[SimplifyLibCalls] Simplify cabs libcall if real or imaginary part of input is zero #97976

HendrikHuebner · 2024-07-07T23:54:27Z

cabs(a + i0) -> abs(a)
cabs(0 +ib) -> abs(b)

Closes #97336

llvmbot · 2024-07-07T23:54:58Z

@llvm/pr-subscribers-llvm-transforms

@llvm/pr-subscribers-libc

Author: Hendrik Hübner (HendrikHuebner)

Changes

cabs(a + i0) -> absf(a)
cabs(0 +ib) -> absf(b)

Issue: #97336
cc: @dtcxzyw

Patch is 25.48 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/97976.diff

20 Files Affected:

(modified) libc/config/darwin/arm/entrypoints.txt (+1)
(modified) libc/config/linux/aarch64/entrypoints.txt (+1)
(modified) libc/config/linux/riscv/entrypoints.txt (+1)
(modified) libc/config/linux/x86_64/entrypoints.txt (+1)
(modified) libc/docs/math/index.rst (+1-1)
(modified) libc/src/math/CMakeLists.txt (+1)
(added) libc/src/math/cospif.h (+18)
(modified) libc/src/math/generic/CMakeLists.txt (+17)
(added) libc/src/math/generic/cospif.cpp (+96)
(modified) libc/src/math/generic/sinpif.cpp (+3-3)
(modified) libc/test/src/math/CMakeLists.txt (+16)
(added) libc/test/src/math/cospif_test.cpp (+120)
(modified) libc/test/src/math/exhaustive/CMakeLists.txt (+16)
(added) libc/test/src/math/exhaustive/cospif_test.cpp (+33)
(modified) libc/test/src/math/smoke/CMakeLists.txt (+11)
(added) libc/test/src/math/smoke/cospif_test.cpp (+34)
(modified) libc/utils/MPFRWrapper/MPFRUtils.cpp (+35)
(modified) libc/utils/MPFRWrapper/MPFRUtils.h (+1)
(modified) llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp (+28-7)
(modified) llvm/test/Transforms/InstCombine/cabs-discrete.ll (+54)

diff --git a/libc/config/darwin/arm/entrypoints.txt b/libc/config/darwin/arm/entrypoints.txt
index cb4603c79c79c..d32745c9c9467 100644
--- a/libc/config/darwin/arm/entrypoints.txt
+++ b/libc/config/darwin/arm/entrypoints.txt
@@ -132,6 +132,7 @@ set(TARGET_LIBM_ENTRYPOINTS
     libc.src.math.coshf
     libc.src.math.cos
     libc.src.math.cosf
+    libc.src.math.cospif
     libc.src.math.erff
     libc.src.math.exp
     libc.src.math.expf
diff --git a/libc/config/linux/aarch64/entrypoints.txt b/libc/config/linux/aarch64/entrypoints.txt
index ff35e8fffec19..79e880b1bec8e 100644
--- a/libc/config/linux/aarch64/entrypoints.txt
+++ b/libc/config/linux/aarch64/entrypoints.txt
@@ -346,6 +346,7 @@ set(TARGET_LIBM_ENTRYPOINTS
     libc.src.math.cos
     libc.src.math.cosf
     libc.src.math.coshf
+    libc.src.math.cospif
     libc.src.math.erff
     libc.src.math.exp
     libc.src.math.exp10
diff --git a/libc/config/linux/riscv/entrypoints.txt b/libc/config/linux/riscv/entrypoints.txt
index 51d85eed9ff16..fb9e4e3763844 100644
--- a/libc/config/linux/riscv/entrypoints.txt
+++ b/libc/config/linux/riscv/entrypoints.txt
@@ -354,6 +354,7 @@ set(TARGET_LIBM_ENTRYPOINTS
     libc.src.math.cos
     libc.src.math.cosf
     libc.src.math.coshf
+    libc.src.math.cospif
     libc.src.math.erff
     libc.src.math.exp
     libc.src.math.exp10
diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
index 3eefa129c9758..6a61b51d60242 100644
--- a/libc/config/linux/x86_64/entrypoints.txt
+++ b/libc/config/linux/x86_64/entrypoints.txt
@@ -371,6 +371,7 @@ set(TARGET_LIBM_ENTRYPOINTS
     libc.src.math.cos
     libc.src.math.cosf
     libc.src.math.coshf
+    libc.src.math.cospif
     libc.src.math.erff
     libc.src.math.exp
     libc.src.math.exp10
diff --git a/libc/docs/math/index.rst b/libc/docs/math/index.rst
index e4da3d42baf7a..6c84b10122677 100644
--- a/libc/docs/math/index.rst
+++ b/libc/docs/math/index.rst
@@ -274,7 +274,7 @@ Higher Math Functions
 +-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
 | cosh      | |check|          |                 |                        |                      |                        | 7.12.5.4               | F.10.2.4                   |
 +-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
-| cospi     |                  |                 |                        |                      |                        | 7.12.4.12              | F.10.1.12                  |
+| cospi     | |check|          |                 |                        |                      |                        | 7.12.4.12              | F.10.1.12                  |
 +-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
 | dsqrt     | N/A              | N/A             |                        | N/A                  |                        | 7.12.14.6              | F.10.11                    |
 +-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
diff --git a/libc/src/math/CMakeLists.txt b/libc/src/math/CMakeLists.txt
index 5b20913134fdf..ce4f8f993526d 100644
--- a/libc/src/math/CMakeLists.txt
+++ b/libc/src/math/CMakeLists.txt
@@ -81,6 +81,7 @@ add_math_entrypoint_object(cos)
 add_math_entrypoint_object(cosf)
 add_math_entrypoint_object(cosh)
 add_math_entrypoint_object(coshf)
+add_math_entrypoint_object(cospif)
 
