[AArch64][AsmParser] Directives should clear transitively implied features (#106625)

The commit ff3f3a5 made it possible to enable transitively implied
features when parsing assembler directives. For example enabling sve2
also enables sve.

This patch allows disabling features which depend on each other. For
example disabling sve also disables sve2.

Author: labrinea

llvm/lib/Target/AArch64/AsmParser/AArch64AsmParser.cpp

@@ -6947,18 +6947,22 @@ static void ExpandCryptoAEK(const AArch64::ArchInfo &ArchInfo,
   }
 }
 
+static SMLoc incrementLoc(SMLoc L, int Offset) {
+  return SMLoc::getFromPointer(L.getPointer() + Offset);
+}
+
 /// parseDirectiveArch
 ///   ::= .arch token
 bool AArch64AsmParser::parseDirectiveArch(SMLoc L) {
-  SMLoc ArchLoc = getLoc();
+  SMLoc CurLoc = getLoc();
 
   StringRef Arch, ExtensionString;
   std::tie(Arch, ExtensionString) =
       getParser().parseStringToEndOfStatement().trim().split('+');
 
   const AArch64::ArchInfo *ArchInfo = AArch64::parseArch(Arch);
   if (!ArchInfo)
-    return Error(ArchLoc, "unknown arch name");
+    return Error(CurLoc, "unknown arch name");
 
   if (parseToken(AsmToken::EndOfStatement))
     return true;
@@ -6978,27 +6982,30 @@ bool AArch64AsmParser::parseDirectiveArch(SMLoc L) {
     ExtensionString.split(RequestedExtensions, '+');
 
   ExpandCryptoAEK(*ArchInfo, RequestedExtensions);
+  CurLoc = incrementLoc(CurLoc, Arch.size());
 
-  FeatureBitset Features = STI.getFeatureBits();
-  setAvailableFeatures(ComputeAvailableFeatures(Features));
   for (auto Name : RequestedExtensions) {
+    // Advance source location past '+'.
+    CurLoc = incrementLoc(CurLoc, 1);
+
     bool EnableFeature = !Name.consume_front_insensitive("no");
 
-    for (const auto &Extension : ExtensionMap) {
-      if (Extension.Name != Name)
-        continue;
+    auto It = llvm::find_if(ExtensionMap, [&Name](const auto &Extension) {
+      return Extension.Name == Name;
+    });
 
-      if (Extension.Features.none())
-        report_fatal_error("unsupported architectural extension: " + Name);
+    if (It == std::end(ExtensionMap))
+      Error(CurLoc, "unsupported architectural extension: " + Name);
 
-      FeatureBitset ToggleFeatures =
-          EnableFeature
-              ? STI.SetFeatureBitsTransitively(~Features & Extension.Features)
-              : STI.ToggleFeature(Features & Extension.Features);
-      setAvailableFeatures(ComputeAvailableFeatures(ToggleFeatures));
-      break;
-    }
+    if (EnableFeature)
+      STI.SetFeatureBitsTransitively(It->Features);
+    else
+      STI.ClearFeatureBitsTransitively(It->Features);
+
+    CurLoc = incrementLoc(CurLoc, Name.size());
   }
+  FeatureBitset Features = ComputeAvailableFeatures(STI.getFeatureBits());
+  setAvailableFeatures(Features);
   return false;
 }
 
@@ -7018,28 +7025,21 @@ bool AArch64AsmParser::parseDirectiveArchExtension(SMLoc L) {
     Name = Name.substr(2);
   }
 
-  MCSubtargetInfo &STI = copySTI();
-  FeatureBitset Features = STI.getFeatureBits();
-  for (const auto &Extension : ExtensionMap) {
-    if (Extension.Name != Name)
-      continue;
-
-    if (Extension.Features.none())
-      return Error(ExtLoc, "unsupported architectural extension: " + Name);
-
-    FeatureBitset ToggleFeatures =
-        EnableFeature
-            ? STI.SetFeatureBitsTransitively(~Features & Extension.Features)
-            : STI.ToggleFeature(Features & Extension.Features);
-    setAvailableFeatures(ComputeAvailableFeatures(ToggleFeatures));
-    return false;
-  }
+  auto It = llvm::find_if(ExtensionMap, [&Name](const auto &Extension) {
+    return Extension.Name == Name;
+  });
 
