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Add builtin for llvm.wasm.memory.size.i32 instrinsic

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This will allow the developer to poll the runtime for currently
allocated memory in the number of Wasm pages. Typical usage:

```zig
var wasm_pages = @wasmMemorySize();
@import("std").debug.assert(wasm_pages > 0);
```
This commit is contained in:
Jakub Konka
2020-05-31 21:11:06 +02:00
committed by Andrew Kelley
parent 12051b02f1
commit ce3f0077cf
4 changed files with 102 additions and 0 deletions
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27
src/codegen.cpp
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@@ -1045,6 +1045,19 @@ static void gen_assertion(CodeGen *g, PanicMsgId msg_id, IrInstGen *source_instr
return gen_assertion_scope(g, msg_id, source_instruction->base.scope);
}
static LLVMValueRef gen_wasm_memory_size(CodeGen *g) {
if (g->wasm_memory_size)
return g->wasm_memory_size;
// declare i32 @llvm.wasm.memory.size.i32(i32) nounwind readonly
LLVMTypeRef param_type = LLVMInt32Type();
LLVMTypeRef fn_type = LLVMFunctionType(LLVMInt32Type(), &param_type, 1, false);
g->wasm_memory_size = LLVMAddFunction(g->module, "llvm.wasm.memory.size.i32", fn_type);
assert(LLVMGetIntrinsicID(g->wasm_memory_size));
return g->wasm_memory_size;
}
static LLVMValueRef get_stacksave_fn_val(CodeGen *g) {
if (g->stacksave_fn_val)
return g->stacksave_fn_val;
@@ -5588,6 +5601,17 @@ static LLVMValueRef ir_render_memcpy(CodeGen *g, IrExecutableGen *executable, Ir
return nullptr;
}
static LLVMValueRef ir_render_wasm_memory_size(CodeGen *g, IrExecutableGen *executable, IrInstGenWasmMemorySize *instruction) {
// When Wasm lands multi-memory support, we can relax this to permit the user specify
// memory index to inquire about. For now, we pass in the recommended default of index 0.
//
// More info:
// https://github.com/sunfishcode/wasm-reference-manual/blob/master/WebAssembly.md#current-linear-memory-size
LLVMValueRef zero = LLVMConstNull(g->builtin_types.entry_i32->llvm_type);
LLVMValueRef val = LLVMBuildCall(g->builder, gen_wasm_memory_size(g), &zero, 1, "");
return val;
}
static LLVMValueRef ir_render_slice(CodeGen *g, IrExecutableGen *executable, IrInstGenSlice *instruction) {
Error err;
@@ -6798,6 +6822,8 @@ static LLVMValueRef ir_render_instruction(CodeGen *g, IrExecutableGen *executabl
return ir_render_splat(g, executable, (IrInstGenSplat *) instruction);
case IrInstGenIdVectorExtractElem:
return ir_render_vector_extract_elem(g, executable, (IrInstGenVectorExtractElem *) instruction);
case IrInstGenIdWasmMemorySize:
return ir_render_wasm_memory_size(g, executable, (IrInstGenWasmMemorySize *) instruction);
}
zig_unreachable();
}
@@ -8660,6 +8686,7 @@ static void define_builtin_fns(CodeGen *g) {
create_builtin_fn(g, BuiltinFnIdAs, "as", 2);
create_builtin_fn(g, BuiltinFnIdCall, "call", 3);
create_builtin_fn(g, BuiltinFnIdBitSizeof, "bitSizeOf", 1);
create_builtin_fn(g, BuiltinFnIdWasmMemorySize, "wasmMemorySize", 0);
}
static const char *bool_to_str(bool b) {