[RISCV] Gate unratified profiles behind -menable-experimental-extensions (#92167)

As discussed in the last sync-up call, because these profiles are not
yet finalised they shouldn't be exposed to users unless they opt-in to
them (much like experimental extensions). We may later want to add a
more specific flag, but reusing `-menable-experimental-extensions`
solves the immediate problem.

This is implemented using the new support for marking profiles s
experimental added in #91993 to move the unratified profiles to
RISCVExperimentalProfile and making the necessary changes to logic in
RISCVISAInfo to handle this.

Author: asb

clang/test/Driver/riscv-profiles.c

@@ -111,7 +111,7 @@
 // RVA22S64: "-target-feature" "+svinval"
 // RVA22S64: "-target-feature" "+svpbmt"
 
-// RUN: %clang --target=riscv64 -### -c %s 2>&1 -march=rva23u64 \
+// RUN: %clang --target=riscv64 -### -c %s 2>&1 -march=rva23u64 -menable-experimental-extensions \
 // RUN:   | FileCheck -check-prefix=RVA23U64 %s
 // RVA23U64: "-target-feature" "+m"
 // RVA23U64: "-target-feature" "+a"
@@ -207,7 +207,7 @@
 // RVA23S64: "-target-feature" "+svnapot"
 // RVA23S64: "-target-feature" "+svpbmt"
 
-// RUN: %clang --target=riscv64 -### -c %s 2>&1 -march=rvb23u64 \
+// RUN: %clang --target=riscv64 -### -c %s 2>&1 -march=rvb23u64 -menable-experimental-extensions \
 // RUN:   | FileCheck -check-prefix=RVB23U64 %s
 // RVB23U64: "-target-feature" "+m"
 // RVB23U64: "-target-feature" "+a"
@@ -284,7 +284,7 @@
 // RVB23S64: "-target-feature" "+svnapot"
 // RVB23S64: "-target-feature" "+svpbmt"
 
-// RUN: %clang --target=riscv32 -### -c %s 2>&1 -march=rvm23u32 \
+// RUN: %clang --target=riscv32 -### -c %s 2>&1 -march=rvm23u32 -menable-experimental-extensions \
 // RUN:   | FileCheck -check-prefix=RVM23U32 %s
 // RVM23U32: "-target-feature" "+m"
 // RVM23U32: "-target-feature" "+zicbop"
@@ -322,3 +322,7 @@
 
 // RUN: not %clang --target=riscv64 -### -c %s 2>&1 -march=rva22u64zfa | FileCheck -check-prefix=INVALID-ADDITIONAL %s
 // INVALID-ADDITIONAL: error: invalid arch name 'rva22u64zfa', additional extensions must be after separator '_'
+
+// RUN: not %clang --target=riscv64 -### -c %s 2>&1 -march=rva23u64 | FileCheck -check-prefix=EXPERIMENTAL-NOFLAG %s
+// EXPERIMENTAL-NOFLAG: error: invalid arch name 'rva23u64'
+// EXPERIMENTAL-NOFLAG: requires '-menable-experimental-extensions' for profile 'rva23u64'

llvm/lib/Target/RISCV/RISCVProfiles.td

@@ -13,6 +13,10 @@ class RISCVProfile<string name, list<SubtargetFeature> features>
   // experimental.
   bit Experimental = false;
 }
+class RISCVExperimentalProfile<string name, list<SubtargetFeature> features>
+    : RISCVProfile<"experimental-"#name, features> {
+  let Experimental = true;
+}
 
 defvar RVI20U32Features = [Feature32Bit, FeatureStdExtI];
 defvar RVI20U64Features = [Feature64Bit, FeatureStdExtI];
@@ -201,8 +205,8 @@ def RVA20U64 : RISCVProfile<"rva20u64", RVA20U64Features>;
 def RVA20S64 : RISCVProfile<"rva20s64", RVA20S64Features>;
 def RVA22U64 : RISCVProfile<"rva22u64", RVA22U64Features>;
 def RVA22S64 : RISCVProfile<"rva22s64", RVA22S64Features>;
-def RVA23U64 : RISCVProfile<"rva23u64", RVA23U64Features>;
-def RVA23S64 : RISCVProfile<"rva23s64", RVA23S64Features>;
-def RVB23U64 : RISCVProfile<"rvb23u64", RVB23U64Features>;
-def RVB23S64 : RISCVProfile<"rvb23s64", RVB23S64Features>;
-def RVM23U32 : RISCVProfile<"rvm23u32", RVM23U32Features>;
+def RVA23U64 : RISCVExperimentalProfile<"rva23u64", RVA23U64Features>;
+def RVA23S64 : RISCVExperimentalProfile<"rva23s64", RVA23S64Features>;
+def RVB23U64 : RISCVExperimentalProfile<"rvb23u64", RVB23U64Features>;
+def RVB23S64 : RISCVExperimentalProfile<"rvb23s64", RVB23S64Features>;
+def RVM23U32 : RISCVExperimentalProfile<"rvm23u32", RVM23U32Features>;

llvm/lib/TargetParser/RISCVISAInfo.cpp

@@ -102,6 +102,10 @@ void llvm::riscvExtensionsHelp(StringMap<StringRef> DescMap) {
   for (const auto &P : SupportedProfiles)
     outs().indent(4) << P.Name << "\n";
 
