[Passes] Move ADCE before DSE & LICM.

The adjustment seems to have very little impact on optimizations.
The only binary change with -O3 MultiSource/SPEC2000/SPEC2006 on X86 is
in consumer-typeset and the size there actually decreases by -0.1%, with
not significant changes in the stats.

On its own, it is mildly positive in terms of compile-time, most likely
due to LICM & DSE having to process slightly less instructions. It
should also be unlikely that DSE/LICM make much new code dead.

http://llvm-compile-time-tracker.com/compare.php?from=df63eedef64d715ce1f31843f7de9c11fe1e597f&to=e3bdfcf94a9eeae6e006d010464f0c1b3550577d&stat=instructions

With DSE & MemorySSA, it gives some nice compile-time improvements, due
to the fact that DSE can re-use the PDT from ADCE, if it does not make
any changes:

http://llvm-compile-time-tracker.com/compare.php?from=15fdd6cd7c24c745df1bb419e72ff66fd138aa7e&to=481f494515fc89cb7caea8d862e40f2c910dc994&stat=instructions

Reviewed By: xbolva00

Differential Revision: https://reviews.llvm.org/D87322

diff --git a/llvm/lib/Passes/PassBuilder.cpp b/llvm/lib/Passes/PassBuilder.cpp
index 6db7f3c..923c1bc 100644 (file)
--- a/llvm/lib/Passes/PassBuilder.cpp
+++ b/llvm/lib/Passes/PassBuilder.cpp
@@ -750,6 +750,12 @@ PassBuilder::buildFunctionSimplificationPipeline(OptimizationLevel Level,
   // redo DCE, etc.
   FPM.addPass(JumpThreadingPass());
   FPM.addPass(CorrelatedValuePropagationPass());
+
+  // 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(DSEPass());
   FPM.addPass(createFunctionToLoopPassAdaptor(
       LICMPass(PTO.LicmMssaOptCap, PTO.LicmMssaNoAccForPromotionCap),
@@ -761,10 +767,6 @@ PassBuilder::buildFunctionSimplificationPipeline(OptimizationLevel Level,
   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());
   invokePeepholeEPCallbacks(FPM, Level);

diff --git a/llvm/lib/Transforms/IPO/PassManagerBuilder.cpp b/llvm/lib/Transforms/IPO/PassManagerBuilder.cpp
index 088f1e2..93c548a 100644 (file)
--- a/llvm/lib/Transforms/IPO/PassManagerBuilder.cpp
+++ b/llvm/lib/Transforms/IPO/PassManagerBuilder.cpp
@@ -482,6 +482,11 @@ void PassManagerBuilder::addFunctionSimplificationPasses(
   if (OptLevel > 1) {
     MPM.add(createJumpThreadingPass());         // Thread jumps
     MPM.add(createCorrelatedValuePropagationPass());
+  }
+  MPM.add(createAggressiveDCEPass()); // Delete dead instructions
+
+  // TODO: Investigate if this is too expensive at O1.
+  if (OptLevel > 1) {
     MPM.add(createDeadStoreEliminationPass());  // Delete dead stores
     MPM.add(createLICMPass(LicmMssaOptCap, LicmMssaNoAccForPromotionCap));
   }
@@ -491,8 +496,6 @@ void PassManagerBuilder::addFunctionSimplificationPasses(
   if (RerollLoops)
     MPM.add(createLoopRerollPass());
 
