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[CompileTime] [Passes] Avoid computing unnecessary analyses. NFC 

Similar to c515b2f39e, If there are no loops in the function as seen
through LI, we should avoid computing the remaining expensive analyses
(such as SCEV, BPI).  Reordered the analyses requests and early return
if there are no loops.

The logic of avoiding expensive analyses is applied to LoopVectorizer,
LoopLoadElimination and LoopUnrollPass, i.e. all function passes which operate
on loops.

This is an NFC with compile time improvement.

Differential Revision: https://reviews.llvm.org/D124529
This commit is contained in:
Anna Thomas 2022-04-27 11:00:58 -04:00
parent f685bce808
commit 205246cb64
4 changed files with 16 additions and 6 deletions
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6
llvm/lib/Transforms/Scalar/LoopLoadElimination.cpp
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@ -706,8 +706,12 @@ FunctionPass *llvm::createLoopLoadEliminationPass() {
PreservedAnalyses LoopLoadEliminationPass::run(Function &F,
FunctionAnalysisManager &AM) {
auto &SE = AM.getResult<ScalarEvolutionAnalysis>(F);
auto &LI = AM.getResult<LoopAnalysis>(F);
// There are no loops in the function. Return before computing other expensive
// analyses.
if (LI.empty())
return PreservedAnalyses::all();
auto &SE = AM.getResult<ScalarEvolutionAnalysis>(F);
auto &TTI = AM.getResult<TargetIRAnalysis>(F);
auto &DT = AM.getResult<DominatorTreeAnalysis>(F);
auto &TLI = AM.getResult<TargetLibraryAnalysis>(F);

6
llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp
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@ -1545,8 +1545,12 @@ PreservedAnalyses LoopFullUnrollPass::run(Loop &L, LoopAnalysisManager &AM,
PreservedAnalyses LoopUnrollPass::run(Function &F,
FunctionAnalysisManager &AM) {
auto &SE = AM.getResult<ScalarEvolutionAnalysis>(F);
auto &LI = AM.getResult<LoopAnalysis>(F);
// There are no loops in the function. Return before computing other expensive
// analyses.
if (LI.empty())
return PreservedAnalyses::all();
auto &SE = AM.getResult<ScalarEvolutionAnalysis>(F);
auto &TTI = AM.getResult<TargetIRAnalysis>(F);
auto &DT = AM.getResult<DominatorTreeAnalysis>(F);
auto &AC = AM.getResult<AssumptionAnalysis>(F);

6
llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
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@ -10732,8 +10732,12 @@ LoopVectorizeResult LoopVectorizePass::runImpl(
PreservedAnalyses LoopVectorizePass::run(Function &F,
FunctionAnalysisManager &AM) {
auto &SE = AM.getResult<ScalarEvolutionAnalysis>(F);
auto &LI = AM.getResult<LoopAnalysis>(F);
// There are no loops in the function. Return before computing other expensive
// analyses.
if (LI.empty())
return PreservedAnalyses::all();
auto &SE = AM.getResult<ScalarEvolutionAnalysis>(F);
auto &TTI = AM.getResult<TargetIRAnalysis>(F);
auto &DT = AM.getResult<DominatorTreeAnalysis>(F);
auto &BFI = AM.getResult<BlockFrequencyAnalysis>(F);

4
llvm/test/Transforms/SCCP/preserve-analysis.ll
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@ -5,10 +5,8 @@
; NEW-PM-DAG: Running analysis: LoopAnalysis on test
; NEW-PM-DAG: Running analysis: DominatorTreeAnalysis on test
; NEW-PM-DAG: Running analysis: AssumptionAnalysis on test
; NEW-PM-DAG: Running analysis: TargetLibraryAnalysis on test
; NEW-PM-DAG: Running analysis: TargetIRAnalysis on test
; NEW-PM: Running pass: SCCPPass on test
; NEW-PM: Running analysis: TargetLibraryAnalysis on test
; NEW-PM-NOT: Running analysis: LoopAnalysis on test
; NEW-PM-NOT: Running analysis: DominatorTreeAnalysis on test
; NEW-PM-NOT: Running analysis: AssumptionAnalysis on test