maxjhandsome
/
llvm-project
forked from OSchip/llvm-project
1
0
Fork 0
Code Issues Pull Requests Packages Releases Wiki Activity

-fno-semantic-interposition: Don't set dso_local on GlobalVariable 

`clang -fpic -fno-semantic-interposition` may set dso_local on variables for -fpic.

GCC folks consider there are 'address interposition' and 'semantic interposition',
and 'disabling semantic interposition' can optimize function calls but
cannot change variable references to use local aliases
(https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100483).

This patch removes dso_local for variables in
`clang -fpic -fno-semantic-interposition` mode so that the built shared objects can
work with copy relocations. Building llvm-project tiself with
-fno-semantic-interposition (D102453) should now be safe with trunk Clang.

Example:
```
// a.c
int var;
int *addr() { return var; }

// old: cannot be interposed
movslq  .Lvar$local(%rip), %rax
// new: can be interposed
movq    var@GOTPCREL(%rip), %rax
movslq  (%rax), %rax
```

The local alias lowering for `GlobalVariable`s is kept in case there is a
future option allowing local aliases.

Reviewed By: rnk

Differential Revision: https://reviews.llvm.org/D102583
This commit is contained in:
Fangrui Song 2021-05-19 16:08:28 -07:00
parent 2f8ac0758b
commit 37561ba89b
9 changed files with 48 additions and 59 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
clang/lib/CodeGen/CodeGenModule.cpp
View File

@ -1007,9 +1007,9 @@ static bool shouldAssumeDSOLocal(const CodeGenModule &CGM,
// On ELF, if -fno-semantic-interposition is specified and the target
// supports local aliases, there will be neither CC1
// -fsemantic-interposition nor -fhalf-no-semantic-interposition. Set
// dso_local if using a local alias is preferable (can avoid GOT
// indirection).
if (!GV->canBenefitFromLocalAlias())
// dso_local on the function if using a local alias is preferable (can avoid
// PLT indirection).
if (!(isa<llvm::Function>(GV) && GV->canBenefitFromLocalAlias()))
return false;
return !(CGM.getLangOpts().SemanticInterposition ||
CGM.getLangOpts().HalfNoSemanticInterposition);

19
clang/test/CodeGen/SystemZ/builtins-systemz-zvector-constrained.c
View File

@ -66,28 +66,17 @@ void test_core(void) {
// CHECK-ASM: vsceg %{{.*}}, 0(%{{.*}},%{{.*}}), 1
vd = vec_xl(idx, cptrd);
// CHECK-ASM-NEXT: lgfrl %r3, idx
// CHECK-ASM-NEXT: lgrl %r4, cptrd
// CHECK-ASM-NEXT: vl %v0, 0(%r3,%r4){{$}}
// CHECK-ASM-NEXT: lgf %r5, 0(%r3)
// CHECK-ASM-NEXT: lg %r13, 0(%r4)
// CHECK-ASM-NEXT: vl %v0, 0(%r5,%r13){{$}}
// CHECK-ASM-NEXT: vst
vd = vec_xld2(idx, cptrd);
// CHECK-ASM-NEXT: lgfrl %r3, idx
// CHECK-ASM-NEXT: lgrl %r4, cptrd
// CHECK-ASM-NEXT: vl %v0, 0(%r3,%r4){{$}}
// CHECK-ASM-NEXT: vst
// CHECK-ASM: vst
vec_xst(vd, idx, ptrd);
// CHECK-ASM-NEXT: vl
// CHECK-ASM-NEXT: lgfrl %r3, idx
// CHECK-ASM-NEXT: lgrl %r4, ptrd
// CHECK-ASM-NEXT: vst %v0, 0(%r3,%r4){{$}}
vec_xstd2(vd, idx, ptrd);
// CHECK-ASM-NEXT: vl
// CHECK-ASM-NEXT: lgfrl %r3, idx
// CHECK-ASM-NEXT: lgrl %r4, ptrd
// CHECK-ASM-NEXT: vst %v0, 0(%r3,%r4){{$}}
vd = vec_splat(vd, 0);
// CHECK: shufflevector <2 x double> %{{.*}}, <2 x double> poison, <2 x i32> zeroinitializer

4
clang/test/CodeGen/attr-weakref2.c
View File

@ -8,7 +8,7 @@ int test1_h(void) {
return test1_g;
}
// CHECK: @test2_f = dso_local global i32 0, align 4
// CHECK: @test2_f = global i32 0, align 4
int test2_f;
static int test2_g __attribute__((weakref("test2_f")));
int test2_h(void) {
@ -25,7 +25,7 @@ int test3_h(void) {
return test3_g;
}
// CHECK: @test4_f = dso_local global i32 0, align 4
// CHECK: @test4_f = global i32 0, align 4
extern int test4_f;
static int test4_g __attribute__((weakref("test4_f")));
int test4_h(void) {

