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JonathanBrouwerJonathanBrouwer
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Rollup merge of rust-lang#146901 - taiki-e:avrtiny, r=Amanieu
Support AVRTiny devices in AVR inline assembly Note: This is still draft and this depends on rust-lang#146900 which adds necessary target feature. (The first commit is from it.) --- Follow-up to rust-lang#131323. AVR has devices that reduce the number of registers, similar to RISC-V's RV32E, which have different ABI than default. This PR supports such devices in inline assembly. Refs: AVR-GCC docs https://gcc.gnu.org/wiki/avr-gcc#Reduced_Tiny > On the Reduced Tiny cores (16 GPRs only) several modifications to the ABI above apply: > > Call-saved registers are: R18–R19, R28–R29. Fixed Registers are R16 (__tmp_reg__) and R17 (__zero_reg__). > > Registers used to pass arguments to functions and return values from functions are R25...R20 (instead of R25...R8). Values that occupy more than 4 registers are returned in memory (instead of more than 8 registers). There is only limited library support both from libgcc and AVR-LibC, for example there is no float support and no printf support. r? @Amanieu @rustbot label +O-AVR +A-inline-assembly
2 parents 7ad4e69 + b2dd13a commit 18759d2

7 files changed

Lines changed: 415 additions & 30 deletions

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‎compiler/rustc_span/src/symbol.rs‎

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -2300,6 +2300,7 @@ symbols! {
23002300
three_way_compare,
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thumb2,
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thumb_mode: "thumb-mode",
2303+
tinyencoding,
23032304
tmm_reg,
23042305
to_owned_method,
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to_string,

‎compiler/rustc_target/src/asm/avr.rs‎

Lines changed: 47 additions & 25 deletions
Original file line numberDiff line numberDiff line change
@@ -1,8 +1,10 @@
11
use std::fmt;
22

3-
use rustc_span::Symbol;
3+
use rustc_data_structures::fx::FxIndexSet;
4+
use rustc_span::{Symbol, sym};
45

56
use super::{InlineAsmArch, InlineAsmType, ModifierInfo};
7+
use crate::spec::{RelocModel, Target};
68

79
def_reg_class! {
810
Avr AvrInlineAsmRegClass {
@@ -52,24 +54,44 @@ impl AvrInlineAsmRegClass {
5254
}
5355
}
5456

57+
pub(crate) fn is_tiny(target_features: &FxIndexSet<Symbol>) -> bool {
58+
target_features.contains(&sym::tinyencoding)
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}
60+
61+
fn not_tiny(
62+
_arch: InlineAsmArch,
63+
_reloc_model: RelocModel,
64+
target_features: &FxIndexSet<Symbol>,
65+
_target: &Target,
66+
_is_clobber: bool,
67+
) -> Result<(), &'static str> {
68+
if is_tiny(target_features) {
69+
Err(
70+
"on AVRTiny, r[2-15] are unavailable, r16 (scratch register) and r17 (zero register) are reserved by LLVM",
71+
)
72+
} else {
73+
Ok(())
74+
}
75+
}
76+
5577
def_regs! {
5678
Avr AvrInlineAsmReg AvrInlineAsmRegClass {
57-
r2: reg = ["r2"],
58-
r3: reg = ["r3"],
59-
r4: reg = ["r4"],
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r5: reg = ["r5"],
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r6: reg = ["r6"],
62-
r7: reg = ["r7"],
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r8: reg = ["r8"],
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r9: reg = ["r9"],
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r10: reg = ["r10"],
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r11: reg = ["r11"],
67-
r12: reg = ["r12"],
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r13: reg = ["r13"],
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r14: reg = ["r14"],
70-
r15: reg = ["r15"],
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r16: reg, reg_upper = ["r16"],
72-
r17: reg, reg_upper = ["r17"],
79+
r2: reg = ["r2"] % not_tiny,
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r3: reg = ["r3"] % not_tiny,
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r4: reg = ["r4"] % not_tiny,
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r5: reg = ["r5"] % not_tiny,
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r6: reg = ["r6"] % not_tiny,
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r7: reg = ["r7"] % not_tiny,
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r8: reg = ["r8"] % not_tiny,
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r9: reg = ["r9"] % not_tiny,
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r10: reg = ["r10"] % not_tiny,
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r11: reg = ["r11"] % not_tiny,
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r12: reg = ["r12"] % not_tiny,
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r13: reg = ["r13"] % not_tiny,
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r14: reg = ["r14"] % not_tiny,
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r15: reg = ["r15"] % not_tiny,
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r16: reg, reg_upper = ["r16"] % not_tiny,
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r17: reg, reg_upper = ["r17"] % not_tiny,
7395
r18: reg, reg_upper = ["r18"],
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r19: reg, reg_upper = ["r19"],
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r20: reg, reg_upper = ["r20"],
@@ -83,14 +105,14 @@ def_regs! {
83105
r30: reg, reg_upper = ["r30", "ZL"],
84106
r31: reg, reg_upper = ["r31", "ZH"],
85107

