[LoongArch] Honor the `--target-abi` option when generating e_flags

[SixWeining]

Summary

Depends on D142685.

llvm/lib/Target/LoongArch/MCTargetDesc/LoongArchAsmBackend.h

 #include "llvm/MC/MCSubtargetInfo.h"
 
 namespace llvm {
 
 class LoongArchAsmBackend : public MCAsmBackend {
   const MCSubtargetInfo &STI;
   uint8_t OSABI;
   bool Is64Bit;
+  const MCTargetOptions &TargetOptions;
 
 public:
-  LoongArchAsmBackend(const MCSubtargetInfo &STI, uint8_t OSABI, bool Is64Bit)
-      : MCAsmBackend(support::little), STI(STI), OSABI(OSABI),
-        Is64Bit(Is64Bit) {}
+  LoongArchAsmBackend(const MCSubtargetInfo &STI, uint8_t OSABI, bool Is64Bit,
+                      const MCTargetOptions &Options)
+      : MCAsmBackend(support::little), STI(STI), OSABI(OSABI), Is64Bit(Is64Bit),
+        TargetOptions(Options) {}
   ~LoongArchAsmBackend() override {}
 
   void applyFixup(const MCAssembler &Asm, const MCFixup &Fixup,
                   const MCValue &Target, MutableArrayRef<char> Data,
                   uint64_t Value, bool IsResolved,
                   const MCSubtargetInfo *STI) const override;
 
   bool shouldForceRelocation(const MCAssembler &Asm, const MCFixup &Fixup,
public:
   void relaxInstruction(MCInst &Inst,
                         const MCSubtargetInfo &STI) const override {}
 
   bool writeNopData(raw_ostream &OS, uint64_t Count,
                     const MCSubtargetInfo *STI) const override;
 
   std::unique_ptr<MCObjectTargetWriter>
   createObjectTargetWriter() const override;
+  const MCTargetOptions &getTargetOptions() const { return TargetOptions; }
 };
 } // end namespace llvm
 
 #endif // LLVM_LIB_TARGET_LOONGARCH_MCTARGETDESC_LOONGARCHASMBACKEND_H

llvm/lib/Target/LoongArch/MCTargetDesc/LoongArchAsmBackend.cpp

 }
 
 MCAsmBackend *llvm::createLoongArchAsmBackend(const Target &T,
                                               const MCSubtargetInfo &STI,
                                               const MCRegisterInfo &MRI,
                                               const MCTargetOptions &Options) {
   const Triple &TT = STI.getTargetTriple();
   uint8_t OSABI = MCELFObjectTargetWriter::getOSABI(TT.getOS());
-  return new LoongArchAsmBackend(STI, OSABI, TT.isArch64Bit());
+  return new LoongArchAsmBackend(STI, OSABI, TT.isArch64Bit(), Options);
 }

llvm/lib/Target/LoongArch/MCTargetDesc/LoongArchELFStreamer.cpp

 //===-- LoongArchELFStreamer.cpp - LoongArch ELF Target Streamer Methods --===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
 // This file provides LoongArch specific target streamer methods.
 //
 //===----------------------------------------------------------------------===//
 
 #include "LoongArchELFStreamer.h"
 #include "LoongArchAsmBackend.h"
+#include "LoongArchBaseInfo.h"
 #include "llvm/BinaryFormat/ELF.h"
 #include "llvm/MC/MCAssembler.h"
 #include "llvm/MC/MCCodeEmitter.h"
 #include "llvm/MC/MCObjectWriter.h"
 
 using namespace llvm;
 
 // This part is for ELF object output.
 LoongArchTargetELFStreamer::LoongArchTargetELFStreamer(
     MCStreamer &S, const MCSubtargetInfo &STI)
     : LoongArchTargetStreamer(S) {
-  // FIXME: select appropriate ABI.
-  setTargetABI(STI.getTargetTriple().isArch64Bit() ? LoongArchABI::ABI_LP64D
-                                                   : LoongArchABI::ABI_ILP32D);
+  auto &MAB = static_cast<LoongArchAsmBackend &>(
+      getStreamer().getAssembler().getBackend());
+  setTargetABI(LoongArchABI::computeTargetABI(
+      STI.getTargetTriple(), MAB.getTargetOptions().getABIName()));
 }
 
 MCELFStreamer &LoongArchTargetELFStreamer::getStreamer() {
   return static_cast<MCELFStreamer &>(Streamer);
 }
 
 void LoongArchTargetELFStreamer::finish() {
   LoongArchTargetStreamer::finish();

llvm/test/CodeGen/LoongArch/e_flags.ll

 ; RUN: llc --mtriple=loongarch32 --filetype=obj %s -o %t-la32
 ; RUN: llvm-readelf -h %t-la32 | FileCheck %s --check-prefixes=ILP32,ABI-D --match-full-lines
+
+; RUN: llc --mtriple=loongarch32 --filetype=obj %s --target-abi=ilp32s -o %t-ilp32s
+; RUN: llvm-readelf -h %t-ilp32s | FileCheck %s --check-prefixes=ILP32,ABI-S --match-full-lines
+
+; RUN: llc --mtriple=loongarch32 --filetype=obj %s --target-abi=ilp32f -o %t-ilp32f
+; RUN: llvm-readelf -h %t-ilp32f | FileCheck %s --check-prefixes=ILP32,ABI-F --match-full-lines
+
+; RUN: llc --mtriple=loongarch32 --filetype=obj %s --target-abi=ilp32d -o %t-ilp32d
+; RUN: llvm-readelf -h %t-ilp32d | FileCheck %s --check-prefixes=ILP32,ABI-D --match-full-lines
+
 ; RUN: llc --mtriple=loongarch64 --filetype=obj %s -o %t-la64
 ; RUN: llvm-readelf -h %t-la64 | FileCheck %s --check-prefixes=LP64,ABI-D --match-full-lines
 
-;; Note that we have not support the -target-abi option to select specific ABI.
-;; See comments in LoongArchELFStreamer.cpp. So here we only check the default behaviour.
-;; After -target-abi is supported, we can add more tests.
+; RUN: llc --mtriple=loongarch64 --filetype=obj %s --target-abi=lp64s -o %t-lp64s
+; RUN: llvm-readelf -h %t-lp64s | FileCheck %s --check-prefixes=LP64,ABI-S --match-full-lines
+
+; RUN: llc --mtriple=loongarch64 --filetype=obj %s --target-abi=lp64f -o %t-lp64f
+; RUN: llvm-readelf -h %t-lp64f | FileCheck %s --check-prefixes=LP64,ABI-F --match-full-lines
+
+; RUN: llc --mtriple=loongarch64 --filetype=obj %s --target-abi=lp64d -o %t-lp64d
+; RUN: llvm-readelf -h %t-lp64d | FileCheck %s --check-prefixes=LP64,ABI-D --match-full-lines
 
 ; LP64: Class: ELF64
 ; ILP32: Class: ELF32
 
+; ABI-S: Flags: 0x41, SOFT-FLOAT, OBJ-v1
+; ABI-F: Flags: 0x42, SINGLE-FLOAT, OBJ-v1
 ; ABI-D: Flags: 0x43, DOUBLE-FLOAT, OBJ-v1
 
 define void @foo() {
   ret void
 }