Make LLVM libc a required dependency and address comments.

Author: lntue

llvm/CMakeLists.txt

@@ -659,15 +659,9 @@ endif()
 
 set(LLVM_ENABLE_Z3_SOLVER_DEFAULT "${Z3_FOUND}")
 
-set(LLVM_INTEGRATE_LIBC "OFF" CACHE STRING "Use LLVM libc code directly if available.")
-
-if(LLVM_INTEGRATE_LIBC)
-  message(STATUS "LLVM_INTEGRATE_LIBC is ${LLVM_INTEGRATE_LIBC}")
-  include(FindLibcCommonUtils)
-  if(NOT TARGET llvm-libc-common-utilities)
-    message(STATUS "LLVM_INTEGRATE_LIBC is set but cannot find LLVM libc at ${libc_path}.")
-    set(LLVM_INTEGRATE_LIBC OFF)
-  endif()
+include(FindLibcCommonUtils)
+if(NOT TARGET llvm-libc-common-utilities)
+  message(FATAL_ERROR "LLVM libc is not found at ${libc_path}.")
 endif()
 
 

llvm/include/llvm/ADT/APFloat.h

@@ -1526,9 +1526,7 @@ class APFloat : public APFloatBase {
   friend IEEEFloat;
   friend DoubleAPFloat;
 
-#ifdef LLVM_INTEGRATE_LIBC
   friend APFloat exp(const APFloat &X, roundingMode RM);
-#endif // LLVM_INTEGRATE_LIBC
 };
 
 static_assert(sizeof(APFloat) == sizeof(detail::IEEEFloat),
@@ -1662,11 +1660,9 @@ inline APFloat maximumnum(const APFloat &A, const APFloat &B) {
   return A < B ? B : A;
 }
 
-#ifdef LLVM_INTEGRATE_LIBC
 /// Implement IEEE 754-2019 exp functions.
 LLVM_READONLY
 APFloat exp(const APFloat &X, RoundingMode RM = APFloat::rmNearestTiesToEven);
-#endif // LLVM_INTEGRATE_LIBC
 
 inline raw_ostream &operator<<(raw_ostream &OS, const APFloat &V) {
   V.print(OS);

llvm/include/llvm/Config/llvm-config.h.cmake

@@ -146,7 +146,4 @@
    coverage bugs, and to 0 otherwise. */
 #cmakedefine01 LLVM_ENABLE_DEBUGLOC_TRACKING_ORIGIN
 
-/* Define if LLVM and clang uses LLVM libc for math computations. */
-#cmakedefine LLVM_INTEGRATE_LIBC
-
 #endif

llvm/lib/Support/APFloat.cpp

@@ -28,10 +28,8 @@
 #include <cstring>
 #include <limits.h>
 
-#ifdef LLVM_INTEGRATE_LIBC
 // Shared headers from LLVM libc
 #include "shared/math.h"
-#endif // LLVM_INTEGRATE_LIBC
 
 #define APFLOAT_DISPATCH_ON_SEMANTICS(METHOD_CALL)                             \
   do {                                                                         \
@@ -5606,7 +5604,6 @@ float APFloat::convertToFloat() const {
   return Temp.getIEEE().convertToFloat();
 }
 
-#ifdef LLVM_INTEGRATE_LIBC
 static constexpr int getFEnvRoundingMode(llvm::RoundingMode rm) {
   switch (rm) {
   case APFloat::rmTowardPositive:
@@ -5622,16 +5619,13 @@ static constexpr int getFEnvRoundingMode(llvm::RoundingMode rm) {
 }
 
 APFloat exp(const APFloat &X, RoundingMode rounding_mode) {
-  assert((&X.getSemantics() == (const llvm::fltSemantics *)&semIEEEsingle) &&
-         "Float semantics is not IEEEsingle");
   if (&X.getSemantics() == (const llvm::fltSemantics *)&semIEEEsingle) {
     float result = LIBC_NAMESPACE::shared::expf(
         X.convertToFloat(), getFEnvRoundingMode(rounding_mode));
     return APFloat(result);
   }
-  llvm_unreachable("Unexpected semantics");
+  assert(false && "Unsupported floating-point semantics");
 }
-#endif // LLVM_INTEGRATE_LIBC
 
 } // namespace llvm
 

llvm/lib/Support/CMakeLists.txt

@@ -385,8 +385,7 @@ target_include_directories(LLVMSupport
   ${LLVM_THIRD_PARTY_DIR}/siphash/include
 )
 
-if(LLVM_INTEGRATE_LIBC)
-  set_property(TARGET LLVMSupport PROPERTY CXX_STANDARD 17)
-  target_include_directories(LLVMSupport PRIVATE "${LLVM_INCLUDE_DIR}/../../libc")
-  target_compile_options(LLVMSupport PRIVATE "-Wno-c99-extensions") # _Complex warnings.
-endif()
+# Integrating LLVM libc's math functions
+set_property(TARGET LLVMSupport PROPERTY CXX_STANDARD 17)
+target_include_directories(LLVMSupport PRIVATE "${LLVM_INCLUDE_DIR}/../../libc")
+target_compile_options(LLVMSupport PRIVATE "-Wno-c99-extensions") # _Complex warnings.

llvm/unittests/ADT/APFloatTest.cpp

@@ -8357,7 +8357,6 @@ TEST(APFloatTest, hasSignBitInMSB) {
   EXPECT_FALSE(APFloat::hasSignBitInMSB(APFloat::Float8E8M0FNU()));
 }
 
-#ifdef LLVM_INTEGRATE_LIBC
 TEST(APFloatTest, expf) {
   std::array<llvm::RoundingMode, 4> allRoundingModes = {
       APFloat::rmNearestTiesToEven, APFloat::rmTowardPositive,
@@ -8431,6 +8430,5 @@ TEST(APFloatTest, expf) {
   EXPECT_EQ(0x1.78b562p-2f,
             llvm::exp(APFloat(-1.0f), APFloat::rmTowardZero).convertToFloat());
 }
-#endif // LLVM_INTEGRATE_LIBC
 
 } // namespace