 add_math_entrypoint_object(erf)
 add_math_entrypoint_object(erff)
diff --git a/libc/src/math/cospif.h b/libc/src/math/cospif.h
new file mode 100644
index 0000000000000..50935bc33e59d
--- /dev/null
+++ b/libc/src/math/cospif.h
@@ -0,0 +1,18 @@
+//===-- Implementation header for cospif ------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC_MATH_COSPIF_H
+#define LLVM_LIBC_SRC_MATH_COSPIF_H
+
+namespace LIBC_NAMESPACE {
+
+float cospif(float x);
+
+} // namespace LIBC_NAMESPACE
+
+#endif // LLVM_LIBC_SRC_MATH_COSPIF_H
diff --git a/libc/src/math/generic/CMakeLists.txt b/libc/src/math/generic/CMakeLists.txt
index d6ea8c54174b6..6ace14063bcb1 100644
--- a/libc/src/math/generic/CMakeLists.txt
+++ b/libc/src/math/generic/CMakeLists.txt
@@ -217,6 +217,23 @@ add_entrypoint_object(
     -O3
 )
 
+add_entrypoint_object(
+  cospif
+  SRCS
+    cospif.cpp
+  HDRS
+    ../cospif.h
+  DEPENDS
+    .sincosf_utils
+    libc.src.__support.FPUtil.fenv_impl
+    libc.src.__support.FPUtil.fp_bits
+    libc.src.__support.FPUtil.fma
+    libc.src.__support.FPUtil.multiply_add
+    libc.src.__support.macros.optimization
+  COMPILE_OPTIONS
+    -O3
+)
+
 add_entrypoint_object(
   sin
   SRCS
diff --git a/libc/src/math/generic/cospif.cpp b/libc/src/math/generic/cospif.cpp
new file mode 100644
index 0000000000000..713619430fe4b
--- /dev/null
+++ b/libc/src/math/generic/cospif.cpp
@@ -0,0 +1,96 @@
+//===-- Single-precision cospi function -----------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/math/cospif.h"
+#include "sincosf_utils.h"
+#include "src/__support/FPUtil/FEnvImpl.h"
+#include "src/__support/FPUtil/FPBits.h"
+#include "src/__support/FPUtil/multiply_add.h"
+#include "src/__support/common.h"
+#include "src/__support/macros/optimization.h"            // LIBC_UNLIKELY
+#include "src/__support/macros/properties/cpu_features.h" // LIBC_TARGET_CPU_HAS_FMA
+
+namespace LIBC_NAMESPACE {
+
+LLVM_LIBC_FUNCTION(float, cospif, (float x)) {
+  using FPBits = typename fputil::FPBits<float>;
+
+  FPBits xbits(x);
+  Sign xsign = xbits.sign();
+  xbits.set_sign(Sign::POS);
+
+  uint32_t x_abs = xbits.uintval();
+  double xd = static_cast<double>(xbits.get_val());
+
+  // Range reduction:
+  // For |x| > 1/32, we perform range reduction as follows:
+  // Find k and y such that:
+  //   x = (k + y) * 1/32
+  //   k is an integer
+  //   |y| < 0.5
+  //
+  // This is done by performing:
+  //   k = round(x * 32)
+  //   y = x * 32 - k
+  //
+  // Once k and y are computed, we then deduce the answer by the cosine of sum
+  // formula:
+  //   cospi(x) = cos((k + y)*pi/32)
+  //          = cos(y*pi/32) * cos(k*pi/32) - sin(y*pi/32) * sin(k*pi/32)
+  // The values of sin(k*pi/32) and cos(k*pi/32) for k = 0..63 are precomputed
+  // and stored using a vector of 32 doubles. Sin(y*pi/32) and cos(y*pi/32) are
+  // computed using degree-7 and degree-6 minimax polynomials generated by
+  // Sollya respectively.
+
+  // The exhautive test passes for smaller values
+  if (LIBC_UNLIKELY(x_abs < 0x38A2'F984U)) {
+
+#if defined(LIBC_TARGET_CPU_HAS_FMA)
+    return fputil::multiply_add(xbits.get_val(), -0x1.0p-25f, 1.0f);
+#else
+    return static_cast<float>(fputil::multiply_add(xd, -0x1.0p-25, 1.0));
+#endif // LIBC_TARGET_CPU_HAS_FMA
+  }
+
+  // Numbers greater or equal to 2^23 are always integers or NaN
+  if (LIBC_UNLIKELY(x_abs >= 0x4B00'0000)) {
+
+    if (LIBC_UNLIKELY(x_abs < 0x4B80'0000)) {
+      return (x_abs & 0x1) ? -1.0f : 1.0f;
+    }
+
+    // x is inf or nan.
+    if (LIBC_UNLIKELY(x_abs >= 0x7f80'0000U)) {
+      if (x_abs == 0x7f80'0000U) {
+        fputil::set_errno_if_required(EDOM);
+        fputil::raise_except_if_required(FE_INVALID);
+      }
+      return x + FPBits::quiet_nan().get_val();
+    }
+
+    return 1.0f;
+  }
+
+  // Combine the results with the sine of sum formula:
+  //   cos(pi * x) = cos((k + y)*pi/32)
+  //          = cos(y*pi/32) * cos(k*pi/32) - sin(y*pi/32) * sin(k*pi/32)
+  //          = (cosm1_y + 1) * cos_k - sin_y * sin_k
+  //          = (cosm1_y * cos_k + cos_k) - sin_y * sin_k
+  double sin_k, cos_k, sin_y, cosm1_y;
+
+  sincospif_eval(xd, sin_k, cos_k, sin_y, cosm1_y);
+
+  if (LIBC_UNLIKELY(sin_y == 0 && cos_k == 0)) {
+    return FPBits::zero(xsign).get_val();
+  }
+
+  return static_cast<float>(fputil::multiply_add(
+      sin_y, -sin_k, fputil::multiply_add(cosm1_y, cos_k, cos_k)));
+}
+
+} // namespace LIBC_NAMESPACE
diff --git a/libc/src/math/generic/sinpif.cpp b/libc/src/math/generic/sinpif.cpp
index 662263c9fc43e..05bdad3ab4d0e 100644
--- a/libc/src/math/generic/sinpif.cpp
+++ b/libc/src/math/generic/sinpif.cpp
@@ -26,13 +26,13 @@ LLVM_LIBC_FUNCTION(float, sinpif, (float x)) {
   double xd = static_cast<double>(x);
 
   // Range reduction:
-  // For |x| > pi/32, we perform range reduction as follows:
+  // For |x| > 1/32, we perform range reduction as follows:
   // Find k and y such that:
   //   x = (k + y) * 1/32
   //   k is an integer
   //   |y| < 0.5
-  // For small range (|x| < 2^45 when FMA instructions are available, 2^22
-  // otherwise), this is done by performing:
+  //
+  // This is done by performing:
   //   k = round(x * 32)
   //   y = x * 32 - k
   //
diff --git a/libc/test/src/math/CMakeLists.txt b/libc/test/src/math/CMakeLists.txt
index 637e6720400ff..0ae7464e8aa40 100644
--- a/libc/test/src/math/CMakeLists.txt
+++ b/libc/test/src/math/CMakeLists.txt
@@ -28,6 +28,22 @@ add_fp_unittest(
     libc.src.__support.FPUtil.fp_bits
 )
 
