[hypermoist]

What

Implements the 66 compiler-rt floating-point builtins that the system libc.prx exports and AnyPS5 did not have, in a new src/FloatBuiltins.cpp:

• arithmetic __add, __sub, __mul, __div (sf3, df3), __neg{s,d}f2
• comparisons __eq, __ne, __lt, __le, __gt, __ge, __unord (sf2, df2)
• __extendsfdf2, __truncdfsf2
• float, double and x87 to 32/64/128-bit integers (__fix*, __fixuns*) and back (__float*, __floatun*)
• complex __mul{s,d,x}c3, __div{s,d,x}c3, and __powixf2

The console ships an older compiler-rt built with FMA contraction, and these follow that binary (the libc.prx bundled with PPSA08427) rather than current compiler-rt:

• the soft-float arithmetic and __truncdfsf2 always round to nearest, ignore FTZ/DAZ and raise no exception flags; here the SSE instruction runs under a default MXCSR that is restored afterwards (GNU inline asm, as Math.cpp already uses), and an invalid operation returns the positive quiet NaN compiler-rt returns instead of the SSE default NaN; __sub* negates the second operand first, like compiler-rt, so a NaN subtrahend comes back with its sign flipped
• __div{s,d}f3 flush a quotient below the smallest normal to a signed zero (old compiler-rt's "Flush denormals to zero")
• __extendsfdf2 keeps signalling NaNs and copies the payload unshifted; __truncdfsf2 quiets and keeps the low 22 payload bits
• float-to-integer conversions do not saturate: the significand is shifted by a count masked to the shift width (32, 64 or 128 bits), as the console code does
• __floatsisf, __floatunsisf and the 128-bit sources round to nearest in integer code; the 64-bit sources use native conversions, which honour MXCSR like the console's cvtsi2s*
• complex multiplication/division use fma exactly where the console's code fuses, a NaN-skipping maximum like its vmaxss/blend sequence, and scale through the x87 like its scalbn (fscale)
• __powixf2(x, 1) returns x unchanged

Recorded in docs/dev/debt/libc.md.

Tested

Linux (CachyOS, GCC Release build, plus a clang -Wall -Wextra syntax check): new guest_float_builtins test passes, as do guest_math and guest_crt. tools/check_conventions.py passes; tools/pr_overlap.py --branch reports no overlap.

Differential test against the console: the libc.prx of PPSA08427 was mapped into a Linux process (PT_LOAD segments, RELATIVE relocations, the stack-protector GOT slot pointed at a dummy guard) and each builtin was called side by side with this implementation on 200,000 random and edge-case inputs (NaNs with payloads, infinities, subnormals, boundary exponents), once with the default MXCSR and once with random rounding modes and FTZ/DAZ, comparing result bits and the MXCSR afterwards. All functions agree bit for bit, except:

• __mul{s,d}c3 and __div{s,d}c3 agree on every value but differ in about 2-6% of cases only in a NaN's payload/sign or in exception flags, because the host fma/logb are not the console's VEX FMA code and libm; noted in the debt entry.
• __floatundidf could not be run on Linux: it is compiler-rt's assembly with a legacy-SSE orpd on an 8-byte-aligned constant, which faults without AMD's misaligned-SSE mode. It is a correctly rounded conversion and is implemented as a native one.

The harness is not part of this PR because it needs the console binary.

Checklist

• Based on current main; no other open PR implements the same functions
• One topic per PR; follow-ups go in a new PR
• No comments in code except technical debt
• Unimplemented paths throw (NotImplemented_nid_no_patch); silent stubs are listed under Silent stubs in their library's technical debt file
• No notes, investigation .md files or images added to the repository (attach them to this PR)
• New third-party code is a submodule built from source
• Generic behaviour, not specific to one title
• Depends on: none
• Unblocks: none
• GPUs tested: n/a
• AI-assisted: yes

🤖 Generated with Claude Code

https://claude.ai/code/session_01Q8tinbP1MUpUaDsbNWnGnu

[github-actions]

