[lld] 58d5a48 - [lld][WebAssembly] Fix regression in function signature checking (#78831)

[via llvm-commits]

Author: Sam Clegg
Date: 2024-01-19T21:45:30-08:00
New Revision: 58d5a486ec641156dcf420d67e075dc0a766fc5e

URL: https://github.com/llvm/llvm-project/commit/58d5a486ec641156dcf420d67e075dc0a766fc5e
DIFF: https://github.com/llvm/llvm-project/commit/58d5a486ec641156dcf420d67e075dc0a766fc5e.diff

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

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.

Added: 
    

Modified: 
    lld/test/wasm/signature-mismatch.s
    lld/wasm/SymbolTable.cpp

Removed: 
    


################################################################################
diff  --git a/lld/test/wasm/signature-mismatch.s b/lld/test/wasm/signature-mismatch.s
index 5d305efca24649..7dc1b8ced3530d 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 c98aa3ee3a7a32..00c347ea3ef243 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);
 }