Rollup merge of rust-lang#64435 - eddyb:arguments-against-arg, r=rkruppe

codegen: use "_N" (like for other locals) instead of "argN", for argument names.

Based on rust-lang#64408 (second commit is new), fixing something I mentioned in rust-lang#64408 (which turned to be an immediate blocker for unifying relevant codepaths).

Closes rust-lang#64408 (by containing it).

r? @rkruppe

src/librustc_codegen_llvm/abi.rs

@@ -229,7 +229,7 @@ impl ArgTypeExt<'ll, 'tcx> for ArgType<'tcx, Ty<'tcx>> {
                 // We instead thus allocate some scratch space...
                 let scratch_size = cast.size(bx);
                 let scratch_align = cast.align(bx);
-                let llscratch = bx.alloca(cast.llvm_type(bx), "abi_cast", scratch_align);
+                let llscratch = bx.alloca(cast.llvm_type(bx), scratch_align);
                 bx.lifetime_start(llscratch, scratch_size);
 
                 // ...where we first store the value...

src/librustc_codegen_llvm/builder.rs

@@ -387,23 +387,17 @@ impl BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
         )
     }
 
-    fn alloca(&mut self, ty: &'ll Type, name: &str, align: Align) -> &'ll Value {
+    fn alloca(&mut self, ty: &'ll Type, align: Align) -> &'ll Value {
         let mut bx = Builder::with_cx(self.cx);
         bx.position_at_start(unsafe {
             llvm::LLVMGetFirstBasicBlock(self.llfn())
         });
-        bx.dynamic_alloca(ty, name, align)
+        bx.dynamic_alloca(ty, align)
     }
 
-    fn dynamic_alloca(&mut self, ty: &'ll Type, name: &str, align: Align) -> &'ll Value {
+    fn dynamic_alloca(&mut self, ty: &'ll Type, align: Align) -> &'ll Value {
         unsafe {
-            let alloca = if name.is_empty() {
-                llvm::LLVMBuildAlloca(self.llbuilder, ty, UNNAMED)
-            } else {
-                let name = SmallCStr::new(name);
-                llvm::LLVMBuildAlloca(self.llbuilder, ty,
-                                      name.as_ptr())
-            };
+            let alloca = llvm::LLVMBuildAlloca(self.llbuilder, ty, UNNAMED);
             llvm::LLVMSetAlignment(alloca, align.bytes() as c_uint);
             alloca
         }
@@ -412,16 +406,9 @@ impl BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
     fn array_alloca(&mut self,
                         ty: &'ll Type,
                         len: &'ll Value,
-                        name: &str,
                         align: Align) -> &'ll Value {
         unsafe {
-            let alloca = if name.is_empty() {
-                llvm::LLVMBuildArrayAlloca(self.llbuilder, ty, len, UNNAMED)
-            } else {
-                let name = SmallCStr::new(name);
-                llvm::LLVMBuildArrayAlloca(self.llbuilder, ty, len,
-                                           name.as_ptr())
-            };
+            let alloca = llvm::LLVMBuildArrayAlloca(self.llbuilder, ty, len, UNNAMED);
             llvm::LLVMSetAlignment(alloca, align.bytes() as c_uint);
             alloca
         }

src/librustc_codegen_llvm/intrinsic.rs

@@ -871,7 +871,7 @@ fn codegen_msvc_try(
         // More information can be found in libstd's seh.rs implementation.
         let i64p = bx.type_ptr_to(bx.type_i64());
         let ptr_align = bx.tcx().data_layout.pointer_align.abi;
-        let slot = bx.alloca(i64p, "slot", ptr_align);
+        let slot = bx.alloca(i64p, ptr_align);
         bx.invoke(func, &[data], normal.llbb(), catchswitch.llbb(), None);
 
         normal.ret(bx.const_i32(0));

