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Add __gnu_thumb1_case_{sqi,uqi,shi,uhi,si} to compiler_rt #24806

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Add __gnu_thumb1_case_{sqi,uqi,shi,uhi,si} to compiler_rt #24806

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94 changes: 94 additions & 0 deletions lib/compiler_rt/arm.zig
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Original file line number Diff line number Diff line change
Expand Up @@ -41,6 +41,14 @@ comptime {
@export(&__aeabi_read_tp, .{ .name = "__aeabi_read_tp", .linkage = common.linkage, .visibility = common.visibility });
}

if (arch.isThumb()) {
@export(&__gnu_thumb1_case_sqi, .{ .name = "__gnu_thumb1_case_sqi", .linkage = common.linkage, .visibility = common.visibility });
@export(&__gnu_thumb1_case_uqi, .{ .name = "__gnu_thumb1_case_uqi", .linkage = common.linkage, .visibility = common.visibility });
@export(&__gnu_thumb1_case_shi, .{ .name = "__gnu_thumb1_case_shi", .linkage = common.linkage, .visibility = common.visibility });
@export(&__gnu_thumb1_case_uhi, .{ .name = "__gnu_thumb1_case_uhi", .linkage = common.linkage, .visibility = common.visibility });
@export(&__gnu_thumb1_case_si, .{ .name = "__gnu_thumb1_case_si", .linkage = common.linkage, .visibility = common.visibility });
}

// floating-point helper functions (single+double-precision reverse subtraction, y – x), see subdf3.zig
@export(&__aeabi_frsub, .{ .name = "__aeabi_frsub", .linkage = common.linkage, .visibility = common.visibility });
@export(&__aeabi_drsub, .{ .name = "__aeabi_drsub", .linkage = common.linkage, .visibility = common.visibility });
Expand Down Expand Up @@ -201,6 +209,92 @@ pub fn __aeabi_ldivmod() callconv(.naked) void {
unreachable;
}

// GCC Thumb1 compressed switch tables: <https://gcc.gnu.org/legacy-ml/gcc-patches/2009-06/msg01698.html>

pub fn __gnu_thumb1_case_sqi() callconv(.naked) void {
@setRuntimeSafety(false);
asm volatile (
\\ push {r1}
\\ mov r1, lr
\\ lsrs r1, r1, #1
\\ lsls r1, r1, #1
\\ ldrsb r1, [r1, r0]
\\ lsls r1, r1, #1
\\ add lr, lr, r1
\\ pop {r1}
\\ bx lr
);
unreachable;
}

pub fn __gnu_thumb1_case_uqi() callconv(.naked) void {
@setRuntimeSafety(false);
asm volatile (
\\ push {r1}
\\ mov r1, lr
\\ lsrs r1, r1, #1
\\ lsls r1, r1, #1
\\ ldrb r1, [r1, r0]
\\ lsls r1, r1, #1
\\ add lr, lr, r1
\\ pop {r1}
\\ bx lr
);
unreachable;
}

pub fn __gnu_thumb1_case_shi() callconv(.naked) void {
@setRuntimeSafety(false);
asm volatile (
\\ push {r0, r1}
\\ mov r1, lr
\\ lsrs r1, r1, #1
\\ lsls r0, r0, #1
\\ lsls r1, r1, #1
\\ ldrsh r1, [r1, r0]
\\ lsls r1, r1, #1
\\ add lr, lr, r1
\\ pop {r0, r1}
\\ bx lr
);
unreachable;
}

pub fn __gnu_thumb1_case_uhi() callconv(.naked) void {
@setRuntimeSafety(false);
asm volatile (
\\ push {r0, r1}
\\ mov r1, lr
\\ lsrs r1, r1, #1
\\ lsls r0, r0, #1
\\ lsls r1, r1, #1
\\ ldrh r1, [r1, r0]
\\ lsls r1, r1, #1
\\ add lr, lr, r1
\\ pop {r0, r1}
\\ bx lr
);
unreachable;
}

pub fn __gnu_thumb1_case_si() callconv(.naked) void {
@setRuntimeSafety(false);
asm volatile (
\\ push {r0, r1}
\\ mov r1, lr
\\ adds r1, r1, #2
\\ lsrs r1, r1, #2
\\ lsls r0, r0, #2
\\ lsls r1, r1, #2
\\ ldr r0, [r1, r0]
\\ adds r0, r0, r1
\\ mov lr, r0
\\ pop {r0, r1}
\\ mov pc, lr
);
unreachable;
}

// Float Arithmetic

fn __aeabi_frsub(a: f32, b: f32) callconv(.{ .arm_aapcs = .{} }) f32 {
Expand Down
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