R600: Remove successive JUMP in AnalyzeBranch when AllowModify is true

This fixes a crash in the OpenCV OpenCL test suite.

There is no lit test for this, because the test would be very large
and could easily be invalidated by changes to the scheduler
or other parts of the compiler.

Patch by:  Vincent Lejeune

llvm-svn: 199919

llvm/lib/Target/R600/R600InstrInfo.cpp

@@ -716,7 +716,13 @@ R600InstrInfo::AnalyzeBranch(MachineBasicBlock &MBB,
     return false;
   }
 
-  // Get the last instruction in the block.
+  // Remove successive JUMP
+  while (I != MBB.begin() && llvm::prior(I)->getOpcode() == AMDGPU::JUMP) {
+      MachineBasicBlock::iterator PriorI = llvm::prior(I);
+      if (AllowModify)
+        I->removeFromParent();
+      I = PriorI;
+  }
   MachineInstr *LastInst = I;
 
   // If there is only one terminator instruction, process it.