2
clang/test/CodeGen/semantic-interposition.c
View File

@ -8,7 +8,7 @@
/// but local aliases are not used.
// RUN: %clang_cc1 -triple x86_64-linux-gnu -emit-llvm -mrelocation-model pic -pic-level 1 -fhalf-no-semantic-interposition %s -o - | FileCheck %s --check-prefixes=PREEMPT,NOMETADATA
// CHECK: @var = dso_local global i32 0, align 4
// CHECK: @var = global i32 0, align 4
// CHECK: @ext_var = external global i32, align 4
// CHECK: @ifunc = ifunc i32 (), bitcast (i8* ()* @ifunc_resolver to i32 ()*)
// CHECK: define dso_local i32 @func()

10
clang/test/CodeGenCUDA/device-stub.cu
View File

@ -61,17 +61,17 @@
#ifndef NOGLOBALS
// NORDC-DAG: @device_var = internal global i32
// RDC-DAG: @device_var = dso_local global i32
// RDC-DAG: @device_var = global i32
// WIN-DAG: @"?device_var@@3HA" = internal global i32
__device__ int device_var;
// NORDC-DAG: @constant_var = internal global i32
// RDC-DAG: @constant_var = dso_local global i32
// RDC-DAG: @constant_var = global i32
// WIN-DAG: @"?constant_var@@3HA" = internal global i32
__constant__ int constant_var;
// NORDC-DAG: @shared_var = internal global i32
// RDC-DAG: @shared_var = dso_local global i32
// RDC-DAG: @shared_var = global i32
// WIN-DAG: @"?shared_var@@3HA" = internal global i32
__shared__ int shared_var;
@ -95,12 +95,12 @@ extern __constant__ int ext_constant_var;
// external device-side variables with definitions should generate
// definitions for the shadows.
// NORDC-DAG: @ext_device_var_def = internal global i32 undef,
// RDC-DAG: @ext_device_var_def = dso_local global i32 undef,
// RDC-DAG: @ext_device_var_def = global i32 undef,
// WIN-DAG: @"?ext_device_var_def@@3HA" = internal global i32 undef
extern __device__ int ext_device_var_def;
__device__ int ext_device_var_def = 1;
// NORDC-DAG: @ext_device_var_def = internal global i32 undef,
// RDC-DAG: @ext_device_var_def = dso_local global i32 undef,
// RDC-DAG: @ext_device_var_def = global i32 undef,
// WIN-DAG: @"?ext_constant_var_def@@3HA" = internal global i32 undef
__constant__ int ext_constant_var_def = 2;

24
clang/test/CodeGenCUDA/device-var-linkage.cu
View File

@ -13,17 +13,17 @@
#include "Inputs/cuda.h"
// DEV-DAG: @v1 = dso_local addrspace(1) externally_initialized global i32 0
// DEV-DAG: @v1 = addrspace(1) externally_initialized global i32 0
// NORDC-H-DAG: @v1 = internal global i32 undef
// RDC-H-DAG: @v1 = dso_local global i32 undef
// RDC-H-DAG: @v1 = global i32 undef
__device__ int v1;
// DEV-DAG: @v2 = dso_local addrspace(4) externally_initialized global i32 0
// DEV-DAG: @v2 = addrspace(4) externally_initialized global i32 0
// NORDC-H-DAG: @v2 = internal global i32 undef
// RDC-H-DAG: @v2 = dso_local global i32 undef
// RDC-H-DAG: @v2 = global i32 undef
__constant__ int v2;
// DEV-DAG: @v3 = dso_local addrspace(1) externally_initialized global i32 addrspace(1)* null
// DEV-DAG: @v3 = addrspace(1) externally_initialized global i32 addrspace(1)* null
// NORDC-H-DAG: @v3 = internal externally_initialized global i32* null
// RDC-H-DAG: @v3 = dso_local externally_initialized global i32* null
// RDC-H-DAG: @v3 = externally_initialized global i32* null
__managed__ int v3;
// DEV-DAG: @ev1 = external addrspace(1) global i32
@ -36,16 +36,16 @@ extern __constant__ int ev2;
// HOST-DAG: @ev3 = external externally_initialized global i32*
extern __managed__ int ev3;
// NORDC-DAG: @_ZL3sv1 = dso_local addrspace(1) externally_initialized global i32 0
// RDC-DAG: @_ZL3sv1.static.[[HASH:.*]] = dso_local addrspace(1) externally_initialized global i32 0
// NORDC-DAG: @_ZL3sv1 = addrspace(1) externally_initialized global i32 0
// RDC-DAG: @_ZL3sv1.static.[[HASH:.*]] = addrspace(1) externally_initialized global i32 0
// HOST-DAG: @_ZL3sv1 = internal global i32 undef
static __device__ int sv1;
// NORDC-DAG: @_ZL3sv2 = dso_local addrspace(4) externally_initialized global i32 0
// RDC-DAG: @_ZL3sv2.static.[[HASH]] = dso_local addrspace(4) externally_initialized global i32 0
// NORDC-DAG: @_ZL3sv2 = addrspace(4) externally_initialized global i32 0
// RDC-DAG: @_ZL3sv2.static.[[HASH]] = addrspace(4) externally_initialized global i32 0
// HOST-DAG: @_ZL3sv2 = internal global i32 undef
static __constant__ int sv2;
// NORDC-DAG: @_ZL3sv3 = dso_local addrspace(1) externally_initialized global i32 addrspace(1)* null
// RDC-DAG: @_ZL3sv3.static.[[HASH]] = dso_local addrspace(1) externally_initialized global i32 addrspace(1)* null
// NORDC-DAG: @_ZL3sv3 = addrspace(1) externally_initialized global i32 addrspace(1)* null
// RDC-DAG: @_ZL3sv3.static.[[HASH]] = addrspace(1) externally_initialized global i32 addrspace(1)* null
// HOST-DAG: @_ZL3sv3 = internal externally_initialized global i32* null
static __managed__ int sv3;

