[lld] [lld][WebAssembly] Fix regression in function signature checking (PR #78831)

[Sam Clegg via llvm-commits]

https://github.com/sbc100 updated https://github.com/llvm/llvm-project/pull/78831

>From 738f7178e8acfaec80ce0322bd52a9edf50f0531 Mon Sep 17 00:00:00 2001
From: Sam Clegg <sbc at chromium.org>
Date: Sat, 20 Jan 2024 05:05:22 +0000
Subject: [PATCH] [lld][WebAssembly] Fix regression in function signature
 checking

Followup to #78658, which caused a regression in emscripten.

When a lazy symbol is added, which resolved and existing undefined
symbol, we don't need/want to replace the undefined symbol with the lazy
one.  Instead we called extract, which replaces the undefined symbol
with the defined one.

The fact that we were first replacing the undefined symbol with a lazy
one before extracting the archive member doesn't normally matter but,
in the case of the function symbol, replacing the undefined symbol with
a lazy symbol means that `addDefinedFunction` sees the existing symbol
as lazy and simply replaces it.

Note that this is consistent with both the ELF code in
`Symbol::resolve(const LazySymbol &other)` and the wasm code prior to
 #78658, neither of which replace the existing symbol with the lazy one
in this case.
---
 lld/test/wasm/signature-mismatch.s | 11 ++++++++++-
 lld/wasm/SymbolTable.cpp           |  2 +-
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/lld/test/wasm/signature-mismatch.s b/lld/test/wasm/signature-mismatch.s
index 5d305efca246496..7dc1b8ced3530d5 100644
--- a/lld/test/wasm/signature-mismatch.s
+++ b/lld/test/wasm/signature-mismatch.s
@@ -8,6 +8,11 @@
 # RUN: wasm-ld -r -o %t.reloc.o %t.main.o %t.ret32.o %t.call.o 2>&1 | FileCheck %s -check-prefix=WARN
 # RUN: obj2yaml %t.reloc.o | FileCheck %s -check-prefix=RELOC
 
+# RUN: rm -f %t.a
+# RUN: ar crS %t.a %t.ret32.o %t.call.o
+# RUN: wasm-ld --export=call_ret32 --export=ret32 -o %t2.wasm %t.main.o %t.a 2>&1 | FileCheck %s -check-prefix=ARCHIVE
+# RUN: obj2yaml %t2.wasm | FileCheck %s -check-prefix=YAML
+
 # RUN: not wasm-ld --fatal-warnings -o %t.wasm %t.main.o %t.ret32.o %t.call.o 2>&1 | FileCheck %s -check-prefix=ERROR
 
 .functype ret32 (i32, i64, i32) -> (i32)
@@ -42,6 +47,10 @@ ret32_address_main:
 # WARN-NEXT: >>> defined as (i32, i64, i32) -> i32 in {{.*}}.main.o
 # WARN-NEXT: >>> defined as (f32) -> i32 in {{.*}}.ret32.o
 
+# ARCHIVE: warning: function signature mismatch: ret32
+# ARCHIVE-NEXT: >>> defined as (i32, i64, i32) -> i32 in {{.*}}.main.o
+# ARCHIVE-NEXT: >>> defined as (f32) -> i32 in {{.*}}.ret32.o
+
 # ERROR: error: function signature mismatch: ret32
 # ERROR-NEXT: >>> defined as (i32, i64, i32) -> i32 in {{.*}}.main.o
 # ERROR-NEXT: >>> defined as (f32) -> i32 in {{.*}}.ret32.o
@@ -56,7 +65,7 @@ ret32_address_main:
 
 # YAML:        - Type:            CUSTOM
 # YAML-NEXT:     Name:            name
-# YAML-NEXT:     FunctionNames:   
+# YAML-NEXT:     FunctionNames:
 # YAML-NEXT:       - Index:           0
 # YAML-NEXT:         Name:            'signature_mismatch:ret32'
 # YAML-NEXT:       - Index:           1
diff --git a/lld/wasm/SymbolTable.cpp b/lld/wasm/SymbolTable.cpp
index c98aa3ee3a7a320..00c347ea3ef2430 100644
--- a/lld/wasm/SymbolTable.cpp
+++ b/lld/wasm/SymbolTable.cpp
@@ -774,7 +774,7 @@ void SymbolTable::addLazy(StringRef name, InputFile *file) {
 
   LLVM_DEBUG(dbgs() << "replacing existing undefined\n");
   const InputFile *oldFile = s->getFile();
-  replaceSymbol<LazySymbol>(s, name, 0, file)->extract();
+  LazySymbol(name, 0, file).extract();
   if (!config->whyExtract.empty())
     ctx.whyExtractRecords.emplace_back(toString(oldFile), s->getFile(), *s);
 }