-  // TODO: Investigate if this is too expensive at O1.
-  MPM.add(createAggressiveDCEPass());         // Delete dead instructions
   MPM.add(createCFGSimplificationPass()); // Merge & remove BBs
   // Clean up after everything.
   MPM.add(createInstructionCombiningPass());

diff --git a/llvm/test/CodeGen/AMDGPU/opt-pipeline.ll b/llvm/test/CodeGen/AMDGPU/opt-pipeline.ll
index 2c157cb..e994286 100644 (file)
--- a/llvm/test/CodeGen/AMDGPU/opt-pipeline.ll
+++ b/llvm/test/CodeGen/AMDGPU/opt-pipeline.ll
@@ -513,9 +513,10 @@
 ; GCN-O2-NEXT:       Lazy Value Information Analysis
 ; GCN-O2-NEXT:       Jump Threading
 ; GCN-O2-NEXT:       Value Propagation
+; GCN-O2-NEXT:       Post-Dominator Tree Construction
+; GCN-O2-NEXT:       Aggressive Dead Code Elimination
 ; GCN-O2-NEXT:       Basic Alias Analysis (stateless AA impl)
 ; GCN-O2-NEXT:       Function Alias Analysis Results
-; GCN-O2-NEXT:       Post-Dominator Tree Construction
 ; GCN-O2-NEXT:       Memory SSA
 ; GCN-O2-NEXT:       Dead Store Elimination
 ; GCN-O2-NEXT:       Natural Loop Information
@@ -528,8 +529,6 @@
 ; GCN-O2-NEXT:       Lazy Block Frequency Analysis
 ; GCN-O2-NEXT:       Loop Pass Manager
 ; GCN-O2-NEXT:         Loop Invariant Code Motion
-; GCN-O2-NEXT:       Post-Dominator Tree Construction
-; GCN-O2-NEXT:       Aggressive Dead Code Elimination
 ; GCN-O2-NEXT:       Simplify the CFG
 ; GCN-O2-NEXT:       Dominator Tree Construction
 ; GCN-O2-NEXT:       Basic Alias Analysis (stateless AA impl)
@@ -876,9 +875,10 @@
 ; GCN-O3-NEXT:       Lazy Value Information Analysis
 ; GCN-O3-NEXT:       Jump Threading
 ; GCN-O3-NEXT:       Value Propagation
+; GCN-O3-NEXT:       Post-Dominator Tree Construction
+; GCN-O3-NEXT:       Aggressive Dead Code Elimination
 ; GCN-O3-NEXT:       Basic Alias Analysis (stateless AA impl)
 ; GCN-O3-NEXT:       Function Alias Analysis Results
-; GCN-O3-NEXT:       Post-Dominator Tree Construction
 ; GCN-O3-NEXT:       Memory SSA
 ; GCN-O3-NEXT:       Dead Store Elimination
 ; GCN-O3-NEXT:       Natural Loop Information
@@ -891,8 +891,6 @@
 ; GCN-O3-NEXT:       Lazy Block Frequency Analysis
 ; GCN-O3-NEXT:       Loop Pass Manager
 ; GCN-O3-NEXT:         Loop Invariant Code Motion
-; GCN-O3-NEXT:       Post-Dominator Tree Construction
-; GCN-O3-NEXT:       Aggressive Dead Code Elimination
 ; GCN-O3-NEXT:       Simplify the CFG
 ; GCN-O3-NEXT:       Dominator Tree Construction
 ; GCN-O3-NEXT:       Basic Alias Analysis (stateless AA impl)

diff --git a/llvm/test/Other/new-pm-defaults.ll b/llvm/test/Other/new-pm-defaults.ll
index 2576f93..af15375 100644 (file)
--- a/llvm/test/Other/new-pm-defaults.ll
+++ b/llvm/test/Other/new-pm-defaults.ll
@@ -202,16 +202,15 @@
 ; CHECK-O23SZ-NEXT: Running analysis: LazyValueAnalysis
 ; CHECK-O23SZ-NEXT: Running pass: CorrelatedValuePropagationPass
 ; CHECK-O23SZ-NEXT: Invalidating analysis: LazyValueAnalysis
+; CHECK-O-NEXT: Running pass: ADCEPass
+; CHECK-O-NEXT: Running analysis: PostDominatorTreeAnalysis
 ; CHECK-O23SZ-NEXT: Running pass: DSEPass
-; CHECK-O23SZ-NEXT: Running analysis: PostDominatorTreeAnalysis
 ; CHECK-O23SZ-NEXT: Starting llvm::Function pass manager run.
 ; CHECK-O23SZ-NEXT: Running pass: LoopSimplifyPass
 ; CHECK-O23SZ-NEXT: Running pass: LCSSAPass
 ; CHECK-O23SZ-NEXT: Finished llvm::Function pass manager run.
 ; CHECK-O23SZ-NEXT: Running pass: LICMPass
 ; CHECK-EP-SCALAR-LATE-NEXT: Running pass: NoOpFunctionPass
-; CHECK-O-NEXT: Running pass: ADCEPass
-; CHECK-O1-NEXT: Running analysis: PostDominatorTreeAnalysis
 ; CHECK-O-NEXT: Running pass: SimplifyCFGPass
 ; CHECK-O-NEXT: Running pass: InstCombinePass
 ; CHECK-EP-PEEPHOLE-NEXT: Running pass: NoOpFunctionPass

