[CodeGen] Mark fma as const for Android

[pirama]

Summary

r318093 sets fma, fmaf, fmal as const for Gnu and MSVC. Android also
does not set errno for these functions. So mark these const for
Android.

[spatel]

lib/Sema/SemaDecl.cpp

13108–13110

Please generalize this comment so it doesn't go stale:
"We make fma on some platforms const because..."

[pirama]

Fix comment.

[pirama]

Thanks for the reviews!

lib/Sema/SemaDecl.cpp

if (unsigned BuiltinID = FD->getBuiltinID()) {
 
     // Mark const if we don't care about errno and that is the only thing
     // preventing the function from being const. This allows IRgen to use LLVM
     // intrinsics for such functions.
     if (!getLangOpts().MathErrno && !FD->hasAttr<ConstAttr>() &&
         Context.BuiltinInfo.isConstWithoutErrno(BuiltinID))
       FD->addAttr(ConstAttr::CreateImplicit(Context, FD->getLocation()));
 
     // We make "fma" on GNU or Windows const because we know it does not set
     // errno in those environments even though it could set errno based on the
     // C standard.
     const llvm::Triple &Trip = Context.getTargetInfo().getTriple();
-    if ((Trip.isGNUEnvironment() || Trip.isOSMSVCRT()) &&
+    if ((Trip.isGNUEnvironment() || Trip.isAndroid() || Trip.isOSMSVCRT()) &&
         !FD->hasAttr<ConstAttr>()) {
       switch (BuiltinID) {
       case Builtin::BI__builtin_fma:
       case Builtin::BI__builtin_fmaf:
       case Builtin::BI__builtin_fmal:
       case Builtin::BIfma:
       case Builtin::BIfmaf:
       case Builtin::BIfmal:

test/CodeGen/math-builtins.c

 // RUN: %clang_cc1 -triple x86_64-unknown-unknown -w -S -o - -emit-llvm              %s | FileCheck %s -check-prefix=NO__ERRNO
 // RUN: %clang_cc1 -triple x86_64-unknown-unknown -w -S -o - -emit-llvm -fmath-errno %s | FileCheck %s -check-prefix=HAS_ERRNO
 // RUN: %clang_cc1 -triple x86_64-unknown-unknown-gnu -w -S -o - -emit-llvm -fmath-errno %s | FileCheck %s --check-prefix=HAS_ERRNO_GNU
+// RUN: %clang_cc1 -triple x86_64-unknown-unknown-android -w -S -o - -emit-llvm -fmath-errno %s | FileCheck %s --check-prefix=HAS_ERRNO_ANDROID
 // RUN: %clang_cc1 -triple x86_64-unknown-windows-msvc -w -S -o - -emit-llvm -fmath-errno %s | FileCheck %s --check-prefix=HAS_ERRNO_WIN
 
 // Test attributes and codegen of math builtins.
 
 void foo(double *d, float f, float *fp, long double *l, int *i, const char *c) {
   f = __builtin_fmod(f,f);    f = __builtin_fmodf(f,f);   f =  __builtin_fmodl(f,f);
 
 // NO__ERRNO: frem double

 // HAS_ERRNO: declare x86_fp80 @fmal(x86_fp80, x86_fp80, x86_fp80) [[NOT_READNONE]]
 
 // On GNU or Win, fma never sets errno, so we can convert to the intrinsic.
 
 // HAS_ERRNO_GNU: declare double @llvm.fma.f64(double, double, double) [[READNONE_INTRINSIC:#[0-9]+]]
 // HAS_ERRNO_GNU: declare float @llvm.fma.f32(float, float, float) [[READNONE_INTRINSIC]]
 // HAS_ERRNO_GNU: declare x86_fp80 @llvm.fma.f80(x86_fp80, x86_fp80, x86_fp80) [[READNONE_INTRINSIC]]
 
+// HAS_ERRNO_ANDROID: declare double @llvm.fma.f64(double, double, double) [[READNONE_INTRINSIC:#[0-9]+]]
+// HAS_ERRNO_ANDROID: declare float @llvm.fma.f32(float, float, float) [[READNONE_INTRINSIC]]
+// HAS_ERRNO_ANDROID: declare x86_fp80 @llvm.fma.f80(x86_fp80, x86_fp80, x86_fp80) [[READNONE_INTRINSIC]]
+
 // HAS_ERRNO_WIN: declare double @llvm.fma.f64(double, double, double) [[READNONE_INTRINSIC:#[0-9]+]]
 // HAS_ERRNO_WIN: declare float @llvm.fma.f32(float, float, float) [[READNONE_INTRINSIC]]
 // Long double is just double on win, so no f80 use/declaration.
 // HAS_ERRNO_WIN-NOT: declare x86_fp80 @llvm.fma.f80(x86_fp80, x86_fp80, x86_fp80)
 
   __builtin_fmax(f,f);       __builtin_fmaxf(f,f);      __builtin_fmaxl(f,f);
 
 // NO__ERRNO: declare double @llvm.maxnum.f64(double, double) [[READNONE_INTRINSIC]]

 // NO__ERRNO: attributes [[READNONE_INTRINSIC]] = { {{.*}}readnone{{.*}} }
 // NO__ERRNO: attributes [[NOT_READNONE]] = { nounwind "correctly{{.*}} }
 
 // HAS_ERRNO: attributes [[NOT_READNONE]] = { nounwind "correctly{{.*}} }
 // HAS_ERRNO: attributes [[READNONE_INTRINSIC]] = { {{.*}}readnone{{.*}} }
 // HAS_ERRNO: attributes [[READNONE]] = { {{.*}}readnone{{.*}} }
 
 // HAS_ERRNO_GNU: attributes [[READNONE_INTRINSIC]] = { {{.*}}readnone{{.*}} }
+// HAS_ERRNO_ANDROID: attributes [[READNONE_INTRINSIC]] = { {{.*}}readnone{{.*}} }
 // HAS_ERRNO_WIN: attributes [[READNONE_INTRINSIC]] = { {{.*}}readnone{{.*}} }