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compiler_rt: document ARM status
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This commit documents the status of Run-time ABI 2022Q3 for ARM excluding
C++ helper functions.
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@andrewrk
Jan Philipp Hafer authored and andrewrk committed Apr 26, 2023
1 parent 66da64d commit f618398
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86 changes: 83 additions & 3 deletions lib/compiler_rt/README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -72,9 +72,11 @@ Integer and Float Operations
| | | | | | **Integer Comparison** |
| ✓ | __cmpsi2 | i32 | i32 | i32 | `(a<b) -> 0, (a==b) -> 1, (a>b) -> 2` |
| ✓ | __cmpdi2 | i64 | i64 | i32 | .. |
| ✗ | __aeabi_lcmp | i64 | i64 | i32 | .. ARM |
| ✓ | __cmpti2 | i128 | i128 | i32 | .. |
| ✓ | __ucmpsi2 | u32 | u32 | i32 | `(a<b) -> 0, (a==b) -> 1, (a>b) -> 2` |
| ✓ | __ucmpdi2 | u64 | u64 | i32 | .. |
| ✗ | __aeabi_ulcmp | u64 | u64 | i32 | .. ARM |
| ✓ | __ucmpti2 | u128 | u128 | i32 | .. |
| | | | | | **Integer Arithmetic** |
| ✓ | __ashlsi3 | i32 | i32 | i32 | `a << b` [^unused_rl78] |
Expand All @@ -94,6 +96,7 @@ Integer and Float Operations
| ✓ | __negti2 | i128 | i128 | i128 | .. |
| ✓ | __mulsi3 | i32 | i32 | i32 | `a * b` |
| ✓ | __muldi3 | i64 | i64 | i64 | .. |
| ✓ | __aeabi_lmul | i64 | i64 | i64 | .. ARM |
| ✓ | __multi3 | i128 | i128 | i128 | .. |
| ✓ | __divsi3 | i32 | i32 | i32 | `a / b` |
| ✓ | __divdi3 | i64 | i64 | i64 | .. |
Expand All @@ -110,10 +113,14 @@ Integer and Float Operations
| ✓ | __umoddi3 | u64 | u64 | u64 | .. |
| ✓ | __umodti3 | u128 | u128 | u128 | .. |
| ✓ | __udivmodsi4 | u32 | u32 | u32 | `a / b, rem.* = a % b` |
| ✓ | __aeabi_uidivmod | u32 | u32 | u32 | .. ARM |
| ✓ | __udivmoddi4 | u64 | u64 | u64 | .. |
| ✓ | __aeabi_uldivmod | u64 | u64 | u64 | .. ARM |
| ✓ | __udivmodti4 | u128 | u128 | u128 | .. |
| ✓ | __divmodsi4 | i32 | i32 | i32 | `a / b, rem.* = a % b` |
| ✓ | __aeabi_idivmod | i32 | i32 | i32 | .. ARM |
| ✓ | __divmoddi4 | i64 | i64 | i64 | .. |
| ✓ | __aeabi_ldivmod | i64 | i64 | i64 | .. ARM |
| ✓ | __divmodti4 | i128 | i128 | i128 | .. [^libgcc_compat] |
| | | | | | **Integer Arithmetic with Trapping Overflow**|
| ✓ | __absvsi2 | i32 | i32 | i32 | abs(a) |
Expand Down Expand Up @@ -142,11 +149,16 @@ Integer and Float Operations
| ✓ | __mulodi4 | i64 | i64 | i64 | .. |