diff --git a/llvm/test/Other/new-pm-thinlto-defaults.ll b/llvm/test/Other/new-pm-thinlto-defaults.ll
index bc1e657..ad16091 100644 (file)
--- a/llvm/test/Other/new-pm-thinlto-defaults.ll
+++ b/llvm/test/Other/new-pm-thinlto-defaults.ll
@@ -175,15 +175,14 @@
 ; CHECK-O23SZ-NEXT: Running analysis: LazyValueAnalysis
 ; CHECK-O23SZ-NEXT: Running pass: CorrelatedValuePropagationPass
 ; CHECK-O23SZ-NEXT: Invalidating analysis: LazyValueAnalysis
+; CHECK-O-NEXT: Running pass: ADCEPass
+; CHECK-O-NEXT: Running analysis: PostDominatorTreeAnalysis
 ; CHECK-O23SZ-NEXT: Running pass: DSEPass
-; CHECK-O23SZ-NEXT: Running analysis: PostDominatorTreeAnalysis on foo
 ; CHECK-O23SZ-NEXT: Starting llvm::Function pass manager run
 ; CHECK-O23SZ-NEXT: Running pass: LoopSimplifyPass
 ; CHECK-O23SZ-NEXT: Running pass: LCSSAPass
 ; CHECK-O23SZ-NEXT: Finished llvm::Function pass manager run
 ; CHECK-O23SZ-NEXT: Running pass: LICMPass on Loop at depth 1 containing: %loop
-; CHECK-O-NEXT: Running pass: ADCEPass
-; CHECK-O1-NEXT: Running analysis: PostDominatorTreeAnalysis
 ; CHECK-O-NEXT: Running pass: SimplifyCFGPass
 ; CHECK-O-NEXT: Running pass: InstCombinePass
 ; CHECK-O-NEXT: Finished llvm::Function pass manager run.

diff --git a/llvm/test/Other/new-pm-thinlto-postlink-pgo-defaults.ll b/llvm/test/Other/new-pm-thinlto-postlink-pgo-defaults.ll
index 0e287cc..84a51d8 100644 (file)
--- a/llvm/test/Other/new-pm-thinlto-postlink-pgo-defaults.ll
+++ b/llvm/test/Other/new-pm-thinlto-postlink-pgo-defaults.ll
@@ -148,13 +148,13 @@
 ; CHECK-O23SZ-NEXT: Running analysis: LazyValueAnalysis
 ; CHECK-O23SZ-NEXT: Running pass: CorrelatedValuePropagationPass
 ; CHECK-O23SZ-NEXT: Invalidating analysis: LazyValueAnalysis
+; CHECK-O-NEXT: Running pass: ADCEPass
 ; CHECK-O23SZ-NEXT: Running pass: DSEPass
 ; CHECK-O23SZ-NEXT: Starting {{.*}}Function pass manager run
 ; CHECK-O23SZ-NEXT: Running pass: LoopSimplifyPass
 ; CHECK-O23SZ-NEXT: Running pass: LCSSAPass
 ; CHECK-O23SZ-NEXT: Finished {{.*}}Function pass manager run
 ; CHECK-O23SZ-NEXT: Running pass: LICMPass
-; CHECK-O-NEXT: Running pass: ADCEPass
 ; CHECK-O-NEXT: Running pass: SimplifyCFGPass
 ; CHECK-O-NEXT: Running pass: InstCombinePass
 ; CHECK-O-NEXT: Finished {{.*}}Function pass manager run.

