[lld] 5c8fd1e - [lld][WebAssembly] Fix use of uninitialized stack data with --wasm64 (#107780)

[via llvm-commits]

Author: Sam Clegg
Date: 2024-09-09T09:28:08-07:00
New Revision: 5c8fd1eece8fff69871cef57a2363dc0f734a7d1

URL: https://github.com/llvm/llvm-project/commit/5c8fd1eece8fff69871cef57a2363dc0f734a7d1
DIFF: https://github.com/llvm/llvm-project/commit/5c8fd1eece8fff69871cef57a2363dc0f734a7d1.diff

LOG: [lld][WebAssembly] Fix use of uninitialized stack data with --wasm64 (#107780)

In the case of `--wasm64` we were setting the type of the init expression
to be 64-bit but were only setting the low 32-bits of the value (by
assigning to Int32).

Fixes: https://github.com/emscripten-core/emscripten/issues/22538

Added: 
    

Modified: 
    lld/wasm/SyntheticSections.cpp

Removed: 
    


################################################################################
diff  --git a/lld/wasm/SyntheticSections.cpp b/lld/wasm/SyntheticSections.cpp
index f02f55519a2512..72d08b849d8e86 100644
--- a/lld/wasm/SyntheticSections.cpp
+++ b/lld/wasm/SyntheticSections.cpp
@@ -587,8 +587,7 @@ void ElemSection::writeBody() {
     initExpr.Inst.Value.Global = WasmSym::tableBase->getGlobalIndex();
   } else {
     bool is64 = config->is64.value_or(false);
-    initExpr.Inst.Opcode = is64 ? WASM_OPCODE_I64_CONST : WASM_OPCODE_I32_CONST;
-    initExpr.Inst.Value.Int32 = config->tableBase;
+    initExpr = intConst(config->tableBase, is64);
   }
   writeInitExpr(os, initExpr);