mirror of
https://github.com/ziglang/zig.git
synced 2025-12-10 08:13:07 +00:00
5d89955543
* goals
- zig as linker for object files generated by other compilers
- zig-specific runtime features for eventual standardisation
* changes
- missing routines are marked with `missing`
- structure inspired by libgcc docs, but improved order and wording
- rename misspelled functions
- reorder and rephrase compiler_rt.zig to reflect documentation
- potential decimal float or fixed-point arithmetic support:
* 'Decimal float library routines' ca. 120 functions
* 'Fixed-point fractional library routines' ca. 300 functions
thanks to @Vexu for multiple reviews and @scheibo for review
268 lines
12 KiB
Markdown
268 lines
12 KiB
Markdown
If hardware lacks basic or specialized functionality, compiler-rt adds such functionality
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for basic arithmetic(s).
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One such example is 64-bit integer multiplication on 32-bit x86.
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Goals:
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1. zig as linker for object files produced by other compilers
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=> `function compatibility` to compiler-rt and libgcc for same-named functions
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* compatibility conflict between compiler-rt and libgcc: prefer compiler-rt
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2. `symbol-level compatibility` low-priority compared to emitted calls by llvm
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* symbol-level compatibility: libgcc even lower priority
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3. add zig-specific language runtime features, see #7265
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* example: arbitrary bit width integer arithmetic
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* lower to call those functions for e.g. multiplying two i12345 numbers together
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* proper naming + documention for standardizing (allow languages to follow our exmaple)
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Current status (tracking libgcc documentation):
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- Integer library routines => almost implemented
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- Soft float library routines => only f80 routines missing
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- Decimal float library routines => unimplemented (~120 functions)
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- Fixed-point fractional library routines => unimplemented (~300 functions)
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- Exception handling routines => unclear, if supported (~32+x undocumented functions)
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- Miscellaneous routines => unclear, if supported (cache control and stack function)
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- No zig-specific language runtime features in compiler-rt yet
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This library is automatically built as-needed for the compilation target and
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then statically linked and therefore is a transparent dependency for the
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programmer.
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For details see `../compiler_rt.zig`.
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The routines in this folder are listed below.
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Routines are annotated as `type source routine // description`, with `routine`
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being the name used in aforementioned `compiler_rt.zig`.
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`dev` means deviating from compiler_rt, `port` ported, `source` is the
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information source for the implementation, `none` means unimplemented.
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Some examples for the naming convention are:
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- dev source name_routine, name_routine2 various implementations for performance, simplicity etc
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- port llvm compiler-rt library routines from [LLVM](http://compiler-rt.llvm.org/)
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* LLVM emits library calls to compiler-rt, if the hardware lacks functionality
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- port musl libc routines from [musl](https://musl.libc.org/)
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If the library or information source is uncommon, use the entry `other` for `source`.
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Please do not break the search by inserting entries in another format than `impl space source`.
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Bugs should be solved by trying to duplicate the bug upstream, if possible.
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* If the bug exists upstream, get it fixed upstream and port the fix downstream to Zig.
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* If the bug only exists in Zig, use the corresponding C code and debug
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both implementations side by side to figure out what is wrong.
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## Integer library routines
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#### Integer Bit operations
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- dev HackersDelight __clzsi2 // count leading zeros
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- dev HackersDelight __clzdi2 // count leading zeros
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- dev HackersDelight __clzti2 // count leading zeros
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- dev HackersDelight __ctzsi2 // count trailing zeros
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- dev HackersDelight __ctzdi2 // count trailing zeros
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- dev HackersDelight __ctzti2 // count trailing zeros
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- dev __ctzsi2 __ffssi2 // find least significant 1 bit
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- dev __ctzsi2 __ffsdi2 // find least significant 1 bit
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- dev __ctzsi2 __ffsti2 // find least significant 1 bit
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- dev BitTwiddlingHacks __paritysi2 // bit parity
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- dev BitTwiddlingHacks __paritydi2 // bit parity
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- dev BitTwiddlingHacks __parityti2 // bit parity
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- dev TAOCP __popcountsi2 // bit population
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- dev TAOCP __popcountdi2 // bit population
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- dev TAOCP __popcountti2 // bit population
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- dev other __bswapsi2 // a byteswapped
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- dev other __bswapdi2 // a byteswapped
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- dev other __bswapti2 // a byteswapped
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#### Integer Comparison
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- port llvm __cmpsi2 // (a<b)=>output=0, (a==b)=>output=1, (a>b)=>output=2
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- port llvm __cmpdi2
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- port llvm __cmpti2
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- port llvm __ucmpsi2 // (a<b)=>output=0, (a==b)=>output=1, (a>b)=>output=2
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- port llvm __ucmpdi2
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- port llvm __ucmpti2