+add_fp_unittest(
+  cospif_test
+  NEED_MPFR
+  SUITE
+    libc-math-unittests
+  SRCS
+    cospif_test.cpp
+  HDRS
+    sdcomp26094.h
+  DEPENDS
+    libc.src.errno.errno
+    libc.src.math.cospif
+    libc.src.__support.CPP.array
+    libc.src.__support.FPUtil.fp_bits
+)
+
 add_fp_unittest(
   sinf_test
   NEED_MPFR
diff --git a/libc/test/src/math/cospif_test.cpp b/libc/test/src/math/cospif_test.cpp
new file mode 100644
index 0000000000000..8a39957d1a274
--- /dev/null
+++ b/libc/test/src/math/cospif_test.cpp
@@ -0,0 +1,120 @@
+//===-- Unittests for cospif ----------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/errno/libc_errno.h"
+#include "src/math/cospif.h"
+#include "test/UnitTest/FPMatcher.h"
+#include "test/src/math/sdcomp26094.h"
+#include "utils/MPFRWrapper/MPFRUtils.h"
+
+using LlvmLibcCospifTest = LIBC_NAMESPACE::testing::FPTest<float>;
+
+using LIBC_NAMESPACE::testing::SDCOMP26094_VALUES;
+
+namespace mpfr = LIBC_NAMESPACE::testing::mpfr;
+
+TEST_F(LlvmLibcCospifTest, SpecialNumbers) {
+  LIBC_NAMESPACE::libc_errno = 0;
+
+  EXPECT_FP_EQ(aNaN, LIBC_NAMESPACE::cospif(aNaN));
+  EXPECT_MATH_ERRNO(0);
+
+  EXPECT_FP_EQ(1.0f, LIBC_NAMESPACE::cospif(0.0f));
+  EXPECT_MATH_ERRNO(0);
+
+  EXPECT_FP_EQ(1.0f, LIBC_NAMESPACE::cospif(-0.0f));
+  EXPECT_MATH_ERRNO(0);
+
+  EXPECT_FP_EQ(aNaN, LIBC_NAMESPACE::cospif(inf));
+  EXPECT_MATH_ERRNO(EDOM);
+
+  EXPECT_FP_EQ(aNaN, LIBC_NAMESPACE::cospif(neg_inf));
+  EXPECT_MATH_ERRNO(EDOM);
+}
+
+TEST_F(LlvmLibcCospifTest, SpecificBitPatterns) {
+  constexpr int N = 36;
+  constexpr uint32_t INPUTS[N] = {
+      0x3f06'0a92U, // x = pi/6
+      0x3f3a'dc51U, // x = 0x1.75b8a2p-1f
+      0x3f49'0fdbU, // x = pi/4
+      0x3f86'0a92U, // x = pi/3
+      0x3fa7'832aU, // x = 0x1.4f0654p+0f
+      0x3fc9'0fdbU, // x = pi/2
+      0x4017'1973U, // x = 0x1.2e32e6p+1f
+      0x4049'0fdbU, // x = pi
+      0x4096'cbe4U, // x = 0x1.2d97c8p+2f
+      0x40c9'0fdbU, // x = 2*pi
+      0x433b'7490U, // x = 0x1.76e92p+7f
+      0x437c'e5f1U, // x = 0x1.f9cbe2p+7f
+      0x4619'9998U, // x = 0x1.33333p+13f
+      0x474d'246fU, // x = 0x1.9a48dep+15f
+      0x4afd'ece4U, // x = 0x1.fbd9c8p+22f
+      0x4c23'32e9U, // x = 0x1.4665d2p+25f
+      0x50a3'e87fU, // x = 0x1.47d0fep+34f
+      0x5239'47f6U, // x = 0x1.728fecp+37f
+      0x53b1'46a6U, // x = 0x1.628d4cp+40f
+      0x55ca'fb2aU, // x = 0x1.95f654p+44f
+      0x588e'f060U, // x = 0x1.1de0cp+50f
+      0x5c07'bcd0U, // x = 0x1.0f79ap+57f
+      0x5ebc'fddeU, // x = 0x1.79fbbcp+62f