+  outs() << "\nExperimental Profiles\n";
+  for (const auto &P : SupportedExperimentalProfiles)
+    outs().indent(4) << P.Name << "\n";
+
   outs() << "\nUse -march to specify the target's extension.\n"
             "For example, clang -march=rv32i_v1p0\n";
 }
@@ -608,12 +612,25 @@ RISCVISAInfo::parseArchString(StringRef Arch, bool EnableExperimentalExtension,
     XLen = 64;
   } else {
     // Try parsing as a profile.
-    auto I = llvm::upper_bound(SupportedProfiles, Arch,
-                               [](StringRef Arch, const RISCVProfile &Profile) {
-                                 return Arch < Profile.Name;
-                               });
-
-    if (I != std::begin(SupportedProfiles) && Arch.starts_with((--I)->Name)) {
+    auto ProfileCmp = [](StringRef Arch, const RISCVProfile &Profile) {
+      return Arch < Profile.Name;
+    };
+    auto I = llvm::upper_bound(SupportedProfiles, Arch, ProfileCmp);
+    bool FoundProfile = I != std::begin(SupportedProfiles) &&
+                        Arch.starts_with(std::prev(I)->Name);
+    if (!FoundProfile) {
+      I = llvm::upper_bound(SupportedExperimentalProfiles, Arch, ProfileCmp);
+      FoundProfile = (I != std::begin(SupportedExperimentalProfiles) &&
+                      Arch.starts_with(std::prev(I)->Name));
+      if (FoundProfile && !EnableExperimentalExtension) {
+        return createStringError(errc::invalid_argument,
+                                 "requires '-menable-experimental-extensions' "
+                                 "for profile '" +
+                                     std::prev(I)->Name + "'");
+      }
+    }
+    if (FoundProfile) {
+      --I;
       std::string NewArch = I->MArch.str();
       StringRef ArchWithoutProfile = Arch.drop_front(I->Name.size());
       if (!ArchWithoutProfile.empty()) {

llvm/test/CodeGen/RISCV/attributes.ll

@@ -265,11 +265,11 @@
 ; RUN: llc -mtriple=riscv64 -mattr=+rva20s64 %s -o - | FileCheck --check-prefix=RVA20S64 %s
 ; RUN: llc -mtriple=riscv64 -mattr=+rva22u64 %s -o - | FileCheck --check-prefix=RVA22U64 %s
 ; RUN: llc -mtriple=riscv64 -mattr=+rva22s64 %s -o - | FileCheck --check-prefix=RVA22S64 %s
-; RUN: llc -mtriple=riscv64 -mattr=+rva23u64 %s -o - | FileCheck --check-prefix=RVA23U64 %s
-; RUN: llc -mtriple=riscv64 -mattr=+rva23s64 %s -o - | FileCheck --check-prefix=RVA23S64 %s
-; RUN: llc -mtriple=riscv64 -mattr=+rvb23u64 %s -o - | FileCheck --check-prefix=RVB23U64 %s
-; RUN: llc -mtriple=riscv64 -mattr=+rvb23s64 %s -o - | FileCheck --check-prefix=RVB23S64 %s
-; RUN: llc -mtriple=riscv32 -mattr=+rvm23u32 %s -o - | FileCheck --check-prefix=RVM23U32 %s
+; RUN: llc -mtriple=riscv64 -mattr=+experimental-rva23u64 %s -o - | FileCheck --check-prefix=RVA23U64 %s
+; RUN: llc -mtriple=riscv64 -mattr=+experimental-rva23s64 %s -o - | FileCheck --check-prefix=RVA23S64 %s
+; RUN: llc -mtriple=riscv64 -mattr=+experimental-rvb23u64 %s -o - | FileCheck --check-prefix=RVB23U64 %s
+; RUN: llc -mtriple=riscv64 -mattr=+experimental-rvb23s64 %s -o - | FileCheck --check-prefix=RVB23S64 %s
+; RUN: llc -mtriple=riscv32 -mattr=+experimental-rvm23u32 %s -o - | FileCheck --check-prefix=RVM23U32 %s
 
 ; CHECK: .attribute 4, 16
 

llvm/unittests/TargetParser/RISCVISAInfoTest.cpp

@@ -726,6 +726,13 @@ TEST(ParseArchString,
       "duplicated standard user-level extension 'zicntr'");
 }
 
+TEST(ParseArchString,
+     RejectsExperimentalProfilesIfEnableExperimentalExtensionsNotSet) {
+  EXPECT_EQ(
+      toString(RISCVISAInfo::parseArchString("rva23u64", false).takeError()),
+      "requires '-menable-experimental-extensions' for profile 'rva23u64'");
+}
+
 TEST(ToFeatures, IIsDroppedAndExperimentalExtensionsArePrefixed) {
   auto MaybeISAInfo1 =
       RISCVISAInfo::parseArchString("rv64im_ztso", true, false);
@@ -1073,12 +1080,14 @@ Supported Profiles
     rva20u64
     rva22s64
     rva22u64
+    rvi20u32
+    rvi20u64
+
+Experimental Profiles
     rva23s64
     rva23u64
     rvb23s64
     rvb23u64
-    rvi20u32
-    rvi20u64
     rvm23u32
 
 Use -march to specify the target's extension.