[LLVMdev] PassManager again...

[Andreas Neustifter]

Hi,

I have trouble making my ProfileInfo-Analysis available in the backend, I have changed llc so it loads the ProfileInfo if requested, the PassManger gives this output:

 > Target Data Layout
 > Create Garbage Collector Module Metadata
 > Basic Alias Analysis (default AA impl)
 > DWARF Information Writer
 > No Profile Information
 > Module Information
 >   ModulePass Manager
 >     Profiling information loader
 >     FunctionPass Manager
 >       Preliminary module verification
 >       Dominator Tree Construction
 >       Module Verifier
 >       Natural Loop Information
 >       Loop Pass Manager
 >         Canonicalize natural loops
 >       Scalar Evolution Analysis
 >       Loop Pass Manager
 >         Induction Variable Users
 >         Canonicalize natural loops
 >         Induction Variable Users
 >         Loop Strength Reduction
 >       Dominance Frontier Construction
 >       Exception handling preparation
 >       Lower Garbage Collection Instructions
 >       Remove unreachable blocks from the CFG
 >       Optimize for code generation
 >       Insert stack protectors
 >       Machine Function Analysis
 >       X86 DAG->DAG Instruction Selection
 >       X86 FP_REG_KILL inserter
...

Okay, so the ProfileInfoLoader is working, but when I examine the executions more closely I see that the ProfileInfo generated by the ProfileInfoLoader is immediately discarded, when the SelectionDAGISel kicks in the "No Profile Info"-Implementation is used:

 > 0x1c1a740   Executing Pass 'Profiling information loader' on Module 'main.c-O0.ll.bc'...
 >  -*- 'Profiling information loader' is the last user of following pass instances. Free these instances
 > 0x1c1a740    Freeing Pass 'Profiling information loader' on Module 'main.c-O0.ll.bc'...
 > 0x1c1a740   Executing Pass 'Function Pass Manager' on Module 'main.c-O0.ll.bc'...
 > 0x1c301a0     Executing Pass 'Preliminary module verification' on Function 'main'...
 > 0x1c301a0     Executing Pass 'Dominator Tree Construction' on Function 'main'...
 > 0x1c301a0     Executing Pass 'Module Verifier' on Function 'main'...
 > 0x1c1ae50       Required Analyses: Preliminary module verification, Dominator Tree Construction
 >  -*- 'Module Verifier' is the last user of following pass instances. Free these instances
 > 0x1c301a0      Freeing Pass 'Module Verifier' on Function 'main'...
 > 0x1c301a0      Freeing Pass 'Preliminary module verification' on Function 'main'...
 > 0x1c301a0     Executing Pass 'Natural Loop Information' on Function 'main'...
 > 0x1c33000       Required Analyses: Dominator Tree Construction
 > 0x1c301a0     Executing Pass 'Loop Pass Manager' on Function 'main'...
 > 0x1c33460       Required Analyses: Natural Loop Information
 > 0x1c301a0     Executing Pass 'Scalar Evolution Analysis' on Function 'main'...
 > 0x1c33cb0       Required Analyses: Natural Loop Information
 > 0x1c301a0     Executing Pass 'Loop Pass Manager' on Function 'main'...
 > 0x1c359b0       Required Analyses: Natural Loop Information
 >  -*- 'Loop Pass Manager' is the last user of following pass instances. Free these instances
 > 0x1c301a0      Freeing Pass 'Scalar Evolution Analysis' on Function 'main'...
 > 0x1c301a0      Freeing Pass 'Natural Loop Information' on Function 'main'...
 > 0x1c301a0     Executing Pass 'Dominance Frontier Construction' on Function 'main'...
 > 0x1c370b0       Required Analyses: Dominator Tree Construction
 > 0x1c301a0     Executing Pass 'Exception handling preparation' on Function 'main'...
 > 0x1c36c70       Required Analyses: Dominator Tree Construction, Dominance Frontier Construction
 > 0x1c36c70       Preserved Analyses: Dominator Tree Construction, Dominance Frontier Construction, Load profile information from llvmprof.out
 >  -*- 'Exception handling preparation' is the last user of following pass instances. Free these instances
 > 0x1c301a0      Freeing Pass 'Exception handling preparation' on Function 'main'...
 > 0x1c301a0      Freeing Pass 'Dominance Frontier Construction' on Function 'main'...
 > 0x1c301a0      Freeing Pass 'Dominator Tree Construction' on Function 'main'...
 > 0x1c301a0     Executing Pass 'Lower Garbage Collection Instructions' on Function 'main'...
 > 0x1c1cec0       Required Analyses: Create Garbage Collector Module Metadata
 > 0x1c1cec0       Preserved Analyses: Load profile information from llvmprof.out
 >  -*- 'Lower Garbage Collection Instructions' is the last user of following pass instances. Free these instances
 > 0x1c301a0      Freeing Pass 'Lower Garbage Collection Instructions' on Function 'main'...
 > 0x1c301a0     Executing Pass 'Remove unreachable blocks from the CFG' on Function 'main'...
 > 0x1c36c00       Preserved Analyses: Load profile information from llvmprof.out
 >  -*- 'Remove unreachable blocks from the CFG' is the last user of following pass instances. Free these instances
 > 0x1c301a0      Freeing Pass 'Remove unreachable blocks from the CFG' on Function 'main'...
 > 0x1c301a0     Executing Pass 'Optimize for code generation' on Function 'main'...
 > 0x1c38430       Preserved Analyses: Load profile information from llvmprof.out
 >  -*- 'Optimize for code generation' is the last user of following pass instances. Free these instances
 > 0x1c301a0      Freeing Pass 'Optimize for code generation' on Function 'main'...
 > 0x1c301a0     Executing Pass 'Insert stack protectors' on Function 'main'...
 > 0x1c325a0       Preserved Analyses: Load profile information from llvmprof.out
 >  -*- 'Insert stack protectors' is the last user of following pass instances. Free these instances
 > 0x1c301a0      Freeing Pass 'Insert stack protectors' on Function 'main'...
 > 0x1c301a0     Executing Pass 'Machine Function Analysis' on Function 'main'...
 > 0x1c301a0     Executing Pass 'X86 DAG->DAG Instruction Selection' on Function 'main'...
 > 0x1c390d0       Required Analyses: No Alias Analysis (always returns 'may' alias), Create Garbage Collector Module Metadata, DWARF Information Writer, Load profile information from llvmprof.out, Machine Function Analysis
...

I was under the impression that it is possible to use the results form an Module-wide analysis in the following FunctionPasses, but in this case this is not working.

Also, I have modified all passes that run between the ProfileInfoLoader and the SelectionDAGISel to preserve the ProfileInfo, each pass reports this properly.

What really puzzles me is that the SelectionDAGISel reports the ProfileInfoLoader as required analysis (last line), so why is the PassManager assuming that the ProfileInfoLoader analysis is not used anymore?

I have tried to make the ProfileInfoLoader the default implementation (instead of "No ProfileInfo") but this gives an assertion while creating the passes:

 > llc:.../include/llvm/PassSupport.h:111: llvm::Pass* llvm::PassInfo::createPass() const: Assertion `NormalCtor && "Cannot call createPass on PassInfo without default ctor!"' failed.

Can someone enlighten me please?

Andi