| ✓ | __muloti4 | i128 | i128 | i128 | .. |
| | | | | | **Float Conversion** |
| ✓ | __extendhfdf2 | f16 | ∅ | f32 | .. |
| ✓ | __extendsfdf2 | f32 | ∅ | f64 | .. |
| ✓ | __aeabi_f2d | f32 | ∅ | f64 | .. |
| ✓ | __extendsftf2 | f32 | ∅ | f128 | .. |
| ✓ | __extendsfxf2 | f32 | ∅ | f80 | .. |
| ✓ | __extenddftf2 | f64 | ∅ | f128 | .. |
| ✓ | __extenddfxf2 | f64 | ∅ | f80 | .. |
| ✗ | __aeabi_h2f | f16 | ∅ | f32 | .. ARM |
| ✗ | __aeabi_h2f_alt | f16 | ∅ | f32 | .. ARM alternate [^VFPv3alt] |
| ✓ | __gnu_h2f_ieee | f16 | ∅ | f32 | .. GNU naming convention |
| ✓ | __truncsfhf2 | f32 | ∅ | f16 | rounding towards zero |
| ✓ | __truncdfhf2 | f64 | ∅ | f16 | .. |
| ✓ | __truncdfsf2 | f64 | ∅ | f32 | .. |
Expand All @@ -157,22 +169,28 @@ Integer and Float Operations
| ✓ | __truncxfhf2 | f80 | ∅ | f16 | .. |
| ✓ | __truncxfsf2 | f80 | ∅ | f32 | .. |
| ✓ | __truncxfdf2 | f80 | ∅ | f64 | .. |
| ✓ | __aeabi_f2h | f32 | ∅ | f16 | .. ARM |
| ✓ | __gnu_f2h_ieee | f32 | ∅ | f16 | ..GNU naming convention |
| ✗ | __aeabi_f2h | f32 | ∅ | f16 | .. ARM |
| ✗ | __aeabi_f2h_alt | f32 | ∅ | f16 | .. ARM alternate [^VFPv3alt] |
| ✓ | __gnu_f2h_ieee | f32 | ∅ | f16 | .. GNU naming convention |
| ✓ | __aeabi_d2h | f64 | ∅ | f16 | .. ARM |
| ✗ | __aeabi_d2h_alt | f64 | ∅ | f16 | .. ARM alternate [^VFPv3alt] |
| ✓ | __aeabi_d2f | f64 | ∅ | f32 | .. ARM |
| ✓ | __trunckfsf2 | f128 | ∅ | f32 | .. PPC |
| ✓ | _Qp_qtos |*f128 | ∅ | f32 | .. SPARC |
| ✓ | __trunckfdf2 | f128 | ∅ | f64 | .. PPC |
| ✓ | _Qp_qtod |*f128 | ∅ | f64 | .. SPARC |
| ✓ | __fixhfsi | f16 | ∅ | i32 | float to int, rounding towards zero |
| ✓ | __fixsfsi | f32 | ∅ | i32 | .. |
| ✓ | __aeabi_f2iz | f32 | ∅ | i32 | .. ARM |
| ✓ | __fixdfsi | f64 | ∅ | i32 | .. |
| ✓ | __aeabi_d2iz | f64 | ∅ | i32 | .. ARM |
| ✓ | __fixtfsi | f128 | ∅ | i32 | .. |
| ✓ | __fixxfsi | f80 | ∅ | i32 | .. |
| ✓ | __fixhfdi | f16 | ∅ | i64 | .. |
| ✓ | __fixsfdi | f32 | ∅ | i64 | .. |
| ✓ | __aeabi_f2lz | f32 | ∅ | i64 | .. ARM |
| ✓ | __fixdfdi | f64 | ∅ | i64 | .. |
| ✓ | __aeabi_d2lz | f64 | ∅ | i64 | .. ARM |
| ✓ | __fixtfdi | f128 | ∅ | i64 | .. |
| ✓ | __fixxfdi | f80 | ∅ | i64 | .. |
| ✓ | __fixhfti | f16 | ∅ | i128 | .. |
Expand All @@ -182,12 +200,16 @@ Integer and Float Operations
| ✓ | __fixxfti | f80 | ∅ | i128 | .. |
| ✓ | __fixunshfsi | f16 | ∅ | u32 | float to uint, rounding towards zero. negative values become 0. |
| ✓ | __fixunssfsi | f32 | ∅ | u32 | .. |