+      0x5fa6'eba7U, // x = 0x1.4dd74ep+64f
+      0x61a4'0b40U, // x = 0x1.48168p+68f
+      0x6386'134eU, // x = 0x1.0c269cp+72f
+      0x6589'8498U, // x = 0x1.13093p+76f
+      0x6600'0001U, // x = 0x1.000002p+77f
+      0x664e'46e4U, // x = 0x1.9c8dc8p+77f
+      0x66b0'14aaU, // x = 0x1.602954p+78f
+      0x67a9'242bU, // x = 0x1.524856p+80f
+      0x6a19'76f1U, // x = 0x1.32ede2p+85f
+      0x6c55'da58U, // x = 0x1.abb4bp+89f
+      0x6f79'be45U, // x = 0x1.f37c8ap+95f
+      0x7276'69d4U, // x = 0x1.ecd3a8p+101f
+      0x7758'4625U, // x = 0x1.b08c4ap+111f
+  };
+
+  for (int i = 0; i < N; ++i) {
+    float x = FPBits(INPUTS[i]).get_val();
+    EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Cospi, x,
+                                   LIBC_NAMESPACE::cospif(x), 0.5);
+    EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Cospi, -x,
+                                   LIBC_NAMESPACE::cospif(-x), 0.5);
+  }
+}
+
+// For small values, sinpi(x) is pi * x.
+TEST_F(LlvmLibcCospifTest, SmallValues) {
+  float x = FPBits(0x1780'0000U).get_val();
+  EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Cospi, x,
+                                 LIBC_NAMESPACE::cospif(x), 0.5);
+
+  x = FPBits(0x0040'0000U).get_val();
+  EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Cospi, x,
+                                 LIBC_NAMESPACE::cospif(x), 0.5);
+}
+
+// SDCOMP-26094: check sinfpi in the cases for which the range reducer
+// returns values furthest beyond its nominal upper bound of pi/4.
+TEST_F(LlvmLibcCospifTest, SDCOMP_26094) {
+  for (uint32_t v : SDCOMP26094_VALUES) {
+    float x = FPBits((v)).get_val();
+    EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Cospi, x,
+                                   LIBC_NAMESPACE::cospif(x), 0.5);
+  }
+}
+
+// sinpi(-n) = -0.0
+// sinpi(+n) = +0.0
+TEST_F(LlvmLibcCospifTest, SignedZeros) {
+  EXPECT_FP_EQ(0.0, LIBC_NAMESPACE::cospif(100.5f));
+  EXPECT_FP_EQ(-0.0, LIBC_NAMESPACE::cospif(-100.5f));
+  EXPECT_FP_EQ(0.0, LIBC_NAMESPACE::cospif(45678.5f));
+  EXPECT_FP_EQ(-0.0, LIBC_NAMESPACE::cospif(-45678.5f));
+  EXPECT_FP_EQ(0.0, LIBC_NAMESPACE::cospif(8000000.5f));
+  EXPECT_FP_EQ(-0.0, LIBC_NAMESPACE::cospif(-8000000.5f));
+}
diff --git a/libc/test/src/math/exhaustive/CMakeLists.txt b/libc/test/src/math/exhaustive/CMakeLists.txt
index 412ca031d0e99..c5f75b51cbd9f 100644
--- a/libc/test/src/math/exhaustive/CMakeLists.txt
+++ b/libc/test/src/math/exhaustive/CMakeLists.txt
@@ -74,6 +74,22 @@ add_fp_unittest(
     -lpthread
 )
 
