This is the first step in preparation for: https://discourse.llvm.org/t/rfc-make-clang-builtin-math-functions-constexpr-with-llvm-libc-to-support-c-23-constexpr-math-functions/86450
Fix #98393
The following errors were reported by Paul Zimmerman: ``` expm1 Running worst cases check in --rndn mode... FAIL x=0x1.c3b93d3b25c91p+8 ref=0x1.9fb21849affd1p+651 z=0x1.9f921849affd1p+651 Running worst cases check in --rndz mode... FAIL x=0x1.d6479eba7c971p+8 ref=0x1.62a88613629b5p+678 z=0x1.62a886135e9b5p+678 Running worst cases check in --rndu mode... FAIL x=0x1.1f0da93354198p+7 ref=0x1.0bd73b73fc74dp+207 z=0x1.0bd73b73fc74cp+207 Running worst cases check in --rndd mode... FAIL x=0x1.93b3037166891p+8 ref=0x1.554f3a5c4535cp+582 z=0x1.554f3a5c4535bp+582 ``` ``` tan Running worst cases check in --rndn mode... FAIL x=0x1.00452f0e0134dp-13 ref=0x1.00452f2367da9p-13 z=0x1.00452f2367daap-13 Running worst cases check in --rndz mode... FAIL x=0x1.89f0f5241255bp-2 ref=0x1.9e997dd861117p-2 z=0x1.9e997dd861118p-2 FAIL x=0x1.045457ae3994p+5 ref=0x1.0c06941768ef3p+1 z=0x1.0c06941768ef4p+1 ```
Context: https://github.com/llvm/llvm-project/pull/87017 - Add proxy header `libc/hdr/math_macros.h` that will: - include `<math.h>` in overlay mode, - include `"include/llvm-libc-macros/math-macros.h"` in full build mode. - Its corresponding CMake target `libc.hdr.math_macros` will only depend on `libc.include.math` and `libc.include.llvm-libc-macros.math_macros` in full build mode. - Replace all `#include "include/llvm-libc-macros/math-macros.h"` with `#include "hdr/math_macros.h"`. - Add dependency to `libc.hdr.math_macros` CMake target when using `add_fp_unittest`. - Update the remaining dependency. - Update bazel overlay: add `libc:hdr_math_macros` target, and replacing all dependency on `libc:llvm_libc_macros_math_macros` with `libc:hdr_math_macros`.
Reland of #84991 A downstream overlay mode user ran into issues with the isnan macro not working in our sources with a specific libc configuration. This patch replaces the last direct includes of math.h with our internal math_macros.h, along with the necessary build system changes.
Having libc_errno outside of the namespace causes versioning issues when trying to link the tests against LLVM-libc. Most of this patch is just moving libc_errno inside the namespace in tests. This isn't necessary in the function implementations since those are already inside the namespace.
The semantics for casting can range from "bitcast" (same representation) to "different representation", to "type promotion". Here we remove the cast operator and force usage of `get_val` as the only function to get the floating point value, making the intent clearer and more consistent.
Clean up usage of `DECLARE_SPECIAL_CONSTANTS` in global scope.
Implementing expm1 function for double precision based on exp function algorithm: - Reduced x = log2(e) * (hi + mid1 + mid2) + lo, where: * hi is an integer * mid1 * 2^-6 is an integer * mid2 * 2^-12 is an integer * |lo| < 2^-13 + 2^-30 - Then exp(x) - 1 = 2^hi * 2^mid1 * 2^mid2 * exp(lo) - 1 ~ 2^hi * (2^mid1 * 2^mid2 * (1 + lo * P(lo)) - 2^(-hi) ) - We evaluate fast pass with P(lo) is a degree-3 Taylor polynomial of (e^lo - 1) / lo in double precision - If the Ziv accuracy test fails, we use degree-6 Taylor polynomial of (e^lo - 1) / lo in double double precision - If the Ziv accuracy test still fails, we re-evaluate everything in 128-bit precision.