[PATCH] D71493: [WebAssembly] Setting export_name implies no_dead_strip

[Sam Clegg via Phabricator via llvm-commits]

sbc100 created this revision.
Herald added subscribers: llvm-commits, cfe-commits, sunfish, aheejin, hiraditya, jgravelle-google, dschuff.
Herald added projects: clang, LLVM.
sbc100 added reviewers: dschuff, sunfish.

This change updates the clang front end to add symbols to llvm.used
when they have explicit export_name attribute.

In also causes the `.export_name` assempler directive to imply the
MCSA_NoDeadStrip symbol attribute.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D71493

Files:
  clang/lib/Sema/SemaDeclAttr.cpp
  clang/test/CodeGen/wasm-export-name.c
  llvm/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmParser.cpp
  llvm/test/MC/WebAssembly/export-name.s


Index: llvm/test/MC/WebAssembly/export-name.s
===================================================================
--- llvm/test/MC/WebAssembly/export-name.s
+++ llvm/test/MC/WebAssembly/export-name.s
@@ -22,5 +22,5 @@
 # CHECK-OBJ-NEXT:       - Index:           0
 # CHECK-OBJ-NEXT:         Kind:            FUNCTION
 # CHECK-OBJ-NEXT:         Name:            foo
-# CHECK-OBJ-NEXT:         Flags:           [ EXPORTED ]
+# CHECK-OBJ-NEXT:         Flags:           [ EXPORTED, NO_STRIP ]
 # CHECK-OBJ-NEXT:         Function:        0
Index: llvm/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmParser.cpp
===================================================================
--- llvm/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmParser.cpp
+++ llvm/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmParser.cpp
@@ -722,6 +722,7 @@
       auto WasmSym = cast<MCSymbolWasm>(Ctx.getOrCreateSymbol(SymName));
       WasmSym->setExportName(ExportName);
       TOut.emitExportName(WasmSym, ExportName);
+      Out.EmitSymbolAttribute(WasmSym, MCSA_NoDeadStrip);
     }
 
     if (DirectiveID.getString() == ".import_module") {
Index: clang/test/CodeGen/wasm-export-name.c
===================================================================
--- clang/test/CodeGen/wasm-export-name.c
+++ clang/test/CodeGen/wasm-export-name.c
@@ -6,6 +6,8 @@
   return 43;
 }
 
+// CHECK: @llvm.used = appending global [1 x i8*] [i8* bitcast (i32 ()* @foo to i8*)]
+
 // CHECK: define i32 @foo() [[A:#[0-9]+]]
 
 // CHECK: attributes [[A]] = {{{.*}} "wasm-export-name"="bar" {{.*}}}
Index: clang/lib/Sema/SemaDeclAttr.cpp
===================================================================
--- clang/lib/Sema/SemaDeclAttr.cpp
+++ clang/lib/Sema/SemaDeclAttr.cpp
@@ -5772,8 +5772,8 @@
   if (!S.checkStringLiteralArgumentAttr(AL, 0, Str, &ArgLoc))
     return;
 
-  FD->addAttr(::new (S.Context)
-                  WebAssemblyExportNameAttr(S.Context, AL, Str));
+  D->addAttr(::new (S.Context) WebAssemblyExportNameAttr(S.Context, AL, Str));
+  D->addAttr(UsedAttr::CreateImplicit(S.Context));
 }
 
 static void handleWebAssemblyImportModuleAttr(Sema &S, Decl *D, const ParsedAttr &AL) {


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