[lld] r353364 - [WebAssembly] Honor WASM_SYMBOL_EXPORT symbol flag

[Sam Clegg via llvm-commits]

Author: sbc
Date: Wed Feb  6 17:53:50 2019
New Revision: 353364

URL: http://llvm.org/viewvc/llvm-project?rev=353364&view=rev
Log:
[WebAssembly] Honor WASM_SYMBOL_EXPORT symbol flag

This flag means that symbol should be exported in the final binary.

The reason for this change is to allow source level annotations to
trigger a given symbol to be exported:
https://github.com/emscripten-core/emscripten/issues/7702

Differential Revision: https://reviews.llvm.org/D57869

Modified:
    lld/trunk/test/wasm/export.ll
    lld/trunk/wasm/Symbols.cpp

Modified: lld/trunk/test/wasm/export.ll
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/wasm/export.ll?rev=353364&r1=353363&r2=353364&view=diff
==============================================================================
--- lld/trunk/test/wasm/export.ll (original)
+++ lld/trunk/test/wasm/export.ll Wed Feb  6 17:53:50 2019
@@ -3,13 +3,29 @@
 ; RUN: wasm-ld --export=hidden_function -o %t.wasm %t.o
 ; RUN: obj2yaml %t.wasm | FileCheck %s
 
+ at llvm.used = appending global [1 x i8*] [i8* bitcast (i32 ()* @used_function to i8*)], section "llvm.metadata"
+
 target triple = "wasm32-unknown-unknown"
 
+; Not exported by default, but forced via commandline
 define hidden i32 @hidden_function() local_unnamed_addr {
 entry:
   ret i32 0
 }
 
+; Not exported by default
+define i32 @default_function() local_unnamed_addr {
+entry:
+  ret i32 0
+}
+
+; Exported because its part of llvm.used
+define i32 @used_function() local_unnamed_addr {
+entry:
+  ret i32 0
+}
+
+; Exported by default
 define void @_start() local_unnamed_addr {
 entry:
   ret void
@@ -17,6 +33,8 @@ entry:
 
 ; CHECK-ERROR: error: symbol exported via --export not found: missing
 
+; CHECK-NOT: - Name: default_function
+
 ; CHECK:        - Type:            EXPORT
 ; CHECK-NEXT:     Exports:
 ; CHECK-NEXT:       - Name:            memory
@@ -31,7 +49,10 @@ entry:
 ; CHECK-NEXT:       - Name:            hidden_function
 ; CHECK-NEXT:         Kind:            FUNCTION
 ; CHECK-NEXT:         Index:           1
-; CHECK-NEXT:       - Name:            _start
+; CHECK-NEXT:       - Name:            used_function
 ; CHECK-NEXT:         Kind:            FUNCTION
 ; CHECK-NEXT:         Index:           2
+; CHECK-NEXT:       - Name:            _start
+; CHECK-NEXT:         Kind:            FUNCTION
+; CHECK-NEXT:         Index:           3
 ; CHECK-NEXT:   - Type:            CODE

Modified: lld/trunk/wasm/Symbols.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/wasm/Symbols.cpp?rev=353364&r1=353363&r2=353364&view=diff
==============================================================================
--- lld/trunk/wasm/Symbols.cpp (original)
+++ lld/trunk/wasm/Symbols.cpp Wed Feb  6 17:53:50 2019
@@ -116,7 +116,7 @@ bool Symbol::isExported() const {
   if (Config->ExportDynamic && !isHidden())
     return true;
 
-  return false;
+  return Flags & WASM_SYMBOL_EXPORTED;
 }
 
 uint32_t FunctionSymbol::getFunctionIndex() const {