[Localizer] Don't trick to be smart for the insertion point

There is no guarantee that the first use of a constant that is traversed
is actually the first in the related basic block. Thus, if we use that
as the insertion point we may end up with definitions that don't
dominate there use.

llvm-svn: 304244

1 files changed, 4 insertions, 6 deletions

diff --git a/llvm/lib/CodeGen/GlobalISel/Localizer.cpp b/llvm/lib/CodeGen/GlobalISel/Localizer.cpp
index c2a568e4b45..c5d0999fe43 100644
--- a/llvm/lib/CodeGen/GlobalISel/Localizer.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/Localizer.cpp
@@ -98,12 +98,10 @@ bool Localizer::runOnMachineFunction(MachineFunction &MF) {
           // Create the localized instruction.
           MachineInstr *LocalizedMI = MF.CloneMachineInstr(&MI);
           LocalizedInstrs.insert(LocalizedMI);
-          // Move it at the right place.
-          MachineInstr &MIUse = *MOUse.getParent();
-          if (MIUse.getParent() == InsertMBB)
-            InsertMBB->insert(MIUse, LocalizedMI);
-          else
-            InsertMBB->insert(InsertMBB->getFirstNonPHI(), LocalizedMI);
+          // Don't try to be smart for the insertion point.
+          // There is no guarantee that the first seen use is the first
+          // use in the block.
+          InsertMBB->insert(InsertMBB->getFirstNonPHI(), LocalizedMI);
 
           // Set a new register for the definition.
           unsigned NewReg =