[libc-commits] [libc] dd8b93a - [libc] Fix x86_64 fenv implementation for windows

[Siva Chandra Reddy via libc-commits]

Author: Siva Chandra Reddy
Date: 2021-07-27T20:53:01Z
New Revision: dd8b93a9e76bc5e3c8fc521fcb06c779371211d3

URL: https://github.com/llvm/llvm-project/commit/dd8b93a9e76bc5e3c8fc521fcb06c779371211d3
DIFF: https://github.com/llvm/llvm-project/commit/dd8b93a9e76bc5e3c8fc521fcb06c779371211d3.diff

LOG: [libc] Fix x86_64 fenv implementation for windows

All fenv functions are also enabled for windows. Since two tests,
enabled_exceptions_test and feholdexcept_test are still failing on
windows, they have been disabled.

Reviewed By: aeubanks

Differential Revision: https://reviews.llvm.org/D106808

Added: 
    

Modified: 
    libc/config/windows/entrypoints.txt
    libc/test/src/fenv/CMakeLists.txt
    libc/utils/FPUtil/x86_64/FEnvImpl.h

Removed: 
    


################################################################################
diff  --git a/libc/config/windows/entrypoints.txt b/libc/config/windows/entrypoints.txt
index 20a59a0184635..38892340e915a 100644
--- a/libc/config/windows/entrypoints.txt
+++ b/libc/config/windows/entrypoints.txt
@@ -41,6 +41,19 @@ set(TARGET_LIBC_ENTRYPOINTS
 )
 
 set(TARGET_LIBM_ENTRYPOINTS
+    # fenv.h entrypoints
+    libc.src.fenv.feclearexcept
+    libc.src.fenv.fegetenv
+    libc.src.fenv.fegetexceptflag
+    libc.src.fenv.fegetround
+    libc.src.fenv.feholdexcept
+    libc.src.fenv.fesetenv
+    libc.src.fenv.fesetexceptflag
+    libc.src.fenv.fesetround
+    libc.src.fenv.feraiseexcept
+    libc.src.fenv.fetestexcept
+    libc.src.fenv.feupdateenv
+
     # math.h entrypoints
     libc.src.math.copysign
     libc.src.math.copysignf

diff  --git a/libc/test/src/fenv/CMakeLists.txt b/libc/test/src/fenv/CMakeLists.txt
index 88d9663ae472d..9ff2c189bab87 100644
--- a/libc/test/src/fenv/CMakeLists.txt
+++ b/libc/test/src/fenv/CMakeLists.txt
@@ -71,9 +71,11 @@ add_libc_unittest(
     libc.utils.FPUtil.fputil
 )
 
-if (NOT LLVM_USE_SANITIZER)
+if (NOT (LLVM_USE_SANITIZER OR (${LIBC_TARGET_OS} STREQUAL "windows")))
   # Sanitizers don't like SIGFPE. So, we will run the 
   # tests which raise SIGFPE only in non-sanitizer builds.
+  # The tests are also disabled for Windows as they fail currently.
+  # TODO: Investigate and fix the windows failures and enable them for Windows.
   add_fp_unittest(
     enabled_exceptions_test
     SUITE

diff  --git a/libc/utils/FPUtil/x86_64/FEnvImpl.h b/libc/utils/FPUtil/x86_64/FEnvImpl.h
index fae74bb5da9bc..b3e5fc58a2e0d 100644
--- a/libc/utils/FPUtil/x86_64/FEnvImpl.h
+++ b/libc/utils/FPUtil/x86_64/FEnvImpl.h
@@ -91,22 +91,9 @@ struct X87StateDescriptor {
   uint16_t StatusWord;
   uint16_t Unused2;
   // TODO: Elaborate the remaining 20 bytes as required.
-#if !(defined(_WIN32))
   uint32_t _[5];
-#endif
 };
 
-struct FPState {
-  X87StateDescriptor X87Status;
-#if !(defined(_WIN32))
-  uint32_t MXCSR;
-#endif
-};
-
-static_assert(
-    sizeof(fenv_t) == sizeof(FPState),
-    "Internal floating point state does not match the public fenv_t type.");
-
 static inline uint16_t getX87ControlWord() {
   uint16_t w;
   __asm__ __volatile__("fnstcw %0" : "=m"(w)::);
@@ -338,7 +325,48 @@ static inline int setRound(int mode) {
   return 0;
 }
 
-#if !(defined(_WIN32))
+namespace internal {
+
+#ifdef _WIN32
+// MSVC fenv.h defines a very simple representation of the floating point state
+// which just consists of control and status words of the x87 unit.
+struct FPState {
+  uint32_t ControlWord;
+  uint32_t StatusWord;
+};
+#else
+struct FPState {
+  X87StateDescriptor X87Status;
+  uint32_t MXCSR;
+};
+#endif // _WIN32
+
+} // namespace internal
+
+static_assert(
+    sizeof(fenv_t) == sizeof(internal::FPState),
+    "Internal floating point state does not match the public fenv_t type.");
+
+#ifdef _WIN32
+static inline int getEnv(fenv_t *envp) {
+  internal::FPState *state = reinterpret_cast<internal::FPState *>(envp);
+  internal::X87StateDescriptor X87Status;
+  internal::getX87StateDescriptor(X87Status);
+  state->ControlWord = X87Status.ControlWord;
+  state->StatusWord = X87Status.StatusWord;
+  return 0;
+}
+
+static inline int setEnv(const fenv_t *envp) {
+  const internal::FPState *state =
+      reinterpret_cast<const internal::FPState *>(envp);
+  internal::X87StateDescriptor X87Status;
+  X87Status.ControlWord = state->ControlWord;
+  X87Status.StatusWord = state->StatusWord;
+  internal::writeX87StateDescriptor(X87Status);
+  return 0;
+}
+#else
 static inline int getEnv(fenv_t *envp) {
   internal::FPState *state = reinterpret_cast<internal::FPState *>(envp);
   internal::getX87StateDescriptor(state->X87Status);