dce between dxil-remove-dead-blocks and hlsl-dxil-lower-handle-for-lib (#2940)

lib/Transforms/IPO/PassManagerBuilder.cpp

@@ -360,6 +360,8 @@ void PassManagerBuilder::populateModulePassManager(
       MPM.add(createDxilConvergentClearPass());
       MPM.add(createMultiDimArrayToOneDimArrayPass());
       MPM.add(createDxilRemoveDeadBlocksPass());
+      MPM.add(createDeadCodeEliminationPass());
+      MPM.add(createGlobalDCEPass());
       MPM.add(createDxilLowerCreateHandleForLibPass());
       MPM.add(createDxilTranslateRawBuffer());
       MPM.add(createDxilLegalizeSampleOffsetPass());
@@ -654,9 +656,10 @@ void PassManagerBuilder::populateModulePassManager(
                                               // DxilModule.
     MPM.add(createMultiDimArrayToOneDimArrayPass());
     MPM.add(createDxilRemoveDeadBlocksPass());
+    MPM.add(createDeadCodeEliminationPass());
+    MPM.add(createGlobalDCEPass());
     MPM.add(createDxilLowerCreateHandleForLibPass());
     MPM.add(createDxilTranslateRawBuffer());
-    MPM.add(createDeadCodeEliminationPass());
     // Always try to legalize sample offsets as loop unrolling
     // is not guaranteed for higher opt levels.
     MPM.add(createDxilLegalizeSampleOffsetPass());