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[lld][WebAssembly] Fix for weak references to data symbols in archives

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Fix a bug where were not handling relocations against weakly undefined
data symbol.  Add a test for this case.  Also ensure that the weak
references to data symbols are not pulled in from archive files by
default (but are if `-u <name>` is added to the command line).

Fixes: PR43696

Differential Revision: https://reviews.llvm.org/D69073

llvm-svn: 375077
This commit is contained in:
Sam Clegg 2019-10-17 03:21:02 +00:00
parent 5926eb5fe6
commit 6c393e9d74
2 changed files with 24 additions and 4 deletions
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26
lld/test/wasm/archive-weak-undefined.ll
View File

@ -1,19 +1,39 @@
; Test that weak undefined symbols do not fetch members from archive files.
; RUN: llc -filetype=obj %s -o %t.o
; RUN: llc -filetype=obj %S/Inputs/ret32.ll -o %t.a1.o
; RUN: llc -filetype=obj %S/Inputs/ret32.ll -o %t.ret32.o
; RUN: llc -filetype=obj %S/Inputs/hello.ll -o %t.hello.o
; RUN: rm -f %t.a
; RUN: llvm-ar rcs %t.a %t.a1.o
; RUN: llvm-ar rcs %t.a %t.ret32.o %t.hello.o
; RUN: wasm-ld %t.o %t.a -o %t.wasm
; RUN: obj2yaml %t.wasm | FileCheck %s
; RUN: wasm-ld -u hello_str %t.o %t.a -o %t2.wasm
; RUN: obj2yaml %t2.wasm | FileCheck %s -check-prefix=CHECK-DATA
target triple = "wasm32-unknown-unknown"
; Weak external function symbol
declare extern_weak i32 @ret32()
; Weak external data symbol
@hello_str = extern_weak global i8*, align 4
define void @_start() {
entry:
br i1 icmp ne (i8** @hello_str, i8** null), label %if.then, label %if.end
if.then:
%call1 = call i32 @ret32()
br label %if.end
if.end:
ret void
}
; Ensure we have no data section. If we do, would mean that hello_str was
; pulled out of the library.
; CHECK-NOT: Type: DATA
; CHECK-DATA: Type: DATA
; CHECK: Name: 'undefined:ret32'
; CHECK-NOT: Name: ret32

2
lld/wasm/InputFiles.cpp
View File

@ -189,7 +189,7 @@ uint32_t ObjFile::calcNewValue(const WasmRelocation &reloc) const {
case R_WASM_MEMORY_ADDR_I32:
case R_WASM_MEMORY_ADDR_LEB:
case R_WASM_MEMORY_ADDR_REL_SLEB:
if (isa<UndefinedData>(sym))
if (isa<UndefinedData>(sym) || sym->isUndefWeak())
return 0;
return cast<DefinedData>(sym)->getVirtualAddress() + reloc.Addend;
case R_WASM_TYPE_INDEX_LEB: