From 585fd8af473354b9dfa7e57c5c6af396fa60945e Mon Sep 17 00:00:00 2001 From: Alon Zakai Date: Fri, 30 Dec 2016 13:41:02 -0800 Subject: memoryBase and tableBase should not be mutable, as we need to use them in segment/element offsets --- src/asm2wasm.h | 25 +++++++++++++++---------- 1 file changed, 15 insertions(+), 10 deletions(-) (limited to 'src') diff --git a/src/asm2wasm.h b/src/asm2wasm.h index 6ed13b79a..fab74189e 100644 --- a/src/asm2wasm.h +++ b/src/asm2wasm.h @@ -649,19 +649,24 @@ void Asm2WasmBuilder::processAsm(Ref ast) { type = WasmType::f64; } if (type != WasmType::none) { - // we need imported globals to be mutable, but wasm doesn't support that yet, so we must - // import an immutable and create a mutable global initialized to its value - import->name = Name(std::string(import->name.str) + "$asm2wasm$import"); + // this is a global import->kind = ExternalKind::Global; import->globalType = type; mappedGlobals.emplace(name, type); - { - auto global = new Global(); - global->name = name; - global->type = type; - global->init = builder.makeGetGlobal(import->name, type); - global->mutable_ = true; - wasm.addGlobal(global); + // tableBase and memoryBase are used as segment/element offsets, and must be constant; + // otherwise, an asm.js import of a constant is mutable, e.g. STACKTOP + if (name != "tableBase" && name != "memoryBase") { + // we need imported globals to be mutable, but wasm doesn't support that yet, so we must + // import an immutable and create a mutable global initialized to its value + import->name = Name(std::string(import->name.str) + "$asm2wasm$import"); + { + auto global = new Global(); + global->name = name; + global->type = type; + global->init = builder.makeGetGlobal(import->name, type); + global->mutable_ = true; + wasm.addGlobal(global); + } } } else { import->kind = ExternalKind::Function; -- cgit v1.2.3