src/librustc_codegen_ssa/mir/block.rs

@@ -276,7 +276,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                 let llslot = match op.val {
                     Immediate(_) | Pair(..) => {
                         let scratch =
-                            PlaceRef::alloca(&mut bx, self.fn_ty.ret.layout, "ret");
+                            PlaceRef::alloca(&mut bx, self.fn_ty.ret.layout);
                         op.val.store(&mut bx, scratch);
                         scratch.llval
                     }
@@ -767,7 +767,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
             match (arg, op.val) {
                 (&mir::Operand::Copy(_), Ref(_, None, _)) |
                 (&mir::Operand::Constant(_), Ref(_, None, _)) => {
-                    let tmp = PlaceRef::alloca(&mut bx, op.layout, "const");
+                    let tmp = PlaceRef::alloca(&mut bx, op.layout);
                     op.val.store(&mut bx, tmp);
                     op.val = Ref(tmp.llval, None, tmp.align);
                 }
@@ -925,7 +925,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
             Immediate(_) | Pair(..) => {
                 match arg.mode {
                     PassMode::Indirect(..) | PassMode::Cast(_) => {
-                        let scratch = PlaceRef::alloca(bx, arg.layout, "arg");
+                        let scratch = PlaceRef::alloca(bx, arg.layout);
                         op.val.store(bx, scratch);
                         (scratch.llval, scratch.align, true)
                     }
@@ -940,7 +940,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                     // think that ATM (Rust 1.16) we only pass temporaries, but we shouldn't
                     // have scary latent bugs around.
 
-                    let scratch = PlaceRef::alloca(bx, arg.layout, "arg");
+                    let scratch = PlaceRef::alloca(bx, arg.layout);
                     base::memcpy_ty(bx, scratch.llval, scratch.align, llval, align,
                                     op.layout, MemFlags::empty());
                     (scratch.llval, scratch.align, true)
@@ -1017,7 +1017,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                 cx.tcx().mk_mut_ptr(cx.tcx().types.u8),
                 cx.tcx().types.i32
             ]));
-            let slot = PlaceRef::alloca(bx, layout, "personalityslot");
+            let slot = PlaceRef::alloca(bx, layout);
             self.personality_slot = Some(slot);
             slot
         }
@@ -1116,15 +1116,15 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                     return if fn_ret.is_indirect() {
                         // Odd, but possible, case, we have an operand temporary,
                         // but the calling convention has an indirect return.
-                        let tmp = PlaceRef::alloca(bx, fn_ret.layout, "tmp_ret");
+                        let tmp = PlaceRef::alloca(bx, fn_ret.layout);
                         tmp.storage_live(bx);
                         llargs.push(tmp.llval);
                         ReturnDest::IndirectOperand(tmp, index)
                     } else if is_intrinsic {
                         // Currently, intrinsics always need a location to store
                         // the result, so we create a temporary `alloca` for the
                         // result.
-                        let tmp = PlaceRef::alloca(bx, fn_ret.layout, "tmp_ret");
+                        let tmp = PlaceRef::alloca(bx, fn_ret.layout);
                         tmp.storage_live(bx);
                         ReturnDest::IndirectOperand(tmp, index)
                     } else {
@@ -1174,7 +1174,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                 LocalRef::Operand(None) => {
                     let dst_layout = bx.layout_of(self.monomorphized_place_ty(&dst.as_ref()));
                     assert!(!dst_layout.ty.has_erasable_regions());
-                    let place = PlaceRef::alloca(bx, dst_layout, "transmute_temp");
+                    let place = PlaceRef::alloca(bx, dst_layout);
                     place.storage_live(bx);
                     self.codegen_transmute_into(bx, src, place);
                     let op = bx.load_operand(place);
@@ -1227,7 +1227,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
             DirectOperand(index) => {
                 // If there is a cast, we have to store and reload.
                 let op = if let PassMode::Cast(_) = ret_ty.mode {
-                    let tmp = PlaceRef::alloca(bx, ret_ty.layout, "tmp_ret");
+                    let tmp = PlaceRef::alloca(bx, ret_ty.layout);
                     tmp.storage_live(bx);
                     bx.store_arg_ty(&ret_ty, llval, tmp);
                     let op = bx.load_operand(tmp);

