[X86][ELF] Prefer lowering MC_GlobalAddress operands to .Lfoo$local for STV_DEFAULT...

This patch restricts the behaviour of referencing via .Lfoo$local
local aliases, introduced in https://reviews.llvm.org/D73230, to
STV_DEFAULT globals only.

Hidden symbols via --fvisiblity=hidden (https://gcc.gnu.org/wiki/Visibility)
is an important scenario.

Benefits:

- Improves the size of object files by using fewer STT_SECTION symbols.

- The code reads a bit better (it was not obvious to me without going
  back to the code reviews why the canBenefitFromLocalAlias function
  currently doesn't consider visibility).

- There is also a side benefit in restoring the effectiveness of the
  --wrap linker option and making the behavior of --wrap consistent
  between LTO and normal builds for references within a translation-unit.
  Note: this --wrap behavior (which is specific to LLD) should not be
  considered reliable. See comments on https://reviews.llvm.org/D73230
  for more.

Differential Revision: https://reviews.llvm.org/D85782

diff --git a/llvm/lib/IR/Globals.cpp b/llvm/lib/IR/Globals.cpp
index dd8e621..ed946ef 100644 (file)
--- a/llvm/lib/IR/Globals.cpp
+++ b/llvm/lib/IR/Globals.cpp
@@ -104,7 +104,8 @@ bool GlobalValue::isInterposable() const {
 
 bool GlobalValue::canBenefitFromLocalAlias() const {
   // See AsmPrinter::getSymbolPreferLocal().
-  return GlobalObject::isExternalLinkage(getLinkage()) && !isDeclaration() &&
+  return hasDefaultVisibility() &&
+         GlobalObject::isExternalLinkage(getLinkage()) && !isDeclaration() &&
          !isa<GlobalIFunc>(this) && !hasComdat();
 }
 

diff --git a/llvm/test/CodeGen/AArch64/emutls.ll b/llvm/test/CodeGen/AArch64/emutls.ll
index 85d2c1a..25be391 100644 (file)
--- a/llvm/test/CodeGen/AArch64/emutls.ll
+++ b/llvm/test/CodeGen/AArch64/emutls.ll
@@ -155,7 +155,6 @@ entry:
 ; ARM64:      .data{{$}}
 ; ARM64:      .globl __emutls_v.i4
 ; ARM64-LABEL: __emutls_v.i4:
-; ARM64-NEXT: .L__emutls_v.i4$local:
 ; ARM64-NEXT: .xword 4
 ; ARM64-NEXT: .xword 4
 ; ARM64-NEXT: .xword 0
@@ -163,7 +162,6 @@ entry:
 
 ; ARM64:      .section .rodata,
 ; ARM64-LABEL: __emutls_t.i4:
-; ARM64-NEXT: .L__emutls_t.i4$local:
 ; ARM64-NEXT: .word 15
 
 ; ARM64-NOT:   __emutls_v.i5:

diff --git a/llvm/test/CodeGen/ARM/emutls.ll b/llvm/test/CodeGen/ARM/emutls.ll
index 4327086..92b656d 100644 (file)
--- a/llvm/test/CodeGen/ARM/emutls.ll
+++ b/llvm/test/CodeGen/ARM/emutls.ll
@@ -238,7 +238,6 @@ entry:
 ; ARM32:      .data{{$}}
 ; ARM32:      .globl __emutls_v.i4
 ; ARM32-LABEL: __emutls_v.i4:
-; ARM32-NEXT:  .L__emutls_v.i4$local:
 ; ARM32-NEXT: .long 4
 ; ARM32-NEXT: .long 4
 ; ARM32-NEXT: .long 0
@@ -246,7 +245,6 @@ entry:
 
 ; ARM32:      .section .rodata,
 ; ARM32-LABEL: __emutls_t.i4:
-; ARM32-NEXT:  .L__emutls_t.i4$local:
 ; ARM32-NEXT: .long 15
 
 ; ARM32-NOT:   __emutls_v.i5:

diff --git a/llvm/test/CodeGen/X86/2008-03-12-ThreadLocalAlias.ll b/llvm/test/CodeGen/X86/2008-03-12-ThreadLocalAlias.ll
index 89d249c..2ca003e 100644 (file)
--- a/llvm/test/CodeGen/X86/2008-03-12-ThreadLocalAlias.ll
+++ b/llvm/test/CodeGen/X86/2008-03-12-ThreadLocalAlias.ll
@@ -12,7 +12,7 @@ target triple = "i386-pc-linux-gnu"
 
 define i32 @foo() {
 ; CHECK-LABEL: foo:
-; CHECK: leal    .L__libc_resp$local@TLSLDM
+; CHECK: leal    __libc_resp@TLSLD
 entry:
        %retval = alloca i32            ; <i32*> [#uses=1]
        %"alloca point" = bitcast i32 0 to i32          ; <i32> [#uses=0]
@@ -27,7 +27,7 @@ return:               ; preds = %entry
 
 define i32 @bar() {
 ; CHECK-LABEL: bar:
-; CHECK: leal    .L__libc_resp$local@TLSLDM
+; CHECK: leal    __libc_resp@TLSLD
 entry:
        %retval = alloca i32            ; <i32*> [#uses=1]
        %"alloca point" = bitcast i32 0 to i32          ; <i32> [#uses=0]

diff --git a/llvm/test/CodeGen/X86/linux-preemption.ll b/llvm/test/CodeGen/X86/linux-preemption.ll
index 49a7bec..15265f4 100644 (file)
--- a/llvm/test/CodeGen/X86/linux-preemption.ll
+++ b/llvm/test/CodeGen/X86/linux-preemption.ll
@@ -20,6 +20,14 @@ define i32* @get_strong_default_global() {
 ; STATIC: movl $strong_default_global, %eax
 ; CHECK32: movl strong_default_global@GOT(%eax), %eax
 