-  return Error(ExtLoc, "unknown architectural extension: " + Name);
-}
+  if (It == std::end(ExtensionMap))
+    return Error(ExtLoc, "unsupported architectural extension: " + Name);
 
-static SMLoc incrementLoc(SMLoc L, int Offset) {
-  return SMLoc::getFromPointer(L.getPointer() + Offset);
+  MCSubtargetInfo &STI = copySTI();
+  if (EnableFeature)
+    STI.SetFeatureBitsTransitively(It->Features);
+  else
+    STI.ClearFeatureBitsTransitively(It->Features);
+  FeatureBitset Features = ComputeAvailableFeatures(STI.getFeatureBits());
+  setAvailableFeatures(Features);
+  return false;
 }
 
 /// parseDirectiveCPU
@@ -7075,30 +7075,22 @@ bool AArch64AsmParser::parseDirectiveCPU(SMLoc L) {
 
     bool EnableFeature = !Name.consume_front_insensitive("no");
 
-    bool FoundExtension = false;
-    for (const auto &Extension : ExtensionMap) {
-      if (Extension.Name != Name)
-        continue;
-
-      if (Extension.Features.none())
-        report_fatal_error("unsupported architectural extension: " + Name);
-
-      FeatureBitset Features = STI.getFeatureBits();
-      FeatureBitset ToggleFeatures =
-          EnableFeature
-              ? STI.SetFeatureBitsTransitively(~Features & Extension.Features)
-              : STI.ToggleFeature(Features & Extension.Features);
-      setAvailableFeatures(ComputeAvailableFeatures(ToggleFeatures));
-      FoundExtension = true;
+    auto It = llvm::find_if(ExtensionMap, [&Name](const auto &Extension) {
+      return Extension.Name == Name;
+    });
 
-      break;
-    }
+    if (It == std::end(ExtensionMap))
+      Error(CurLoc, "unsupported architectural extension: " + Name);
 
-    if (!FoundExtension)
-      Error(CurLoc, "unsupported architectural extension");
+    if (EnableFeature)
+      STI.SetFeatureBitsTransitively(It->Features);
+    else
+      STI.ClearFeatureBitsTransitively(It->Features);
 
     CurLoc = incrementLoc(CurLoc, Name.size());
   }
+  FeatureBitset Features = ComputeAvailableFeatures(STI.getFeatureBits());
+  setAvailableFeatures(Features);
   return false;
 }
 

llvm/test/MC/AArch64/SVE/directive-arch-negative.s

@@ -0,0 +1,8 @@
+// RUN: not llvm-mc -triple aarch64 -filetype asm -o - %s 2>&1 | FileCheck %s
+
+// Check that setting +nosve implies +nosve2
+.arch armv9-a+nosve
+
+adclb z0.s, z1.s, z31.s
+// CHECK: error: instruction requires: sve2
+// CHECK-NEXT: adclb z0.s, z1.s, z31.s

llvm/test/MC/AArch64/SVE/directive-arch_extension-negative.s

@@ -1,7 +1,12 @@
 // RUN: not llvm-mc -triple aarch64 -filetype asm -o - %s 2>&1 | FileCheck %s
 
-.arch_extension nosve
+.arch_extension sve2+nosve
 
 ptrue   p0.b, pow2
 // CHECK: error: instruction requires: sve or sme
 // CHECK-NEXT: ptrue   p0.b, pow2
+
+// Check that setting +nosve implies +nosve2
+adclb z0.s, z1.s, z31.s
+// CHECK: error: instruction requires: sve2
+// CHECK-NEXT: adclb z0.s, z1.s, z31.s

llvm/test/MC/AArch64/SVE/directive-cpu-negative.s

@@ -1,6 +1,11 @@
 // RUN: not llvm-mc -triple aarch64 -filetype asm -o - %s 2>&1 | FileCheck %s
 
