)]}'
{
  "commit": "99906d2063631b1dafd4263e5d37b1d928d45bbf",
  "tree": "ef9f51de3a49638cf0ecd55b68a94123aa51d8b2",
  "parents": [
    "46fb5a63ec16967c39e8388d08492b1483229c4a"
  ],
  "author": {
    "name": "Tue Ly",
    "email": "lntue@google.com",
    "time": "Thu May 11 11:10:02 2023 -0400"
  },
  "committer": {
    "name": "Copybara-Service",
    "email": "copybara-worker@google.com",
    "time": "Tue May 23 07:50:43 2023 -0700"
  },
  "message": "[libc][math] Implement double precision log2 function correctly rounded to all rounding modes.\n\nImplement double precision log2 function correctly rounded to all\nrounding modes.\n\nSee https://reviews.llvm.org/D150014 for a more detail description of the algorithm.\n\n**Performance**\n\n  - For `0.5 \u003c\u003d x \u003c\u003d 2`, the fast pass hitting rate is about 99.91%.\n\n  - Reciprocal throughput from CORE-MATH\u0027s perf tool on Ryzen 5900X:\n```\n$ ./perf.sh log2\nGNU libc version: 2.35\nGNU libc release: stable\n\n-- CORE-MATH reciprocal throughput -- with FMA\n[####################] 100 %\nNtrial \u003d 20 ; Min \u003d 15.458 + 0.204 clc/call; Median-Min \u003d 0.224 clc/call; Max \u003d 15.867 clc/call;\n\n-- CORE-MATH reciprocal throughput -- without FMA (-march\u003dx86-64-v2)\n[####################] 100 %\nNtrial \u003d 20 ; Min \u003d 23.711 + 0.524 clc/call; Median-Min \u003d 0.443 clc/call; Max \u003d 25.307 clc/call;\n\n-- System LIBC reciprocal throughput --\n[####################] 100 %\nNtrial \u003d 20 ; Min \u003d 14.807 + 0.199 clc/call; Median-Min \u003d 0.211 clc/call; Max \u003d 15.137 clc/call;\n\n-- LIBC reciprocal throughput -- with FMA\n[####################] 100 %\nNtrial \u003d 20 ; Min \u003d 17.666 + 0.274 clc/call; Median-Min \u003d 0.298 clc/call; Max \u003d 18.531 clc/call;\n\n-- LIBC reciprocal throughput -- without FMA\n[####################] 100 %\nNtrial \u003d 20 ; Min \u003d 26.534 + 0.418 clc/call; Median-Min \u003d 0.462 clc/call; Max \u003d 27.327 clc/call;\n\n```\n  - Latency from CORE-MATH\u0027s perf tool on Ryzen 5900X:\n```\n$ ./perf.sh log2 --latency\nGNU libc version: 2.35\nGNU libc release: stable\n\n-- CORE-MATH latency -- with FMA\n[####################] 100 %\nNtrial \u003d 20 ; Min \u003d 46.048 + 1.643 clc/call; Median-Min \u003d 1.694 clc/call; Max \u003d 48.018 clc/call;\n\n-- CORE-MATH latency -- without FMA (-march\u003dx86-64-v2)\n[####################] 100 %\nNtrial \u003d 20 ; Min \u003d 62.333 + 0.138 clc/call; Median-Min \u003d 0.119 clc/call; Max \u003d 62.583 clc/call;\n\n-- System LIBC latency --\n[####################] 100 %\nNtrial \u003d 20 ; Min \u003d 45.206 + 1.503 clc/call; Median-Min \u003d 1.467 clc/call; Max \u003d 47.229 clc/call;\n\n-- LIBC latency -- with FMA\n[####################] 100 %\nNtrial \u003d 20 ; Min \u003d 43.042 + 0.454 clc/call; Median-Min \u003d 0.484 clc/call; Max \u003d 43.912 clc/call;\n\n-- LIBC latency -- without FMA\n[####################] 100 %\nNtrial \u003d 20 ; Min \u003d 57.016 + 1.636 clc/call; Median-Min \u003d 1.655 clc/call; Max \u003d 58.816 clc/call;\n```\n  - Accurate pass latency:\n```\n$ ./perf.sh log2 --latency --simple_stat\nGNU libc version: 2.35\nGNU libc release: stable\n\n-- CORE-MATH latency -- with FMA\n177.632\n\n-- CORE-MATH latency -- without FMA (-march\u003dx86-64-v2)\n231.332\n\n-- LIBC latency -- with FMA\n459.751\n\n-- LIBC latency -- without FMA\n463.850\n```\n\nReviewed By: zimmermann6\n\nDifferential Revision: https://reviews.llvm.org/D150374\n\nGitOrigin-RevId: 111d27484132c0692c214880576dc4a37fd6d645\n",
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