diff --git a/src/librustc_codegen_llvm/asm.rs b/src/librustc_codegen_llvm/asm.rs index 5d27f8eab3e..f1bb41bceba 100644 --- a/src/librustc_codegen_llvm/asm.rs +++ b/src/librustc_codegen_llvm/asm.rs @@ -30,7 +30,7 @@ pub fn codegen_inline_asm( ia: &hir::InlineAsm, outputs: Vec>, mut inputs: Vec<&'ll Value> -) { +) -> bool { let mut ext_constraints = vec![]; let mut output_types = vec![]; @@ -97,6 +97,10 @@ pub fn codegen_inline_asm( ia.alignstack, dialect ); + if r.is_none() { + return false; + } + let r = r.unwrap(); // Again, based on how many outputs we have let outputs = ia.outputs.iter().zip(&outputs).filter(|&(ref o, _)| !o.is_indirect); @@ -117,6 +121,8 @@ pub fn codegen_inline_asm( llvm::LLVMSetMetadata(r, kind, llvm::LLVMMDNodeInContext(bx.cx.llcx, &val, 1)); } + + return true; } pub fn codegen_global_asm<'a, 'tcx>(cx: &CodegenCx<'a, 'tcx>, diff --git a/src/librustc_codegen_llvm/builder.rs b/src/librustc_codegen_llvm/builder.rs index e3526a5a2ee..77de88997e4 100644 --- a/src/librustc_codegen_llvm/builder.rs +++ b/src/librustc_codegen_llvm/builder.rs @@ -737,7 +737,7 @@ impl Builder<'a, 'll, 'tcx> { pub fn inline_asm_call(&self, asm: *const c_char, cons: *const c_char, inputs: &[&'ll Value], output: &'ll Type, volatile: bool, alignstack: bool, - dia: AsmDialect) -> &'ll Value { + dia: AsmDialect) -> Option<&'ll Value> { self.count_insn("inlineasm"); let volatile = if volatile { llvm::True } @@ -753,9 +753,17 @@ impl Builder<'a, 'll, 'tcx> { debug!("Asm Output Type: {:?}", output); let fty = Type::func(&argtys[..], output); unsafe { - let v = llvm::LLVMRustInlineAsm( - fty, asm, cons, volatile, alignstack, dia); - self.call(v, inputs, None) + // Ask LLVM to verify that the constraints are well-formed. + let constraints_ok = llvm::LLVMRustInlineAsmVerify(fty, cons); + debug!("Constraint verification result: {:?}", constraints_ok); + if constraints_ok == llvm::True { + let v = llvm::LLVMRustInlineAsm( + fty, asm, cons, volatile, alignstack, dia); + Some(self.call(v, inputs, None)) + } else { + // LLVM has detected an issue with our constaints, bail out + None + } } } diff --git a/src/librustc_codegen_llvm/diagnostics.rs b/src/librustc_codegen_llvm/diagnostics.rs index 94776f17c79..242b7a1a119 100644 --- a/src/librustc_codegen_llvm/diagnostics.rs +++ b/src/librustc_codegen_llvm/diagnostics.rs @@ -47,4 +47,26 @@ unsafe { simd_add(i32x2(0, 0), i32x2(1, 2)); } // ok! ``` "##, +E0668: r##" +Malformed inline assembly rejected by LLVM. + +LLVM checks the validity of the constraints and the assembly string passed to +it. This error implies that LLVM seems something wrong with the inline +assembly call. + +In particular, it can happen if you forgot the closing bracket of a register +constraint (see issue #51430): +```ignore (error-emitted-at-codegen-which-cannot-be-handled-by-compile_fail) +#![feature(asm)] + +fn main() { + let rax: u64; + unsafe { + asm!("" :"={rax"(rax)); + println!