26
clang/test/CodeGenCUDA/managed-var.cu
View File

@ -27,21 +27,21 @@ struct vec {
float x,y,z;
};
// DEV-DAG: @x.managed = dso_local addrspace(1) externally_initialized global i32 1, align 4
// DEV-DAG: @x = dso_local addrspace(1) externally_initialized global i32 addrspace(1)* null
// DEV-DAG: @x.managed = addrspace(1) externally_initialized global i32 1, align 4
// DEV-DAG: @x = addrspace(1) externally_initialized global i32 addrspace(1)* null
// NORDC-DAG: @x.managed = internal global i32 1
// RDC-DAG: @x.managed = dso_local global i32 1
// RDC-DAG: @x.managed = global i32 1
// NORDC-DAG: @x = internal externally_initialized global i32* null
// RDC-DAG: @x = dso_local externally_initialized global i32* null
// RDC-DAG: @x = externally_initialized global i32* null
// HOST-DAG: @[[DEVNAMEX:[0-9]+]] = {{.*}}c"x\00"
__managed__ int x = 1;
// DEV-DAG: @v.managed = dso_local addrspace(1) externally_initialized global [100 x %struct.vec] zeroinitializer, align 4
// DEV-DAG: @v = dso_local addrspace(1) externally_initialized global [100 x %struct.vec] addrspace(1)* null
// DEV-DAG: @v.managed = addrspace(1) externally_initialized global [100 x %struct.vec] zeroinitializer, align 4
// DEV-DAG: @v = addrspace(1) externally_initialized global [100 x %struct.vec] addrspace(1)* null
__managed__ vec v[100];
// DEV-DAG: @v2.managed = dso_local addrspace(1) externally_initialized global <{ %struct.vec, [99 x %struct.vec] }> <{ %struct.vec { float 1.000000e+00, float 1.000000e+00, float 1.000000e+00 }, [99 x %struct.vec] zeroinitializer }>, align 4
// DEV-DAG: @v2 = dso_local addrspace(1) externally_initialized global <{ %struct.vec, [99 x %struct.vec] }> addrspace(1)* null
// DEV-DAG: @v2.managed = addrspace(1) externally_initialized global <{ %struct.vec, [99 x %struct.vec] }> <{ %struct.vec { float 1.000000e+00, float 1.000000e+00, float 1.000000e+00 }, [99 x %struct.vec] zeroinitializer }>, align 4
// DEV-DAG: @v2 = addrspace(1) externally_initialized global <{ %struct.vec, [99 x %struct.vec] }> addrspace(1)* null
__managed__ vec v2[100] = {{1, 1, 1}};
// DEV-DAG: @ex.managed = external addrspace(1) global i32, align 4
@ -50,16 +50,16 @@ __managed__ vec v2[100] = {{1, 1, 1}};
// HOST-DAG: @ex = external externally_initialized global i32*
extern __managed__ int ex;
// NORDC-D-DAG: @_ZL2sx.managed = dso_local addrspace(1) externally_initialized global i32 1, align 4
// NORDC-D-DAG: @_ZL2sx = dso_local addrspace(1) externally_initialized global i32 addrspace(1)* null
// RDC-D-DAG: @_ZL2sx.static.[[HASH:.*]].managed = dso_local addrspace(1) externally_initialized global i32 1, align 4
// RDC-D-DAG: @_ZL2sx.static.[[HASH]] = dso_local addrspace(1) externally_initialized global i32 addrspace(1)* null
// NORDC-D-DAG: @_ZL2sx.managed = addrspace(1) externally_initialized global i32 1, align 4
// NORDC-D-DAG: @_ZL2sx = addrspace(1) externally_initialized global i32 addrspace(1)* null
// RDC-D-DAG: @_ZL2sx.static.[[HASH:.*]].managed = addrspace(1) externally_initialized global i32 1, align 4
// RDC-D-DAG: @_ZL2sx.static.[[HASH]] = addrspace(1) externally_initialized global i32 addrspace(1)* null
// HOST-DAG: @_ZL2sx.managed = internal global i32 1
// HOST-DAG: @_ZL2sx = internal externally_initialized global i32* null
// NORDC-DAG: @[[DEVNAMESX:[0-9]+]] = {{.*}}c"_ZL2sx\00"
// RDC-DAG: @[[DEVNAMESX:[0-9]+]] = {{.*}}c"_ZL2sx.static.[[HASH:.*]]\00"
// POSTFIX: @_ZL2sx.static.[[HASH:.*]] = dso_local addrspace(1) externally_initialized global i32 addrspace(1)* null
// POSTFIX: @_ZL2sx.static.[[HASH:.*]] = addrspace(1) externally_initialized global i32 addrspace(1)* null
// POSTFIX: @[[DEVNAMESX:[0-9]+]] = {{.*}}c"_ZL2sx.static.[[HASH]]\00"
static __managed__ int sx = 1;