86-
r3r2: reg_pair = ["r3r2"],
87-
r5r4: reg_pair = ["r5r4"],
88-
r7r6: reg_pair = ["r7r6"],
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r9r8: reg_pair = ["r9r8"],
90-
r11r10: reg_pair = ["r11r10"],
91-
r13r12: reg_pair = ["r13r12"],
92-
r15r14: reg_pair = ["r15r14"],
93-
r17r16: reg_pair = ["r17r16"],
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r3r2: reg_pair = ["r3r2"] % not_tiny,
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r5r4: reg_pair = ["r5r4"] % not_tiny,
110+
r7r6: reg_pair = ["r7r6"] % not_tiny,
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r9r8: reg_pair = ["r9r8"] % not_tiny,
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r11r10: reg_pair = ["r11r10"] % not_tiny,
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r13r12: reg_pair = ["r13r12"] % not_tiny,
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r15r14: reg_pair = ["r15r14"] % not_tiny,
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r17r16: reg_pair = ["r17r16"] % not_tiny,
94116
r19r18: reg_pair = ["r19r18"],
95117
r21r20: reg_pair = ["r21r20"],
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r23r22: reg_pair = ["r23r22"],

‎compiler/rustc_target/src/asm/mod.rs‎

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Original file line numberDiff line numberDiff line change
@@ -932,6 +932,7 @@ pub enum InlineAsmClobberAbi {
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AArch64NoX18,
933933
Arm64EC,
934934
Avr,
935+
AvrTiny,
935936
RiscV,
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RiscVE,
937938
LoongArch,
@@ -993,7 +994,11 @@ impl InlineAsmClobberAbi {
993994
_ => Err(&["C", "system", "efiapi"]),
994995
},
995996
InlineAsmArch::Avr => match name {
996-
"C" | "system" => Ok(InlineAsmClobberAbi::Avr),
997+
"C" | "system" => Ok(if avr::is_tiny(target_features) {
998+
InlineAsmClobberAbi::AvrTiny
999+
} else {
1000+
InlineAsmClobberAbi::Avr
1001+
}),
9971002
_ => Err(&["C", "system"]),
9981003
},
9991004
InlineAsmArch::LoongArch32 | InlineAsmArch::LoongArch64 => match name {
@@ -1168,6 +1173,13 @@ impl InlineAsmClobberAbi {
11681173
// is used.
11691174
}
11701175
},
1176+
InlineAsmClobberAbi::AvrTiny => clobbered_regs! {
1177+
Avr AvrInlineAsmReg {
1178+
// Refs: https://gcc.gnu.org/wiki/avr-gcc#Reduced_Tiny
1179+
1180+
r20, r21, r22, r23, r24, r25, r26, r27, r30, r31,
1181+
}
1182+
},
11711183
InlineAsmClobberAbi::RiscV => clobbered_regs! {
11721184
RiscV RiscVInlineAsmReg {
11731185
// ra

‎tests/codegen-llvm/asm/avr-clobbers.rs‎

Lines changed: 10 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -1,7 +1,11 @@
11
//@ add-minicore
22
//@ assembly-output: emit-asm
3-
//@ compile-flags: --target avr-none -C target-cpu=atmega328p
4-
//@ needs-llvm-components: avr
3+
//@ revisions: avr avrtiny
4+
//@[avr] compile-flags: --target avr-none -C target-cpu=atmega328p
5+
//@[avr] needs-llvm-components: avr
6+
//@[avrtiny] compile-flags: --target avr-none -C target-cpu=attiny104
7+
//@[avrtiny] needs-llvm-components: avr
8+
// ignore-tidy-linelength
59

