Add more compiler-rt functions for ARM platform

Author: LemonBoy

lib/std/special/compiler_rt.zig

@@ -75,6 +75,9 @@ comptime {
     @export("__floatsisf", @import("compiler_rt/floatsiXf.zig").__floatsisf, linkage);
     @export("__floatdidf", @import("compiler_rt/floatdidf.zig").__floatdidf, linkage);
     @export("__floatsitf", @import("compiler_rt/floatsiXf.zig").__floatsitf, linkage);
+
+    @export("__floatunsisf", @import("compiler_rt/floatunsisf.zig").__floatunsisf, linkage);
+    @export("__floatundisf", @import("compiler_rt/floatundisf.zig").__floatundisf, linkage);
     @export("__floatunsidf", @import("compiler_rt/floatunsidf.zig").__floatunsidf, linkage);
     @export("__floatundidf", @import("compiler_rt/floatundidf.zig").__floatundidf, linkage);
 
@@ -183,6 +186,8 @@ comptime {
         @export("__aeabi_l2d", @import("compiler_rt/floatdidf.zig").__floatdidf, linkage);
         @export("__aeabi_ui2d", @import("compiler_rt/floatunsidf.zig").__floatunsidf, linkage);
         @export("__aeabi_ul2d", @import("compiler_rt/floatundidf.zig").__floatundidf, linkage);
+        @export("__aeabi_ui2f", @import("compiler_rt/floatunsisf.zig").__floatunsisf, linkage);
+        @export("__aeabi_ul2f", @import("compiler_rt/floatundisf.zig").__floatundisf, linkage);
 
         @export("__aeabi_fneg", @import("compiler_rt/negXf2.zig").__negsf2, linkage);
         @export("__aeabi_dneg", @import("compiler_rt/negXf2.zig").__negdf2, linkage);

lib/std/special/compiler_rt/floatundisf.zig

@@ -0,0 +1,86 @@
+const builtin = @import("builtin");
+const std = @import("std");
+const maxInt = std.math.maxInt;
+
+const FLT_MANT_DIG = 24;
+
+pub extern fn __floatundisf(arg: u64) f32 {
+    @setRuntimeSafety(builtin.is_test);
+
+    if (arg == 0) return 0;
+
+    var a = arg;
+    const N: usize = @TypeOf(a).bit_count;
+    // Number of significant digits
+    const sd = N - @clz(u64, a);
+    // 8 exponent
+    var e = @intCast(u32, sd) - 1;
+
+    if (sd > FLT_MANT_DIG) {
+        //  start:  0000000000000000000001xxxxxxxxxxxxxxxxxxxxxxPQxxxxxxxxxxxxxxxxxx
+        //  finish: 000000000000000000000000000000000000001xxxxxxxxxxxxxxxxxxxxxxPQR
+        //                                                12345678901234567890123456
+        //  1 = msb 1 bit
+        //  P = bit FLT_MANT_DIG-1 bits to the right of 1
+        //  Q = bit FLT_MANT_DIG bits to the right of 1
+        //  R = "or" of all bits to the right of Q
+        switch (sd) {
+            FLT_MANT_DIG + 1 => a <<= 1,
+            FLT_MANT_DIG + 2 => {},
+            else => {
+                const shift_amt = @intCast(u6, ((N + FLT_MANT_DIG + 2) - sd));
+                const all_ones: u64 = maxInt(u64);
+                a = (a >> @intCast(u6, sd - (FLT_MANT_DIG + 2))) |
+                    @boolToInt(a & (all_ones >> shift_amt) != 0);
+            },
+        }
+        // Or P into R
+        a |= @boolToInt((a & 4) != 0);
+        // round - this step may add a significant bit
+        a += 1;
+        // dump Q and R
+        a >>= 2;
+        // a is now rounded to FLT_MANT_DIG or FLT_MANT_DIG+1 bits
+        if ((a & (@as(u64, 1) << FLT_MANT_DIG)) != 0) {
+            a >>= 1;
+            e += 1;
+        }
+        // a is now rounded to FLT_MANT_DIG bits
+    } else {
+        a <<= @intCast(u6, FLT_MANT_DIG - sd);
+        // a is now rounded to FLT_MANT_DIG bits
+    }
+
+    const result: u32 = ((e + 127) << 23) | // exponent
+        @truncate(u32, a & 0x007FFFFF); // mantissa
+    return @bitCast(f32, result);
+}
+
+fn test__floatundisf(a: u64, expected: f32) void {
+    std.testing.expectEqual(expected, __floatundisf(a));
+}
+
+test "floatundisf" {
+    test__floatundisf(0, 0.0);
+    test__floatundisf(1, 1.0);
+    test__floatundisf(2, 2.0);
+    test__floatundisf(0x7FFFFF8000000000, 0x1.FFFFFEp+62F);
+    test__floatundisf(0x7FFFFF0000000000, 0x1.FFFFFCp+62F);
+    test__floatundisf(0x8000008000000000, 0x1p+63F);
+    test__floatundisf(0x8000010000000000, 0x1.000002p+63F);
+    test__floatundisf(0x8000000000000000, 0x1p+63F);
+    test__floatundisf(0x8000000000000001, 0x1p+63F);
+    test__floatundisf(0xFFFFFFFFFFFFFFFE, 0x1p+64F);
+    test__floatundisf(0xFFFFFFFFFFFFFFFF, 0x1p+64F);
+    test__floatundisf(0x0007FB72E8000000, 0x1.FEDCBAp+50F);
+    test__floatundisf(0x0007FB72EA000000, 0x1.FEDCBAp+50F);
+    test__floatundisf(0x0007FB72EB000000, 0x1.FEDCBAp+50F);
+    test__floatundisf(0x0007FB72EBFFFFFF, 0x1.FEDCBAp+50F);
+    test__floatundisf(0x0007FB72EC000000, 0x1.FEDCBCp+50F);
+    test__floatundisf(0x0007FB72E8000001, 0x1.FEDCBAp+50F);
+    test__floatundisf(0x0007FB72E6000000, 0x1.FEDCBAp+50F);
+    test__floatundisf(0x0007FB72E7000000, 0x1.FEDCBAp+50F);
+    test__floatundisf(0x0007FB72E7FFFFFF, 0x1.FEDCBAp+50F);
+    test__floatundisf(0x0007FB72E4000001, 0x1.FEDCBAp+50F);
+    test__floatundisf(0x0007FB72E4000000, 0x1.FEDCB8p+50F);
+}

