[clang] Make -fveclib={ArmPL,SLEEF} imply -fno-math-errno

clang/include/clang/Basic/DiagnosticDriverKinds.td

@@ -502,6 +502,10 @@ def err_sls_hardening_arm_not_supported : Error<
 def warn_drv_large_data_threshold_invalid_code_model: Warning<
   "'%0' only applies to medium and large code models">,
   InGroup<UnusedCommandLineArgument>;
+def warn_drv_math_errno_enabled_after_veclib: Warning<
+  "math errno enabled by '%0' after it was implicitly disabled by '%1',"
+  " this may limit the utilization of the vector library">,
+  InGroup<MathErrnoEnabledWithVecLib>;
 
 def note_drv_command_failed_diag_msg : Note<
   "diagnostic msg: %0">;

clang/include/clang/Basic/DiagnosticGroups.td

@@ -125,6 +125,7 @@ def FloatZeroConversion : DiagGroup<"float-zero-conversion">;
 def FloatConversion :
   DiagGroup<"float-conversion", [FloatOverflowConversion,
                                  FloatZeroConversion]>;
+def MathErrnoEnabledWithVecLib : DiagGroup<"math-errno-enabled-with-veclib">;
 
 def FrameAddress : DiagGroup<"frame-address">;
 def FreeNonHeapObject : DiagGroup<"free-nonheap-object">;

clang/include/clang/Driver/Options.td

@@ -3410,7 +3410,8 @@ def fno_experimental_isel : Flag<["-"], "fno-experimental-isel">, Group<f_clang_
   Alias<fno_global_isel>;
 def fveclib : Joined<["-"], "fveclib=">, Group<f_Group>,
   Visibility<[ClangOption, CC1Option, FlangOption, FC1Option]>,
-    HelpText<"Use the given vector functions library">,
+    HelpText<"Use the given vector functions library."
+             "Note: In clang -fveclib={ArmPL,SLEEF} implies -fno-math-errno">,
     Values<"Accelerate,libmvec,MASSV,SVML,SLEEF,Darwin_libsystem_m,ArmPL,AMDLIBM,none">,
     NormalizedValuesScope<"llvm::driver::VectorLibrary">,
     NormalizedValues<["Accelerate", "LIBMVEC", "MASSV", "SVML", "SLEEF",

clang/lib/Driver/ToolChains/Clang.cpp

@@ -41,6 +41,7 @@
 #include "clang/Driver/SanitizerArgs.h"
 #include "clang/Driver/Types.h"
 #include "clang/Driver/XRayArgs.h"
+#include "llvm/ADT/ScopeExit.h"
 #include "llvm/ADT/SmallSet.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/BinaryFormat/Magic.h"
@@ -2854,6 +2855,14 @@ static void RenderFloatingPointOptions(const ToolChain &TC, const Driver &D,
                                        bool OFastEnabled, const ArgList &Args,
                                        ArgStringList &CmdArgs,
                                        const JobAction &JA) {
+  // List of veclibs which when used with -fveclib imply -fno-math-errno.
+  constexpr std::array VecLibImpliesNoMathErrno{llvm::StringLiteral("ArmPL"),
+                                                llvm::StringLiteral("SLEEF")};
+  bool NoMathErrnoWasImpliedByVecLib = false;
+  const Arg *VecLibArg = nullptr;
+  // Track the arg (if any) that enabled errno after -fveclib for diagnostics.
+  const Arg *ArgThatEnabledMathErrnoAfterVecLib = nullptr;
+
   // Handle various floating point optimization flags, mapping them to the
   // appropriate LLVM code generation flags. This is complicated by several
   // "umbrella" flags, so we do this by stepping through the flags incrementally
@@ -2960,6 +2969,12 @@ static void RenderFloatingPointOptions(const ToolChain &TC, const Driver &D,
   }
 