diff --git a/llvm/test/Other/new-pm-thinlto-postlink-samplepgo-defaults.ll b/llvm/test/Other/new-pm-thinlto-postlink-samplepgo-defaults.ll
index da63b95..4616fc3 100644 (file)
--- a/llvm/test/Other/new-pm-thinlto-postlink-samplepgo-defaults.ll
+++ b/llvm/test/Other/new-pm-thinlto-postlink-samplepgo-defaults.ll
@@ -156,13 +156,13 @@
 ; CHECK-O23SZ-NEXT: Running analysis: LazyValueAnalysis
 ; CHECK-O23SZ-NEXT: Running pass: CorrelatedValuePropagationPass
 ; CHECK-O23SZ-NEXT: Invalidating analysis: LazyValueAnalysis
+; CHECK-O-NEXT: Running pass: ADCEPass
 ; CHECK-O23SZ-NEXT: Running pass: DSEPass
 ; CHECK-O23SZ-NEXT: Starting {{.*}}Function pass manager run
 ; CHECK-O23SZ-NEXT: Running pass: LoopSimplifyPass
 ; CHECK-O23SZ-NEXT: Running pass: LCSSAPass
 ; CHECK-O23SZ-NEXT: Finished {{.*}}Function pass manager run
 ; CHECK-O23SZ-NEXT: Running pass: LICMPass
-; CHECK-O-NEXT: Running pass: ADCEPass
 ; CHECK-O-NEXT: Running pass: SimplifyCFGPass
 ; CHECK-O-NEXT: Running pass: InstCombinePass
 ; CHECK-O3-NEXT: Running pass: ControlHeightReductionPass on foo

diff --git a/llvm/test/Other/new-pm-thinlto-prelink-pgo-defaults.ll b/llvm/test/Other/new-pm-thinlto-prelink-pgo-defaults.ll
index 11bd207..ffcc6ec 100644 (file)
--- a/llvm/test/Other/new-pm-thinlto-prelink-pgo-defaults.ll
+++ b/llvm/test/Other/new-pm-thinlto-prelink-pgo-defaults.ll
@@ -198,13 +198,13 @@
 ; CHECK-O23SZ-NEXT: Running analysis: LazyValueAnalysis
 ; CHECK-O23SZ-NEXT: Running pass: CorrelatedValuePropagationPass
 ; CHECK-O23SZ-NEXT: Invalidating analysis: LazyValueAnalysis
+; CHECK-O-NEXT: Running pass: ADCEPass
 ; CHECK-O23SZ-NEXT: Running pass: DSEPass
 ; CHECK-O23SZ-NEXT: Starting {{.*}}Function pass manager run
 ; CHECK-O23SZ-NEXT: Running pass: LoopSimplifyPass
 ; CHECK-O23SZ-NEXT: Running pass: LCSSAPass
 ; CHECK-O23SZ-NEXT: Finished {{.*}}Function pass manager run
 ; CHECK-O23SZ-NEXT: Running pass: LICMPass
-; CHECK-O-NEXT: Running pass: ADCEPass
 ; CHECK-O-NEXT: Running pass: SimplifyCFGPass
 ; CHECK-O-NEXT: Running pass: InstCombinePass
 ; CHECK-O3-NEXT: Running pass: ControlHeightReductionPass on foo