610
#![crate_type = "rlib"]
711
#![feature(no_core, asm_experimental_arch)]
@@ -25,14 +29,16 @@ pub unsafe fn sreg_is_not_clobbered_if_preserve_flags_is_used() {
2529
}
2630

2731
// CHECK-LABEL: @clobber_abi
28-
// CHECK: asm sideeffect "", "={r18},={r19},={r20},={r21},={r22},={r23},={r24},={r25},={r26},={r27},={r30},={r31},~{sreg}"()
32+
// avr: asm sideeffect "", "={r18},={r19},={r20},={r21},={r22},={r23},={r24},={r25},={r26},={r27},={r30},={r31},~{sreg}"()
33+
// avrtiny: asm sideeffect "", "={r20},={r21},={r22},={r23},={r24},={r25},={r26},={r27},={r30},={r31},~{sreg}"()
2934
#[no_mangle]
3035
pub unsafe fn clobber_abi() {
3136
asm!("", clobber_abi("C"), options(nostack, nomem));
3237
}
3338

3439
// CHECK-LABEL: @clobber_abi_with_preserved_flags
35-
// CHECK: asm sideeffect "", "={r18},={r19},={r20},={r21},={r22},={r23},={r24},={r25},={r26},={r27},={r30},={r31}"()
40+
// avr: asm sideeffect "", "={r18},={r19},={r20},={r21},={r22},={r23},={r24},={r25},={r26},={r27},={r30},={r31}"()
41+
// avrtiny: asm sideeffect "", "={r20},={r21},={r22},={r23},={r24},={r25},={r26},={r27},={r30},={r31}"()
3642
#[no_mangle]
3743
pub unsafe fn clobber_abi_with_preserved_flags() {
3844
asm!("", clobber_abi("C"), options(nostack, nomem, preserves_flags));

‎tests/ui/asm/avr/bad-reg.avr.stderr‎

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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,56 @@
1+
error: invalid register `Y`: the frame pointer cannot be used as an operand for inline asm
2+
--> $DIR/bad-reg.rs:19:18
3+
|
4+
LL | asm!("", out("Y") _);
5+
| ^^^^^^^^^^
6+
7+
error: invalid register `YL`: the frame pointer cannot be used as an operand for inline asm
8+
--> $DIR/bad-reg.rs:21:18
9+
|
10+
LL | asm!("", out("YL") _);
11+
| ^^^^^^^^^^^
12+
13+
error: invalid register `YH`: the frame pointer cannot be used as an operand for inline asm
14+
--> $DIR/bad-reg.rs:23:18
15+
|
16+
LL | asm!("", out("YH") _);
17+
| ^^^^^^^^^^^
18+
19+
error: invalid register `SP`: the stack pointer cannot be used as an operand for inline asm
20+
--> $DIR/bad-reg.rs:25:18
21+
|
22+
LL | asm!("", out("SP") _);
23+
| ^^^^^^^^^^^
24+
25+
error: invalid register `SPL`: the stack pointer cannot be used as an operand for inline asm
26+
--> $DIR/bad-reg.rs:27:18
27+
|
28+
LL | asm!("", out("SPL") _);
29+
| ^^^^^^^^^^^^
30+
31+
error: invalid register `SPH`: the stack pointer cannot be used as an operand for inline asm
32+
--> $DIR/bad-reg.rs:29:18
33+
|
34+
LL | asm!("", out("SPH") _);
35+
| ^^^^^^^^^^^^
36+
37+
error: invalid register `r0`: LLVM reserves r0 (scratch register) and r1 (zero register)
38+
--> $DIR/bad-reg.rs:31:18
39+
|
40+
LL | asm!("", out("r0") _);
41+
| ^^^^^^^^^^^
42+
43+
error: invalid register `r1`: LLVM reserves r0 (scratch register) and r1 (zero register)
44+
--> $DIR/bad-reg.rs:33:18
45+
|
46+
LL | asm!("", out("r1") _);
47+
| ^^^^^^^^^^^
48+
49+
error: invalid register `r1r0`: LLVM reserves r0 (scratch register) and r1 (zero register)
50+
--> $DIR/bad-reg.rs:35:18
51+
|
52+
LL | asm!("", out("r1r0") _);
53+
| ^^^^^^^^^^^^^
54+
55+
error: aborting due to 9 previous errors
56+

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