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#### Integer Arithmetic
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- none none __ashlsi3 // a << b unused in llvm, missing (e.g. used by rl78)
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- port llvm __ashldi3 // a << b
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- port llvm __ashlti3 // a << b
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- none none __ashrsi3 // a >> b arithmetic (sign fill) missing (e.g. used by rl78)
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- port llvm __ashrdi3 // a >> b arithmetic (sign fill)
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- port llvm __ashrti3 // a >> b arithmetic (sign fill)
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- none none __lshrsi3 // a >> b logical (zero fill) missing (e.g. used by rl78)
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- port llvm __lshrdi3 // a >> b logical (zero fill)
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- port llvm __lshrti3 // a >> b logical (zero fill)
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- port llvm __negdi2 // -a symbol-level compatibility: libgcc
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- port llvm __negti2 // -a unnecessary: unused in backends
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- port llvm __mulsi3 // a * b signed
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- port llvm __muldi3 // a * b signed
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- port llvm __multi3 // a * b signed
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- port llvm __divsi3 // a / b signed
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- port llvm __divdi3 // a / b signed
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- port llvm __divti3 // a / b signed
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- port llvm __udivsi3 // a / b unsigned
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- port llvm __udivdi3 // a / b unsigned
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- port llvm __udivti3 // a / b unsigned
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- port llvm __modsi3 // a % b signed
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- port llvm __moddi3 // a % b signed
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- port llvm __modti3 // a % b signed
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- port llvm __umodsi3 // a % b unsigned
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- port llvm __umoddi3 // a % b unsigned
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- port llvm __umodti3 // a % b unsigned
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- port llvm __udivmoddi4 // a / b, rem.* = a % b unsigned
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- port llvm __udivmodti4 // a / b, rem.* = a % b unsigned
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- port llvm __udivmodsi4 // a / b, rem.* = a % b unsigned
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- port llvm __divmodsi4 // a / b, rem.* = a % b signed, ARM
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#### Integer Arithmetic with trapping overflow
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- dev BitTwiddlingHacks __absvsi2 // abs(a)
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- dev BitTwiddlingHacks __absvdi2 // abs(a)
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- dev BitTwiddlingHacks __absvti2 // abs(a)
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- port llvm __negvsi2 // -a symbol-level compatibility: libgcc
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- port llvm __negvdi2 // -a unnecessary: unused in backends
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- port llvm __negvti2 // -a
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- TODO upstreaming __addvsi3..__mulvti3 after testing panics works
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- dev HackersDelight __addvsi3 // a + b
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- dev HackersDelight __addvdi3 // a + b
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- dev HackersDelight __addvti3 // a + b
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- dev HackersDelight __subvsi3 // a - b
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- dev HackersDelight __subvdi3 // a - b
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- dev HackersDelight __subvti3 // a - b
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- dev HackersDelight __mulvsi3 // a * b
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- dev HackersDelight __mulvdi3 // a * b
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- dev HackersDelight __mulvti3 // a * b
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#### Integer Arithmetic which returns if overflow (would be faster without pointer)
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- dev HackersDelight __addosi4 // a + b, overflow=>ov.*=1 else 0
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- dev HackersDelight __addodi4 // (completeness + performance, llvm does not use them)
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- dev HackersDelight __addoti4 //
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- dev HackersDelight __subosi4 // a - b, overflow=>ov.*=1 else 0
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- dev HackersDelight __subodi4 // (completeness + performance, llvm does not use them)
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- dev HackersDelight __suboti4 //
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- dev HackersDelight __mulosi4 // a * b, overflow=>ov.*=1 else 0
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- dev HackersDelight __mulodi4 // (required by llvm)
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- dev HackersDelight __muloti4 //
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## Float library routines
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#### Float Conversion
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- todo todo __extendsfdf2 // extend a f32 => f64
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- todo todo __extendsftf2 // extend a f32 => f128
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- dev llvm __extendsfxf2 // extend a f32 => f80
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- todo todo __extenddftf2 // extend a f64 => f128
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- dev llvm __extenddfxf2 // extend a f64 => f80
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- todo todo __truncdfsf2 // truncate a to narrower mode of return type, rounding towards zero
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- todo todo __trunctfdf2 //
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- todo todo __trunctfsf2 //
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- dev llvm __truncxfsf2 //
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- dev llvm __truncxfdf2 //
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- todo todo __fixsfsi // convert a to i32, rounding towards zero
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- todo todo __fixdfsi //
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- todo todo __fixtfsi //
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- none none __fixxfsi // missing
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- todo todo __fixsfdi // convert a to i64, rounding towards zero
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- todo todo __fixdfdi //
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- todo todo __fixtfdi //
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- none none __fixxfdi // missing
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- todo todo __fixsfti // convert a to i128, rounding towards zero
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- todo todo __fixdfti //
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- todo todo __fixtfdi //
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- none none __fixxfti // missing
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- __fixunssfsi // convert to u32, rounding towards zero. negative values become 0.
