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[PassManager][PhaseOrdering] lower expects before running simplifyCFG 

If we run passes before lowering llvm.expect intrinsics to metadata,
then those passes have no way to act on the hints provided by llvm.expect.
SimplifyCFG is the known offender, and we made it smarter about profile
metadata in D98898.

In the motivating example from https://llvm.org/PR49336 , this means we
were ignoring the recommended method for a programmer to tell the compiler
that a compare+branch is expensive. This change appears to solve that case -
the metadata survives to the backend, the compare order is as expected in IR,
and the backend does not do anything to reverse it.

We make the same change to the old pass manager to keep things synchronized.

Differential Revision: https://reviews.llvm.org/D100213
This commit is contained in:
Sanjay Patel 2021-04-12 12:20:32 -04:00
parent dd31b2c6e5
commit 330619a3a6
15 changed files with 25 additions and 21 deletions
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4
llvm/lib/Passes/PassBuilder.cpp
View File

@ -1066,10 +1066,12 @@ PassBuilder::buildModuleSimplificationPipeline(OptimizationLevel Level,
// Create an early function pass manager to cleanup the output of the
// frontend.
FunctionPassManager EarlyFPM(DebugLogging);
// Lower llvm.expect to metadata before attempting transforms.
// Compare/branch metadata may alter the behavior of passes like SimplifyCFG.
EarlyFPM.addPass(LowerExpectIntrinsicPass());
EarlyFPM.addPass(SimplifyCFGPass());
EarlyFPM.addPass(SROA());
EarlyFPM.addPass(EarlyCSEPass());
EarlyFPM.addPass(LowerExpectIntrinsicPass());
if (PTO.Coroutines)
EarlyFPM.addPass(CoroEarlyPass());
if (Level == OptimizationLevel::O3)

4
llvm/lib/Transforms/IPO/PassManagerBuilder.cpp
View File

@ -316,10 +316,12 @@ void PassManagerBuilder::populateFunctionPassManager(
addInitialAliasAnalysisPasses(FPM);
// Lower llvm.expect to metadata before attempting transforms.
// Compare/branch metadata may alter the behavior of passes like SimplifyCFG.
FPM.add(createLowerExpectIntrinsicPass());
FPM.add(createCFGSimplificationPass());
FPM.add(createSROAPass());
FPM.add(createEarlyCSEPass());
FPM.add(createLowerExpectIntrinsicPass());
}
// Do PGO instrumentation generation or use pass as the option specified.

6
llvm/test/CodeGen/AMDGPU/opt-pipeline.ll
View File

@ -41,11 +41,11 @@
; GCN-O1-NEXT: Basic Alias Analysis (stateless AA impl)
; GCN-O1-NEXT: Function Alias Analysis Results
; GCN-O1-NEXT: Simplify well-known AMD library calls
; GCN-O1-NEXT: Lower 'expect' Intrinsics
; GCN-O1-NEXT: Simplify the CFG
; GCN-O1-NEXT: Dominator Tree Construction
; GCN-O1-NEXT: SROA
; GCN-O1-NEXT: Early CSE
; GCN-O1-NEXT: Lower 'expect' Intrinsics
; GCN-O1-NEXT: Pass Arguments:
; GCN-O1-NEXT: Target Library Information
@ -350,11 +350,11 @@
; GCN-O2-NEXT: Basic Alias Analysis (stateless AA impl)
; GCN-O2-NEXT: Function Alias Analysis Results
; GCN-O2-NEXT: Simplify well-known AMD library calls
; GCN-O2-NEXT: Lower 'expect' Intrinsics
; GCN-O2-NEXT: Simplify the CFG
; GCN-O2-NEXT: Dominator Tree Construction
; GCN-O2-NEXT: SROA
; GCN-O2-NEXT: Early CSE
; GCN-O2-NEXT: Lower 'expect' Intrinsics
; GCN-O2-NEXT: Pass Arguments:
; GCN-O2-NEXT: Target Library Information
@ -704,11 +704,11 @@
; GCN-O3-NEXT: Basic Alias Analysis (stateless AA impl)
; GCN-O3-NEXT: Function Alias Analysis Results
; GCN-O3-NEXT: Simplify well-known AMD library calls
; GCN-O3-NEXT: Lower 'expect' Intrinsics
; GCN-O3-NEXT: Simplify the CFG
; GCN-O3-NEXT: Dominator Tree Construction
; GCN-O3-NEXT: SROA
; GCN-O3-NEXT: Early CSE
; GCN-O3-NEXT: Lower 'expect' Intrinsics
; GCN-O3-NEXT: Pass Arguments:
; GCN-O3-NEXT: Target Library Information

