Revert "As a follow-up to my initial mail to llvm-dev here's a first pass at the O1 described there."

This reverts commit 8ff85ed905a7306977d07a5cd67ab4d5a56fafb4.

This commit introduced 9 new failures on lldb buildbot host at http://lab.llvm.org:8014/builders/lldb-aarch64-ubuntu

Following tests were failing:
    lldb-api :: functionalities/tail_call_frames/ambiguous_tail_call_seq1/TestAmbiguousTailCallSeq1.py
    lldb-api :: functionalities/tail_call_frames/ambiguous_tail_call_seq2/TestAmbiguousTailCallSeq2.py
    lldb-api :: functionalities/tail_call_frames/disambiguate_call_site/TestDisambiguateCallSite.py
    lldb-api :: functionalities/tail_call_frames/disambiguate_paths_to_common_sink/TestDisambiguatePathsToCommonSink.py
    lldb-api :: functionalities/tail_call_frames/disambiguate_tail_call_seq/TestDisambiguateTailCallSeq.py
    lldb-api :: functionalities/tail_call_frames/inlining_and_tail_calls/TestInliningAndTailCalls.py
    lldb-api :: functionalities/tail_call_frames/sbapi_support/TestTailCallFrameSBAPI.py
    lldb-api :: functionalities/tail_call_frames/thread_step_out_message/TestArtificialFrameStepOutMessage.py
    lldb-api :: functionalities/tail_call_frames/thread_step_out_or_return/TestSteppingOutWithArtificialFrames.py
    lldb-api :: functionalities/tail_call_frames/unambiguous_sequence/TestUnambiguousTailCalls.py

Tags: #llvm
Differential Revision: https://reviews.llvm.org/D65410

1 files changed, 19 insertions, 29 deletions

diff --git a/llvm/lib/Passes/PassBuilder.cpp b/llvm/lib/Passes/PassBuilder.cpp
index b22921b2b87..5896dbf5bb9 100644
--- a/llvm/lib/Passes/PassBuilder.cpp
+++ b/llvm/lib/Passes/PassBuilder.cpp
@@ -400,25 +400,21 @@ PassBuilder::buildFunctionSimplificationPipeline(OptimizationLevel Level,
   FPM.addPass(EarlyCSEPass(true /* Enable mem-ssa. */));
 
   // Hoisting of scalars and load expressions.
-  if (Level > O1) {
-    if (EnableGVNHoist)
-      FPM.addPass(GVNHoistPass());
-
-    // Global value numbering based sinking.
-    if (EnableGVNSink) {
-      FPM.addPass(GVNSinkPass());
-      FPM.addPass(SimplifyCFGPass());
-    }
+  if (EnableGVNHoist)
+    FPM.addPass(GVNHoistPass());
+
+  // Global value numbering based sinking.
+  if (EnableGVNSink) {
+    FPM.addPass(GVNSinkPass());
+    FPM.addPass(SimplifyCFGPass());
   }
 
   // Speculative execution if the target has divergent branches; otherwise nop.
-  if (Level > O1) {
-    FPM.addPass(SpeculativeExecutionPass());
+  FPM.addPass(SpeculativeExecutionPass());
 
-    // Optimize based on known information about branches, and cleanup afterward.
-    FPM.addPass(JumpThreadingPass());
-    FPM.addPass(CorrelatedValuePropagationPass());
-  }
+  // Optimize based on known information about branches, and cleanup afterward.
+  FPM.addPass(JumpThreadingPass());
+  FPM.addPass(CorrelatedValuePropagationPass());
   FPM.addPass(SimplifyCFGPass());
   if (Level == O3)
     FPM.addPass(AggressiveInstCombinePass());
@@ -432,12 +428,10 @@ PassBuilder::buildFunctionSimplificationPipeline(OptimizationLevel Level,
   // For PGO use pipeline, try to optimize memory intrinsics such as memcpy
   // using the size value profile. Don't perform this when optimizing for size.
   if (PGOOpt && PGOOpt->Action == PGOOptions::IRUse &&
-      !isOptimizingForSize(Level) && Level > O1)
+      !isOptimizingForSize(Level))
     FPM.addPass(PGOMemOPSizeOpt());
 
-  // TODO: Investigate the cost/benefit of tail call elimination on debugging.
-  if (Level > O1)
-    FPM.addPass(TailCallElimPass());
+  FPM.addPass(TailCallElimPass());
   FPM.addPass(SimplifyCFGPass());
 
   // Form canonically associated expression trees, and simplify the trees using
@@ -464,7 +458,6 @@ PassBuilder::buildFunctionSimplificationPipeline(OptimizationLevel Level,
 
   // Rotate Loop - disable header duplication at -Oz
   LPM1.addPass(LoopRotatePass(Level != Oz));
-  // TODO: Investigate promotion cap for O1.
   LPM1.addPass(LICMPass(PTO.LicmMssaOptCap, PTO.LicmMssaNoAccForPromotionCap));
   LPM1.addPass(SimpleLoopUnswitchPass());
   LPM2.addPass(IndVarSimplifyPass());
@@ -532,21 +525,18 @@ PassBuilder::buildFunctionSimplificationPipeline(OptimizationLevel Level,
 
   // Re-consider control flow based optimizations after redundancy elimination,
   // redo DCE, etc.
-  if (Level > O1) {
-    FPM.addPass(JumpThreadingPass());
-    FPM.addPass(CorrelatedValuePropagationPass());
-    FPM.addPass(DSEPass());
-    FPM.addPass(createFunctionToLoopPassAdaptor(
-        LICMPass(PTO.LicmMssaOptCap, PTO.LicmMssaNoAccForPromotionCap),
-        EnableMSSALoopDependency, DebugLogging));
-  }
+  FPM.addPass(JumpThreadingPass());
+  FPM.addPass(CorrelatedValuePropagationPass());
+  FPM.addPass(DSEPass());
+  FPM.addPass(createFunctionToLoopPassAdaptor(
+      LICMPass(PTO.LicmMssaOptCap, PTO.LicmMssaNoAccForPromotionCap),
+      EnableMSSALoopDependency, DebugLogging));
 
   for (auto &C : ScalarOptimizerLateEPCallbacks)
     C(FPM, Level);
 
   // Finally, do an expensive DCE pass to catch all the dead code exposed by
   // the simplifications and basic cleanup after all the simplifications.
-  // TODO: Investigate if this is too expensive.
   FPM.addPass(ADCEPass());
   FPM.addPass(SimplifyCFGPass());
   FPM.addPass(InstCombinePass());