src/librustc_codegen_ssa/mir/mod.rs

@@ -268,11 +268,13 @@ pub fn codegen_mir<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
                 debug!("alloc: {:?} ({}) -> place", local, name);
                 if layout.is_unsized() {
                     let indirect_place =
-                        PlaceRef::alloca_unsized_indirect(&mut bx, layout, &name.as_str());
+                        PlaceRef::alloca_unsized_indirect(&mut bx, layout);
+                    bx.set_var_name(indirect_place.llval, name);
                     // FIXME: add an appropriate debuginfo
                     LocalRef::UnsizedPlace(indirect_place)
                 } else {
-                    let place = PlaceRef::alloca(&mut bx, layout, &name.as_str());
+                    let place = PlaceRef::alloca(&mut bx, layout);
+                    bx.set_var_name(place.llval, name);
                     if dbg {
                         let (scope, span) = fx.debug_loc(mir::SourceInfo {
                             span: decl.source_info.span,
@@ -293,14 +295,13 @@ pub fn codegen_mir<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
                 } else if memory_locals.contains(local) {
                     debug!("alloc: {:?} -> place", local);
                     if layout.is_unsized() {
-                        let indirect_place = PlaceRef::alloca_unsized_indirect(
-                            &mut bx,
-                            layout,
-                            &format!("{:?}", local),
-                        );
+                        let indirect_place = PlaceRef::alloca_unsized_indirect(&mut bx, layout);
+                        bx.set_var_name(indirect_place.llval, format_args!("{:?}", local));
                         LocalRef::UnsizedPlace(indirect_place)
                     } else {
-                        LocalRef::Place(PlaceRef::alloca(&mut bx, layout, &format!("{:?}", local)))
+                        let place = PlaceRef::alloca(&mut bx, layout);
+                        bx.set_var_name(place.llval, format_args!("{:?}", local));
+                        LocalRef::Place(place)
                     }
                 } else {
                     // If this is an immediate local, we do not create an
@@ -452,10 +453,11 @@ fn arg_local_refs<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
     mir.args_iter().enumerate().map(|(arg_index, local)| {
         let arg_decl = &mir.local_decls[local];
 
+        // FIXME(eddyb) don't allocate a `String` unless it gets used.
         let name = if let Some(name) = arg_decl.name {
             name.as_str().to_string()
         } else {
-            format!("arg{}", arg_index)
+            format!("{:?}", local)
         };
 
         if Some(local) == mir.spread_arg {
@@ -470,7 +472,8 @@ fn arg_local_refs<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
                 _ => bug!("spread argument isn't a tuple?!")
             };
 
-            let place = PlaceRef::alloca(bx, bx.layout_of(arg_ty), &name);
+            let place = PlaceRef::alloca(bx, bx.layout_of(arg_ty));
+            bx.set_var_name(place.llval, name);
             for i in 0..tupled_arg_tys.len() {
                 let arg = &fx.fn_ty.args[idx];
                 idx += 1;
@@ -558,11 +561,13 @@ fn arg_local_refs<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
             llarg_idx += 1;
             let indirect_operand = OperandValue::Pair(llarg, llextra);
 
-            let tmp = PlaceRef::alloca_unsized_indirect(bx, arg.layout, &name);
+            let tmp = PlaceRef::alloca_unsized_indirect(bx, arg.layout);
+            bx.set_var_name(tmp.llval, name);
             indirect_operand.store(bx, tmp);
             tmp
         } else {
-            let tmp = PlaceRef::alloca(bx, arg.layout, &name);
+            let tmp = PlaceRef::alloca(bx, arg.layout);
+            bx.set_var_name(tmp.llval, name);
             if fx.fn_ty.c_variadic && last_arg_idx.map(|idx| arg_index == idx).unwrap_or(false) {
                 let va_list_did = match tcx.lang_items().va_list() {
                     Some(did) => did,

src/librustc_codegen_ssa/mir/operand.rs

@@ -367,7 +367,7 @@ impl<'a, 'tcx, V: CodegenObject> OperandValue<V> {
 
         // Allocate an appropriate region on the stack, and copy the value into it
         let (llsize, _) = glue::size_and_align_of_dst(bx, unsized_ty, Some(llextra));
-        let lldst = bx.array_alloca(bx.cx().type_i8(), llsize, "unsized_tmp", max_align);
+        let lldst = bx.array_alloca(bx.cx().type_i8(), llsize, max_align);
         bx.memcpy(lldst, max_align, llptr, min_align, llsize, flags);
 
         // Store the allocated region and the extra to the indirect place.

src/librustc_codegen_ssa/mir/place.rs

@@ -71,25 +71,21 @@ impl<'a, 'tcx, V: CodegenObject> PlaceRef<'tcx, V> {
     pub fn alloca<Bx: BuilderMethods<'a, 'tcx, Value = V>>(
         bx: &mut Bx,
         layout: TyLayout<'tcx>,
-        name: &str
     ) -> Self {
-        debug!("alloca({:?}: {:?})", name, layout);
         assert!(!layout.is_unsized(), "tried to statically allocate unsized place");
-        let tmp = bx.alloca(bx.cx().backend_type(layout), name, layout.align.abi);
+        let tmp = bx.alloca(bx.cx().backend_type(layout), layout.align.abi);
         Self::new_sized(tmp, layout)
     }
 