   for (const Arg *A : Args) {
+    auto CheckMathErrnoForVecLib =
+        llvm::make_scope_exit([&, MathErrnoBeforeArg = MathErrno] {
+          if (NoMathErrnoWasImpliedByVecLib && !MathErrnoBeforeArg && MathErrno)
+            ArgThatEnabledMathErrnoAfterVecLib = A;
+        });
+
     switch (A->getOption().getID()) {
     // If this isn't an FP option skip the claim below
     default: continue;
@@ -3125,6 +3140,13 @@ static void RenderFloatingPointOptions(const ToolChain &TC, const Driver &D,
       TrappingMathPresent = true;
       FPExceptionBehavior = "strict";
       break;
+    case options::OPT_fveclib:
+      VecLibArg = A;
+      NoMathErrnoWasImpliedByVecLib =
+          llvm::is_contained(VecLibImpliesNoMathErrno, A->getValue());
+      if (NoMathErrnoWasImpliedByVecLib)
+        MathErrno = false;
+      break;
     case options::OPT_fno_trapping_math:
       if (!TrappingMathPresent && !FPExceptionBehavior.empty() &&
           FPExceptionBehavior != "ignore")
@@ -3338,8 +3360,13 @@ static void RenderFloatingPointOptions(const ToolChain &TC, const Driver &D,
   if (ApproxFunc)
     CmdArgs.push_back("-fapprox-func");
 
-  if (MathErrno)
+  if (MathErrno) {
     CmdArgs.push_back("-fmath-errno");
+    if (NoMathErrnoWasImpliedByVecLib)
+      D.Diag(clang::diag::warn_drv_math_errno_enabled_after_veclib)
+          << ArgThatEnabledMathErrnoAfterVecLib->getAsString(Args)
+          << VecLibArg->getAsString(Args);
+  }
 
  if (AssociativeMath && ReciprocalMath && !SignedZeros && ApproxFunc &&
      !TrappingMath)

clang/test/Driver/autocomplete.c

@@ -114,6 +114,7 @@
 // WARNING-NEXT: -Wmain-return-type
 // WARNING-NEXT: -Wmalformed-warning-check
 // WARNING-NEXT: -Wmany-braces-around-scalar-init
+// WARNING-NEXT: -Wmath-errno-enabled-with-veclib
 // WARNING-NEXT: -Wmathematical-notation-identifier-extension
 // WARNING-NEXT: -Wmax-tokens
 // WARNING-NEXT: -Wmax-unsigned-zero