| ✓ | __aeabi_f2uiz | f32 | ∅ | u32 | .. ARM |
| ✓ | __fixunsdfsi | f64 | ∅ | u32 | .. |
| ✓ | __aeabi_d2uiz | f64 | ∅ | u32 | .. ARM |
| ✓ | __fixunstfsi | f128 | ∅ | u32 | .. |
| ✓ | __fixunsxfsi | f80 | ∅ | u32 | .. |
| ✓ | __fixunshfdi | f16 | ∅ | u64 | .. |
| ✓ | __fixunssfdi | f32 | ∅ | u64 | .. |
| ✓ | __aeabi_f2ulz | f32 | ∅ | u64 | .. ARM |
| ✓ | __fixunsdfdi | f64 | ∅ | u64 | .. |
| ✓ | __aeabi_d2ulz | f64 | ∅ | u64 | .. ARM |
| ✓ | __fixunstfdi | f128 | ∅ | u64 | .. |
| ✓ | __fixunsxfdi | f80 | ∅ | u64 | .. |
| ✓ | __fixunshfti | f16 | ∅ | u128 | .. |
Expand All @@ -197,11 +219,15 @@ Integer and Float Operations
| ✓ | __fixunsxfti | f80 | ∅ | u128 | .. |
| ✓ | __floatsihf | i32 | ∅ | f16 | int to float |
| ✓ | __floatsisf | i32 | ∅ | f32 | .. |
| ✓ | __aeabi_i2f | i32 | ∅ | f32 | .. ARM |
| ✓ | __floatsidf | i32 | ∅ | f64 | .. |
| ✓ | __aeabi_i2d | i32 | ∅ | f64 | .. ARM |
| ✓ | __floatsitf | i32 | ∅ | f128 | .. |
| ✓ | __floatsixf | i32 | ∅ | f80 | .. |
| ✓ | __floatdisf | i64 | ∅ | f32 | .. |
| ✓ | __aeabi_l2f | i64 | ∅ | f32 | .. ARM |
| ✓ | __floatdidf | i64 | ∅ | f64 | .. |
| ✓ | __aeabi_l2d | i64 | ∅ | f64 | .. ARM |
| ✓ | __floatditf | i64 | ∅ | f128 | .. |
| ✓ | __floatdixf | i64 | ∅ | f80 | .. |
| ✓ | __floattihf | i128 | ∅ | f16 | .. |
Expand All @@ -211,12 +237,16 @@ Integer and Float Operations
| ✓ | __floattixf | i128 | ∅ | f80 | .. |
| ✓ | __floatunsihf | u32 | ∅ | f16 | uint to float |
| ✓ | __floatunsisf | u32 | ∅ | f32 | .. |
| ✓ | __aeabi_ui2f | u32 | ∅ | f32 | .. ARM |
| ✓ | __floatunsidf | u32 | ∅ | f64 | .. |
| ✓ | __aeabi_ui2d | u32 | ∅ | f64 | .. ARM |
| ✓ | __floatunsitf | u32 | ∅ | f128 | .. |
| ✓ | __floatunsixf | u32 | ∅ | f80 | .. |
| ✓ | __floatundihf | u64 | ∅ | f16 | .. |
| ✓ | __floatundisf | u64 | ∅ | f32 | .. |
| ✓ | __aeabi_ul2f | u64 | ∅ | f32 | .. ARM |
| ✓ | __floatundidf | u64 | ∅ | f64 | .. |
| ✓ | __aeabi_ul2d | u64 | ∅ | f64 | .. ARM |
| ✓ | __floatunditf | u64 | ∅ | f128 | .. |
| ✓ | __floatundixf | u64 | ∅ | f80 | .. |
| ✓ | __floatuntihf | u128 | ∅ | f16 | .. |
Expand Down Expand Up @@ -353,6 +383,7 @@ Integer and Float Operations
[^noptr_faster]: Operations without pointer and without C struct semantics lead to better optimizations.
[^perf_addition]: Has better performance than standard method due to 2s complement semantics.
Not provided by LLVM and libgcc.
[^VFPv3alt]: Converts IEEE-format to VFPv3 alternative-format.

