X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FCodeGen%2FBranchFolding.cpp;h=193bbb610f792065626009ae1a0d53593c8c3cd6;hb=5657c01949dca6c012ac60d242d1a8d2ffdf5603;hp=fe8ce522f065dbbea940e354ad1da652a8c57240;hpb=1465d61bdd36cfd6021036a527895f0dd358e97d;p=oota-llvm.git

diff --git a/lib/CodeGen/BranchFolding.cpp b/lib/CodeGen/BranchFolding.cpp
index fe8ce522f06..193bbb610f7 100644
--- a/lib/CodeGen/BranchFolding.cpp
+++ b/lib/CodeGen/BranchFolding.cpp
@@ -27,6 +27,7 @@
 #include "llvm/Target/TargetRegisterInfo.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
+#include "llvm/Support/ErrorHandling.h"
 #include "llvm/ADT/SmallSet.h"
 #include "llvm/ADT/Statistic.h"
 #include "llvm/ADT/STLExtras.h"
@@ -191,7 +192,7 @@ bool BranchFolder::runOnMachineFunction(MachineFunction &MF) {
   for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; I++) {
     MachineBasicBlock *MBB = I, *TBB = 0, *FBB = 0;
     SmallVector<MachineOperand, 4> Cond;
-    if (!TII->AnalyzeBranch(*MBB, TBB, FBB, Cond))
+    if (!TII->AnalyzeBranch(*MBB, TBB, FBB, Cond, true))
       EverMadeChange |= MBB->CorrectExtraCFGEdges(TBB, FBB, !Cond.empty());
     EverMadeChange |= OptimizeImpDefsBlock(MBB);
   }
@@ -434,7 +435,7 @@ static void FixTail(MachineBasicBlock* CurMBB, MachineBasicBlock *SuccBB,
   MachineBasicBlock *TBB = 0, *FBB = 0;
   SmallVector<MachineOperand, 4> Cond;
   if (I != MF->end() &&
-      !TII->AnalyzeBranch(*CurMBB, TBB, FBB, Cond)) {
+      !TII->AnalyzeBranch(*CurMBB, TBB, FBB, Cond, true)) {
     MachineBasicBlock *NextBB = I;
     if (TBB == NextBB && !Cond.empty() && !FBB) {
       if (!TII->ReverseBranchCondition(Cond)) {
@@ -461,7 +462,7 @@ static bool MergeCompare(const std::pair<unsigned,MachineBasicBlock*> &p,
       // _GLIBCXX_DEBUG checks strict weak ordering, which involves comparing
       // an object with itself.
 #ifndef _GLIBCXX_DEBUG
-      assert(0 && "Predecessor appears twice");
+      llvm_unreachable("Predecessor appears twice");
 #endif
       return false;
     }
@@ -711,7 +712,7 @@ bool BranchFolder::TailMergeBlocks(MachineFunction &MF) {
           continue;
         MachineBasicBlock *TBB = 0, *FBB = 0;
         SmallVector<MachineOperand, 4> Cond;
-        if (!TII->AnalyzeBranch(*PBB, TBB, FBB, Cond)) {
+        if (!TII->AnalyzeBranch(*PBB, TBB, FBB, Cond, true)) {
           // Failing case:  IBB is the target of a cbr, and
           // we cannot reverse the branch.
           SmallVector<MachineOperand, 4> NewCond(Cond);
@@ -845,7 +846,7 @@ bool BranchFolder::CanFallThrough(MachineBasicBlock *CurBB,
 bool BranchFolder::CanFallThrough(MachineBasicBlock *CurBB) {
   MachineBasicBlock *TBB = 0, *FBB = 0;
   SmallVector<MachineOperand, 4> Cond;
-  bool CurUnAnalyzable = TII->AnalyzeBranch(*CurBB, TBB, FBB, Cond);
+  bool CurUnAnalyzable = TII->AnalyzeBranch(*CurBB, TBB, FBB, Cond, true);
   return CanFallThrough(CurBB, CurUnAnalyzable, TBB, FBB, Cond);
 }
 
@@ -910,7 +911,7 @@ void BranchFolder::OptimizeBlock(MachineBasicBlock *MBB) {
   MachineBasicBlock *PriorTBB = 0, *PriorFBB = 0;
   SmallVector<MachineOperand, 4> PriorCond;
   bool PriorUnAnalyzable =
-    TII->AnalyzeBranch(PrevBB, PriorTBB, PriorFBB, PriorCond);
+    TII->AnalyzeBranch(PrevBB, PriorTBB, PriorFBB, PriorCond, true);
   if (!PriorUnAnalyzable) {
     // If the CFG for the prior block has extra edges, remove them.
     MadeChange |= PrevBB.CorrectExtraCFGEdges(PriorTBB, PriorFBB,
@@ -1023,7 +1024,7 @@ void BranchFolder::OptimizeBlock(MachineBasicBlock *MBB) {
   // Analyze the branch in the current block.
   MachineBasicBlock *CurTBB = 0, *CurFBB = 0;
   SmallVector<MachineOperand, 4> CurCond;
-  bool CurUnAnalyzable = TII->AnalyzeBranch(*MBB, CurTBB, CurFBB, CurCond);
+  bool CurUnAnalyzable= TII->AnalyzeBranch(*MBB, CurTBB, CurFBB, CurCond, true);
   if (!CurUnAnalyzable) {
     // If the CFG for the prior block has extra edges, remove them.
     MadeChange |= MBB->CorrectExtraCFGEdges(CurTBB, CurFBB, !CurCond.empty());
@@ -1092,6 +1093,21 @@ void BranchFolder::OptimizeBlock(MachineBasicBlock *MBB) {
             } else {
               DidChange = true;
               PMBB->ReplaceUsesOfBlockWith(MBB, CurTBB);
+              // If this change resulted in PMBB ending in a conditional
+              // branch where both conditions go to the same destination,
+              // change this to an unconditional branch (and fix the CFG).
+              MachineBasicBlock *NewCurTBB = 0, *NewCurFBB = 0;
+              SmallVector<MachineOperand, 4> NewCurCond;
+              bool NewCurUnAnalyzable = TII->AnalyzeBranch(*PMBB, NewCurTBB,
+                      NewCurFBB, NewCurCond, true);
+              if (!NewCurUnAnalyzable && NewCurTBB && NewCurTBB == NewCurFBB) {
+                TII->RemoveBranch(*PMBB);
+                NewCurCond.clear(); 
+                TII->InsertBranch(*PMBB, NewCurTBB, 0, NewCurCond);
+                MadeChange = true;
+                ++NumBranchOpts;
+                PMBB->CorrectExtraCFGEdges(NewCurTBB, NewCurFBB, false);
+              }
             }
           }