[PPC64] Parse -elfv1 -elfv2 when specified on target triple

Summary:
For big-endian powerpc64, the default ABI is ELFv1. OpenPower ABI ELFv2 is supported when -mabi=elfv2 is specified. FreeBSD support for PowerPC64 ELFv2 ABI with LLVM is in progress[1]. This patch adds an alternative way to specify ELFv2 ABI on target triple [2].

The following results are expected:

ELFv1 when using:
-target powerpc64-unknown-freebsd12.0
-target powerpc64-unknown-freebsd12.0 -mabi=elfv1
-target powerpc64-unknown-freebsd12.0-elfv1

ELFv2 when using:
-target powerpc64-unknown-freebsd12.0 -mabi=elfv2
-target powerpc64-unknown-freebsd12.0-elfv2

[1] https://wiki.freebsd.org/powerpc/llvm-elfv2
[2] https://clang.llvm.org/docs/CrossCompilation.html

Patch by Alfredo Dal'Ava Júnior!

Differential Revision: https://reviews.llvm.org/D61950

llvm-svn: 361355

clang/lib/Basic/Targets/PPC.h

@@ -379,13 +379,11 @@ public:
 
     if ((Triple.getArch() == llvm::Triple::ppc64le)) {
       resetDataLayout("e-m:e-i64:64-n32:64");
-      ABI = "elfv2";
     } else {
       resetDataLayout("E-m:e-i64:64-n32:64");
-      ABI = "elfv1";
     }
 
-    switch (getTriple().getOS()) {
+    switch (Triple.getOS()) {
     case llvm::Triple::FreeBSD:
       LongDoubleWidth = LongDoubleAlign = 64;
       LongDoubleFormat = &llvm::APFloat::IEEEdouble();

llvm/include/llvm/ADT/Triple.h

@@ -202,6 +202,8 @@ public:
     CODE16,
     EABI,
     EABIHF,
+    ELFv1,
+    ELFv2,
     Android,
     Musl,
     MuslEABI,

llvm/lib/Support/Triple.cpp

@@ -228,6 +228,8 @@ StringRef Triple::getEnvironmentTypeName(EnvironmentType Kind) {
   case CODE16: return "code16";
   case EABI: return "eabi";
   case EABIHF: return "eabihf";
+  case ELFv1: return "elfv1";
+  case ELFv2: return "elfv2";
   case Android: return "android";
   case Musl: return "musl";
   case MuslEABI: return "musleabi";
@@ -521,6 +523,8 @@ static Triple::EnvironmentType parseEnvironment(StringRef EnvironmentName) {
   return StringSwitch<Triple::EnvironmentType>(EnvironmentName)
     .StartsWith("eabihf", Triple::EABIHF)
     .StartsWith("eabi", Triple::EABI)
+    .StartsWith("elfv1", Triple::ELFv1)
+    .StartsWith("elfv2", Triple::ELFv2)
     .StartsWith("gnuabin32", Triple::GNUABIN32)
     .StartsWith("gnuabi64", Triple::GNUABI64)
     .StartsWith("gnueabihf", Triple::GNUEABIHF)

llvm/lib/Target/PowerPC/PPCTargetMachine.cpp

@@ -214,6 +214,8 @@ static PPCTargetMachine::PPCABI computeTargetABI(const Triple &TT,
   case Triple::ppc64le:
     return PPCTargetMachine::PPC_ABI_ELFv2;
   case Triple::ppc64:
+    if (TT.getEnvironment() == llvm::Triple::ELFv2)
+      return PPCTargetMachine::PPC_ABI_ELFv2;
     return PPCTargetMachine::PPC_ABI_ELFv1;
   default:
     return PPCTargetMachine::PPC_ABI_UNKNOWN;

llvm/test/CodeGen/PowerPC/ppc64-elf-abi.ll

@@ -5,6 +5,11 @@
 ; RUN: llc -verify-machineinstrs -mtriple=powerpc64le-unknown-linux-gnu -target-abi elfv1 < %s | FileCheck %s -check-prefix=CHECK-ELFv1
 ; RUN: llc -verify-machineinstrs -mtriple=powerpc64le-unknown-linux-gnu -target-abi elfv2 < %s | FileCheck %s -check-prefix=CHECK-ELFv2
 
+; RUN: llc -verify-machineinstrs -mtriple=powerpc64-unknown-freebsd < %s | FileCheck %s -check-prefix=CHECK-ELFv1
+; RUN: llc -verify-machineinstrs -mtriple=powerpc64-unknown-freebsd -target-abi elfv1 < %s | FileCheck %s -check-prefix=CHECK-ELFv1
+; RUN: llc -verify-machineinstrs -mtriple=powerpc64-unknown-freebsd -target-abi elfv2 < %s | FileCheck %s -check-prefix=CHECK-ELFv2
+; RUN: llc -verify-machineinstrs -mtriple=powerpc64-unknown-freebsd-elfv1  < %s | FileCheck %s -check-prefix=CHECK-ELFv1
+; RUN: llc -verify-machineinstrs -mtriple=powerpc64-unknown-freebsd-elfv2  < %s | FileCheck %s -check-prefix=CHECK-ELFv2
+
 ; CHECK-ELFv2: .abiversion 2
 ; CHECK-ELFv1-NOT: .abiversion 2
-