10
clang/test/CodeGenCUDA/static-device-var-rdc.cu
View File

@ -51,14 +51,14 @@
// HOST-DAG: @_ZL1y = internal global i32 undef
// Test normal static device variables
// INT-DEV-DAG: @_ZL1x = dso_local addrspace(1) externally_initialized global i32 0
// INT-DEV-DAG: @_ZL1x = addrspace(1) externally_initialized global i32 0
// INT-HOST-DAG: @[[DEVNAMEX:[0-9]+]] = {{.*}}c"_ZL1x\00"
// Test externalized static device variables
// EXT-DEV-DAG: @_ZL1x.static.[[HASH:.*]] = dso_local addrspace(1) externally_initialized global i32 0
// EXT-DEV-DAG: @_ZL1x.static.[[HASH:.*]] = addrspace(1) externally_initialized global i32 0
// EXT-HOST-DAG: @[[DEVNAMEX:[0-9]+]] = {{.*}}c"_ZL1x.static.[[HASH:.*]]\00"
// POSTFIX: @_ZL1x.static.[[HASH:.*]] = dso_local addrspace(1) externally_initialized global i32 0
// POSTFIX: @_ZL1x.static.[[HASH:.*]] = addrspace(1) externally_initialized global i32 0
// POSTFIX: @[[DEVNAMEX:[0-9]+]] = {{.*}}c"_ZL1x.static.[[HASH]]\00"
static __device__ int x;
@ -69,11 +69,11 @@ static __device__ int x;
static __device__ int x2;
// Test normal static device variables
// INT-DEV-DAG: @_ZL1y = dso_local addrspace(4) externally_initialized global i32 0
// INT-DEV-DAG: @_ZL1y = addrspace(4) externally_initialized global i32 0
// INT-HOST-DAG: @[[DEVNAMEY:[0-9]+]] = {{.*}}c"_ZL1y\00"
// Test externalized static device variables
// EXT-DEV-DAG: @_ZL1y.static.[[HASH]] = dso_local addrspace(4) externally_initialized global i32 0
// EXT-DEV-DAG: @_ZL1y.static.[[HASH]] = addrspace(4) externally_initialized global i32 0
// EXT-HOST-DAG: @[[DEVNAMEY:[0-9]+]] = {{.*}}c"_ZL1y.static.[[HASH]]\00"
static __constant__ int y;

6
clang/test/OpenMP/declare_target_only_one_side_compilation.cpp
View File

@ -67,9 +67,9 @@ static int GY;
// DEVICE-NOT: llvm.used
// DEVICE-NOT: omp_offload
// HOST-DAG: @G7 = dso_local global i32 0, align 4
// HOST-DAG: @G7 = global i32 0, align 4
// HOST-DAG: @_ZL2G8 = internal global i32 0, align 4
// HOST-DAG: @G9 = dso_local global i32 0, align 4
// HOST-DAG: @G9 = global i32 0, align 4
// HOST-DAG: @_ZL3G10 = internal global i32 0, align 4
// HOST-DAG: @G11 = dso_local global i32 0, align 4
// HOST-DAG: @G11 = global i32 0, align 4
// HOST-DAG: @_ZL3G12 = internal global i32 0, align 4