Auto merge of rust-lang#2748 - Aaron1011:wasm32-support, r=RalfJung

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`.

Author: bors

src/tools/miri/ci.sh

@@ -108,7 +108,8 @@ case $HOST_TARGET in
     MIRI_TEST_TARGET=i686-pc-windows-msvc run_tests
     MIRI_TEST_TARGET=x86_64-unknown-freebsd run_tests_minimal hello integer vec panic/panic concurrency/simple atomic data_race env/var
     MIRI_TEST_TARGET=aarch64-linux-android run_tests_minimal hello integer vec panic/panic
-    MIRI_TEST_TARGET=wasm32-wasi run_tests_minimal no_std integer
+    MIRI_TEST_TARGET=wasm32-wasi run_tests_minimal no_std integer strings
+    MIRI_TEST_TARGET=wasm32-unknown-unknown run_tests_minimal no_std integer strings
     MIRI_TEST_TARGET=thumbv7em-none-eabihf MIRI_NO_STD=1 run_tests_minimal no_std # no_std embedded architecture
     MIRI_TEST_TARGET=tests/avr.json MIRI_NO_STD=1 run_tests_minimal no_std # JSON target file
     ;;

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(),

src/tools/miri/test_dependencies/Cargo.lock

@@ -14,6 +14,12 @@ version = "1.3.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "bef38d45163c2f1dde094a7dfd33ccf595c92905c8f8f4fdc18d06fb1037718a"
 
+[[package]]
+name = "bumpalo"
+version = "3.11.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "572f695136211188308f16ad2ca5c851a712c464060ae6974944458eb83880ba"
+
 [[package]]
 name = "bytes"
 version = "1.3.0"
@@ -44,8 +50,10 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c05aeb6a22b8f62540c194aac980f2115af067bfe15a0734d7277a768d396b31"
 dependencies = [
  "cfg-if",
+ "js-sys",
  "libc",
  "wasi 0.11.0+wasi-snapshot-preview1",
+ "wasm-bindgen",
 ]
 
 [[package]]
@@ -57,6 +65,15 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "js-sys"
+version = "0.3.60"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "49409df3e3bf0856b916e2ceaca09ee28e6871cf7d9ce97a692cacfdb2a25a47"
+dependencies = [
+ "wasm-bindgen",
+]
+
 [[package]]
 name = "libc"
 version = "0.2.139"
@@ -123,6 +140,12 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "once_cell"
+version = "1.17.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6f61fba1741ea2b3d6a1e3178721804bb716a68a6aeba1149b5d52e3d464ea66"
+
 [[package]]
 name = "page_size"
 version = "0.5.0"
@@ -316,6 +339,60 @@ version = "0.11.0+wasi-snapshot-preview1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9c8d87e72b64a3b4db28d11ce29237c246188f4f51057d65a7eab63b7987e423"
 
+[[package]]
+name = "wasm-bindgen"
+version = "0.2.83"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "eaf9f5aceeec8be17c128b2e93e031fb8a4d469bb9c4ae2d7dc1888b26887268"
+dependencies = [
+ "cfg-if",
+ "wasm-bindgen-macro",
+]
+
+[[package]]
+name = "wasm-bindgen-backend"
+version = "0.2.83"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4c8ffb332579b0557b52d268b91feab8df3615f265d5270fec2a8c95b17c1142"
+dependencies = [
+ "bumpalo",
+ "log",
+ "once_cell",
+ "proc-macro2",
+ "quote",
+ "syn",
+ "wasm-bindgen-shared",
+]
+
+[[package]]
+name = "wasm-bindgen-macro"
+version = "0.2.83"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "052be0f94026e6cbc75cdefc9bae13fd6052cdcaf532fa6c45e7ae33a1e6c810"
+dependencies = [
+ "quote",
+ "wasm-bindgen-macro-support",
+]
+
+[[package]]
+name = "wasm-bindgen-macro-support"
+version = "0.2.83"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "07bc0c051dc5f23e307b13285f9d75df86bfdf816c5721e573dec1f9b8aa193c"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+ "wasm-bindgen-backend",
+ "wasm-bindgen-shared",
+]
+
+[[package]]
+name = "wasm-bindgen-shared"
+version = "0.2.83"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1c38c045535d93ec4f0b4defec448e4291638ee608530863b1e2ba115d4fff7f"
+
 [[package]]
 name = "winapi"
 version = "0.3.9"

src/tools/miri/test_dependencies/Cargo.toml

@@ -13,7 +13,7 @@ libc = "0.2"
 num_cpus = "1.10.1"
 
 getrandom_1 = { package = "getrandom", version = "0.1" }
-getrandom = { version = "0.2" }
+getrandom = { version = "0.2", features = ["js"] }
 rand = { version = "0.8", features = ["small_rng"] }
 
 [target.'cfg(not(any(target_arch = "wasm32", target_arch = "wasm64")))'.dependencies]