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llvm-mirror/test/ThinLTO/X86/index-const-prop2.ll
Fangrui Song d41ca54775 [ThinLTO] Drop dso_local if a GlobalVariable satisfies isDeclarationForLinker()
dso_local leads to direct access even if the definition is not within this compilation unit (it is
still in the same linkage unit). On ELF, such a relocation (e.g. R_X86_64_PC32) referencing a
STB_GLOBAL STV_DEFAULT object can cause a linker error in a -shared link.

If the linkage is changed to available_externally, the dso_local flag should be dropped, so that no
direct access will be generated.

The current behavior is benign, because -fpic does not assume dso_local
(clang/lib/CodeGen/CodeGenModule.cpp:shouldAssumeDSOLocal).
If we do that for -fno-semantic-interposition (D73865), there will be an
R_X86_64_PC32 linker error without this patch.

Reviewed By: tejohnson

Differential Revision: https://reviews.llvm.org/D74751
2020-04-07 15:46:01 -07:00

106 lines
3.7 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.
; RUN: opt -module-summary %s -o %t1.bc
; RUN: opt -module-summary %p/Inputs/index-const-prop.ll -o %t2.bc
; RUN: llvm-lto2 run %t1.bc %t2.bc -save-temps \
; RUN: -r=%t2.bc,foo,pl \
; RUN: -r=%t2.bc,bar,pl \
; RUN: -r=%t2.bc,baz,pl \
; RUN: -r=%t2.bc,rand, \
; RUN: -r=%t2.bc,gBar,pl \
; RUN: -r=%t1.bc,main,plx \
; RUN: -r=%t1.bc,main2,pl \
; RUN: -r=%t1.bc,foo, \
; RUN: -r=%t1.bc,bar, \
; RUN: -r=%t1.bc,baz, \
; RUN: -r=%t1.bc,gBar, \
; RUN: -o %t3
; RUN: llvm-dis %t3.1.3.import.bc -o - | FileCheck %s --check-prefix=IMPORT
; RUN: llvm-dis %t3.1.5.precodegen.bc -o - | FileCheck %s --check-prefix=CODEGEN
; Now check that we won't internalize global (gBar) if it's externally referenced
; RUN: llvm-lto2 run %t1.bc %t2.bc -save-temps \
; RUN: -r=%t2.bc,foo,pl \
; RUN: -r=%t2.bc,bar,pl \
; RUN: -r=%t2.bc,baz,pl \
; RUN: -r=%t2.bc,rand, \
; RUN: -r=%t2.bc,gBar,plx \
; RUN: -r=%t1.bc,main,plx \
; RUN: -r=%t1.bc,main2,pl \
; RUN: -r=%t1.bc,foo, \
; RUN: -r=%t1.bc,bar, \
; RUN: -r=%t1.bc,baz, \
; RUN: -r=%t1.bc,gBar, \
; RUN: -o %t4
; RUN: llvm-dis %t4.1.3.import.bc -o - | FileCheck %s --check-prefix=IMPORT2
; Run again but with main2 exported instead of main to check that write only
; variables are optimized out.
; RUN: llvm-lto2 run %t1.bc %t2.bc -save-temps \
; RUN: -r=%t2.bc,foo,pl \
; RUN: -r=%t2.bc,bar,pl \
; RUN: -r=%t2.bc,baz,pl \
; RUN: -r=%t2.bc,rand, \
; RUN: -r=%t2.bc,gBar,pl \
; RUN: -r=%t1.bc,main,pl \
; RUN: -r=%t1.bc,main2,plx \
; RUN: -r=%t1.bc,foo, \
; RUN: -r=%t1.bc,bar, \
; RUN: -r=%t1.bc,baz, \
; RUN: -r=%t1.bc,gBar, \
; RUN: -o %t5
; RUN: llvm-dis %t5.1.3.import.bc -o - | FileCheck %s --check-prefix=IMPORT-WRITEONLY
; RUN: llvm-dis %t5.1.5.precodegen.bc -o - | FileCheck %s --check-prefix=CODEGEN2
; Check that gFoo and gBar were eliminated from source module together
; with corresponsing stores
; RUN: llvm-dis %t5.2.5.precodegen.bc -o - | FileCheck %s --check-prefix=CODEGEN2-SRC
; IMPORT: @gFoo.llvm.0 = internal unnamed_addr global i32 1, align 4
; IMPORT-NEXT: @gBar = internal local_unnamed_addr global i32 2, align 4
; IMPORT: !DICompileUnit({{.*}})
; Write only variables are imported with a zero initializer.
; IMPORT-WRITEONLY: @gFoo.llvm.0 = internal unnamed_addr global i32 0
; IMPORT-WRITEONLY: @gBar = internal local_unnamed_addr global i32 0
; CODEGEN: i32 @main()
; CODEGEN-NEXT: ret i32 3
; IMPORT2: @gBar = available_externally local_unnamed_addr global i32 2, align 4
; CODEGEN2: i32 @main2
; CODEGEN2-NEXT: %1 = tail call i32 @rand()
; CODEGEN2-NEXT: %2 = tail call i32 @rand()
; CODEGEN2-NEXT: ret i32 0
; CODEGEN2-SRC: void @baz()
; CODEGEN2-SRC-NEXT: %1 = tail call i32 @rand()
; CODEGEN2-SRC-NEXT: %2 = tail call i32 @rand()
; CODEGEN2-SRC-NEXT: ret void
target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-pc-linux-gnu"
; We should be able to link external definition of gBar to its declaration
@gBar = external global i32
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
}
define i32 @main2() local_unnamed_addr {
tail call void @baz()
ret i32 0
}
declare i32 @foo(...) local_unnamed_addr
declare i32 @bar(...) local_unnamed_addr
declare void @baz() local_unnamed_addr