dda73336ad
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)
64 lines
3.5 KiB
LLVM
64 lines
3.5 KiB
LLVM
; Test to check the callgraph in summary
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; RUN: opt -module-summary %s -o %t.o
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; RUN: llvm-bcanalyzer -dump %t.o | FileCheck %s
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; RUN: opt -module-summary %p/Inputs/thinlto-alias.ll -o %t2.o
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; RUN: llvm-dis -o - %t2.o | FileCheck %s --check-prefix=DIS
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; Round trip it through llvm-as
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; RUN: llvm-dis -o - %t2.o | llvm-as -o - | llvm-dis -o - | FileCheck %s --check-prefix=DIS
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; RUN: llvm-lto -thinlto -o %t3 %t.o %t2.o
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; RUN: llvm-bcanalyzer -dump %t3.thinlto.bc | FileCheck %s --check-prefix=COMBINED
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; RUN: llvm-dis -o - %t3.thinlto.bc | FileCheck %s --check-prefix=COMBINED-DIS
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; Round trip it through llvm-as
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; RUN: llvm-dis -o - %t3.thinlto.bc | llvm-as -o - | llvm-dis -o - | FileCheck %s --check-prefix=COMBINED-DIS
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; CHECK: <SOURCE_FILENAME
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; "main"
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; CHECK-NEXT: <FUNCTION op0=0 op1=4
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; "analias"
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; CHECK-NEXT: <FUNCTION op0=4 op1=7
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; CHECK: <GLOBALVAL_SUMMARY_BLOCK
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; CHECK-NEXT: <VERSION
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; CHECK-NEXT: <FLAGS
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; See if the call to func is registered.
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; The value id 1 matches the second FUNCTION record above.
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; CHECK-NEXT: <PERMODULE_PROFILE {{.*}} op7=1
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; CHECK-NEXT: </GLOBALVAL_SUMMARY_BLOCK>
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; CHECK: <STRTAB_BLOCK
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; CHECK-NEXT: blob data = 'mainanalias{{.*}}'
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; COMBINED: <GLOBALVAL_SUMMARY_BLOCK
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; COMBINED-NEXT: <VERSION
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; COMBINED-NEXT: <FLAGS
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; See if the call to analias is registered, using the expected value id.
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; COMBINED-NEXT: <VALUE_GUID op0=[[ALIASID:[0-9]+]] op1=-5751648690987223394/>
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; COMBINED-NEXT: <VALUE_GUID
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; COMBINED-NEXT: <VALUE_GUID op0=[[ALIASEEID:[0-9]+]] op1=-1039159065113703048/>
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; COMBINED-NEXT: <COMBINED_PROFILE {{.*}} op9=[[ALIASID]]
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; COMBINED-NEXT: <COMBINED_PROFILE {{.*}}
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; COMBINED-NEXT: <COMBINED_ALIAS {{.*}} op3=[[ALIASEEID]]
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; COMBINED-NEXT: </GLOBALVAL_SUMMARY_BLOCK
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; ModuleID = 'thinlto-function-summary-callgraph.ll'
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target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
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target triple = "x86_64-unknown-linux-gnu"
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; Function Attrs: nounwind uwtable
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define i32 @main() {
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entry:
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call void (...) @analias()
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ret i32 0
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}
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declare void @analias(...)
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; DIS: ^0 = module: (path: "{{.*}}", hash: (0, 0, 0, 0, 0))
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; DIS: ^1 = gv: (name: "analias", summaries: (alias: (module: ^0, flags: (linkage: external, visibility: default, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0, importType: definition), aliasee: ^2))) ; guid = 12695095382722328222
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; DIS: ^2 = gv: (name: "aliasee", summaries: (function: (module: ^0, flags: (linkage: external, visibility: default, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0, importType: definition), insts: 1))) ; guid = 17407585008595848568
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; COMBINED-DIS: ^0 = module: (path: "{{.*}}thinlto-alias.ll.tmp.o", hash: (0, 0, 0, 0, 0))
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; COMBINED-DIS: ^1 = module: (path: "{{.*}}thinlto-alias.ll.tmp2.o", hash: (0, 0, 0, 0, 0))
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; COMBINED-DIS: ^2 = gv: (guid: 12695095382722328222, summaries: (alias: (module: ^1, flags: (linkage: external, visibility: default, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0, importType: definition), aliasee: ^4)))
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; COMBINED-DIS: ^3 = gv: (guid: 15822663052811949562, summaries: (function: (module: ^0, flags: (linkage: external, visibility: default, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0, importType: definition), insts: 2, calls: ((callee: ^2)))))
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; COMBINED-DIS: ^4 = gv: (guid: 17407585008595848568, summaries: (function: (module: ^1, flags: (linkage: external, visibility: default, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0, importType: definition), insts: 1)))
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