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llvm codegen: fix f16,f32,f64 nan bitcasts

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@bitCast from integer NaN representation to float NaN resulted in
changed bits in float. This only happened with signaled NaN.

- added test for signaled NaN
- added tests for quiet NaN (for completeness)

closes #14198
This commit is contained in:
Michael Dusan 2023-01-04 15:18:17 -05:00 • committed by Andrew Kelley
parent b89158d6fd
commit e0fb4c29cb
3 changed files with 32 additions and 4 deletions
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17
src/codegen/llvm.zig
View file

@ -3287,15 +3287,24 @@ pub const DeclGen = struct {
.Float => {
const llvm_ty = try dg.lowerType(tv.ty);
switch (tv.ty.floatBits(target)) {
16 => if (intrinsicsAllowed(tv.ty, target)) {
return llvm_ty.constReal(tv.val.toFloat(f16));
} else {
16 => {
const repr = @bitCast(u16, tv.val.toFloat(f16));
const llvm_i16 = dg.context.intType(16);
const int = llvm_i16.constInt(repr, .False);
return int.constBitCast(llvm_ty);
},
32, 64 => return llvm_ty.constReal(tv.val.toFloat(f64)),
32 => {
const repr = @bitCast(u32, tv.val.toFloat(f32));
const llvm_i32 = dg.context.intType(32);
const int = llvm_i32.constInt(repr, .False);
return int.constBitCast(llvm_ty);
},
64 => {
const repr = @bitCast(u64, tv.val.toFloat(f64));
const llvm_i64 = dg.context.intType(64);
const int = llvm_i64.constInt(repr, .False);
return int.constBitCast(llvm_ty);
},
80 => {
const float = tv.val.toFloat(f80);
const repr = std.math.break_f80(float);

1
test/behavior.zig
View file

@ -241,6 +241,7 @@ test {
{
_ = @import("behavior/bugs/13063.zig");
_ = @import("behavior/bugs/11227.zig");
_ = @import("behavior/bugs/14198.zig");
_ = @import("behavior/export.zig");
}

18
test/behavior/bugs/14198.zig Normal file
View file

@ -0,0 +1,18 @@
const std = @import("std");
const math = std.math;
const mem = std.mem;
const testing = std.testing;
test "nan memory equality" {
// signaled
try testing.expect(mem.eql(u8, mem.asBytes(&math.nan_u16), mem.asBytes(&math.nan_f16)));
try testing.expect(mem.eql(u8, mem.asBytes(&math.nan_u32), mem.asBytes(&math.nan_f32)));
try testing.expect(mem.eql(u8, mem.asBytes(&math.nan_u64), mem.asBytes(&math.nan_f64)));
try testing.expect(mem.eql(u8, mem.asBytes(&math.nan_u128), mem.asBytes(&math.nan_f128)));
// quiet
try testing.expect(mem.eql(u8, mem.asBytes(&math.qnan_u16), mem.asBytes(&math.qnan_f16)));
try testing.expect(mem.eql(u8, mem.asBytes(&math.qnan_u32), mem.asBytes(&math.qnan_f32)));
try testing.expect(mem.eql(u8, mem.asBytes(&math.qnan_u64), mem.asBytes(&math.qnan_f64)));
try testing.expect(mem.eql(u8, mem.asBytes(&math.qnan_u128), mem.asBytes(&math.qnan_f128)));
}