[MC][LoongArch] Change default cpu in MCSubtargetInfo. (#114922)

The default value of this CPU affects the `FeatureBits` obtained by
`LoongArchTargetELFStreamer` when creating an ELF file, and it will
further affect the `Flags` field in the generated file.

So, the default CPU value should be consistent with the
`initializeSubtargetDependencies` in `LoongArchSubtarget.cpp`.
Otherwise, the `Flags` field may be unexpected.

(cherry picked from commit 75c2888)

Author: ylzsx

lld/test/ELF/emulation-loongarch.s

@@ -37,7 +37,7 @@
 # LA32-NEXT:   StringTableSectionIndex:
 # LA32-NEXT: }
 
-# RUN: llvm-mc -filetype=obj -triple=loongarch64 %s -o %t.o
+# RUN: llvm-mc -filetype=obj -triple=loongarch64 -mattr=+d %s -o %t.o
 # RUN: ld.lld %t.o -o %t
 # RUN: llvm-readobj --file-headers %t | FileCheck --check-prefix=LA64 %s
 # RUN: ld.lld -m elf64loongarch %t.o -o %t

lld/test/ELF/loongarch-interlink.test

@@ -3,9 +3,9 @@
 
 # RUN: yaml2obj %t/blob.yaml -o %t/blob.o
 # RUN: yaml2obj %t/v0-lp64d.yaml -o %t/v0-lp64d.o
-# RUN: llvm-mc --filetype=obj --triple=loongarch64-unknown-gnu %t/start.s -o %t/v1-lp64d.o
+# RUN: llvm-mc --filetype=obj --triple=loongarch64-unknown-gnu --mattr=+d %t/start.s -o %t/v1-lp64d.o
 # RUN: llvm-mc --filetype=obj --triple=loongarch64-unknown-gnusf %t/start.s -o %t/v1-lp64s.o
-# RUN: llvm-mc --filetype=obj --triple=loongarch64-unknown-gnu %t/bar.s -o %t/v1-b-lp64d.o
+# RUN: llvm-mc --filetype=obj --triple=loongarch64-unknown-gnu --mattr=+d %t/bar.s -o %t/v1-b-lp64d.o
 
 ## Check that binary input results in e_flags=0 output.
 # RUN: ld.lld -m elf64loongarch -b binary %t/blob.bin -o %t/blob.out

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

@@ -55,7 +55,7 @@ static MCInstrInfo *createLoongArchMCInstrInfo() {
 static MCSubtargetInfo *
 createLoongArchMCSubtargetInfo(const Triple &TT, StringRef CPU, StringRef FS) {
   if (CPU.empty() || CPU == "generic")
-    CPU = TT.isArch64Bit() ? "la464" : "generic-la32";
+    CPU = TT.isArch64Bit() ? "generic-la64" : "generic-la32";
   return createLoongArchMCSubtargetInfoImpl(TT, CPU, /*TuneCPU*/ CPU, FS);
 }
 

llvm/test/CodeGen/LoongArch/e_flags.ll

@@ -1,3 +1,6 @@
+; RUN: llc --mtriple=loongarch32 --filetype=obj %s -o %t-la32s
+; RUN: llvm-readelf -h %t-la32s | FileCheck %s --check-prefixes=ILP32,ABI-S --match-full-lines
+
 ; RUN: llc --mtriple=loongarch32 -mattr=+d --filetype=obj %s -o %t-la32
 ; RUN: llvm-readelf -h %t-la32 | FileCheck %s --check-prefixes=ILP32,ABI-D --match-full-lines
 
@@ -10,6 +13,9 @@
 ; RUN: llc --mtriple=loongarch32 -mattr=+d --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 -mattr=+d --filetype=obj %s -o %t-la64d
+; RUN: llvm-readelf -h %t-la64d | FileCheck %s --check-prefixes=LP64,ABI-D --match-full-lines
+
 ; RUN: llc --mtriple=loongarch64 -mattr=+d --filetype=obj %s -o %t-la64
 ; RUN: llvm-readelf -h %t-la64 | FileCheck %s --check-prefixes=LP64,ABI-D --match-full-lines