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The motivating use case is to support import the function declaration across modules to construct call graph edges for indirect calls [1] when importing the function definition costs too much compile time (e.g., the function is too large has no `noinline` attribute). 1. Currently, when the compiled IR module doesn't have a function definition but its postlink combined summary contains the function summary or a global alias summary with this function as aliasee, the function definition will be imported from source module by IRMover. The implementation is in FunctionImporter::importFunctions [2] 2. In order for FunctionImporter to import a declaration of a function, both function summary and alias summary need to carry the def / decl state. Specifically, all existing summary fields doesn't differ across import modules, but the def / decl state of is decided by `<ImportModule, Function>`. This change encodes the def/decl state in `GlobalValueSummary::GVFlags`. In the subsequent changes 1. The indexing step `computeImportForModule` [3] will compute the set of definitions and the set of declarations for each module, and passing on the information to bitcode writer. 2. Bitcode writer will look up the def/decl state and sets the state when it writes out the flag value. This is demonstrated in https://github.com/llvm/llvm-project/pull/87600 3. Function importer will read the def/decl state when reading the combined summary to figure out two sets of global values, and IRMover will be updated to import the declaration (aka linkGlobalValuePrototype [4]) into the destination module. - The next change is https://github.com/llvm/llvm-project/pull/87600 [1] mentioned in rfc https://discourse.llvm.org/t/rfc-for-better-call-graph-sort-build-a-more-complete-call-graph-by-adding-more-indirect-call-edges/74029#support-cross-module-function-declaration-import-5 [2]3b337242ee/llvm/lib/Transforms/IPO/FunctionImport.cpp (L1608-L1764)
[3]3b337242ee/llvm/lib/Transforms/IPO/FunctionImport.cpp (L856)
[4]3b337242ee/llvm/lib/Linker/IRMover.cpp (L605)
25 lines
6.2 KiB
LLVM
25 lines
6.2 KiB
LLVM
;; Test memprof summary parsing (tests all types/fields in various combinations).
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; RUN: llvm-as %s -o - | llvm-dis -o - | FileCheck %s
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; ModuleID = 'thinlto-memprof-summary.thinlto.bc'
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^0 = module: (path: "thinlto-memprof-summary.o", hash: (1369602428, 2747878711, 259090915, 2507395659, 1141468049))
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;; Function with single alloc, multiple memprof MIBs, no versioning
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^1 = gv: (guid: 23, summaries: (function: (module: ^0, flags: (linkage: external, visibility: default, notEligibleToImport: 0, live: 0, dsoLocal: 1, canAutoHide: 0, importType: definition), insts: 2, funcFlags: (readNone: 0, readOnly: 0, noRecurse: 0, returnDoesNotAlias: 0, noInline: 1, alwaysInline: 0, noUnwind: 0, mayThrow: 0, hasUnknownCall: 0, mustBeUnreachable: 0), allocs: ((versions: (none), memProf: ((type: notcold, stackIds: (8632435727821051414)), (type: cold, stackIds: (15025054523792398438, 12345678)), (type: hot, stackIds: (987654321))))))))
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;; Function with callsite stack ids calling above function, no versioning
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^2 = gv: (guid: 25, summaries: (function: (module: ^0, flags: (linkage: external, visibility: default, notEligibleToImport: 0, live: 0, dsoLocal: 1, canAutoHide: 0, importType: definition), insts: 22, funcFlags: (readNone: 0, readOnly: 0, noRecurse: 1, returnDoesNotAlias: 0, noInline: 1, alwaysInline: 0, noUnwind: 0, mayThrow: 0, hasUnknownCall: 0, mustBeUnreachable: 0), calls: ((callee: ^1)), callsites: ((callee: ^1, clones: (0), stackIds: (8632435727821051414)), (callee: ^1, clones: (0), stackIds: (15025054523792398438, 12345678)), (callee: ^1, clones: (0), stackIds: (23456789))))))
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;; Function with multiple allocs, multiple memprof MIBs, multiple versions
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^3 = gv: (guid: 26, summaries: (function: (module: ^0, flags: (linkage: external, visibility: default, notEligibleToImport: 0, live: 0, dsoLocal: 1, canAutoHide: 0, importType: definition), insts: 2, funcFlags: (readNone: 0, readOnly: 0, noRecurse: 0, returnDoesNotAlias: 0, noInline: 1, alwaysInline: 0, noUnwind: 0, mayThrow: 0, hasUnknownCall: 0, mustBeUnreachable: 0), allocs: ((versions: (cold, notcold), memProf: ((type: notcold, stackIds: (3456789)), (type: cold, stackIds: (456789)))), (versions: (notcold, cold), memProf: ((type: cold, stackIds: (3456789)), (type: notcold, stackIds: (456789))))))))
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;; Function with callsite stack ids calling above function, multiple versions
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^4 = gv: (guid: 27, summaries: (function: (module: ^0, flags: (linkage: external, visibility: default, notEligibleToImport: 0, live: 0, dsoLocal: 1, canAutoHide: 0, importType: definition), insts: 22, funcFlags: (readNone: 0, readOnly: 0, noRecurse: 1, returnDoesNotAlias: 0, noInline: 1, alwaysInline: 0, noUnwind: 0, mayThrow: 0, hasUnknownCall: 0, mustBeUnreachable: 0), calls: ((callee: ^3)), callsites: ((callee: ^3, clones: (0, 1), stackIds: (3456789)), (callee: ^3, clones: (1, 1), stackIds: (456789))))))
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;; Function with null callsite stack id (can happen in distributed indexes if callsite not imported)
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^5 = gv: (guid: 28, summaries: (function: (module: ^0, flags: (linkage: external, visibility: default, notEligibleToImport: 0, live: 0, dsoLocal: 1, canAutoHide: 0, importType: definition), insts: 22, funcFlags: (readNone: 0, readOnly: 0, noRecurse: 1, returnDoesNotAlias: 0, noInline: 1, alwaysInline: 0, noUnwind: 0, mayThrow: 0, hasUnknownCall: 0, mustBeUnreachable: 0), callsites: ((callee: null, clones: (0), stackIds: (8632435727821051414))))))
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; Make sure we get back from llvm-dis what we put in via llvm-as.
