Apple clang version 11.0.3 (clang-1103.0.32.29)

$ g++ -O0 -mllvm -debug-pass=Structure prog.cpp
Pass Arguments:  -tti -targetlibinfo -ee-instrument
Target Transform Information
Target Library Information
  FunctionPass Manager
    Instrument function entry/exit with calls to e.g. mcount() (pre inlining)
Pass Arguments:  -tti -targetlibinfo -assumption-cache-tracker -profile-summary-info -forceattrs -domtree -loops -lazy-branch-prob -lazy-block-freq -opt-remark-emitter -basicaa -aa -lower-matrix-type -basiccg -always-inline
Target Transform Information
Target Library Information
Assumption Cache Tracker
Profile summary info
  ModulePass Manager
    Force set function attributes
    FunctionPass Manager
      Dominator Tree Construction
      Natural Loop Information
      Lazy Branch Probability Analysis
      Lazy Block Frequency Analysis
      Optimization Remark Emitter
      Basic Alias Analysis (stateless AA impl)
      Function Alias Analysis Results
      Lower operations on the matrix type
    CallGraph Construction
    Call Graph SCC Pass Manager
      Inliner for always_inline functions
Pass Arguments:  -tti -targetlibinfo -targetpassconfig -machinemoduleinfo -tbaa -scoped-noalias -assumption-cache-tracker -collector-metadata -machine-branch-prob -pre-isel-intrinsic-lowering -atomic-expand -domtree -basicaa -gc-lowering -shadow-stack-gc-lowering -unreachableblockelim -post-inline-ee-instrument -scalarize-masked-mem-intrin -expand-reductions -indirectbr-expand -rewrite-symbols -domtree -dwarfehprepare -safe-stack -stack-protector -finalize-isel -localstackalloc -x86-slh -machinedomtree -x86-flags-copy-lowering -phi-node-elimination -twoaddressinstruction -regallocfast -edge-bundles -x86-codegen -lazy-machine-block-freq -machine-opt-remark-emitter -prologepilog -postrapseudos -x86-pseudo -gc-analysis -funclet-layout -stackmap-liveness -livedebugvalues -fentry-insert -xray-instrumentation -patchable-function -x86-darwin-stack-probe-emitter -lazy-machine-block-freq -machine-opt-remark-emitter
Target Transform Information
Target Library Information
Target Pass Configuration
Machine Module Information
Type-Based Alias Analysis
Scoped NoAlias Alias Analysis
Assumption Cache Tracker
Create Garbage Collector Module Metadata
Machine Branch Probability Analysis
  ModulePass Manager
    Pre-ISel Intrinsic Lowering
    FunctionPass Manager
      Expand Atomic instructions
      Dominator Tree Construction
      Basic Alias Analysis (stateless AA impl)
      Lower Garbage Collection Instructions
      Shadow Stack GC Lowering
      Remove unreachable blocks from the CFG
      Instrument function entry/exit with calls to e.g. mcount() (post inlining)
      Scalarize Masked Memory Intrinsics
      Expand reduction intrinsics
      Expand indirectbr instructions
    Rewrite Symbols
    FunctionPass Manager
      Dominator Tree Construction
      Exception handling preparation
      Safe Stack instrumentation pass
      Insert stack protectors
      X86 DAG->DAG Instruction Selection
      X86 PIC Global Base Reg Initialization
      Finalize ISel and expand pseudo-instructions
      Local Stack Slot Allocation
      X86 speculative load hardening
      MachineDominator Tree Construction
      X86 EFLAGS copy lowering
      X86 DynAlloca Expander
      Eliminate PHI nodes for register allocation
      Two-Address instruction pass
      Fast Register Allocator
      Bundle Machine CFG Edges
      X86 FP Stackifier
      Lazy Machine Block Frequency Analysis
      Machine Optimization Remark Emitter
      Prologue/Epilogue Insertion & Frame Finalization
      Post-RA pseudo instruction expansion pass
      X86 pseudo instruction expansion pass
      Analyze Machine Code For Garbage Collection
      X86 Indirect Branch Tracking
      X86 vzeroupper inserter
      X86 Discriminate Memory Operands
      X86 Insert Cache Prefetches
      Contiguously Lay Out Funclets
      StackMap Liveness Analysis
      Live DEBUG_VALUE analysis
      Insert fentry calls
      Insert XRay ops
      Implement the 'patchable-function' attribute
      X86 Retpoline Thunks
      X86 Darwin Stack Probe Emitter
      Lazy Machine Block Frequency Analysis
      Machine Optimization Remark Emitter
      X86 Assembly Printer
      Free MachineFunction