) {
> +      DestA = FallThru;
> +      AddedFallThrough = true;
> +    }
>   }
> -
> -  // Remove superfluous edges. I.e., those which aren't destinations of this
> -  // basic block, duplicate edges, or landing pads.
> -  SmallPtrSet<const MachineBasicBlock*, 8> SeenMBBs;
> +  
>   MachineBasicBlock::succ_iterator SI = succ_begin();
> +  MachineBasicBlock *OrigDestA = DestA, *OrigDestB = DestB;
>   while (SI != succ_end()) {
>     const MachineBasicBlock *MBB = *SI;
> -    if (!SeenMBBs.insert(MBB) ||
> -        (MBB != DestA && MBB != DestB && !MBB->isLandingPad())) {
> -      // This is a superfluous edge, remove it.
> -      SI = removeSuccessor(SI);
> -      Changed = true;
> -    } else {
> +    if (MBB == DestA) {
> +      DestA = 0;
> +      ++SI;
> +    } else if (MBB == DestB) {
> +      DestB = 0;
> +      ++SI;
> +    } else if (MBB->isLandingPad() && 
> +               MBB != OrigDestA && MBB != OrigDestB) {
>       ++SI;
> +    } else {
> +      // Otherwise, this is a superfluous edge, remove it.
> +      SI = removeSuccessor(SI);
> +      MadeChange = true;
>     }
>   }
> 
> -  return Changed;
> +  if (!AddedFallThrough)
> +    assert(DestA == 0 && DestB == 0 && "MachineCFG is missing edges!");
> +  else if (isCond)
> +    assert(DestA == 0 && "MachineCFG is missing edges!");
> +
> +  return MadeChange;
> }
> 
> /// findDebugLoc - find the next valid DebugLoc starting at MBBI, skipping
> 
> 
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