[Analysis] Disable exp/exp2/pow finite lib calls on Android with -ffast-math.

[minseong.kim]

Summary

Since r322087, glibc's finite lib calls are generated when possible.
However, glibc is not supported on Android. Therefore this change
enables llvm to finely distinguish between linux and Android for
unsupported library calls. The change also include some regression
tests.

[srhines]

Thanks for fixing this. We were just starting to encounter build issues with the _finite functions, and wondering about the best way to approach it. This is very clean.

[minseong.kim]

Thanks for the review.

lib/Analysis/TargetLibraryInfo.cpp

static void initialize(TargetLibraryInfoImpl &TLI, const Triple &T,
   // http://svn.freebsd.org/base/head/lib/libc/string/flsl.c
   // http://svn.freebsd.org/base/head/lib/libc/string/flsll.c
   if (!T.isOSFreeBSD()) {
     TLI.setUnavailable(LibFunc_fls);
     TLI.setUnavailable(LibFunc_flsl);
     TLI.setUnavailable(LibFunc_flsll);
   }
 
+  // Android uses bionic instead of glibc. So disable some finite
+  // lib calls in glibc for Android. The list of unsupported lib
+  // calls for Android may expand as the need arises.
+  if (T.isAndroid()) {
+    TLI.setUnavailable(LibFunc_exp_finite);
+    TLI.setUnavailable(LibFunc_exp2_finite);
+    TLI.setUnavailable(LibFunc_pow_finite);
+  }
+
   // The following functions are available on at least Linux:
   if (!T.isOSLinux()) {
     TLI.setUnavailable(LibFunc_dunder_strdup);
     TLI.setUnavailable(LibFunc_dunder_strtok_r);
     TLI.setUnavailable(LibFunc_dunder_isoc99_scanf);
     TLI.setUnavailable(LibFunc_dunder_isoc99_sscanf);
     TLI.setUnavailable(LibFunc_under_IO_getc);
     TLI.setUnavailable(LibFunc_under_IO_putc);

test/CodeGen/AArch64/illegal-float-ops.ll

 ; RUN: llc -mtriple=aarch64-none-linux-gnu -verify-machineinstrs -o - %s | FileCheck %s
+; RUN: llc -mtriple=aarch64-linux-android -verify-machineinstrs -o - %s | FileCheck --check-prefix=ANDROID-AARCH64 %s
 
 @varfloat = global float 0.0
 @vardouble = global double 0.0
 @varfp128 = global fp128 zeroinitializer
 
 declare float @llvm.cos.f32(float)
 declare double @llvm.cos.f64(double)
 declare fp128 @llvm.cos.f128(fp128)
; CHECK-LABEL: test_fmuladd:
   %fmuladdfp128 = call fp128 @llvm.fmuladd.f128(fp128 %fp128, fp128 %fp128, fp128 %fp128)
   store fp128 %fmuladdfp128, fp128* @varfp128
 ; CHECK-NOT: bl fmal
 ; CHECK: bl __multf3
 ; CHECK: bl __addtf3
 
   ret void
 }
+
+define void @test_exp_finite(double %double) #0 {
+  %expdouble = call double @llvm.exp.f64(double %double)
+  store double %expdouble, double* @vardouble
+  ; ANDROID-AARCH64-NOT: bl __exp_finite
+  ; CHECK: bl __exp_finite
+
+  ret void
+}
+
+define void @test_exp2_finite(double %double) #0 {
+  %expdouble = call double @llvm.exp2.f64(double %double)
+  store double %expdouble, double* @vardouble
+  ; ANDROID-AARCH64-NOT: bl __exp2_finite
+  ; CHECK: bl __exp2_finite
+
+  ret void
+}
+
+define void @test_pow_finite(double %double) #0 {
+  %powdouble = call double @llvm.pow.f64(double %double, double %double)
+  store double %powdouble, double* @vardouble
+  ; ANDROID-AARCH64-NOT: bl __pow_finite
+  ; CHECK: bl __pow_finite
+  ret void
+}
+
+attributes #0 = { "no-infs-fp-math"="true" "no-nans-fp-math"="true" }