[WebAssembly] Fix undefined weak function symbols in LTO builds
Summary: Fixes PR40219
Subscribers: dschuff, mehdi_amini, inglorion, jgravelle-google, aheejin, sunfish, steven_wu, dexonsmith, llvm-commits
Differential Revision: https://reviews.llvm.org/D57420
git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@352575 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/wasm/lto/weak-undefined.ll b/test/wasm/lto/weak-undefined.ll
new file mode 100644
index 0000000..54b302e
--- /dev/null
+++ b/test/wasm/lto/weak-undefined.ll
@@ -0,0 +1,20 @@
+; RUN: llvm-as %s -o %t.o
+; RUN: wasm-ld %t.o -o %t.wasm
+; RUN: obj2yaml %t.wasm | FileCheck %s
+
+; Test that undefined weak external functions are handled in the LTO case
+; We had a bug where stub function generation was failing because functions
+; that are in bitcode (pre-LTO) don't have signatures assigned.
+
+target datalayout = "e-m:e-p:32:32-i64:64-n32:64-S128"
+target triple = "wasm32-unknown-unknown"
+
+declare extern_weak i32 @foo()
+
+define void @_start() #0 {
+entry:
+ %call2 = call i32 @foo()
+ ret void
+}
+
+; CHECK: Name: undefined function foo
diff --git a/wasm/Driver.cpp b/wasm/Driver.cpp
index eb32802..860d9f5 100644
--- a/wasm/Driver.cpp
+++ b/wasm/Driver.cpp
@@ -587,9 +587,6 @@
Symbol *EntrySym = nullptr;
if (!Config->Relocatable) {
- // Add synthetic dummies for weak undefined functions.
- handleWeakUndefines();
-
if (!Config->Shared && !Config->Entry.empty()) {
EntrySym = handleUndefined(Config->Entry);
if (EntrySym && EntrySym->isDefined())
@@ -613,6 +610,11 @@
if (errorCount())
return;
+ // Add synthetic dummies for weak undefined functions. Must happen
+ // after LTO otherwise functions may not yet have signatures.
+ if (!Config->Relocatable)
+ handleWeakUndefines();
+
if (EntrySym)
EntrySym->setHidden(false);