diff --git a/llvm/test/Other/new-pm-thinlto-prelink-samplepgo-defaults.ll b/llvm/test/Other/new-pm-thinlto-prelink-samplepgo-defaults.ll
index 19a1fd5..1bb1bc0 100644 (file)
--- a/llvm/test/Other/new-pm-thinlto-prelink-samplepgo-defaults.ll
+++ b/llvm/test/Other/new-pm-thinlto-prelink-samplepgo-defaults.ll
@@ -154,13 +154,13 @@
 ; CHECK-O23SZ-NEXT: Running analysis: LazyValueAnalysis
 ; CHECK-O23SZ-NEXT: Running pass: CorrelatedValuePropagationPass
 ; CHECK-O23SZ-NEXT: Invalidating analysis: LazyValueAnalysis
+; CHECK-O-NEXT: Running pass: ADCEPass
 ; CHECK-O23SZ-NEXT: Running pass: DSEPass
 ; CHECK-O23SZ-NEXT: Starting {{.*}}Function pass manager run
 ; CHECK-O23SZ-NEXT: Running pass: LoopSimplifyPass
 ; CHECK-O23SZ-NEXT: Running pass: LCSSAPass
 ; CHECK-O23SZ-NEXT: Finished {{.*}}Function pass manager run
 ; CHECK-O23SZ-NEXT: Running pass: LICMPass
-; CHECK-O-NEXT: Running pass: ADCEPass
 ; CHECK-O-NEXT: Running pass: SimplifyCFGPass
 ; CHECK-O-NEXT: Running pass: InstCombinePass
 ; CHECK-O3-NEXT: Running pass: ControlHeightReductionPass on foo

diff --git a/llvm/test/Other/opt-O2-pipeline.ll b/llvm/test/Other/opt-O2-pipeline.ll
index 4d94420..e5f4371 100644 (file)
--- a/llvm/test/Other/opt-O2-pipeline.ll
+++ b/llvm/test/Other/opt-O2-pipeline.ll
@@ -160,9 +160,10 @@
 ; CHECK-NEXT:         Lazy Value Information Analysis
 ; CHECK-NEXT:         Jump Threading
 ; CHECK-NEXT:         Value Propagation
+; CHECK-NEXT:         Post-Dominator Tree Construction
+; CHECK-NEXT:         Aggressive Dead Code Elimination
 ; CHECK-NEXT:         Basic Alias Analysis (stateless AA impl)
 ; CHECK-NEXT:         Function Alias Analysis Results
-; CHECK-NEXT:         Post-Dominator Tree Construction
 ; CHECK-NEXT:         Memory SSA
 ; CHECK-NEXT:         Dead Store Elimination
 ; CHECK-NEXT:         Natural Loop Information
@@ -175,8 +176,6 @@
 ; CHECK-NEXT:         Lazy Block Frequency Analysis
 ; CHECK-NEXT:         Loop Pass Manager
 ; CHECK-NEXT:           Loop Invariant Code Motion
-; CHECK-NEXT:         Post-Dominator Tree Construction
-; CHECK-NEXT:         Aggressive Dead Code Elimination
 ; CHECK-NEXT:         Simplify the CFG
 ; CHECK-NEXT:         Dominator Tree Construction
 ; CHECK-NEXT:         Basic Alias Analysis (stateless AA impl)

diff --git a/llvm/test/Other/opt-O3-pipeline-enable-matrix.ll b/llvm/test/Other/opt-O3-pipeline-enable-matrix.ll
index 5c3f2a5..1f3d763 100644 (file)
--- a/llvm/test/Other/opt-O3-pipeline-enable-matrix.ll
+++ b/llvm/test/Other/opt-O3-pipeline-enable-matrix.ll
@@ -165,9 +165,10 @@
 ; CHECK-NEXT:         Lazy Value Information Analysis
 ; CHECK-NEXT:         Jump Threading
 ; CHECK-NEXT:         Value Propagation
+; CHECK-NEXT:         Post-Dominator Tree Construction
+; CHECK-NEXT:         Aggressive Dead Code Elimination
 ; CHECK-NEXT:         Basic Alias Analysis (stateless AA impl)
 ; CHECK-NEXT:         Function Alias Analysis Results
-; CHECK-NEXT:         Post-Dominator Tree Construction
 ; CHECK-NEXT:         Memory SSA
 ; CHECK-NEXT:         Dead Store Elimination
 ; CHECK-NEXT:         Natural Loop Information
@@ -180,8 +181,6 @@
 ; CHECK-NEXT:         Lazy Block Frequency Analysis
 ; CHECK-NEXT:         Loop Pass Manager
 ; CHECK-NEXT:           Loop Invariant Code Motion
-; CHECK-NEXT:         Post-Dominator Tree Construction
-; CHECK-NEXT:         Aggressive Dead Code Elimination
 ; CHECK-NEXT:         Simplify the CFG
 ; CHECK-NEXT:         Dominator Tree Construction
 ; CHECK-NEXT:         Basic Alias Analysis (stateless AA impl)

