[PATCH] D127741: [Disassembler] Add +all CPU feature to subtargetInfo and use it for disassembling AArch64

[Denis via Phabricator via llvm-commits]

treapster created this revision.
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It think it's reasonable to enable all supported extensions when we are disassembling something because we don't want to [hardcode](hhtps://reviews.llvm.org/D121999) it in gdb, objdump, bolt and whatever other places use disassembler in llvm. The only reason not to do it I can think of is if there are conflicting instructions with the same encoding in different extensions, but it doesn't seem possible within one archeticture. We probably should use +all on x86 and other platforms? I'm not sure how test for this should look like, because disassembler is used by at least three tools I know of(gdb, objdump, BOLT), so it's not clear where should we put it, and how to make sure that all new instructions are added to it. Waiting for your feedback.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D127741

Files:
  bolt/lib/Core/BinaryContext.cpp
  lldb/source/Plugins/Disassembler/LLVMC/DisassemblerLLVMC.cpp
  llvm/lib/MC/MCSubtargetInfo.cpp
  llvm/tools/llvm-objdump/llvm-objdump.cpp


Index: llvm/tools/llvm-objdump/llvm-objdump.cpp
===================================================================
--- llvm/tools/llvm-objdump/llvm-objdump.cpp
+++ llvm/tools/llvm-objdump/llvm-objdump.cpp
@@ -1693,6 +1693,10 @@
   if (!MAttrs.empty())
     for (unsigned I = 0; I != MAttrs.size(); ++I)
       Features.AddFeature(MAttrs[I]);
+  else {
+    if (Obj->getArch() == llvm::Triple::aarch64)
+      Features.AddFeature("+all");
+  }
 
   std::unique_ptr<const MCRegisterInfo> MRI(
       TheTarget->createMCRegInfo(TripleName));
Index: llvm/lib/MC/MCSubtargetInfo.cpp
===================================================================
--- llvm/lib/MC/MCSubtargetInfo.cpp
+++ llvm/lib/MC/MCSubtargetInfo.cpp
@@ -198,6 +198,8 @@
       Help(ProcDesc, ProcFeatures);
     else if (Feature == "+cpuhelp")
       cpuHelp(ProcDesc);
+    else if (Feature == "+all")
+      Bits.set();
     else
       ApplyFeatureFlag(Bits, Feature, ProcFeatures);
   }
Index: lldb/source/Plugins/Disassembler/LLVMC/DisassemblerLLVMC.cpp
===================================================================
--- lldb/source/Plugins/Disassembler/LLVMC/DisassemblerLLVMC.cpp
+++ lldb/source/Plugins/Disassembler/LLVMC/DisassemblerLLVMC.cpp
@@ -1179,16 +1179,9 @@
       features_str += "+dspr2,";
   }
 
-  // If any AArch64 variant, enable latest ISA with all extensions.
+  // If any AArch64 variant, enable all features.
   if (triple.isAArch64()) {
-    features_str += "+v9.3a,";
-    std::vector<llvm::StringRef> features;
-    // Get all possible features
-    llvm::AArch64::getExtensionFeatures(-1, features);
-    features_str += llvm::join(features, ",");
-
-    if (triple.getVendor() == llvm::Triple::Apple)
-      cpu = "apple-latest";
+    features_str += "+all";
   }
 
   if (triple.isRISCV()) {
Index: bolt/lib/Core/BinaryContext.cpp
===================================================================
--- bolt/lib/Core/BinaryContext.cpp
+++ bolt/lib/Core/BinaryContext.cpp
@@ -124,8 +124,7 @@
     break;
   case llvm::Triple::aarch64:
     ArchName = "aarch64";
-    FeaturesStr = "+fp-armv8,+neon,+crypto,+dotprod,+crc,+lse,+ras,+rdm,"
-                  "+fullfp16,+spe,+fuse-aes,+rcpc";
+    FeaturesStr = "+all";
     break;
   default:
     return createStringError(std::errc::not_supported,


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