Implement att_syntax option

Author: Amanieu

src/librustc_ast_lowering/expr.rs

@@ -980,6 +980,15 @@ impl<'hir> LoweringContext<'_, 'hir> {
             struct_span_err!(self.sess, sp, E0472, "asm! is unsupported on this target").emit();
             return hir::ExprKind::Err;
         };
+        if asm.options.contains(asm::InlineAsmOptions::ATT_SYNTAX) {
+            match asm_arch {
+                asm::InlineAsmArch::X86 | asm::InlineAsmArch::X86_64 => {}
+                _ => self
+                    .sess
+                    .struct_span_err(sp, "the `att_syntax` option is only supported on x86")
+                    .emit(),
+            }
+        }
 
         // Lower operands to HIR, filter_map skips any operands with invalid
         // register classes.

src/librustc_ast_pretty/pprust.rs

@@ -2118,6 +2118,9 @@ impl<'a> State<'a> {
                         if opts.contains(InlineAsmOptions::NOSTACK) {
                             options.push("nostack");
                         }
+                        if opts.contains(InlineAsmOptions::ATT_SYNTAX) {
+                            options.push("att_syntax");
+                        }
                         s.commasep(Inconsistent, &options, |s, &opt| {
                             s.word(opt);
                         });

src/librustc_builtin_macros/asm.rs

@@ -279,9 +279,11 @@ fn parse_options<'a>(p: &mut Parser<'a>, args: &mut AsmArgs) -> Result<(), Diagn
             args.options |= InlineAsmOptions::PRESERVES_FLAGS;
         } else if p.eat(&token::Ident(sym::noreturn, false)) {
             args.options |= InlineAsmOptions::NORETURN;
-        } else {
-            p.expect(&token::Ident(sym::nostack, false))?;
+        } else if p.eat(&token::Ident(sym::nostack, false)) {
             args.options |= InlineAsmOptions::NOSTACK;
+        } else {
+            p.expect(&token::Ident(sym::att_syntax, false))?;
+            args.options |= InlineAsmOptions::ATT_SYNTAX;
         }
 
         // Allow trailing commas

src/librustc_codegen_llvm/asm.rs

@@ -269,7 +269,11 @@ impl AsmBuilderMethods<'tcx> for Builder<'a, 'll, 'tcx> {
             tys => self.type_struct(&tys, false),
         };
         let dialect = match asm_arch {
-            InlineAsmArch::X86 | InlineAsmArch::X86_64 => LlvmAsmDialect::Intel,
+            InlineAsmArch::X86 | InlineAsmArch::X86_64
+                if !options.contains(InlineAsmOptions::ATT_SYNTAX) =>
+            {
+                LlvmAsmDialect::Intel
+            }
             _ => LlvmAsmDialect::Att,
         };
         let result = inline_asm_call(

src/librustc_hir_pretty/lib.rs

@@ -1503,6 +1503,9 @@ impl<'a> State<'a> {
                         if opts.contains(InlineAsmOptions::NOSTACK) {
                             options.push("nostack");
                         }
+                        if opts.contains(InlineAsmOptions::ATT_SYNTAX) {
+                            options.push("att_syntax");
+                        }
                         s.commasep(Inconsistent, &options, |s, &opt| {
                             s.word(opt);
                         });

src/librustc_span/symbol.rs

@@ -160,6 +160,7 @@ symbols! {
         attr,
         attributes,
         attr_literals,
+        att_syntax,
         augmented_assignments,
         automatically_derived,
         avx512_target_feature,

src/librustc_target/asm/mod.rs

@@ -426,6 +426,7 @@ bitflags::bitflags! {
         const PRESERVES_FLAGS = 1 << 3;
         const NORETURN = 1 << 4;
         const NOSTACK = 1 << 5;
+        const ATT_SYNTAX = 1 << 6;
     }
 }
 

src/test/ui/asm/parse-error.stderr

@@ -64,23 +64,23 @@ error: argument to `sym` must be a path expression
 LL |         asm!("{}", sym foo + bar);
    |                        ^^^^^^^^^
 
-error: expected one of `)`, `nomem`, `noreturn`, `nostack`, `preserves_flags`, `pure`, or `readonly`, found `foo`
+error: expected one of `)`, `att_syntax`, `nomem`, `noreturn`, `nostack`, `preserves_flags`, `pure`, or `readonly`, found `foo`
   --> $DIR/parse-error.rs:31:26
    |
 LL |         asm!("", options(foo));
-   |                          ^^^ expected one of 7 possible tokens
+   |                          ^^^ expected one of 8 possible tokens
 
 error: expected one of `)` or `,`, found `foo`
   --> $DIR/parse-error.rs:33:32
    |
 LL |         asm!("", options(nomem foo));
    |                                ^^^ expected one of `)` or `,`
 
-error: expected one of `)`, `nomem`, `noreturn`, `nostack`, `preserves_flags`, `pure`, or `readonly`, found `foo`
+error: expected one of `)`, `att_syntax`, `nomem`, `noreturn`, `nostack`, `preserves_flags`, `pure`, or `readonly`, found `foo`
   --> $DIR/parse-error.rs:35:33
    |
 LL |         asm!("", options(nomem, foo));
-   |                                 ^^^ expected one of 7 possible tokens
+   |                                 ^^^ expected one of 8 possible tokens
 
 error: asm options cannot be specified multiple times
   --> $DIR/parse-error.rs:37:29