+@strong_hidden_global = hidden global i32 42
+define i32* @get_hidden_default_global() {
+  ret i32* @strong_hidden_global
+}
+; CHECK: leaq strong_hidden_global(%rip), %rax
+; STATIC: movl $strong_hidden_global, %eax
+; CHECK32: leal strong_hidden_global@GOTOFF(%eax), %eax
+
 @weak_default_global = weak global i32 42
 define i32* @get_weak_default_global() {
   ret i32* @weak_default_global
@@ -96,6 +104,14 @@ define i32* @get_strong_default_alias() {
 ; STATIC: movl $strong_default_alias, %eax
 ; CHECK32: movl strong_default_alias@GOT(%eax), %eax
 
+@strong_hidden_alias = hidden alias i32, i32* @aliasee
+define i32* @get_strong_hidden_alias() {
+  ret i32* @strong_hidden_alias
+}
+; CHECK: leaq strong_hidden_alias(%rip), %rax
+; STATIC: movl $strong_hidden_alias, %eax
+; CHECK32: leal strong_hidden_alias@GOTOFF(%eax), %eax
+
 @weak_default_alias = weak alias i32, i32* @aliasee
 define i32* @get_weak_default_alias() {
   ret i32* @weak_default_alias
@@ -149,6 +165,16 @@ define void()* @get_strong_default_function() {
 ; STATIC: movl $strong_default_function, %eax
 ; CHECK32: movl strong_default_function@GOT(%eax), %eax
 
+define hidden void @strong_hidden_function() {
+  ret void
+}
+define void()* @get_strong_hidden_function() {
+  ret void()* @strong_hidden_function
+}
+; CHECK: leaq strong_hidden_function(%rip), %rax
+; STATIC: movl $strong_hidden_function, %eax
+; CHECK32: leal strong_hidden_function@GOTOFF(%eax), %eax
+
 define weak void @weak_default_function() {
   ret void
 }
@@ -234,6 +260,9 @@ define void()* @get_external_preemptable_function() {
 
 ; COMMON:      .globl strong_default_alias
 ; COMMON-NEXT: .set strong_default_alias, aliasee
+; COMMON-NEXT: .globl strong_hidden_alias
+; COMMON-NEXT: .hidden strong_hidden_alias
+; COMMON-NEXT: .set strong_hidden_alias, aliasee
 ; COMMON-NEXT: .weak weak_default_alias
 ; COMMON-NEXT: .set weak_default_alias, aliasee
 ; COMMON-NEXT: .globl strong_local_alias

diff --git a/llvm/test/CodeGen/X86/semantic-interposition-comdat.ll b/llvm/test/CodeGen/X86/semantic-interposition-comdat.ll
index d0efd4d..d11be2d 100644 (file)
--- a/llvm/test/CodeGen/X86/semantic-interposition-comdat.ll
+++ b/llvm/test/CodeGen/X86/semantic-interposition-comdat.ll
@@ -3,7 +3,7 @@
 $comdat_func = comdat any
 
 ; CHECK-LABEL: func2:
-; CHECK-NEXT: .Lfunc2$local
+; CHECK-NOT: .Lfunc2$local
 
 declare void @func()
 

diff --git a/llvm/test/CodeGen/X86/tailcallpic1.ll b/llvm/test/CodeGen/X86/tailcallpic1.ll
index 717cc1f..ed101fc 100644 (file)
--- a/llvm/test/CodeGen/X86/tailcallpic1.ll
+++ b/llvm/test/CodeGen/X86/tailcallpic1.ll
@@ -12,5 +12,5 @@ define fastcc i32 @tailcaller(i32 %in1, i32 %in2) {
 entry:
        %tmp11 = tail call fastcc i32 @tailcallee( i32 %in1, i32 %in2, i32 %in1, i32 %in2 )             ; <i32> [#uses=1]
        ret i32 %tmp11
-; CHECK: jmp .Ltailcallee$local
+; CHECK: jmp tailcallee
 }

diff --git a/llvm/test/CodeGen/X86/tailcallpic3.ll b/llvm/test/CodeGen/X86/tailcallpic3.ll
index 13b160a..edc5805 100644 (file)
--- a/llvm/test/CodeGen/X86/tailcallpic3.ll
+++ b/llvm/test/CodeGen/X86/tailcallpic3.ll
@@ -16,7 +16,7 @@ entry:
   ret void
 }
 ; CHECK: tailcall_hidden:
-; CHECK: jmp .Ltailcallee_hidden$local
+; CHECK: jmp tailcallee_hidden
 
 define internal void @tailcallee_internal() {
 entry:

diff --git a/llvm/test/CodeGen/X86/tailccpic1.ll b/llvm/test/CodeGen/X86/tailccpic1.ll
index dbdc56a..de8f221 100644 (file)
--- a/llvm/test/CodeGen/X86/tailccpic1.ll
+++ b/llvm/test/CodeGen/X86/tailccpic1.ll
@@ -12,5 +12,5 @@ define tailcc i32 @tailcaller(i32 %in1, i32 %in2) {
 entry:
        %tmp11 = tail call tailcc i32 @tailcallee( i32 %in1, i32 %in2, i32 %in1, i32 %in2 )             ; <i32> [#uses=1]
        ret i32 %tmp11
-; CHECK: jmp .Ltailcallee$local
+; CHECK: jmp tailcallee
 }