lib/std/special/compiler_rt/floatunsisf.zig

@@ -0,0 +1,53 @@
+const builtin = @import("builtin");
+const std = @import("std");
+const maxInt = std.math.maxInt;
+
+const significandBits = 23;
+const exponentBias = 127;
+const implicitBit = @as(u32, 1) << significandBits;
+
+pub extern fn __floatunsisf(arg: u32) f32 {
+    @setRuntimeSafety(builtin.is_test);
+
+    if (arg == 0) return 0.0;
+
+    // The exponent is the width of abs(a)
+    const exp = @as(u32, 31) - @clz(u32, arg);
+
+    var mantissa: u32 = undefined;
+    if (exp <= significandBits) {
+        // Shift a into the significand field and clear the implicit bit
+        const shift = @intCast(u5, significandBits - exp);
+        mantissa = @as(u32, arg) << shift ^ implicitBit;
+    } else {
+        const shift = @intCast(u5, exp - significandBits);
+        // Round to the nearest number after truncation
+        mantissa = @as(u32, arg) >> shift ^ implicitBit;
+        // Align to the left and check if the truncated part is halfway over
+        const round = arg << @intCast(u5, 31 - shift);
+        mantissa += @boolToInt(round > 0x80000000);
+        // Tie to even
+        mantissa += mantissa & 1;
+    }
+
+    // Use the addition instead of a or since we may have a carry from the
+    // mantissa to the exponent
+    var result = mantissa;
+    result += (exp + exponentBias) << significandBits;
+
+    return @bitCast(f32, result);
+}
+
+fn test_one_floatunsisf(a: u32, expected: u32) void {
+    const r = __floatunsisf(a);
+    std.testing.expect(@bitCast(u32, r) == expected);
+}
+
+test "floatunsisf" {
+    // Test the produced bit pattern
+    test_one_floatunsisf(0, 0);
+    test_one_floatunsisf(1, 0x3f800000);
+    test_one_floatunsisf(0x7FFFFFFF, 0x4f000000);
+    test_one_floatunsisf(0x80000000, 0x4f000000);
+    test_one_floatunsisf(0xFFFFFFFF, 0x4f800000);
+}