clang/test/Driver/fveclib.c

@@ -49,3 +49,56 @@
 
 // RUN: %clang -### --target=aarch64-linux-gnu -fveclib=ArmPL -flto %s 2>&1 | FileCheck --check-prefix=CHECK-LTO-ARMPL %s
 // CHECK-LTO-ARMPL: "-plugin-opt=-vector-library=ArmPL"
+
+
+/* Verify that -fmath-errno is set correctly for the vector library. */
+
+// RUN: %clang -### --target=x86_64-unknown-linux-gnu -fveclib=LIBMVEC %s 2>&1 | FileCheck --check-prefix=CHECK-ERRNO-LIBMVEC %s
+// CHECK-ERRNO-LIBMVEC: "-fveclib=LIBMVEC"
+// CHECK-ERRNO-LIBMVEC-SAME: "-fmath-errno"
+
+// RUN: %clang -### --target=powerpc64-unknown-linux-gnu -fveclib=MASSV %s 2>&1 | FileCheck --check-prefix=CHECK-ERRNO-MASSV %s
+// CHECK-ERRNO-MASSV: "-fveclib=MASSV"
+// CHECK-ERRNO-MASSV-SAME: "-fmath-errno"
+
+// RUN: %clang -### --target=x86_64-unknown-linux-gnu -fveclib=SVML %s 2>&1 | FileCheck --check-prefix=CHECK-ERRNO-SVML %s
+// CHECK-ERRNO-SVML: "-fveclib=SVML"
+// CHECK-ERRNO-SVML-SAME: "-fmath-errno"
+
+// RUN: %clang -### --target=aarch64-linux-gnu -fveclib=SLEEF %s 2>&1 | FileCheck --check-prefix=CHECK-ERRNO-SLEEF %s
+// CHECK-ERRNO-SLEEF-NOT: "-fmath-errno"
+// CHECK-ERRNO-SLEEF: "-fveclib=SLEEF"
+// CHECK-ERRNO-SLEEF-NOT: "-fmath-errno"
+
+// RUN: %clang -### --target=aarch64-linux-gnu -fveclib=ArmPL %s 2>&1 | FileCheck --check-prefix=CHECK-ERRNO-ARMPL %s
+// CHECK-ERRNO-ARMPL-NOT: "-fmath-errno"
+// CHECK-ERRNO-ARMPL: "-fveclib=ArmPL"
+// CHECK-ERRNO-ARMPL-NOT: "-fmath-errno"
+
+// RUN: %clang -### --target=aarch64-linux-gnu -fveclib=ArmPL -fmath-errno %s 2>&1 | FileCheck --check-prefix=CHECK-REENABLE-ERRNO-ARMPL %s
+// CHECK-REENABLE-ERRNO-ARMPL: math errno enabled by '-fmath-errno' after it was implicitly disabled by '-fveclib=ArmPL', this may limit the utilization of the vector library [-Wmath-errno-enabled-with-veclib]
+// CHECK-REENABLE-ERRNO-ARMPL: "-fveclib=ArmPL"
+// CHECK-REENABLE-ERRNO-ARMPL-SAME: "-fmath-errno"
+
+// RUN: %clang -### --target=aarch64-linux-gnu -fveclib=SLEEF -fmath-errno %s 2>&1 | FileCheck --check-prefix=CHECK-REENABLE-ERRNO-SLEEF %s
+// CHECK-REENABLE-ERRNO-SLEEF: math errno enabled by '-fmath-errno' after it was implicitly disabled by '-fveclib=SLEEF', this may limit the utilization of the vector library [-Wmath-errno-enabled-with-veclib]
+// CHECK-REENABLE-ERRNO-SLEEF: "-fveclib=SLEEF"
+// CHECK-REENABLE-ERRNO-SLEEF-SAME: "-fmath-errno"
+
+// RUN: %clang -### --target=aarch64-linux-gnu -fveclib=ArmPL -fno-fast-math %s 2>&1 | FileCheck --check-prefix=CHECK-REENABLE-ERRNO-NFM %s
+// CHECK-REENABLE-ERRNO-NFM: math errno enabled by '-fno-fast-math' after it was implicitly disabled by '-fveclib=ArmPL', this may limit the utilization of the vector library [-Wmath-errno-enabled-with-veclib]
+// CHECK-REENABLE-ERRNO-NFM: "-fveclib=ArmPL"
+// CHECK-REENABLE-ERRNO-NFM-SAME: "-fmath-errno"
+
+// RUN: %clang -### --target=aarch64-linux-gnu -fveclib=ArmPL -ffp-model=strict %s 2>&1 | FileCheck --check-prefix=CHECK-REENABLE-ERRNO-FP-MODEL %s
+// CHECK-REENABLE-ERRNO-FP-MODEL: math errno enabled by '-ffp-model=strict' after it was implicitly disabled by '-fveclib=ArmPL', this may limit the utilization of the vector library [-Wmath-errno-enabled-with-veclib]
+// CHECK-REENABLE-ERRNO-FP-MODEL: "-fveclib=ArmPL"
+// CHECK-REENABLE-ERRNO-FP-MODEL-SAME: "-fmath-errno"
+
+/* Verify the warning points at the last arg to enable -fmath-errno. */
+// RUN: %clang -### --target=aarch64-linux-gnu -fveclib=ArmPL -fno-fast-math -fno-math-errno -ffp-model=strict %s 2>&1 | FileCheck --check-prefix=CHECK-ENABLED-LAST %s
+// CHECK-ENABLED-LAST: math errno enabled by '-ffp-model=strict' after it was implicitly disabled by '-fveclib=ArmPL', this may limit the utilization of the vector library [-Wmath-errno-enabled-with-veclib]
+
+/* Verify no warning when math-errno is re-enabled for a different veclib (that does not imply -fno-math-errno). */
+// RUN: %clang -### --target=aarch64-linux-gnu -fveclib=ArmPL -fmath-errno -fveclib=LIBMVEC %s 2>&1 | FileCheck --check-prefix=CHECK-REPEAT-VECLIB %s
+// CHECK-REPEAT-VECLIB-NOT: math errno enabled