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

@ -79,6 +79,7 @@
; CHECK-O-NEXT: Running analysis: TargetLibraryAnalysis
; CHECK-O-NEXT: Running analysis: PreservedCFGCheckerAnalysis on foo
; CHECK-O-NEXT: Starting llvm::Function pass manager run.
; CHECK-O-NEXT: Running pass: LowerExpectIntrinsicPass
; CHECK-O-NEXT: Running pass: SimplifyCFGPass
; CHECK-O-NEXT: Running analysis: TargetIRAnalysis
; CHECK-O-NEXT: Running analysis: AssumptionAnalysis
@ -86,7 +87,6 @@
; CHECK-O-NEXT: Running analysis: DominatorTreeAnalysis
; CHECK-O-NEXT: Running pass: EarlyCSEPass
; CHECK-O-NEXT: Running analysis: TargetLibraryAnalysis
; CHECK-O-NEXT: Running pass: LowerExpectIntrinsicPass
; CHECK-O3-NEXT: Running pass: CallSiteSplittingPass
; CHECK-O-NEXT: Finished llvm::Function pass manager run.
; CHECK-EP-PIPELINE-EARLY-SIMPLIFICATION-NEXT: Running pass: NoOpModulePass

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

@ -20,10 +20,10 @@
; USE_POST_LINK: Running pass: PGOMemOPSizeOpt
; SAMPLE_USE_O: Running pass: AddDiscriminatorsPass
; SAMPLE_USE_PRE_LINK: Running pass: AddDiscriminatorsPass
; SAMPLE_USE: Running pass: LowerExpectIntrinsicPass
; SAMPLE_USE: Running pass: SimplifyCFGPass
; SAMPLE_USE: Running pass: SROA
; SAMPLE_USE: Running pass: EarlyCSEPass
; SAMPLE_USE: Running pass: LowerExpectIntrinsicPass
; SAMPLE_USE_POST_LINK: Running pass: InstCombinePass
; SAMPLE_USE: Running pass: SampleProfileLoaderPass
; SAMPLE_USE_O: Running pass: PGOIndirectCallPromotion

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

@ -64,6 +64,7 @@
; CHECK-PRELINK-O-NODIS-NEXT: Running analysis: InnerAnalysisManagerProxy
; CHECK-O-NEXT: Running analysis: TargetLibraryAnalysis
; CHECK-O-NEXT: Starting llvm::Function pass manager run.
; CHECK-O-NEXT: Running pass: LowerExpectIntrinsicPass
; CHECK-O-NEXT: Running pass: SimplifyCFGPass
; CHECK-O-NEXT: Running analysis: TargetIRAnalysis
; CHECK-O-NEXT: Running analysis: AssumptionAnalysis
@ -71,7 +72,6 @@
; CHECK-O-NEXT: Running analysis: DominatorTreeAnalysis
; CHECK-O-NEXT: Running pass: EarlyCSEPass
; CHECK-O-NEXT: Running analysis: TargetLibraryAnalysis
; CHECK-O-NEXT: Running pass: LowerExpectIntrinsicPass
; CHECK-O3-NEXT: Running pass: CallSiteSplittingPass
; CHECK-O-NEXT: Finished llvm::Function pass manager run.
; CHECK-POSTLINK-O-NEXT: Running pass: LowerTypeTestsPass

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

@ -34,6 +34,7 @@
; CHECK-O-NEXT: Running pass: InferFunctionAttrsPass
; CHECK-O-NEXT: Running analysis: TargetLibraryAnalysis
; CHECK-O-NEXT: Starting {{.*}}Function pass manager run.
; CHECK-O-NEXT: Running pass: LowerExpectIntrinsicPass
; CHECK-O-NEXT: Running pass: SimplifyCFGPass
; CHECK-O-NEXT: Running analysis: TargetIRAnalysis
; CHECK-O-NEXT: Running analysis: AssumptionAnalysis
@ -41,7 +42,6 @@
; CHECK-O-NEXT: Running analysis: DominatorTreeAnalysis
; CHECK-O-NEXT: Running pass: EarlyCSEPass
; CHECK-O-NEXT: Running analysis: TargetLibraryAnalysis
; CHECK-O-NEXT: Running pass: LowerExpectIntrinsicPass
; CHECK-O3-NEXT: Running pass: CallSiteSplittingPass
; CHECK-O-NEXT: Finished {{.*}}Function pass manager run.
; CHECK-O-NEXT: Running pass: LowerTypeTestsPass

