[RISCV] Remove SeenExtMap from RISCVISAInfo::parseArchString. (#97506)

Use the Exts map directly instead of adding to a temporary MapVector
first.

There are a couple functional change from this.
-If an unknown extension is duplicated, we will now print an error for
it being unknown instead of an error for it being duplicated. 
-If an unknown extension is followed by an underscore with no extension after
it, we will error for the unknown extension instead of the dangling
underscore.

These don't seem like serious changes to me. I've updated tests
accordingly.

Author: topperc

clang/test/Driver/riscv-arch.c

@@ -306,7 +306,7 @@
 // RUN: not %clang --target=riscv32-unknown-elf -march=rv32ixabc_ -### %s \
 // RUN: -fsyntax-only 2>&1 | FileCheck -check-prefix=RV32-XSEP %s
 // RV32-XSEP: error: invalid arch name 'rv32ixabc_',
-// RV32-XSEP: extension name missing after separator '_'
+// RV32-XSEP: unsupported non-standard user-level extension 'xabc'
 
 // RUN: not %clang --target=riscv32-unknown-elf -march=rv32ixabc_a -### %s \
 // RUN: -fsyntax-only 2>&1 | FileCheck -check-prefix=RV32-PREFIX %s
@@ -318,10 +318,10 @@
 // RV32-X-ORDER: error: invalid arch name 'rv32ixdef_sabc',
 // RV32-X-ORDER  unsupported non-standard user-level extension 'xdef'
 
-// RUN: not %clang --target=riscv32-unknown-elf -march=rv32ixabc_xabc -### %s \
+// RUN: not %clang --target=riscv32-unknown-elf -march=rv32im_m -### %s \
 // RUN: -fsyntax-only 2>&1 | FileCheck -check-prefix=RV32-XDUP %s
-// RV32-XDUP: error: invalid arch name 'rv32ixabc_xabc',
-// RV32-XDUP: duplicated non-standard user-level extension 'xabc'
+// RV32-XDUP: error: invalid arch name 'rv32im_m',
+// RV32-XDUP: duplicated standard user-level extension 'm'
 
 // RUN: not %clang --target=riscv32-unknown-elf -march=rv32ixabc_xdef -### %s \
 // RUN: -fsyntax-only 2>&1 | FileCheck -check-prefix=RV32-X-X-INVAL %s

llvm/lib/TargetParser/RISCVISAInfo.cpp

@@ -7,9 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/TargetParser/RISCVISAInfo.h"
-#include "llvm/ADT/MapVector.h"
 #include "llvm/ADT/STLExtras.h"
-#include "llvm/ADT/SetVector.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/Errc.h"
@@ -558,9 +556,6 @@ RISCVISAInfo::parseArchString(StringRef Arch, bool EnableExperimentalExtension,
         "profile name");
 
   std::unique_ptr<RISCVISAInfo> ISAInfo(new RISCVISAInfo(XLen));
-  MapVector<std::string, RISCVISAUtils::ExtensionVersion,
-            std::map<std::string, unsigned>>
-      SeenExtMap;
 
   // The canonical order specified in ISA manual.
   // Ref: Table 22.1 in RISC-V User-Level ISA V2.2
@@ -583,8 +578,7 @@ RISCVISAInfo::parseArchString(StringRef Arch, bool EnableExperimentalExtension,
             EnableExperimentalExtension, ExperimentalExtensionVersionCheck))
       return std::move(E);
 
-    // Postpone AddExtension until end of this function
-    SeenExtMap[StringRef(&Baseline, 1).str()] = {Major, Minor};
+    ISAInfo->Exts[std::string(1, Baseline)] = {Major, Minor};
     break;
   case 'g':
     // g expands to extensions in RISCVGImplications.
@@ -597,11 +591,11 @@ RISCVISAInfo::parseArchString(StringRef Arch, bool EnableExperimentalExtension,
     // No matter which version is given to `g`, we always set imafd to default
     // version since the we don't have clear version scheme for that on
     // ISA spec.
-    for (const auto *Ext : RISCVGImplications) {
+    for (const char *Ext : RISCVGImplications) {
       auto Version = findDefaultVersion(Ext);
       assert(Version && "Default extension version not found?");
       // Postpone AddExtension until end of this function
-      SeenExtMap[Ext] = {Version->Major, Version->Minor};
+      ISAInfo->Exts[std::string(Ext)] = {Version->Major, Version->Minor};
     }
     break;
   }
@@ -662,23 +656,19 @@ RISCVISAInfo::parseArchString(StringRef Arch, bool EnableExperimentalExtension,
       if (Name.size() == 1)
         Ext = Ext.substr(ConsumeLength);
 
-      // Check if duplicated extension.
-      if (SeenExtMap.contains(Name.str()))
+      if (!RISCVISAInfo::isSupportedExtension(Name))
+        return getErrorForInvalidExt(Name);
+
+      // Insert and error for duplicates.
+      if (!ISAInfo->Exts
+               .emplace(Name.str(),
+                        RISCVISAUtils::ExtensionVersion{Major, Minor})
+               .second)
         return getError("duplicated " + Desc + " '" + Name + "'");
 
-      SeenExtMap[Name.str()] = {Major, Minor};
     } while (!Ext.empty());
   }
 
-  // Check all Extensions are supported.
-  for (auto &SeenExtAndVers : SeenExtMap) {
-    const std::string &ExtName = SeenExtAndVers.first;
-
-    if (!RISCVISAInfo::isSupportedExtension(ExtName))
-      return getErrorForInvalidExt(ExtName);
-    ISAInfo->Exts[ExtName] = SeenExtAndVers.second;
-  }
-
   return RISCVISAInfo::postProcessAndChecking(std::move(ISAInfo));
 }