Progress report (55d2fb6 → f8b611b)

📈 System libraries: 88.91% (+0.2%, +66 implemented functions)

✅ 66 implemented

Library	Name
libc	__adddf3_nid_postfix
libc	__addsf3_nid_postfix
libc	__divdc3_nid_postfix
libc	__divdf3_nid_postfix
libc	__divsc3_nid_postfix
libc	__divsf3_nid_postfix
libc	__divxc3_nid_postfix
libc	__eqdf2_nid_postfix
libc	__eqsf2_nid_postfix
libc	__extendsfdf2_nid_postfix
libc	__fixdfdi_nid_postfix
libc	__fixdfsi_nid_postfix
libc	__fixdfti_nid_postfix
libc	__fixsfdi_nid_postfix
libc	__fixsfsi_nid_postfix
libc	__fixsfti_nid_postfix
libc	__fixunsdfdi_nid_postfix
libc	__fixunsdfsi_nid_postfix
libc	__fixunsdfti_nid_postfix
libc	__fixunssfdi_nid_postfix
libc	__fixunssfsi_nid_postfix
libc	__fixunssfti_nid_postfix
libc	__fixunsxfdi_nid_postfix
libc	__fixunsxfsi_nid_postfix
libc	__fixunsxfti_nid_postfix
libc	__fixxfdi_nid_postfix
libc	__fixxfti_nid_postfix
libc	__floatdidf_nid_postfix
libc	__floatdisf_nid_postfix
libc	__floatdixf_nid_postfix
libc	__floatsidf_nid_postfix
libc	__floatsisf_nid_postfix
libc	__floattidf_nid_postfix
libc	__floattisf_nid_postfix
libc	__floattixf_nid_postfix
libc	__floatundidf_nid_postfix
libc	__floatundisf_nid_postfix
libc	__floatundixf_nid_postfix
libc	__floatunsidf_nid_postfix
libc	__floatunsisf_nid_postfix
libc	__floatuntidf_nid_postfix
libc	__floatuntisf_nid_postfix
libc	__floatuntixf_nid_postfix
libc	__gedf2_nid_postfix
libc	__gesf2_nid_postfix
libc	__gtdf2_nid_postfix
libc	__gtsf2_nid_postfix
libc	__ledf2_nid_postfix
libc	__lesf2_nid_postfix
libc	__ltdf2_nid_postfix
libc	__ltsf2_nid_postfix
libc	__muldc3_nid_postfix
libc	__muldf3_nid_postfix
libc	__mulsc3_nid_postfix
libc	__mulsf3_nid_postfix
libc	__mulxc3_nid_postfix
libc	__nedf2_nid_postfix
libc	__negdf2_nid_postfix
libc	__negsf2_nid_postfix
libc	__nesf2_nid_postfix
libc	__powixf2_nid_postfix
libc	__subdf3_nid_postfix
libc	__subsf3_nid_postfix
libc	__truncdfsf2_nid_postfix
libc	__unorddf2_nid_postfix
libc	__unordsf2_nid_postfix

[github-actions]

Some comparisons could not be completed because a pull request conflicts with the base branch. Review these shared files manually before concluding that there is no overlap.

Pull request	Shared files not compared
PR 3987	docs/dev/debt/libc.md
PR 5021	core/libs/prx/libc/CMakeLists.txt docs/dev/debt/libc.md
PR 5303	docs/dev/debt/libc.md
PR 6044	core/libs/prx/libc/CMakeLists.txt
PR 6226	docs/dev/debt/libc.md
PR 6565	docs/dev/debt/libc.md
PR 7039	docs/dev/debt/libc.md
PR 7081	core/libs/prx/libc/CMakeLists.txt docs/dev/debt/libc.md
PR 7084	core/libs/prx/libc/CMakeLists.txt
PR 7201	core/libs/prx/libc/CMakeLists.txt
PR 7332	core/libs/prx/libc/CMakeLists.txt docs/dev/debt/libc.md