From 54be8aad7976b81231f0a71fa2051e0b6528f107 Mon Sep 17 00:00:00 2001 From: Aaron Hill Date: Thu, 5 Jan 2023 21:41:53 -0600 Subject: [PATCH] Ignore symbol shim clash when symbol is provided by `compiler_builtins` When this happens, we ignore the symbol from `compiler_builtins` in favor of Miri's builtin support. This allows Miri to target platforms like wasm32-unknown-unknown, where functions like `memcmp` are provided by `compiler_builtins`. --- src/tools/miri/src/helpers.rs | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/src/tools/miri/src/helpers.rs b/src/tools/miri/src/helpers.rs index c11c6104c284..527d31d1f0ae 100644 --- a/src/tools/miri/src/helpers.rs +++ b/src/tools/miri/src/helpers.rs @@ -943,7 +943,16 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> { link_name: Symbol, ) -> InterpResult<'tcx, ()> { self.check_abi(abi, exp_abi)?; - if let Some((body, _)) = self.eval_context_mut().lookup_exported_symbol(link_name)? { + if let Some((body, instance)) = self.eval_context_mut().lookup_exported_symbol(link_name)? { + // If compiler-builtins is providing the symbol, then don't treat it as a clash. + // We'll use our built-in implementation in `emulate_foreign_item_by_name` for increased + // performance. Note that this means we won't catch any undefined behavior in + // compiler-builtins when running other crates, but Miri can still be run on + // compiler-builtins itself (or any crate that uses it as a normal dependency) + if self.eval_context_ref().tcx.is_compiler_builtins(instance.def_id().krate) { + return Ok(()); + } + throw_machine_stop!(TerminationInfo::SymbolShimClashing { link_name, span: body.span.data(),