-.cpu generic+sve+nosve
+.cpu generic+sve2+nosve
 ptrue   p0.b, pow2
 // CHECK: error: instruction requires: sve or sme
 // CHECK-NEXT: ptrue   p0.b, pow2
+
+// Check that setting +nosve implies +nosve2
+adclb z0.s, z1.s, z31.s
+// CHECK: error: instruction requires: sve2
+// CHECK-NEXT: adclb z0.s, z1.s, z31.s

llvm/test/MC/AArch64/directive-arch-negative.s

@@ -12,10 +12,13 @@
 # CHECK-NEXT: 	aese v0.8h, v1.8h
 # CHECK-NEXT:	^
 
-// We silently ignore invalid features.
 	.arch armv8+foo
 	aese v0.8h, v1.8h
 
+# CHECK: error: unsupported architectural extension: foo
+# CHECK-NEXT:   .arch armv8+foo
+# CHECK-NEXT:               ^
+
 # CHECK: error: invalid operand for instruction
 # CHECK-NEXT:	aese v0.8h, v1.8h
 # CHECK-NEXT:	^

llvm/test/MC/AArch64/directive-arch_extension-negative.s

@@ -4,7 +4,7 @@
 // RUN: -filetype asm -o - %s 2>&1 | FileCheck %s
 
 .arch_extension axp64
-// CHECK: error: unknown architectural extension: axp64
+// CHECK: error: unsupported architectural extension: axp64
 // CHECK-NEXT: .arch_extension axp64
 
 crc32cx w0, w1, x3
@@ -49,6 +49,8 @@ fminnm d0, d0, d1
 // CHECK: [[@LINE-1]]:1: error: instruction requires: fp
 // CHECK-NEXT: fminnm d0, d0, d1
 
+// nofp implied nosimd, so reinstate it
+.arch_extension simd
 addp v0.4s, v0.4s, v0.4s
 // CHECK-NOT: [[@LINE-1]]:1: error: instruction requires: neon
 .arch_extension nosimd
@@ -70,6 +72,8 @@ casa w5, w7, [x20]
 // CHECK: [[@LINE-1]]:1: error: instruction requires: lse
 // CHECK-NEXT: casa w5, w7, [x20]
 
+// nolse implied nolse128, so reinstate it
+.arch_extension lse128
 swpp x0, x2, [x3]
 // CHECK-NOT: [[@LINE-1]]:1: error: instruction requires: lse128
 .arch_extension nolse128
@@ -84,6 +88,8 @@ cfp rctx, x0
 // CHECK: [[@LINE-1]]:5: error: CFPRCTX requires: predres
 // CHECK-NEXT: cfp rctx, x0
 
+// nopredres implied nopredres2, so reinstate it
+.arch_extension predres2
 cosp rctx, x0
 // CHECK-NOT: [[@LINE-1]]:6: error: COSP requires: predres2
 .arch_extension nopredres2
@@ -133,6 +139,8 @@ ldapr x0, [x1]
 // CHECK: [[@LINE-1]]:1: error: instruction requires: rcpc
 // CHECK-NEXT: ldapr x0, [x1]
 
+// norcpc implied norcpc3, so reinstate it
+.arch_extension rcpc3
 stilp w24, w0, [x16, #-8]!
 // CHECK-NOT: [[@LINE-1]]:1: error: instruction requires: rcpc3
 .arch_extension norcpc3
@@ -169,6 +177,8 @@ cpyfp [x0]!, [x1]!, x2!
 // CHECK: [[@LINE-1]]:1: error: instruction requires: mops
 // CHECK-NEXT: cpyfp [x0]!, [x1]!, x2!
 
+// nolse128 implied nod128, so reinstate it
+.arch_extension d128
 // This needs to come before `.arch_extension nothe` as it uses an instruction
 // that requires both the and d128
 sysp #0, c2, c0, #0, x0, x1
@@ -204,6 +214,8 @@ umax x0, x1, x2
 // CHECK: [[@LINE-1]]:1: error: instruction requires: cssc
 // CHECK-NEXT: umax x0, x1, x2
 
+// noras implied norasv2, so reinstate it
+.arch_extension rasv2
 mrs x0, ERXGSR_EL1
 // CHECK-NOT: [[@LINE-1]]:9: error: expected readable system register
 .arch_extension norasv2