[X86] Don't alter HasOpaqueSPAdjustment after we've relied on it

We rely on HasOpaqueSPAdjustment not changing after we've calculated
things based on it.  Things like whether or not we can use 'rep;movs' to
copy bytes around, that sort of thing.  If it changes, invariants in the
backend will quietly break.  This situation arose when we had a call to
memcpy *and* a COPY of the FLAGS register where we would attempt to
reference local variables using %esi, a register that was clobbered by
the 'rep;movs'.

This fixes PR26124.

llvm-svn: 257730

1 files changed, 1 insertions, 1 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index 9f8759df0ba..c075da4738a 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -634,7 +634,7 @@ bool SelectionDAGISel::runOnMachineFunction(MachineFunction &mf) {
   }
 
   if (TLI->hasCopyImplyingStackAdjustment(MF))
-    MFI->setHasOpaqueSPAdjustment(true);
+    MFI->setHasCopyImplyingStackAdjustment(true);
 
   // Freeze the set of reserved registers now that MachineFrameInfo has been
   // set up. All the information required by getReservedRegs() should be