ARM: Default to apcs-gnu ABI for NetBSD

[olista01]

Summary

r216662 changed the default ABi for 32-bit ARM targets to be "aapcs" when no environment is given in the triple, however NetBSD requires it to be "apcs-gnu".

[olista01]

Allow all environments for NetBSD.

Is the trailing - in the triple intentional?

Yes, the triple has four parts (the environment comes after the last "-") and I'm not trying to test the triple parser here.

[olista01]

This was accepted by email, but did not reach Phab.

[olista01]

Committed revision 217141.

lib/Driver/Tools.cpp

if (Triple.getEnvironment() == llvm::Triple::EABI ||
         StringRef(CPUName).startswith("cortex-m")) {
       ABIName = "aapcs";
     } else {
       ABIName = "apcs-gnu";
     }
   } else if (Triple.isOSWindows()) {
     // FIXME: this is invalid for WindowsCE
     ABIName = "aapcs";
+  } else if (Triple.getOS() == llvm::Triple::NetBSD) {
+    if (Triple.getEnvironment() == llvm::Triple::EABI)
+      ABIName = "aapcs";
+    else
+      ABIName = "apcs-gnu";
   } else {
     // Select the default based on the platform.
     switch(Triple.getEnvironment()) {
     case llvm::Triple::Android:
     case llvm::Triple::GNUEABI:
     case llvm::Triple::GNUEABIHF:
       ABIName = "aapcs-linux";
       break;

test/Driver/arm-abi.c

 // RUN:   | FileCheck -check-prefix=CHECK-APCS-GNU %s
 // RUN: %clang -target thumb--darwin- -arch armv7m %s -### -o %t.o 2>&1 \
 // RUN:   | FileCheck -check-prefix=CHECK-AAPCS %s
 
 // Windows targets default to AAPCS, regardless of environment
 // RUN: %clang -target arm--windows-gnueabi %s -### -o %t.o 2>&1 \
 // RUN:   | FileCheck -check-prefix=CHECK-AAPCS %s
 
+// NetBSD defaults to apcs-gnu, but can also use aapcs
+// RUN: %clang -target arm--netbsd- %s -### -o %t.o 2>&1 \
+// RUN:   | FileCheck -check-prefix=CHECK-APCS-GNU %s
+// RUN: %clang -target arm--netbsd-eabi %s -### -o %t.o 2>&1 \
+// RUN:   | FileCheck -check-prefix=CHECK-AAPCS %s
+
 // Otherwise, ABI is celected based on environment
 // RUN: %clang -target arm---android %s -### -o %t.o 2>&1 \
 // RUN:   | FileCheck -check-prefix=CHECK-AAPCS-LINUX %s
 // RUN: %clang -target arm---gnueabi %s -### -o %t.o 2>&1 \
 // RUN:   | FileCheck -check-prefix=CHECK-AAPCS-LINUX %s
 // RUN: %clang -target arm---gnueabihf %s -### -o %t.o 2>&1 \
 // RUN:   | FileCheck -check-prefix=CHECK-AAPCS-LINUX %s
 // RUN: %clang -target arm---eabi %s -### -o %t.o 2>&1 \