+add_fp_unittest(
+  cospif_test
+  NO_RUN_POSTBUILD
+  NEED_MPFR
+  SUITE
+    libc_math_exhaustive_tests
+  SRCS
+    cospif_test.cpp
+  DEPENDS
+    .exhaustive_test
+    libc.src.math.cospif
+    libc.src.__support.FPUtil.fp_bits
+  LINK_LIBRARIES
+    -lpthread
+)
+
 add_fp_unittest(
   sincosf_test
   NO_RUN_POSTBUILD
diff --git a/libc/test/src/math/exhaustive/cospif_test.cpp b/libc/test/src/math/exhaustive/cospif_test.cpp
new file mode 100644
index 0000000000000..59077d5909937
--- /dev/null
+++ b/libc/test/src/math/exhaustive/cospif_test.cpp
@@ -0,0 +1,33 @@
+//===-- Exhaustive test for cospif ----------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "exhaustive_test.h"
+#include "src/math/cospif.h"
+#include "utils/MPFRWrapper/MPFRUtils.h"
+
+namespace mpfr = LIBC_NAMESPACE::testing::mpfr;
+
+using LlvmLibcCospifExhaustiveTest =
+    LlvmLibcUnaryOpExhaustiveMathTest<float, mpfr::Operation::Cospi,
+                                      LIBC_NAMESPACE::cospif>;
+
+static constexpr uint32_t POS_START = 0x0000'0000U;
+static constexpr uint32_t POS_STOP = 0x7f80'0000U;
+
+// Range: [0, Inf]
+TEST_F(LlvmLibcCospifExhaustiveTest, PostiveRange) {
+  test_full_range_all_roundings(POS_START, POS_STOP);
+}
+
+// Range: [-Inf, 0]
+static constexpr uint32_t NEG_START = 0xb000'0000U;
+static constexpr uint32_t NEG_STOP = 0xff80'0000U;
+
+TEST_F(LlvmLibcCospifExhaustiveTest, NegativeRange) {
+  test_full_range_all_roundings(NEG_START, NEG_STOP);
+}
diff --git a/libc/test/src/math/smoke/CMakeLists.txt b/libc/test/src/math/smoke/CMakeLists.txt
index 1b269edaa2477..72d04439e2d93 100644
--- a/libc/test/src/math/smoke/CMakeLists.txt
+++ b/libc/test/src/math/smoke/CMakeLists.txt
@@ -10,6 +10,17 @@ add_fp_unittest(
   DEPENDS
     libc.src.errno.errno
     libc.src.math.cosf
+)
+
+add_fp_unittest(
+  cospif_test
+  SUITE
+    libc-math-smoke-tests
+  SRCS
+    cospif_test.cpp
+  DEPENDS
+    libc.src.errno.errno
+    libc.src.math.cospif
     libc.src.__support.CPP.array
     libc.src.__support.FPUtil.fp_bits
 )
diff --git a/libc/test/src/math/smoke/cospif_test.cpp b/libc/test/src/math/smoke/cospif_test.cpp
new file mode 100644
index 0000000000000..007c4c45e3b15
--- /dev/null
+++ b/libc/test/src/math/smoke/cospif_test.cpp
@@ -0,0 +1,34 @@
+//===-- Unittests for cospif ----------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/errno/libc_errno.h"
+#include "src/math/cospif.h"
+#include "test/UnitTest/FPMatcher.h"
+
+#include <stdint.h>
+
+using LlvmLibcCospifTest = LIBC_NAMESPACE::testing::FPTest<float>;
+
+TEST_F(LlvmLibcCospifTest, SpecialNumbers) {
+  LIBC_NAMESPACE::libc_errno = 0;
+
+  EXPECT_FP_EQ(aNaN, LIBC_NAMESPACE::cospif(aNaN));
+  EXPECT_MATH_ERRNO(0);
+
+  EXPECT_FP_EQ(1.0f, LIBC_NAMESPACE::cospif(0.0f));
+  EXPECT_MATH_ERRNO(0);
+
+  EXPECT_FP_EQ(1.0f, LIBC_NAMESPACE::cospif(-0.0f));
+  EXPECT_MATH_ERRNO(0);
+
+  EXPECT_FP_EQ(aNaN, LIBC_NAMESPACE::cospif(inf));
+  EXPECT_MATH_ERRNO(EDOM);
+
+  EXPECT_FP_EQ(aNaN, LIBC_NAMESPACE::cospif(neg_inf));
+  EXPECT_MATH_ERRNO(EDOM);
+}
diff --git a/libc/utils/MPFRWrapper/MPFRUtils.cpp b/libc/utils/MPFRWrapper/MPFRUtils.cpp
index f0a653824bea2..6548fc36cb6b4 100644
--- a/libc/utils/MPFRWrapper/MPFRUtils.cpp
+++ b/libc/utils/MPFRWrapper/MPFRUtils.cpp
@@ -239,6 +239,39 @@ class MPFRNumber {
     return result;
   }
 
