vendor/llvm/llvm-r142614

1 files changed, 21 insertions, 0 deletions

diff --git a/lib/Target/ARM/Thumb2ITBlockPass.cpp b/lib/Target/ARM/Thumb2ITBlockPass.cpp
index 360ec009e201..b6274007b237 100644
--- a/lib/Target/ARM/Thumb2ITBlockPass.cpp
+++ b/lib/Target/ARM/Thumb2ITBlockPass.cpp
@@ -124,6 +124,27 @@ Thumb2ITBlockPass::MoveCopyOutOfITBlock(MachineInstr *MI,
   if (Uses.count(DstReg) || Defs.count(SrcReg))
     return false;
 
+  // If the CPSR is defined by this copy, then we don't want to move it. E.g.,
+  // if we have:
+  //
+  //   movs  r1, r1
+  //   rsb   r1, 0
+  //   movs  r2, r2
+  //   rsb   r2, 0
+  //
+  // we don't want this to be converted to:
+  //
+  //   movs  r1, r1
+  //   movs  r2, r2
+  //   itt   mi
+  //   rsb   r1, 0
+  //   rsb   r2, 0
+  //
+  const MCInstrDesc &MCID = MI->getDesc();
+  if (MCID.hasOptionalDef() &&
+      MI->getOperand(MCID.getNumOperands() - 1).getReg() == ARM::CPSR)
+    return false;
+
   // Then peek at the next instruction to see if it's predicated on CC or OCC.
   // If not, then there is nothing to be gained by moving the copy.
   MachineBasicBlock::iterator I = MI; ++I;