diff --git a/llvm/test/Other/opt-O3-pipeline.ll b/llvm/test/Other/opt-O3-pipeline.ll
index d910ad5..99f4019 100644 (file)
--- a/llvm/test/Other/opt-O3-pipeline.ll
+++ b/llvm/test/Other/opt-O3-pipeline.ll
@@ -165,9 +165,10 @@
 ; CHECK-NEXT:         Lazy Value Information Analysis
 ; CHECK-NEXT:         Jump Threading
 ; CHECK-NEXT:         Value Propagation
+; CHECK-NEXT:         Post-Dominator Tree Construction
+; CHECK-NEXT:         Aggressive Dead Code Elimination
 ; CHECK-NEXT:         Basic Alias Analysis (stateless AA impl)
 ; CHECK-NEXT:         Function Alias Analysis Results
-; CHECK-NEXT:         Post-Dominator Tree Construction
 ; CHECK-NEXT:         Memory SSA
 ; CHECK-NEXT:         Dead Store Elimination
 ; CHECK-NEXT:         Natural Loop Information
@@ -180,8 +181,6 @@
 ; CHECK-NEXT:         Lazy Block Frequency Analysis
 ; CHECK-NEXT:         Loop Pass Manager
 ; CHECK-NEXT:           Loop Invariant Code Motion
-; CHECK-NEXT:         Post-Dominator Tree Construction
-; CHECK-NEXT:         Aggressive Dead Code Elimination
 ; CHECK-NEXT:         Simplify the CFG
 ; CHECK-NEXT:         Dominator Tree Construction
 ; CHECK-NEXT:         Basic Alias Analysis (stateless AA impl)

diff --git a/llvm/test/Other/opt-Os-pipeline.ll b/llvm/test/Other/opt-Os-pipeline.ll
index d89f907..a38062a 100644 (file)
--- a/llvm/test/Other/opt-Os-pipeline.ll
+++ b/llvm/test/Other/opt-Os-pipeline.ll
@@ -146,9 +146,10 @@
 ; CHECK-NEXT:         Lazy Value Information Analysis
 ; CHECK-NEXT:         Jump Threading
 ; CHECK-NEXT:         Value Propagation
+; CHECK-NEXT:         Post-Dominator Tree Construction
+; CHECK-NEXT:         Aggressive Dead Code Elimination
 ; CHECK-NEXT:         Basic Alias Analysis (stateless AA impl)
 ; CHECK-NEXT:         Function Alias Analysis Results
-; CHECK-NEXT:         Post-Dominator Tree Construction
 ; CHECK-NEXT:         Memory SSA
 ; CHECK-NEXT:         Dead Store Elimination
 ; CHECK-NEXT:         Natural Loop Information
@@ -161,8 +162,6 @@
 ; CHECK-NEXT:         Lazy Block Frequency Analysis
 ; CHECK-NEXT:         Loop Pass Manager
 ; CHECK-NEXT:           Loop Invariant Code Motion
-; CHECK-NEXT:         Post-Dominator Tree Construction
-; CHECK-NEXT:         Aggressive Dead Code Elimination
 ; CHECK-NEXT:         Simplify the CFG
 ; CHECK-NEXT:         Dominator Tree Construction
 ; CHECK-NEXT:         Basic Alias Analysis (stateless AA impl)