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llvm-project/llvm/test/Bitcode/upgrade-subprogram.ll

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DI: Reverse direction of subprogram -> function edge. Previously, subprograms contained a metadata reference to the function they described. Because most clients need to get or set a subprogram for a given function rather than the other way around, this created unneeded inefficiency. For example, many passes needed to call the function llvm::makeSubprogramMap() to build a mapping from functions to subprograms, and the IR linker needed to fix up function references in a way that caused quadratic complexity in the IR linking phase of LTO. This change reverses the direction of the edge by storing the subprogram as function-level metadata and removing DISubprogram's function field. Since this is an IR change, a bitcode upgrade has been provided. Fixes PR23367. An upgrade script for textual IR for out-of-tree clients is attached to the PR. Differential Revision: http://reviews.llvm.org/D14265 llvm-svn: 252219
2015-11-06 06:03:56 +08:00
; RUN: llvm-dis < %s.bc | FileCheck %s
; RUN: verify-uselistorder < %s.bc
; CHECK: define void @foo() !dbg [[SP:![0-9]+]]
define void @foo() {
ret void
}
!llvm.module.flags = !{!0}
!0 = !{i32 2, !"Debug Info Version", i32 3}
!llvm.dbg.cu = !{!1}
[PR27284] Reverse the ownership between DICompileUnit and DISubprogram. Currently each Function points to a DISubprogram and DISubprogram has a scope field. For member functions the scope is a DICompositeType. DIScopes point to the DICompileUnit to facilitate type uniquing. Distinct DISubprograms (with isDefinition: true) are not part of the type hierarchy and cannot be uniqued. This change removes the subprograms list from DICompileUnit and instead adds a pointer to the owning compile unit to distinct DISubprograms. This would make it easy for ThinLTO to strip unneeded DISubprograms and their transitively referenced debug info. Motivation ---------- Materializing DISubprograms is currently the most expensive operation when doing a ThinLTO build of clang. We want the DISubprogram to be stored in a separate Bitcode block (or the same block as the function body) so we can avoid having to expensively deserialize all DISubprograms together with the global metadata. If a function has been inlined into another subprogram we need to store a reference the block containing the inlined subprogram. Attached to https://llvm.org/bugs/show_bug.cgi?id=27284 is a python script that updates LLVM IR testcases to the new format. http://reviews.llvm.org/D19034 <rdar://problem/25256815> llvm-svn: 266446
2016-04-15 23:57:41 +08:00
!1 = distinct !DICompileUnit(language: DW_LANG_C99, file: !2, emissionKind: FullDebug)
DI: Reverse direction of subprogram -> function edge. Previously, subprograms contained a metadata reference to the function they described. Because most clients need to get or set a subprogram for a given function rather than the other way around, this created unneeded inefficiency. For example, many passes needed to call the function llvm::makeSubprogramMap() to build a mapping from functions to subprograms, and the IR linker needed to fix up function references in a way that caused quadratic complexity in the IR linking phase of LTO. This change reverses the direction of the edge by storing the subprogram as function-level metadata and removing DISubprogram's function field. Since this is an IR change, a bitcode upgrade has been provided. Fixes PR23367. An upgrade script for textual IR for out-of-tree clients is attached to the PR. Differential Revision: http://reviews.llvm.org/D14265 llvm-svn: 252219
2015-11-06 06:03:56 +08:00
!2 = !DIFile(filename: "foo.c", directory: "/path/to/dir")
; CHECK: [[SP]] = distinct !DISubprogram
!3 = distinct !DISubprogram(file: !2, scope: !2, line: 51, name: "foo", function: void ()* @foo, type: !4)
!4 = !DISubroutineType(types: !{})