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

@ -36,6 +36,7 @@
; CHECK-O-NEXT: Running analysis: InnerAnalysisManagerProxy
; CHECK-O-NEXT: Running analysis: TargetLibraryAnalysis
; CHECK-O-NEXT: Starting {{.*}}Function pass manager run.
; CHECK-O-NEXT: Running pass: LowerExpectIntrinsicPass
; CHECK-O-NEXT: Running pass: SimplifyCFGPass
; CHECK-O-NEXT: Running analysis: TargetIRAnalysis
; CHECK-O-NEXT: Running analysis: AssumptionAnalysis
@ -43,7 +44,6 @@
; CHECK-O-NEXT: Running analysis: DominatorTreeAnalysis
; CHECK-O-NEXT: Running pass: EarlyCSEPass
; CHECK-O-NEXT: Running analysis: TargetLibraryAnalysis
; CHECK-O-NEXT: Running pass: LowerExpectIntrinsicPass
; CHECK-O3-NEXT: Running pass: CallSiteSplittingPass
; CHECK-O-NEXT: Running pass: InstCombinePass on foo
; CHECK-O-NEXT: Running analysis: OptimizationRemarkEmitterAnalysis on foo

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

@ -35,6 +35,7 @@
; CHECK-O-NEXT: Running analysis: InnerAnalysisManagerProxy
; CHECK-O-NEXT: Running analysis: TargetLibraryAnalysis
; CHECK-O-NEXT: Starting {{.*}}Function pass manager run.
; CHECK-O-NEXT: Running pass: LowerExpectIntrinsicPass
; CHECK-O-NEXT: Running pass: SimplifyCFGPass
; CHECK-O-NEXT: Running analysis: TargetIRAnalysis
; CHECK-O-NEXT: Running analysis: AssumptionAnalysis
@ -42,7 +43,6 @@
; CHECK-O-NEXT: Running analysis: DominatorTreeAnalysis
; CHECK-O-NEXT: Running pass: EarlyCSEPass
; CHECK-O-NEXT: Running analysis: TargetLibraryAnalysis
; CHECK-O-NEXT: Running pass: LowerExpectIntrinsicPass
; CHECK-O3-NEXT: Running pass: CallSiteSplittingPass
; CHECK-O-NEXT: Finished {{.*}}Function pass manager run.
; CHECK-O-NEXT: Running pass: IPSCCPPass

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

@ -34,6 +34,7 @@
; CHECK-O-NEXT: Running pass: InferFunctionAttrsPass
; CHECK-O-NEXT: Running analysis: TargetLibraryAnalysis
; CHECK-O-NEXT: Starting {{.*}}Function pass manager run.
; CHECK-O-NEXT: Running pass: LowerExpectIntrinsicPass
; CHECK-O-NEXT: Running pass: SimplifyCFGPass
; CHECK-O-NEXT: Running analysis: TargetIRAnalysis
; CHECK-O-NEXT: Running analysis: AssumptionAnalysis
@ -41,7 +42,6 @@
; CHECK-O-NEXT: Running analysis: DominatorTreeAnalysis
; CHECK-O-NEXT: Running pass: EarlyCSEPass
; CHECK-O-NEXT: Running analysis: TargetLibraryAnalysis
; CHECK-O-NEXT: Running pass: LowerExpectIntrinsicPass
; CHECK-O3-NEXT: Running pass: CallSiteSplittingPass
; CHECK-O-NEXT: Running pass: InstCombinePass on foo
; CHECK-O-NEXT: Running analysis: OptimizationRemarkEmitterAnalysis on foo