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; CHECK: ^0 = module: (path: "thinlto-memprof-summary.o", hash: (1369602428, 2747878711, 259090915, 2507395659, 1141468049))
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; CHECK: ^1 = gv: (guid: 23, summaries: (function: (module: ^0, flags: (linkage: external, visibility: default, notEligibleToImport: 0, live: 0, dsoLocal: 1, canAutoHide: 0, importType: definition), insts: 2, funcFlags: (readNone: 0, readOnly: 0, noRecurse: 0, returnDoesNotAlias: 0, noInline: 1, alwaysInline: 0, noUnwind: 0, mayThrow: 0, hasUnknownCall: 0, mustBeUnreachable: 0), allocs: ((versions: (none), memProf: ((type: notcold, stackIds: (8632435727821051414)), (type: cold, stackIds: (15025054523792398438, 12345678)), (type: hot, stackIds: (987654321))))))))
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; CHECK: ^2 = gv: (guid: 25, summaries: (function: (module: ^0, flags: (linkage: external, visibility: default, notEligibleToImport: 0, live: 0, dsoLocal: 1, canAutoHide: 0, importType: definition), insts: 22, funcFlags: (readNone: 0, readOnly: 0, noRecurse: 1, returnDoesNotAlias: 0, noInline: 1, alwaysInline: 0, noUnwind: 0, mayThrow: 0, hasUnknownCall: 0, mustBeUnreachable: 0), calls: ((callee: ^1)), callsites: ((callee: ^1, clones: (0), stackIds: (8632435727821051414)), (callee: ^1, clones: (0), stackIds: (15025054523792398438, 12345678)), (callee: ^1, clones: (0), stackIds: (23456789))))))
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; CHECK: ^3 = gv: (guid: 26, summaries: (function: (module: ^0, flags: (linkage: external, visibility: default, notEligibleToImport: 0, live: 0, dsoLocal: 1, canAutoHide: 0, importType: definition), insts: 2, funcFlags: (readNone: 0, readOnly: 0, noRecurse: 0, returnDoesNotAlias: 0, noInline: 1, alwaysInline: 0, noUnwind: 0, mayThrow: 0, hasUnknownCall: 0, mustBeUnreachable: 0), allocs: ((versions: (cold, notcold), memProf: ((type: notcold, stackIds: (3456789)), (type: cold, stackIds: (456789)))), (versions: (notcold, cold), memProf: ((type: cold, stackIds: (3456789)), (type: notcold, stackIds: (456789))))))))
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; CHECK: ^4 = gv: (guid: 27, summaries: (function: (module: ^0, flags: (linkage: external, visibility: default, notEligibleToImport: 0, live: 0, dsoLocal: 1, canAutoHide: 0, importType: definition), insts: 22, funcFlags: (readNone: 0, readOnly: 0, noRecurse: 1, returnDoesNotAlias: 0, noInline: 1, alwaysInline: 0, noUnwind: 0, mayThrow: 0, hasUnknownCall: 0, mustBeUnreachable: 0), calls: ((callee: ^3)), callsites: ((callee: ^3, clones: (0, 1), stackIds: (3456789)), (callee: ^3, clones: (1, 1), stackIds: (456789))))))
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; CHECK: ^5 = gv: (guid: 28, summaries: (function: (module: ^0, flags: (linkage: external, visibility: default, notEligibleToImport: 0, live: 0, dsoLocal: 1, canAutoHide: 0, importType: definition), insts: 22, funcFlags: (readNone: 0, readOnly: 0, noRecurse: 1, returnDoesNotAlias: 0, noInline: 1, alwaysInline: 0, noUnwind: 0, mayThrow: 0, hasUnknownCall: 0, mustBeUnreachable: 0), callsites: ((callee: null, clones: (0), stackIds: (8632435727821051414))))))
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