From cd65a15d81b32636c5097200446cc6d6afc7199b Mon Sep 17 00:00:00 2001 From: Yawning Angel Date: Fri, 15 Dec 2023 17:29:59 +0900 Subject: src: `enable_target_feature` should add features, not overwrite `llvm_features` being empty is the default state, and implies the presence of certain features. Previously if any target features were explicitly enabled by the `enable_target_feature` attribute, they were added comma separated to `llvm_features`. For example: `lzcnt,popcnt,...,sse4.2,sse` This was causing LLVM to try to target a CPU that *ONLY* has the explicitly enabled features. This now will prefix explicitly enabled features with a `+`, and preserve the existing `llvm_features` string by appending to it if it is set. --- src/llvm_backend.cpp | 41 ++++++++++++++++++++++++++++++++++++++++- 1 file changed, 40 insertions(+), 1 deletion(-) (limited to 'src/llvm_backend.cpp') diff --git a/src/llvm_backend.cpp b/src/llvm_backend.cpp index ca71a0f45..b90fd8495 100644 --- a/src/llvm_backend.cpp +++ b/src/llvm_backend.cpp @@ -2531,7 +2531,46 @@ gb_internal bool lb_generate_code(lbGenerator *gen) { */ if (build_context.target_features_set.entries.count != 0) { - llvm_features = target_features_set_to_cstring(permanent_allocator(), false); + // Prefix all of the features with a `+`, because we are + // enabling additional features. + char const *additional_features = target_features_set_to_cstring(permanent_allocator(), false, true); + + String f_string = make_string_c(llvm_features); + String a_string = make_string_c(additional_features); + isize f_len = f_string.len; + + if (f_len == 0) { + // The common case is that llvm_features is empty, so + // the target_features_set additions can be used as is. + llvm_features = additional_features; + } else { + // The user probably specified `-microarch:native`, so + // llvm_features is populated by LLVM's idea of what + // the host CPU supports. + // + // As far as I can tell, (which is barely better than + // wild guessing), a bitset is formed by parsing the + // string left to right. + // + // So, llvm_features + ',' + additonal_features, will + // makes the target_features_set override llvm_features. + + char *tmp = gb_alloc_array(permanent_allocator(), char, f_len + 1 + a_string.len + 1); + isize len = 0; + + // tmp = f_string + gb_memmove(tmp, f_string.text, f_string.len); + len += f_string.len; + // tmp += ',' + tmp[len++] = ','; + // tmp += a_string + gb_memmove(tmp + len, a_string.text, a_string.len); + len += a_string.len; + // tmp += NUL + tmp[len++] = 0; + + llvm_features = tmp; + } } // GB_ASSERT_MSG(LLVMTargetHasAsmBackend(target)); -- cgit v1.2.3