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- __fixunsdfsi //
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- __fixunstfsi //
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- __fixunsxfsi // missing
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- __fixunssfdi // convert to u64, rounding towards zero. negative values become 0.
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- __fixunsdfdi //
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- __fixunstfdi //
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- __fixunsxfdi // missing
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- __fixunssfti // convert to u128, rounding towards zero. negative values become 0.
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- __fixunsdfti //
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- __fixunstfdi //
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- __fixunsxfti // missing
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- __floatsisf // convert i32 to floating point
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- __floatsidf //
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- __floatsitf //
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- __floatsixf // missing
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- __floatdisf // convert i64 to floating point
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- __floatdidf //
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- __floatditf //
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- __floatdixf // missing
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- __floattisf // convert i128 to floating point
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- __floattidf //
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- __floattixf // missing
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- __floatunsisf // convert i32 to floating point
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- __floatunsidf //
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- __floatunsitf //
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- __floatunsixf // missing
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- __floatundisf // convert i64 to floating point
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- __floatundidf //
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- __floatunditf //
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- __floatundixf // missing
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- __floatuntisf // convert i128 to floating point
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- __floatuntidf //
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- __floatuntitf //
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- __floatuntixf // missing
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#### Float Comparison
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- __cmpsf2 // return (a<b)=>-1,(a==b)=>0,(a>b)=>1,Nan=>1 dont rely on this
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- __cmpdf2 // exported from __lesf2, __ledf2, __letf2 (below)
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- __cmptf2 //
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- __unordsf2 // (input==NaN) => out!=0 else out=0,
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- __unorddf2 // __only reliable for (input!=Nan)__
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- __unordtf2 //
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- __eqsf2 // (a!=NaN) and (b!=Nan) and (a==b) => output=0
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- __eqdf2 //
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- __eqtf2 //
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- __nesf2 // (a==NaN) or (b==Nan) or (a!=b) => output!=0
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- __nedf2 //
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- __netf2 //
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- __gesf2 // (a!=Nan) and (b!=Nan) and (a>=b) => output>=0
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- __gedf2 //
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- __getf2 //
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- __ltsf2 // (a!=Nan) and (b!=Nan) and (a<b) => output<0
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- __ltdf2 //
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- __lttf2 //
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- __lesf2 // (a!=Nan) and (b!=Nan) and (a<=b) => output<=0
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- __ledf2 //
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- __letf2 //
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- __gtsf2 // (a!=Nan) and (b!=Nan) and (a>b) => output>0
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- __gtdf2 //
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- __gttf2 //
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#### Float Arithmetic
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- __addsf3 // a + b f32
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- __adddf3 // a + b f64
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- __addtf3 // a + b f128
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- __addxf3 // a + b f80
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- __aeabi_fadd // a + b f64 ARM: AAPCS
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- __aeabi_dadd // a + b f64 ARM: AAPCS
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- __subsf3 // a - b
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- __subdf3 // a - b
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- __subtf3 // a - b
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- __subxf3 // a - b f80
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- __aeabi_fsub // a - b f64 ARM: AAPCS
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- __aeabi_dsub // a - b f64 ARM: AAPCS
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- __mulsf3 // a * b
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- __muldf3 // a * b
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- __multf3 // a * b
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- __mulxf3 // a * b missing
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- __divsf3 // a / b
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- __divdf3 // a / b
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- __divtf3 // a / b
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- __divxf3 // a / b missing
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- __negsf2 // -a symbol-level compatibility: libgcc uses this for the rl78
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- __negdf2 // -a unnecessary: can be lowered directly to a xor
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- __negtf2 // -a
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- __negxf2 // -a
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#### Floating point raised to integer power
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- __powisf2 // unclear, if supported a ^ b
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- __powidf2 //
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- __powitf2 //
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- __powixf2 //
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- __mulsc3 // unsupported (a+ib) * (c+id)
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- __muldc3 //
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- __multc3 //
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- __mulxc3 //
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- __divsc3 // unsupported (a+ib) * / (c+id)
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- __divdc3 //
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- __divtc3 //
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- __divxc3 //
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