[libc-commits] [libc] [libc][math] Fix sqrtf128 implicit conversions. (PR #127154)
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Thu Feb 13 17:26:09 PST 2025
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-libc
Author: None (lntue)
<details>
<summary>Changes</summary>
This fixes rv32 buildbot failure from https://github.com/llvm/llvm-project/pull/122578
---
Full diff: https://github.com/llvm/llvm-project/pull/127154.diff
1 Files Affected:
- (modified) libc/src/math/generic/sqrtf128.cpp (+7-6)
``````````diff
diff --git a/libc/src/math/generic/sqrtf128.cpp b/libc/src/math/generic/sqrtf128.cpp
index c844d3afa11c8..3aa7db8362734 100644
--- a/libc/src/math/generic/sqrtf128.cpp
+++ b/libc/src/math/generic/sqrtf128.cpp
@@ -383,25 +383,26 @@ LLVM_LIBC_FUNCTION(float128, sqrtf128, (float128 x)) {
// 1 so just need to add shifted m and 1.
Int128 t1 = t0;
Int128 sgn = t0 >> 127; // sign of the difference
- t1 -= (m << 1) ^ sgn;
- t1 += 1 + sgn;
+ Int128 m_xor_sgn = static_cast<Int128>(m << 1) ^ sgn;
+ t1 -= m_xor_sgn;
+ t1 += Int128(1) + sgn;
Int128 sgn1 = t1 >> 127;
if (LIBC_UNLIKELY(sgn == sgn1)) {
t0 = t1;
v -= sgn << 15;
- t1 -= (m << 1) ^ sgn;
- t1 += 1 + sgn;
+ t1 -= m_xor_sgn;
+ t1 += Int128(1) + sgn;
}
if (t1 == 0) {
// 1 ulp offset brings again an exact root
- v = (m - (2 * sgn + 1)) << 15;
+ v = (m - static_cast<UInt128>((sgn << 1) + 1)) << 15;
} else {
t1 += t0;
Int128 side = t1 >> 127; // select what is closer m or m+-1
v &= ~UInt128(0) << 15; // wipe the fractional bits
- v -= ((sgn & side) | (~sgn & 1)) << (15 + side);
+ v -= ((sgn & side) | (~sgn & 1)) << (15 + static_cast<int>(side));
v |= 1; // add sticky bit since we cannot have an exact mid-point
// situation
}
``````````
</details>
https://github.com/llvm/llvm-project/pull/127154
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