[lld] 4b8e2d8 - [lld][WebAssembly] Fix crash on function signature mismatch with --relocatable

[Sam Clegg via llvm-commits]

Author: Sam Clegg
Date: 2020-04-25T10:26:11-07:00
New Revision: 4b8e2d8e81adf3aa1ea79fe0b908100c4ea69f65

URL: https://github.com/llvm/llvm-project/commit/4b8e2d8e81adf3aa1ea79fe0b908100c4ea69f65
DIFF: https://github.com/llvm/llvm-project/commit/4b8e2d8e81adf3aa1ea79fe0b908100c4ea69f65.diff

LOG: [lld][WebAssembly] Fix crash on function signature mismatch with --relocatable

These stub new function were not being added to the symbol table
which in turn meant that we were crashing when trying to output
relocations against them.

Differential Revision: https://reviews.llvm.org/D78779

Added: 
    

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

Removed: 
    


################################################################################
diff  --git a/lld/test/wasm/signature-mismatch.ll b/lld/test/wasm/signature-mismatch.ll
index 116d81823ab0..bb9204ea7e45 100644
--- a/lld/test/wasm/signature-mismatch.ll
+++ b/lld/test/wasm/signature-mismatch.ll
@@ -1,8 +1,13 @@
 ; RUN: llc -filetype=obj %p/Inputs/ret32.ll -o %t.ret32.o
 ; RUN: llc -filetype=obj %p/Inputs/call-ret32.ll -o %t.call.o
 ; RUN: llc -filetype=obj %s -o %t.main.o
+
 ; RUN: wasm-ld --export=call_ret32 --export=ret32 -o %t.wasm %t.main.o %t.ret32.o %t.call.o 2>&1 | FileCheck %s -check-prefix=WARN
 ; RUN: obj2yaml %t.wasm | FileCheck %s -check-prefix=YAML
+
+; 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: not wasm-ld --fatal-warnings -o %t.wasm %t.main.o %t.ret32.o %t.call.o 2>&1 | FileCheck %s -check-prefix=ERROR
 
 target triple = "wasm32-unknown-unknown"
@@ -49,3 +54,38 @@ declare i32 @ret32(i32, i64, i32) local_unnamed_addr
 ; YAML-NEXT:         Name:            call_ret32
 ; YAML-NEXT: ...
 
+;      RELOC:     Name:            linking
+; RELOC-NEXT:     Version:         2
+; RELOC-NEXT:     SymbolTable:
+; RELOC-NEXT:       - Index:           0
+; RELOC-NEXT:         Kind:            FUNCTION
+; RELOC-NEXT:         Name:            _start
+; RELOC-NEXT:         Flags:           [ VISIBILITY_HIDDEN ]
+; RELOC-NEXT:         Function:        1
+; RELOC-NEXT:       - Index:           1
+; RELOC-NEXT:         Kind:            FUNCTION
+; RELOC-NEXT:         Name:            ret32
+; RELOC-NEXT:         Flags:           [ VISIBILITY_HIDDEN ]
+; RELOC-NEXT:         Function:        2
+; RELOC-NEXT:       - Index:           2
+; RELOC-NEXT:         Kind:            DATA
+; RELOC-NEXT:         Name:            ret32_address_main
+; RELOC-NEXT:         Flags:           [  ]
+; RELOC-NEXT:         Segment:         0
+; RELOC-NEXT:         Size:            4
+; RELOC-NEXT:       - Index:           3
+; RELOC-NEXT:         Kind:            FUNCTION
+; RELOC-NEXT:         Name:            call_ret32
+; RELOC-NEXT:         Flags:           [ VISIBILITY_HIDDEN ]
+; RELOC-NEXT:         Function:        3
+; RELOC-NEXT:       - Index:           4
+; RELOC-NEXT:         Kind:            DATA
+; RELOC-NEXT:         Name:            ret32_address
+; RELOC-NEXT:         Flags:           [  ]
+; RELOC-NEXT:         Segment:         1
+; RELOC-NEXT:         Size:            4
+; RELOC-NEXT:       - Index:           5
+; RELOC-NEXT:         Kind:            FUNCTION
+; RELOC-NEXT:         Name:            'signature_mismatch:ret32'
+; RELOC-NEXT:         Flags:           [ BINDING_LOCAL ]
+; RELOC-NEXT:         Function:        0

diff  --git a/lld/wasm/SymbolTable.cpp b/lld/wasm/SymbolTable.cpp
index 99d18178eeac..6f6706e36aab 100644
--- a/lld/wasm/SymbolTable.cpp
+++ b/lld/wasm/SymbolTable.cpp
@@ -642,8 +642,10 @@ InputFunction *SymbolTable::replaceWithUnreachable(Symbol *sym,
   auto *func = make<SyntheticFunction>(sig, sym->getName(), debugName);
   func->setBody(unreachableFn);
   syntheticFunctions.emplace_back(func);
-  replaceSymbol<DefinedFunction>(sym, sym->getName(), sym->flags, nullptr,
-                                 func);
+  // Mark new symbols as local. For relocatable output we don't want them
+  // to be exported outside the object file.
+  replaceSymbol<DefinedFunction>(sym, debugName, WASM_SYMBOL_BINDING_LOCAL,
+                                 nullptr, func);
   return func;
 }