[lld][WebAssembly] Fix filename when reporting references to undefined symbols

[sbc100]

When an undefined symbol is referenced from more than one file we were reporting all undefined symbols as originating from just one of them.

This came up while working on WebAssembly/tool-conventions#158 where undefined symbols in one object file were being reported as coming from another.

[llvmbot]

@llvm/pr-subscribers-lld-wasm

@llvm/pr-subscribers-lld

Author: Sam Clegg (sbc100)

Changes

When an undefined symbol is referenced from more than one file we were reporting all undefined symbols as originating from just one of them.

This came up while working on WebAssembly/tool-conventions#158 where undefined symbols in one object file were being reported as coming from another.

---

Full diff: https://github.com/llvm/llvm-project/pull/97444.diff

2 Files Affected:

• (modified) lld/test/wasm/unresolved-symbols.s (+33-19)
• (modified) lld/wasm/Relocations.cpp (+4-4)

diff --git a/lld/test/wasm/unresolved-symbols.s b/lld/test/wasm/unresolved-symbols.s
index 6e183e1878b3a..49e9fb1f87b44 100644
--- a/lld/test/wasm/unresolved-symbols.s
+++ b/lld/test/wasm/unresolved-symbols.s
@@ -1,30 +1,33 @@
-# RUN: llvm-mc -filetype=obj -triple=wasm32-unknown-unknown %s -o %t1.o
+# RUN: split-file %s %t
+# RUN: llvm-mc -filetype=obj -triple=wasm32-unknown-unknown %t/main.s -o %t/main.o
+# RUN: llvm-mc -filetype=obj -triple=wasm32-unknown-unknown %t/secondary.s -o %t/secondary.o
 
-## Check that %t1.o contains undefined symbol undef_func.
-# RUN: not wasm-ld %t1.o -o /dev/null 2>&1 | \
+## Check that %t/main.o contains undefined symbol undef_func.
+# RUN: not wasm-ld --no-gc-sections %t/main.o %t/secondary.o -o /dev/null 2>&1 | \
 # RUN:   FileCheck -check-prefix=ERRUND %s
-# ERRUND: error: {{.*}}1.o: undefined symbol: undef_func
+# ERRUND: error: {{.*}}main.o: undefined symbol: undef_func
+# ERRUND: error: {{.*}}secondary.o: undefined symbol: undef_func
 
 ## report-all is the default one. Check that we get the same error
-# RUN: not wasm-ld %t1.o -o /dev/null --unresolved-symbols=report-all 2>&1 | \
+# RUN: not wasm-ld --no-gc-sections %t/main.o %t/secondary.o -o /dev/null --unresolved-symbols=report-all 2>&1 | \
 # RUN:   FileCheck -check-prefix=ERRUND %s
 
 ## Error out if unknown option value was set.
-# RUN: not wasm-ld %t1.o -o /dev/null --unresolved-symbols=xxx 2>&1 | \
+# RUN: not wasm-ld %t/main.o -o /dev/null --unresolved-symbols=xxx 2>&1 | \
 # RUN:   FileCheck -check-prefix=ERR1 %s
 # ERR1: unknown --unresolved-symbols value: xxx
 ## Check alias.
-# RUN: not wasm-ld %t1.o -o /dev/null --unresolved-symbols xxx 2>&1 | \
+# RUN: not wasm-ld %t/main.o -o /dev/null --unresolved-symbols xxx 2>&1 | \
 # RUN:   FileCheck -check-prefix=ERR1 %s
 
 ## Ignore all should not produce error and should not produce
 ## any imports.  It should create a stub function in the place of the missing
 ## function symbol.
-# RUN: wasm-ld %t1.o -o %t2.wasm --unresolved-symbols=ignore-all
+# RUN: wasm-ld %t/main.o -o %t2.wasm --unresolved-symbols=ignore-all
 # RUN: obj2yaml %t2.wasm | FileCheck -check-prefix=IGNORE %s
 
 ## --warn-unresolved-symbols should behave the same
-# RUN: wasm-ld %t1.o -o %t2.wasm --warn-unresolved-symbols
+# RUN: wasm-ld %t/main.o -o %t2.wasm --warn-unresolved-symbols
 # RUN: obj2yaml %t2.wasm | FileCheck -check-prefix=IGNORE %s
 
 # IGNORE-NOT: - Type:            IMPORT
@@ -61,7 +64,7 @@
 ## by importing them but still report errors/warning for missing data symbols.
 ## `--allow-undefined` should behave like `--import-undefined` +
 ## `--unresolve-symbols=ignore`
-# RUN: wasm-ld %t1.o -o %t3.wasm --import-undefined --unresolved-symbols=ignore-all
+# RUN: wasm-ld %t/main.o -o %t3.wasm --import-undefined --unresolved-symbols=ignore-all
 # RUN: obj2yaml %t3.wasm | FileCheck -check-prefix=IMPORT %s
 #      IMPORT:  - Type:            IMPORT
 # IMPORT-NEXT:    Imports:
@@ -72,23 +75,25 @@
 # IMPORT-NEXT:  - Type:            FUNCTION
 
