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[lld][WebAssembly] Fix spurious signature mismatch warnings 

Summary:
This a follow up on: https://reviews.llvm.org/D62153

Handle the case where there are multiple object files that contain
undefined references to the same function.  We only generate a function
variant if the existing symbol is directly called.

See: https://github.com/emscripten-core/emscripten/issues/8995

Subscribers: dschuff, jgravelle-google, aheejin, sunfish, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D67015

llvm-svn: 370509
This commit is contained in:
Sam Clegg 2019-08-30 19:50:59 +00:00
parent 6ccd673206
commit fecfc5920a
2 changed files with 17 additions and 2 deletions
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8
lld/test/wasm/signature-mismatch-unknown.ll
View File

@ -3,6 +3,14 @@
; RUN: wasm-ld --fatal-warnings -o %t.wasm %t.ret32.o %t.main.o
; RUN: wasm-ld --fatal-warnings -o %t.wasm %t.main.o %t.ret32.o
; Also test the case where there are two different object files that contains
; referneces ret32:
; %t.main.o: Does not call ret32 directly; used the wrong signature.
; %t.call-ret32.o: Calls ret32 directly; uses the correct signature.
; RUN: llc -filetype=obj %p/Inputs/call-ret32.ll -o %t.call-ret32.o
; RUN: wasm-ld --export=call_ret32 --fatal-warnings -o %t.wasm %t.main.o %t.call-ret32.o %t.ret32.o
; RUN: wasm-ld --export=call_ret32 --fatal-warnings -o %t.wasm %t.call-ret32.o %t.main.o %t.ret32.o
target triple = "wasm32-unknown-unknown"
; Function declartion with incorrect signature.

11
lld/wasm/SymbolTable.cpp
View File

@ -425,9 +425,16 @@ Symbol *SymbolTable::addUndefinedFunction(StringRef name, StringRef importName,
}
if (!existingFunction->signature && sig)
existingFunction->signature = sig;
if (isCalledDirectly && !signatureMatches(existingFunction, sig))
if (getFunctionVariant(s, sig, file, &s))
if (isCalledDirectly && !signatureMatches(existingFunction, sig)) {
auto* existingUndefined = dyn_cast<UndefinedFunction>(existingFunction);
// If the existing undefined functions is not called direcltly then let
// this one take precedence. Otherwise the existing function is either
// direclty called or defined, in which case we need a function variant.
if (existingUndefined && !existingUndefined->isCalledDirectly)
replaceSym();
else if (getFunctionVariant(s, sig, file, &s))
replaceSym();
}
}
return s;