+  MPFRNumber cospi() const {
+    MPFRNumber result(*this);
+
+#if MPFR_VERSION_MAJOR > 4 ||                                                  \
+    (MPFR_VERSION_MAJOR == 4 && MPFR_VERSION_MINOR >= 2)
+    mpfr_cospi(result.value, value, mpfr_rounding);
+    return result;
+#else
+    MPFRNumber value_frac(*this);
+    mpfr_frac(value_frac.value, value, MPFR_RNDN);
+
+    if (mpfr_cmp_si(value_frac.value, 0.0) == 0) {
+      mpz_t integer_part;
+      mpz_init(integer_part);
+      mpfr_get_z(integer_part, value, MPFR_RNDN);
+
+      if (mpz_tstbit(integer_part, 0)) {
+        mpfr_set_si(result.value, -1.0, MPFR_RNDN); // odd
+      } else {
+        mpfr_set_si(result.value, 1.0, MPFR_RNDN); // even
+      }
+      return result;
+    }
+
+    MPFRNumber value_pi(0.0, 1280);
+    mpfr_const_pi(value_pi.value, MPFR_RNDN);
+    mpfr_mul(value_pi.value, value_pi.value, value, MPFR_RNDN);
+    mpfr_cos(result.value, value_pi.value, mpfr_rounding);
+
+    return result;
+#endif
+  }
+
   MPFRNumber erf() const {
     MPFRNumber result(*this);
     mpfr_erf(result.value, value, mpfr_rounding);
@@ -675,6 +708,8 @@ unary_operation(Operation op, InputType input, unsigned int precision,
     return mpfrInput.cos();
   case Operation::Cosh:
     return mpfrInput.cosh();
+  case Operation::Cospi:
+    return mpfrInput.cospi();
   case Operation::Erf:
 ...
[truncated]