 ## Check that --import-undefined reports unresolved data symbols.
-# RUN: not wasm-ld %t1.o -o %t3.wasm --import-undefined --unresolved-symbols=report-all 2>&1 | FileCheck -check-prefix=IMPORTUNDEFINED %s
-# IMPORTUNDEFINED-NOT: error: {{.*}}1.o: undefined symbol: undef_func
-# IMPORTUNDEFINED: error: {{.*}}1.o: undefined symbol: undef_data
+# RUN: not wasm-ld %t/main.o -o %t3.wasm --import-undefined --unresolved-symbols=report-all 2>&1 | FileCheck -check-prefix=IMPORTUNDEFINED %s
+# IMPORTUNDEFINED-NOT: error: {{.*}}main.o: undefined symbol: undef_func
+# IMPORTUNDEFINED: error: {{.*}}main.o: undefined symbol: undef_data
 
 ## Do not report undefines if linking relocatable.
-# RUN: wasm-ld -r %t1.o -o %t4.wasm --unresolved-symbols=report-all
+# RUN: wasm-ld -r %t/main.o -o %t4.wasm --unresolved-symbols=report-all
 # RUN: llvm-readobj %t4.wasm > /dev/null 2>&1
 
-.functype undef_func () -> ()
-.functype get_data_addr () -> (i32)
-.functype get_func_addr () -> (i32)
-
 ## import-dynamic should fail due to incompatible relocations.
-# RUN: not wasm-ld %t1.o -o %t5.wasm --unresolved-symbols=import-dynamic 2>&1 | FileCheck -check-prefix=ERRNOPIC %s
+# RUN: not wasm-ld %t/main.o -o %t5.wasm --unresolved-symbols=import-dynamic 2>&1 | FileCheck -check-prefix=ERRNOPIC %s
 # ERRNOPIC: relocation R_WASM_MEMORY_ADDR_SLEB cannot be used against symbol `undef_data`; recompile with -fPIC
 # ERRNOPIC: relocation R_WASM_TABLE_INDEX_SLEB cannot be used against symbol `undef_func`; recompile with -fPIC
 
+#--- main.s
+
+.functype undef_func () -> ()
+.functype get_data_addr () -> (i32)
+.functype get_func_addr () -> (i32)
+
 .globl _start
 _start:
     .functype _start () -> ()
@@ -112,3 +117,12 @@ get_func_addr:
     i32.const undef_func
     return
     end_function
+
+#--- secondary.s
+
+.functype undef_func () -> ()
+.globl foo
+foo:
+    .functype foo () -> ()
+    call undef_func
+    end_function
diff --git a/lld/wasm/Relocations.cpp b/lld/wasm/Relocations.cpp
index 09b0a24ff011a..09861319e77dc 100644
--- a/lld/wasm/Relocations.cpp
+++ b/lld/wasm/Relocations.cpp
@@ -42,14 +42,14 @@ static bool allowUndefined(const Symbol* sym) {
   return config->allowUndefinedSymbols.count(sym->getName()) != 0;
 }
 
-static void reportUndefined(Symbol *sym) {
+static void reportUndefined(ObjFile *file, Symbol *sym) {
   if (!allowUndefined(sym)) {
     switch (config->unresolvedSymbols) {
     case UnresolvedPolicy::ReportError:
-      error(toString(sym->getFile()) + ": undefined symbol: " + toString(*sym));
+      error(toString(file) + ": undefined symbol: " + toString(*sym));
       break;
     case UnresolvedPolicy::Warn:
-      warn(toString(sym->getFile()) + ": undefined symbol: " + toString(*sym));
+      warn(toString(file) + ": undefined symbol: " + toString(*sym));
       break;
     case UnresolvedPolicy::Ignore:
       LLVM_DEBUG(dbgs() << "ignoring undefined symbol: " + toString(*sym) +
@@ -171,7 +171,7 @@ void scanRelocations(InputChunk *chunk) {
       }
     } else if (sym->isUndefined() && !config->relocatable && !sym->isWeak()) {
       // Report undefined symbols
-      reportUndefined(sym);
+      reportUndefined(file, sym);
     }
   }
 }

[aheejin]

main.o and secondary.o too?

[sbc100]

Yes, that is what I want to test here. Without this change the references in secondard.o are reported (incorrectly) as coming from main.o.

[sbc100]

I updated the comment to make it more clear what I am testing here.

[dschuff]

TIL split-file is a thing...

[sbc100]

Yeah its kind of nice! One downside is that the test files themselves are less independently useful, but thats seems like a minor things compared to the hassle of splitting out secondary files into the Input/ diretory.