Decimal float library routines

Expand Down Expand Up @@ -712,8 +743,57 @@ TODO brief description
| | | | | | | |**BigInt Arithmetic which Return on Overflow**[^noptr_faster]|

Further content (conditionally) exported with C abi:

ARM-only routines

| Done | Name | a | b | Out | Comment |
| ---- | -------- | --- | --- | -----| ----------------------|
| | | | | | **Float Comparison** |
|✗|__aeabi_cfcmpeq | f32 | f32 | void | `a == b` result in PSR ZC flags[^PSRZC] |
|✗|__aeabi_cfcmple | f32 | f32 | void | `a <= b` result .. |
|✗|__aeabi_cfrcmple| f32 | f32 | void | `b <= a` .. |
|✗|__aeabi_cdcmpeq | f64 | f64 | void | `a == b` .. |
|✗|__aeabi_cdcmple | f64 | f64 | void | `a <= b` .. |
|✗|__aeabi_cdrcmple| f64 | f64 | void | `b <= a` .. |
| | | | | | **Float Arithmetic** |
|✗|__aeabi_frsub | f64 | f64 | f64 | `b - a` |
|✗|__aeabi_drsub | f64 | f64 | f64 | .. |
| | | | | | **Special** |
|✓|__aeabi_read_tp | ∅ | ∅ | *u8 | ret tls pointer |
|✗|__aeabi_idiv0 | i32 | ∅ | i32 | div by 0 modifier |
|✗|__aeabi_ldiv0 | i64 | ∅ | i64 | div by 0 modifier |
| | | | | | **Unaligned memory access** |
|✗|__aeabi_uread4 |[*]u8| ∅ | i32 | ret value read |
|✗|__aeabi_uwrite4 | i32 |[*]u8| i32 | ret value written |
|✗|__aeabi_uread8 |[*]u8| ∅ | i64 | .. |
|✗|__aeabi_uwrite8 | i64 |[*]u8| i64 | .. |


| Done | Name | a | b | c | Comment |
| ---- | -------- | --- | --- | -----| ----------------------|
| | | | | | **Memory copy, move and set** |
|✓|__aeabi_memcpy8 |[*]u8|[*]u8| usize| *dest, *src, size |
|✓|__aeabi_memcpy4 |[*]u8|[*]u8| usize| .. |
|✓|__aeabi_memcpy |[*]u8|[*]u8| usize| .. |
|✓|__aeabi_memmove8|[*]u8|[*]u8| usize| *dest, *src, size |
|✓|__aeabi_memmove4|[*]u8|[*]u8| usize| .. |
|✓|__aeabi_memmove |[*]u8|[*]u8| usize| .. |
|✓|__aeabi_memset8 |[*]u8|usize| i32 | *dest, size, char |
|✓|__aeabi_memset4 |[*]u8|usize| i32 | .. |
|✓|__aeabi_memset |[*]u8|usize| i32 | .. |
|✓|__aeabi_memclr8 |[*]u8| u32 | usize| *dest, size |
|✓|__aeabi_memclr4 |[*]u8| u32 | usize| .. |
|✓|__aeabi_memclr |[*]u8| u32 | usize| .. |
|✓|__aeabi_uwrite8 | i64 |[*]u8| i64 | .. |

- __aeabi_read_tp

[^PSRZC]: return result in the CPSR Z and C flag. C is clear only if the
operands are ordered and the first operand is less than the second.
Z is set only when the operands are ordered and equal.
Preserves all core registers except ip, lr, and the CPSR.

- aarch64 outline atomics
- arm routines (memory routines + memclr [setting to 0], divmod routines and stubs for unwind_cpp)
- atomics
- bcmp
- clear cache
Expand Down
11 changes: 10 additions & 1 deletion lib/compiler_rt/arm.zig
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Original file line number Diff line number Diff line change
@@ -1,4 +1,5 @@
// ARM specific builtins
//! Implementation of ARM specific builtins for Run-time ABI
//! This file includes all ARM-only functions.
const std = @import("std");
const builtin = @import("builtin");
const arch = builtin.cpu.arch;
Expand Down Expand Up @@ -38,6 +39,9 @@ comptime {
if (builtin.os.tag == .linux) {
@export(__aeabi_read_tp, .{ .name = "__aeabi_read_tp", .linkage = common.linkage, .visibility = common.visibility });
}

// floating-point helper functions (double-precision reverse subtraction, y – x), see subdf3.zig
@export(__aeabi_drsub, .{ .name = "__aeabi_drsub", .linkage = common.linkage, .visibility = common.visibility });
}
}
}
Expand Down Expand Up @@ -186,3 +190,8 @@ pub fn __aeabi_ldivmod() callconv(.Naked) void {
::: "memory");
unreachable;
}

pub fn __aeabi_drsub(a: f64, b: f64) callconv(.AAPCS) f64 {
const neg_a = @bitCast(f64, @bitCast(u64, a) ^ (@as(u64, 1) << 63));
return b + neg_a;
}

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