HendrikHuebner · 2024-07-08T00:02:32Z

Can someone remove the libc tag? I accidentally pushed some commits which didn't belong here at first.

llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp

HendrikHuebner · 2024-07-09T08:59:14Z

@dtcxzyw I just noticed another mistake I made, I did not handle array type inputs correctly. If Op has type "ArrayTy", how can I get the first and second element and check if one is zero? In the existing code, IRBuilderBase.createExtractValue is used, but I can't use this to check for zeros because it actually modifies the IR and which should not happen in case there is no zero.

dtcxzyw · 2024-07-09T09:19:30Z

@dtcxzyw I just noticed another mistake I made, I did not handle array type inputs correctly. If Op has type "ArrayTy", how can I get the first and second element and check if one is zero? In the existing code, IRBuilderBase.createExtractValue is used, but I can't use this to check for zeros because it actually modifies the IR and which should not happen in case there is no zero.

IIRC ConstantFolder::FoldExtractValue should handle this case. You can just push the array tests then I can have a look :)

HendrikHuebner · 2024-07-09T16:00:49Z

IIRC ConstantFolder::FoldExtractValue should handle this case. You can just push the array tests then I can have a look :)

Hmm... I dont think the array is a constant when it is passed to the cabs function. So this probably means its not so trivial to check whether one of its elements is constant..? In that case I will skip the optimization for array inputs.

dtcxzyw

LGTM. Thank you!

dtcxzyw · 2024-07-09T16:26:24Z

llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp

+      IRBuilderBase::FastMathFlagGuard Guard(B);
+      B.setFastMathFlags(CI->getFastMathFlags());
+
+      return copyFlags(


Can you add a test for FMF propagation?

I will add the fast flag to the negative zero tests if thats okay. This would reduce the number of total tests

I can't get the negative zero test to work for fp128. Do you know how I can create a 128bit negative zero literal in IR? I tried 0xL80000000000000000000000000000000 but debugging revealed that this apparently gets turned into a very small positive number when I tried to call dump() on the value.

Please use 0xL00000000000000008000000000000000.