2
llvm/test/Other/opt-O2-pipeline.ll
View File

@ -12,11 +12,11 @@
; CHECK-NEXT: Module Verifier
; CHECK-EXT: Good Bye World Pass
; CHECK-NOEXT-NOT: Good Bye World Pass
; CHECK-NEXT: Lower 'expect' Intrinsics
; CHECK-NEXT: Simplify the CFG
; CHECK-NEXT: Dominator Tree Construction
; CHECK-NEXT: SROA
; CHECK-NEXT: Early CSE
; CHECK-NEXT: Lower 'expect' Intrinsics
; CHECK-NEXT: Pass Arguments:
; CHECK-NEXT: Target Library Information
; CHECK-NEXT: Target Transform Information

2
llvm/test/Other/opt-O3-pipeline-enable-matrix.ll
View File

@ -12,11 +12,11 @@
; CHECK-NEXT: Module Verifier
; CHECK-EXT: Good Bye World Pass
; CHECK-NOEXT-NOT: Good Bye World Pass
; CHECK-NEXT: Lower 'expect' Intrinsics
; CHECK-NEXT: Simplify the CFG
; CHECK-NEXT: Dominator Tree Construction
; CHECK-NEXT: SROA
; CHECK-NEXT: Early CSE
; CHECK-NEXT: Lower 'expect' Intrinsics
; CHECK-NEXT: Pass Arguments:
; CHECK-NEXT: Target Library Information
; CHECK-NEXT: Target Transform Information

2
llvm/test/Other/opt-O3-pipeline.ll
View File

@ -12,11 +12,11 @@
; CHECK-NEXT: Module Verifier
; CHECK-EXT: Good Bye World Pass
; CHECK-NOEXT-NOT: Good Bye World Pass
; CHECK-NEXT: Lower 'expect' Intrinsics
; CHECK-NEXT: Simplify the CFG
; CHECK-NEXT: Dominator Tree Construction
; CHECK-NEXT: SROA
; CHECK-NEXT: Early CSE
; CHECK-NEXT: Lower 'expect' Intrinsics
; CHECK-NEXT: Pass Arguments:
; CHECK-NEXT: Target Library Information
; CHECK-NEXT: Target Transform Information

2
llvm/test/Other/opt-Os-pipeline.ll
View File

@ -12,11 +12,11 @@
; CHECK-NEXT: Module Verifier
; CHECK-EXT: Good Bye World Pass
; CHECK-NOEXT-NOT: Good Bye World Pass
; CHECK-NEXT: Lower 'expect' Intrinsics
; CHECK-NEXT: Simplify the CFG
; CHECK-NEXT: Dominator Tree Construction
; CHECK-NEXT: SROA
; CHECK-NEXT: Early CSE
; CHECK-NEXT: Lower 'expect' Intrinsics
; CHECK-NEXT: Pass Arguments:
; CHECK-NEXT: Target Library Information
; CHECK-NEXT: Target Transform Information

10
llvm/test/Transforms/PhaseOrdering/expect.ll
View File

@ -1,7 +1,6 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt -O2 -S < %s | FileCheck %s
; FIXME:
; Given an "expect" on a compare, we should not combine
; that compare with other instructions in a way that the
; backend can't undo. Expect lowering becomes metadata,
@ -10,10 +9,11 @@
define void @PR49336(i32 %delta, i32 %tag_type, i8* %ip) {
; CHECK-LABEL: @PR49336(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[TOBOOL:%.*]] = icmp slt i32 [[DELTA:%.*]], 0
; CHECK-NEXT: [[CMP1:%.*]] = icmp ne i32 [[TAG_TYPE:%.*]], 0
; CHECK-NEXT: [[OR_COND:%.*]] = and i1 [[TOBOOL]], [[CMP1]]
; CHECK-NEXT: br i1 [[OR_COND]], label [[IF_THEN2:%.*]], label [[IF_END3:%.*]]
; CHECK-NEXT: [[CMP:%.*]] = icmp slt i32 [[DELTA:%.*]], 0
; CHECK-NEXT: br i1 [[CMP]], label [[IF_THEN:%.*]], label [[IF_END3:%.*]], !prof !0
; CHECK: if.then:
; CHECK-NEXT: [[CMP1_NOT:%.*]] = icmp eq i32 [[TAG_TYPE:%.*]], 0
; CHECK-NEXT: br i1 [[CMP1_NOT]], label [[IF_END3]], label [[IF_THEN2:%.*]]
; CHECK: if.then2:
; CHECK-NEXT: store i8 42, i8* [[IP:%.*]], align 1
; CHECK-NEXT: br label [[IF_END3]]