("Accumulator is: {}", rax); + } +} +``` +"##, + } diff --git a/src/librustc_codegen_llvm/llvm/ffi.rs b/src/librustc_codegen_llvm/llvm/ffi.rs index 845f2fa9f45..8485db4210c 100644 --- a/src/librustc_codegen_llvm/llvm/ffi.rs +++ b/src/librustc_codegen_llvm/llvm/ffi.rs @@ -1208,6 +1208,9 @@ extern "C" { AlignStack: Bool, Dialect: AsmDialect) -> &Value; + pub fn LLVMRustInlineAsmVerify(Ty: &Type, + Constraints: *const c_char) + -> Bool; pub fn LLVMRustDebugMetadataVersion() -> u32; pub fn LLVMRustVersionMajor() -> u32; diff --git a/src/librustc_codegen_llvm/mir/statement.rs b/src/librustc_codegen_llvm/mir/statement.rs index b4eb7615f98..6bd41bfe16f 100644 --- a/src/librustc_codegen_llvm/mir/statement.rs +++ b/src/librustc_codegen_llvm/mir/statement.rs @@ -86,7 +86,11 @@ impl FunctionCx<'a, 'll, 'tcx> { self.codegen_operand(&bx, input).immediate() }).collect(); - asm::codegen_inline_asm(&bx, asm, outputs, input_vals); + let res = asm::codegen_inline_asm(&bx, asm, outputs, input_vals); + if !res { + span_err!(bx.sess(), statement.source_info.span, E0668, + "malformed inline assembly"); + } bx } mir::StatementKind::FakeRead(..) | diff --git a/src/rustllvm/RustWrapper.cpp b/src/rustllvm/RustWrapper.cpp index 9b9c908ea52..f1ab1d4ddfa 100644 --- a/src/rustllvm/RustWrapper.cpp +++ b/src/rustllvm/RustWrapper.cpp @@ -426,6 +426,11 @@ extern "C" LLVMValueRef LLVMRustInlineAsm(LLVMTypeRef Ty, char *AsmString, HasSideEffects, IsAlignStack, fromRust(Dialect))); } +extern "C" bool LLVMRustInlineAsmVerify(LLVMTypeRef Ty, + char *Constraints) { + return InlineAsm::Verify(unwrap(Ty), Constraints); +} + extern "C" void LLVMRustAppendModuleInlineAsm(LLVMModuleRef M, const char *Asm) { unwrap(M)->appendModuleInlineAsm(StringRef(Asm)); } diff --git a/src/test/ui/inline-asm-bad-constraint.rs b/src/test/ui/inline-asm-bad-constraint.rs new file mode 100644 index 00000000000..654f230741e --- /dev/null +++ b/src/test/ui/inline-asm-bad-constraint.rs @@ -0,0 +1,47 @@ +// Copyright 2018 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 or the MIT license +// , at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +// Test that the compiler will catch invalid inline assembly constraints. + +#![feature(asm)] + +extern "C" { + fn foo(a: usize); +} + +fn main() { + bad_register_constraint(); + bad_input(); + wrong_size_output(); +} + +// Issue #54130 +fn bad_register_constraint() { + let rax: u64; + unsafe { + asm!("" :"={rax"(rax)) //~ ERROR E0668 + }; + println!("Accumulator is: {}", rax); +} + +// Issue #54376 +fn bad_input() { + unsafe { + asm!("callq $0" : : "0"(foo)) //~ ERROR E0668 + }; +} + +fn wrong_size_output() { + let rax: u64 = 0; + unsafe { + asm!("addb $1, $0" : "={rax}"((0i32, rax))); //~ ERROR E0668 + } + println!("rax: {}", rax); +} diff --git a/src/test/ui/inline-asm-bad-constraint.stderr b/src/test/ui/inline-asm-bad-constraint.stderr new file mode 100644 index 00000000000..ce1f274749f --- /dev/null +++ b/src/test/ui/inline-asm-bad-constraint.stderr @@ -0,0 +1,21 @@ +error[E0668]: malformed inline assembly + --> $DIR/inline-asm-bad-constraint.rs:29:9 + | +LL | asm!("" :"={rax"(rax)) //~ ERROR E0668 + | ^^^^^^^^^^^^^^^^^^^^^^ + +error[E0668]: malformed inline assembly + --> $DIR/inline-asm-bad-constraint.rs:37:9 + | +LL | asm!("callq $0" : : "0"(foo)) //~ ERROR E0668 + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +error[E0668]: malformed inline assembly + --> $DIR/inline-asm-bad-constraint.rs:44:9 + | +LL | asm!("addb $1, $0" : "={rax}"((0i32, rax))); //~ ERROR E0668 + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +error: aborting due to 3 previous errors + +For more information about this error, try `rustc --explain E0668`.