You can always write out fpext float -0.0 to fp128 and run that through instsimplify to see how it's printed

llvm-ci · 2024-07-11T11:37:32Z

LLVM Buildbot has detected a new failure on builder sanitizer-aarch64-linux-fuzzer running on sanitizer-buildbot11 while building llvm at step 2 "annotate".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/159/builds/1861

Here is the relevant piece of the build log for the reference:

Step 2 (annotate) failure: 'python ../sanitizer_buildbot/sanitizers/zorg/buildbot/builders/sanitizers/buildbot_selector.py' (failure)
...
+ JOBS=48
+ RunFuzzerTest libxml2-v2.9.2
+ echo @@@BUILD_STEP test libxml2-v2.9.2 fuzzer@@@
+ ln -sf /b/sanitizer-aarch64-linux-fuzzer/build/llvm/lib/Fuzzer .
@@@BUILD_STEP test libxml2-v2.9.2 fuzzer@@@
+ export FUZZING_ENGINE=fsanitize_fuzzer
+ FUZZING_ENGINE=fsanitize_fuzzer
++ pwd
+ /b/sanitizer-aarch64-linux-fuzzer/build/fuzzer-test-suite/build-and-test.sh libxml2-v2.9.2
Cloning into 'SRC'...
command timed out: 1200 seconds without output running [b'python', b'../sanitizer_buildbot/sanitizers/zorg/buildbot/builders/sanitizers/buildbot_selector.py'], attempting to kill
process killed by signal 9
program finished with exit code -1
elapsedTime=1247.032540
Step 9 (test libxml2-v2.9.2 fuzzer) failure: test libxml2-v2.9.2 fuzzer (failure)
@@@BUILD_STEP test libxml2-v2.9.2 fuzzer@@@
+ export FUZZING_ENGINE=fsanitize_fuzzer
+ FUZZING_ENGINE=fsanitize_fuzzer
++ pwd
+ /b/sanitizer-aarch64-linux-fuzzer/build/fuzzer-test-suite/build-and-test.sh libxml2-v2.9.2
Cloning into 'SRC'...

command timed out: 1200 seconds without output running [b'python', b'../sanitizer_buildbot/sanitizers/zorg/buildbot/builders/sanitizers/buildbot_selector.py'], attempting to kill
process killed by signal 9
program finished with exit code -1
elapsedTime=1247.032540

… input is zero (llvm#97976) cabs(a + i0) -> abs(a) cabs(0 +ib) -> abs(b) Closes llvm#97336

llvmbot added libc llvm:transforms labels Jul 7, 2024

HendrikHuebner force-pushed the dev/cabs branch from 389cf0c to e90e07e Compare July 7, 2024 23:59

lntue removed the libc label Jul 8, 2024

dtcxzyw requested review from arsenm and jcranmer-intel July 8, 2024 03:13

dtcxzyw changed the title ~~[LLVM] Simplify cabs libcall if real or imaginary part of input is zero~~ [SimplifyLibCalls] Simplify cabs libcall if real or imaginary part of input is zero Jul 8, 2024

dtcxzyw reviewed Jul 8, 2024

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llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp Outdated Show resolved Hide resolved

HendrikHuebner force-pushed the dev/cabs branch from e90e07e to 7e725db Compare July 9, 2024 16:22

dtcxzyw approved these changes Jul 9, 2024

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HendrikHuebner force-pushed the dev/cabs branch 2 times, most recently from 86142ca to f8e7763 Compare July 10, 2024 09:48

HendrikHuebner added 4 commits July 11, 2024 10:23

Simplify cabs libcall if real or imaginary part is zero

366efcb

Add more tests

d42984b

Fix tests and handle signed zeros

9a62113

Fix fp128 signed zero literal

963b85c

HendrikHuebner force-pushed the dev/cabs branch from f8e7763 to 963b85c Compare July 11, 2024 08:23

arsenm approved these changes Jul 11, 2024

View reviewed changes

dtcxzyw merged commit e980990 into llvm:main Jul 11, 2024
5 of 6 checks passed

aaryanshukla pushed a commit to aaryanshukla/llvm-project that referenced this pull request Jul 14, 2024

[SimplifyLibCalls] Simplify cabs libcall if real or imaginary part of…

ad024cf

… input is zero (llvm#97976) cabs(a + i0) -> abs(a) cabs(0 +ib) -> abs(b) Closes llvm#97336

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