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llvm-mirror/test/ThinLTO/X86/index-const-prop.ll
David Blaikie 1b84262428 ThinLTO: Do not import debug info for imported global constants
It looks like this isn't necessary (in any tests I've done, it results
in the global being described with no location or value in the imported
side - while it's still fully described in the place it's imported from)
& results in significant/pathological debug info growth to home these
location-less global variable descriptions on the import side.

This is a rather pressing/important issue to address - this regressed
executable size for one example I'm looking at by 15%, object size is probably
similar though I haven't measured it, and a 22x increase in the number of CUs
in the cu_index in split DWARF DWP files, creating a similarly large regression
in the time it takes llvm-symbolizer to run on such binaries.

Reviewers: tejohnson, evgeny777

Differential Revision: https://reviews.llvm.org/D55309

llvm-svn: 348416
2018-12-05 21:42:17 +00:00

50 lines
2.2 KiB
LLVM

; Check constant propagation in thinlto combined summary. This allows us to do 2 things:
; 1. Internalize global definition which is not used externally if all accesses to it are read-only
; 2. Make a local copy of internal definition if all accesses to it are readonly. This allows constant
; folding it during optimziation phase.
; -stats requires asserts
; REQUIRES: asserts
; RUN: opt -module-summary %s -o %t1.bc
; RUN: opt -module-summary %p/Inputs/index-const-prop.ll -o %t2.bc
; RUN: llvm-lto -thinlto-action=thinlink -o %t3.index.bc %t1.bc %t2.bc
; RUN: llvm-lto -thinlto-action=import -exported-symbol=main %t1.bc -thinlto-index=%t3.index.bc -o %t1.imported.bc -stats 2>&1 | FileCheck %s --check-prefix=STATS
; RUN: llvm-dis %t1.imported.bc -o - | FileCheck %s --check-prefix=IMPORT
; RUN: llvm-lto -thinlto-action=optimize %t1.imported.bc -o - | llvm-dis - -o - | FileCheck %s --check-prefix=OPTIMIZE
; STATS: 2 module-summary-index - Number of live global variables marked read only
; Check that we don't internalize gBar when it is exported
; RUN: llvm-lto -thinlto-action=import -exported-symbol main -exported-symbol gBar %t1.bc -thinlto-index=%t3.index.bc -o %t1.imported2.bc
; RUN: llvm-dis %t1.imported2.bc -o - | FileCheck %s --check-prefix=IMPORT2
; IMPORT: @gFoo.llvm.0 = internal unnamed_addr global i32 1, align 4, !dbg !0
; IMPORT-NEXT: @gBar = internal local_unnamed_addr global i32 2, align 4, !dbg !5
; IMPORT: !DICompileUnit({{.*}})
; OPTIMIZE: define i32 @main
; OPTIMIZE-NEXT: ret i32 3
; IMPORT2: @gBar = available_externally local_unnamed_addr global i32 2, align 4, !dbg !5
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-pc-linux-gnu"
@gBar = external global i32
; Should not be counted in the stats of live read only variables since it is
; dead and will be dropped anyway.
@gDead = internal unnamed_addr global i32 1, align 4
define i32 @main() local_unnamed_addr {
%call = tail call i32 bitcast (i32 (...)* @foo to i32 ()*)()
%call1 = tail call i32 bitcast (i32 (...)* @bar to i32 ()*)()
%add = add nsw i32 %call1, %call
ret i32 %add
}
declare i32 @foo(...) local_unnamed_addr
declare i32 @bar(...) local_unnamed_addr