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[Passes] Move ADCE before DSE & LICM.

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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
This commit is contained in:
Florian Hahn
2020-10-21 10:21:50 +01:00
parent 782b8f0d38
commit 88241ffb56
13 changed files with 31 additions and 34 deletions
Download Patch File Download Diff File Expand all files Collapse all files

10
llvm/lib/Passes/PassBuilder.cpp
View File

@@ -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);

7
llvm/lib/Transforms/IPO/PassManagerBuilder.cpp
View File

@@ -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());

10
llvm/test/CodeGen/AMDGPU/opt-pipeline.ll
View File

@@ -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)

5
llvm/test/Other/new-pm-defaults.ll
View File

@@ -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

5
llvm/test/Other/new-pm-thinlto-defaults.ll
View File

@@ -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.

2
llvm/test/Other/new-pm-thinlto-postlink-pgo-defaults.ll
View File

@@ -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.

2
llvm/test/Other/new-pm-thinlto-postlink-samplepgo-defaults.ll
View File

@@ -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

2
llvm/test/Other/new-pm-thinlto-prelink-pgo-defaults.ll
View File

@@ -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

2
llvm/test/Other/new-pm-thinlto-prelink-samplepgo-defaults.ll
View File

@@ -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

5
llvm/test/Other/opt-O2-pipeline.ll
View File

@@ -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)

5
llvm/test/Other/opt-O3-pipeline-enable-matrix.ll
View File

@@ -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)

5
llvm/test/Other/opt-O3-pipeline.ll
View File

@@ -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)

5
llvm/test/Other/opt-Os-pipeline.ll
View File

@@ -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)