     /// Returns a place for an indirect reference to an unsized place.
     pub fn alloca_unsized_indirect<Bx: BuilderMethods<'a, 'tcx, Value = V>>(
         bx: &mut Bx,
         layout: TyLayout<'tcx>,
-        name: &str,
     ) -> Self {
-        debug!("alloca_unsized_indirect({:?}: {:?})", name, layout);
         assert!(layout.is_unsized(), "tried to allocate indirect place for sized values");
         let ptr_ty = bx.cx().tcx().mk_mut_ptr(layout.ty);
         let ptr_layout = bx.cx().layout_of(ptr_ty);
-        Self::alloca(bx, ptr_layout, name)
+        Self::alloca(bx, ptr_layout)
     }
 
     pub fn len<Cx: ConstMethods<'tcx, Value = V>>(

src/librustc_codegen_ssa/mir/rvalue.rs

@@ -64,7 +64,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                         // index into the struct, and this case isn't
                         // important enough for it.
                         debug!("codegen_rvalue: creating ugly alloca");
-                        let scratch = PlaceRef::alloca(&mut bx, operand.layout, "__unsize_temp");
+                        let scratch = PlaceRef::alloca(&mut bx, operand.layout);
                         scratch.storage_live(&mut bx);
                         operand.val.store(&mut bx, scratch);
                         base::coerce_unsized_into(&mut bx, scratch, dest);

src/librustc_codegen_ssa/traits/builder.rs

@@ -109,13 +109,12 @@ pub trait BuilderMethods<'a, 'tcx>:
         rhs: Self::Value,
     ) -> (Self::Value, Self::Value);
 
-    fn alloca(&mut self, ty: Self::Type, name: &str, align: Align) -> Self::Value;
-    fn dynamic_alloca(&mut self, ty: Self::Type, name: &str, align: Align) -> Self::Value;
+    fn alloca(&mut self, ty: Self::Type, align: Align) -> Self::Value;
+    fn dynamic_alloca(&mut self, ty: Self::Type, align: Align) -> Self::Value;
     fn array_alloca(
         &mut self,
         ty: Self::Type,
         len: Self::Value,
-        name: &str,
         align: Align,
     ) -> Self::Value;
 

src/test/codegen/adjustments.rs

@@ -3,7 +3,7 @@
 #![crate_type = "lib"]
 
 // Hack to get the correct size for the length part in slices
-// CHECK: @helper([[USIZE:i[0-9]+]] %arg0)
+// CHECK: @helper([[USIZE:i[0-9]+]] %_1)
 #[no_mangle]
 pub fn helper(_: usize) {
 }

src/test/codegen/fastcall-inreg.rs

@@ -49,27 +49,27 @@
 #![crate_type = "lib"]
 
 pub mod tests {
-    // CHECK: @f1(i32 inreg %arg0, i32 inreg %arg1, i32 %arg2)
+    // CHECK: @f1(i32 inreg %_1, i32 inreg %_2, i32 %_3)
     #[no_mangle]
     pub extern "fastcall" fn f1(_: i32, _: i32, _: i32) {}
 
-    // CHECK: @f2(i32* inreg %arg0, i32* inreg %arg1, i32* %arg2)
+    // CHECK: @f2(i32* inreg %_1, i32* inreg %_2, i32* %_3)
     #[no_mangle]
     pub extern "fastcall" fn f2(_: *const i32, _: *const i32, _: *const i32) {}
 
-    // CHECK: @f3(float %arg0, i32 inreg %arg1, i32 inreg %arg2, i32 %arg3)
+    // CHECK: @f3(float %_1, i32 inreg %_2, i32 inreg %_3, i32 %_4)
     #[no_mangle]
     pub extern "fastcall" fn f3(_: f32, _: i32, _: i32, _: i32) {}
 
-    // CHECK: @f4(i32 inreg %arg0, float %arg1, i32 inreg %arg2, i32 %arg3)
+    // CHECK: @f4(i32 inreg %_1, float %_2, i32 inreg %_3, i32 %_4)
     #[no_mangle]
     pub extern "fastcall" fn f4(_: i32, _: f32, _: i32, _: i32) {}
 
-    // CHECK: @f5(i64 %arg0, i32 %arg1)
+    // CHECK: @f5(i64 %_1, i32 %_2)
     #[no_mangle]
     pub extern "fastcall" fn f5(_: i64, _: i32) {}
 
-    // CHECK: @f6(i1 inreg zeroext %arg0, i32 inreg %arg1, i32 %arg2)
+    // CHECK: @f6(i1 inreg zeroext %_1, i32 inreg %_2, i32 %_3)
     #[no_mangle]
     pub extern "fastcall" fn f6(_: bool, _: i32, _: i32) {}
 }