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[ARM64] When compiling for ELF in PIC mode, local symbols shouldn't go through the GOT 

There's no need for local symbols to go through the GOT, in fact it seems GNU ld is not even emitting GOT entries for local symbols and will error out when trying to resolve a GOT relocation for a local symbol.

This bug triggers when bootstrapping clang on AArch64 Linux with -fPIC and the ARM64 backend. The AArch64 backend is not affected.

With this commit it's now possible to bootstrap clang on AArch64 Linux with the ARM64 backend (-fPIC, -O3).

llvm-svn: 207226
This commit is contained in:
Tilmann Scheller 2014-04-25 13:43:18 +00:00
parent f828526268
commit 2c65bbddd8
2 changed files with 24 additions and 1 deletions
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3
llvm/lib/Target/ARM64/ARM64Subtarget.cpp
View File

@ -77,7 +77,8 @@ ARM64Subtarget::ClassifyGlobalReference(const GlobalValue *GV,
return (isDecl || GV->isWeakForLinker()) ? ARM64II::MO_GOT return (isDecl || GV->isWeakForLinker()) ? ARM64II::MO_GOT
: ARM64II::MO_NO_FLAG; : ARM64II::MO_NO_FLAG;
else else
return ARM64II::MO_GOT; // No need to go through the GOT for local symbols on ELF.
return GV->hasLocalLinkage() ? ARM64II::MO_NO_FLAG : ARM64II::MO_GOT;
} }
return ARM64II::MO_NO_FLAG; return ARM64II::MO_NO_FLAG;

22
llvm/test/CodeGen/ARM64/pic-local-symbol.ll Normal file
View File

@ -0,0 +1,22 @@
; RUN: llc -mtriple=arm64-unknown-linux-gnu -relocation-model=pic < %s | FileCheck %s
@a = internal unnamed_addr global i32 0, align 4
@.str = private unnamed_addr constant [6 x i8] c"test\0A\00", align 1
define i32 @get() {
; CHECK: get:
; CHECK: adrp x{{[0-9]+}}, a
; CHECK-NEXT: ldr w{{[0-9]+}}, [x{{[0-9]}}, :lo12:a]
%res = load i32* @a, align 4
ret i32 %res
}
define void @foo() nounwind {
; CHECK: foo:
; CHECK: adrp x{{[0-9]}}, .L.str
; CHECK-NEXT: add x{{[0-9]}}, x{{[0-9]}}, :lo12:.L.str
tail call void @bar(i8* getelementptr inbounds ([6 x i8]* @.str, i64 0, i64 0))
ret void
}
declare void @bar(i8*)