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Use indirect call in pre-checker function to avoid relocation in XIP mode (#3142)

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The stack profiler `aot_func#xxx` calls the wrapped function of `aot_func_internal#xxx`
by using symbol reference,  but in some platform like xtensa, it’s translated into a native
long call, which needs to resolve the indirect address by relocation and breaks the XIP
feature which requires the eliminating of relocation.

The solution is to change the symbol reference into an indirect call through the lookup
table, the code will be like this:
```llvm
call_wrapped_func:                                ; preds = %stack_bound_check_block
  %func_addr1 = getelementptr inbounds ptr, ptr %func_ptrs_ptr, i32 75
  %func_tmp2 = load ptr, ptr %func_addr1, align 4
  tail call void %func_tmp2(ptr %exec_env)
  ret void
```
This commit is contained in:
dongsheng28849455
2024-02-27 11:17:57 +08:00
committed by GitHub
parent 2349df1271
commit 4f6d70bc52
4 changed files with 132 additions and 17 deletions
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53
core/iwasm/compilation/aot_llvm.c
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@ -24,6 +24,8 @@ create_native_stack_bound(const AOTCompContext *comp_ctx,
static bool
create_native_stack_top_min(const AOTCompContext *comp_ctx,
AOTFuncContext *func_ctx);
static bool
create_func_ptrs(const AOTCompContext *comp_ctx, AOTFuncContext *func_ctx);
LLVMTypeRef
wasm_type_to_llvm_type(const AOTCompContext *comp_ctx,
@ -537,8 +539,51 @@ aot_build_precheck_function(AOTCompContext *comp_ctx, LLVMModuleRef module,
if (ret_type == VOID_TYPE) {
name = "";
}
LLVMValueRef retval =
LLVMBuildCall2(b, func_type, wrapped_func, params, param_count, name);
LLVMValueRef retval;
if (comp_ctx->is_indirect_mode
&& !strncmp(comp_ctx->target_arch, "xtensa", 6)) {
/* call wrapped_func indirectly */
if (!create_func_ptrs(comp_ctx, func_ctx)) {
goto fail;
}
LLVMTypeRef func_ptr_type;
LLVMValueRef wrapped_func_indirect;
uint32 import_func_count = comp_ctx->comp_data->import_func_count;
uint32 func_count = comp_ctx->func_ctx_count;
/* Check function index */
if (func_index >= import_func_count + func_count) {
aot_set_last_error("Function index out of range.");
goto fail;
}
/* Get function type */
if (!(func_ptr_type = LLVMPointerType(func_type, 0))) {
aot_set_last_error("create LLVM function type failed.");
goto fail;
}
/*
* func_index layout :
* aot_func#xxx, range from 0 ~ func_conut - 1;
* aot_func#internal#xxx, range from func_conut ~ 2 * func_conut - 1;
*/
if (!(wrapped_func_indirect = aot_get_func_from_table(
comp_ctx, func_ctx->func_ptrs, func_ptr_type,
func_index + func_count + import_func_count))) {
goto fail;
}
/* Call the function indirectly */
retval = LLVMBuildCall2(b, func_type, wrapped_func_indirect, params,
param_count, name);
}
else
retval = LLVMBuildCall2(b, func_type, wrapped_func, params, param_count,
name);
if (!retval) {
goto fail;
}
@ -734,7 +779,9 @@ aot_add_llvm_func(AOTCompContext *comp_ctx, LLVMModuleRef module,
}
if (need_precheck) {
if (!comp_ctx->is_jit_mode)
if (!comp_ctx->is_jit_mode
&& !(comp_ctx->is_indirect_mode
&& !strncmp(comp_ctx->target_arch, "xtensa", 6)))
LLVMSetLinkage(func, LLVMInternalLinkage);
unsigned int kind =
LLVMGetEnumAttributeKindForName("noinline", strlen("noinline"));