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b053fc1c92
implementing PR12013. We now compile the testcase to: __Z4testv: ## @_Z4testv ## BB#0: ## %_ZN4llvm15SmallVectorImplIiE9push_backERKi.exit pushq %rbx subq $64, %rsp leaq 32(%rsp), %rbx movq %rbx, (%rsp) leaq 64(%rsp), %rax movq %rax, 16(%rsp) movl $1, 32(%rsp) leaq 36(%rsp), %rax movq %rax, 8(%rsp) leaq (%rsp), %rdi callq __Z1gRN4llvm11SmallVectorIiLj8EEE movq (%rsp), %rdi cmpq %rbx, %rdi je LBB0_2 ## BB#1: callq _free LBB0_2: ## %_ZN4llvm11SmallVectorIiLj8EED1Ev.exit addq $64, %rsp popq %rbx ret instead of: __Z4testv: ## @_Z4testv ## BB#0: pushq %rbx subq $64, %rsp xorl %eax, %eax leaq (%rsp), %rbx addq $32, %rbx movq %rbx, (%rsp) movq %rbx, 8(%rsp) leaq 64(%rsp), %rcx movq %rcx, 16(%rsp) je LBB0_2 ## BB#1: movl $1, 32(%rsp) movq %rbx, %rax LBB0_2: ## %_ZN4llvm15SmallVectorImplIiE9push_backERKi.exit addq $4, %rax movq %rax, 8(%rsp) leaq (%rsp), %rdi callq __Z1gRN4llvm11SmallVectorIiLj8EEE movq (%rsp), %rdi cmpq %rbx, %rdi je LBB0_4 ## BB#3: callq _free LBB0_4: ## %_ZN4llvm11SmallVectorIiLj8EED1Ev.exit addq $64, %rsp popq %rbx ret This doesn't shrink clang noticably though. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@150944 91177308-0d34-0410-b5e6-96231b3b80d8 |
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|---|---|---|
| .. | ||
| IPA | ||
| AliasAnalysis.cpp | ||
| AliasAnalysisCounter.cpp | ||
| AliasAnalysisEvaluator.cpp | ||
| AliasDebugger.cpp | ||
| AliasSetTracker.cpp | ||
| Analysis.cpp | ||
| BasicAliasAnalysis.cpp | ||
| BlockFrequencyInfo.cpp | ||
| BranchProbabilityInfo.cpp | ||
| CaptureTracking.cpp | ||
| CFGPrinter.cpp | ||
| CMakeLists.txt | ||
| ConstantFolding.cpp | ||
| DbgInfoPrinter.cpp | ||
| DebugInfo.cpp | ||
| DIBuilder.cpp | ||
| DominanceFrontier.cpp | ||
| DomPrinter.cpp | ||
| InlineCost.cpp | ||
| InstCount.cpp | ||
| InstructionSimplify.cpp | ||
| Interval.cpp | ||
| IntervalPartition.cpp | ||
| IVUsers.cpp | ||
| LazyValueInfo.cpp | ||
| LibCallAliasAnalysis.cpp | ||
| LibCallSemantics.cpp | ||
| Lint.cpp | ||
| LLVMBuild.txt | ||
| Loads.cpp | ||
| LoopDependenceAnalysis.cpp | ||
| LoopInfo.cpp | ||
| LoopPass.cpp | ||
| Makefile | ||
| MemDepPrinter.cpp | ||
| MemoryBuiltins.cpp | ||
| MemoryDependenceAnalysis.cpp | ||
| ModuleDebugInfoPrinter.cpp | ||
| NoAliasAnalysis.cpp | ||
| PathNumbering.cpp | ||
| PathProfileInfo.cpp | ||
| PathProfileVerifier.cpp | ||
| PHITransAddr.cpp | ||
| PostDominators.cpp | ||
| ProfileEstimatorPass.cpp | ||
| ProfileInfo.cpp | ||
| ProfileInfoLoader.cpp | ||
| ProfileInfoLoaderPass.cpp | ||
| ProfileVerifierPass.cpp | ||
| README.txt | ||
| RegionInfo.cpp | ||
| RegionPass.cpp | ||
| RegionPrinter.cpp | ||
| ScalarEvolution.cpp | ||
| ScalarEvolutionAliasAnalysis.cpp | ||
| ScalarEvolutionExpander.cpp | ||
| ScalarEvolutionNormalization.cpp | ||
| SparsePropagation.cpp | ||
| Trace.cpp | ||
| TypeBasedAliasAnalysis.cpp | ||
| ValueTracking.cpp | ||
Analysis Opportunities:
//===---------------------------------------------------------------------===//
In test/Transforms/LoopStrengthReduce/quadradic-exit-value.ll, the
ScalarEvolution expression for %r is this:
{1,+,3,+,2}<loop>
Outside the loop, this could be evaluated simply as (%n * %n), however
ScalarEvolution currently evaluates it as
(-2 + (2 * (trunc i65 (((zext i64 (-2 + %n) to i65) * (zext i64 (-1 + %n) to i65)) /u 2) to i64)) + (3 * %n))
In addition to being much more complicated, it involves i65 arithmetic,
which is very inefficient when expanded into code.
//===---------------------------------------------------------------------===//
In formatValue in test/CodeGen/X86/lsr-delayed-fold.ll,
ScalarEvolution is forming this expression:
((trunc i64 (-1 * %arg5) to i32) + (trunc i64 %arg5 to i32) + (-1 * (trunc i64 undef to i32)))
This could be folded to
(-1 * (trunc i64 undef to i32))
//===---------------------------------------------------------------------===//