MCAlignFragment: Rename fields and use uint8_t FillLen

MaskRay · MaskRay · commit 1fbfa333f64b · 2025-07-13T14:07:10.000-07:00
* Rename the vague `Value` to `Fill`.
* FillLen is at most 8. Making the field smaller to facilitate encoding
  MCAlignFragment as a MCFragment union member.
* Replace an unreachable report_fatal_error with assert.
diff --git a/llvm/include/llvm/MC/MCELFStreamer.h b/llvm/include/llvm/MC/MCELFStreamer.h
@@ -70,7 +70,7 @@ class MCELFStreamer : public MCObjectStreamer {
 
   void emitIdent(StringRef IdentString) override;
 
-  void emitValueToAlignment(Align, int64_t, unsigned, unsigned) override;
+  void emitValueToAlignment(Align, int64_t, uint8_t, unsigned) override;
 
   void emitCGProfileEntry(const MCSymbolRefExpr *From,
                           const MCSymbolRefExpr *To, uint64_t Count) override;
diff --git a/llvm/include/llvm/MC/MCObjectStreamer.h b/llvm/include/llvm/MC/MCObjectStreamer.h
@@ -131,8 +131,8 @@ class MCObjectStreamer : public MCStreamer {
   void emitBundleLock(bool AlignToEnd) override;
   void emitBundleUnlock() override;
   void emitBytes(StringRef Data) override;
-  void emitValueToAlignment(Align Alignment, int64_t Value = 0,
-                            unsigned ValueSize = 1,
+  void emitValueToAlignment(Align Alignment, int64_t Fill = 0,
+                            uint8_t FillLen = 1,
                             unsigned MaxBytesToEmit = 0) override;
   void emitCodeAlignment(Align ByteAlignment, const MCSubtargetInfo *STI,
                          unsigned MaxBytesToEmit = 0) override;
diff --git a/llvm/include/llvm/MC/MCSection.h b/llvm/include/llvm/MC/MCSection.h
@@ -469,39 +469,36 @@ class MCRelaxableFragment : public MCEncodedFragment {
 };
 
 class MCAlignFragment : public MCFragment {
-  /// The alignment to ensure, in bytes.
-  Align Alignment;
-
   /// Flag to indicate that (optimal) NOPs should be emitted instead
   /// of using the provided value. The exact interpretation of this flag is
   /// target dependent.
   bool EmitNops : 1;
 
-  /// Value to use for filling padding bytes.
-  int64_t Value;
+  /// The alignment to ensure, in bytes.
+  Align Alignment;
 
   /// The size of the integer (in bytes) of \p Value.
-  unsigned ValueSize;
+  uint8_t FillLen;
 
   /// The maximum number of bytes to emit; if the alignment
   /// cannot be satisfied in this width then this fragment is ignored.
   unsigned MaxBytesToEmit;
 
+  /// Value to use for filling padding bytes.
+  int64_t Fill;
+
   /// When emitting Nops some subtargets have specific nop encodings.
   const MCSubtargetInfo *STI = nullptr;
 
 public:
-  MCAlignFragment(Align Alignment, int64_t Value, unsigned ValueSize,
+  MCAlignFragment(Align Alignment, int64_t Fill, uint8_t FillLen,
                   unsigned MaxBytesToEmit)
-      : MCFragment(FT_Align, false), Alignment(Alignment), EmitNops(false),
-        Value(Value), ValueSize(ValueSize), MaxBytesToEmit(MaxBytesToEmit) {}
+      : MCFragment(FT_Align, false), EmitNops(false), Alignment(Alignment),
+        FillLen(FillLen), MaxBytesToEmit(MaxBytesToEmit), Fill(Fill) {}
 
   Align getAlignment() const { return Alignment; }
-
-  int64_t getValue() const { return Value; }
-
-  unsigned getValueSize() const { return ValueSize; }
-
+  int64_t getFill() const { return Fill; }
+  uint8_t getFillLen() const { return FillLen; }
   unsigned getMaxBytesToEmit() const { return MaxBytesToEmit; }
 
   bool hasEmitNops() const { return EmitNops; }
diff --git a/llvm/include/llvm/MC/MCStreamer.h b/llvm/include/llvm/MC/MCStreamer.h
@@ -807,14 +807,14 @@ class LLVM_ABI MCStreamer {
   /// This used to implement the .align assembler directive.
   ///
   /// \param Alignment - The alignment to reach.
-  /// \param Value - The value to use when filling bytes.
-  /// \param ValueSize - The size of the integer (in bytes) to emit for
+  /// \param Fill - The value to use when filling bytes.
+  /// \param FillLen - The size of the integer (in bytes) to emit for
   /// \p Value. This must match a native machine width.
   /// \param MaxBytesToEmit - The maximum numbers of bytes to emit, or 0. If
   /// the alignment cannot be reached in this many bytes, no bytes are
   /// emitted.
-  virtual void emitValueToAlignment(Align Alignment, int64_t Value = 0,
-                                    unsigned ValueSize = 1,
+  virtual void emitValueToAlignment(Align Alignment, int64_t Fill = 0,
+                                    uint8_t FillLen = 1,
                                     unsigned MaxBytesToEmit = 0);
 
   /// Emit nops until the byte alignment \p ByteAlignment is reached.
diff --git a/llvm/lib/MC/MCAsmStreamer.cpp b/llvm/lib/MC/MCAsmStreamer.cpp
@@ -269,8 +269,8 @@ class MCAsmStreamer final : public MCStreamer {
                               std::optional<int64_t> Value, unsigned ValueSize,
                               unsigned MaxBytesToEmit);
 
-  void emitValueToAlignment(Align Alignment, int64_t Value = 0,
-                            unsigned ValueSize = 1,
+  void emitValueToAlignment(Align Alignment, int64_t Fill = 0,
+                            uint8_t FillLen = 1,
                             unsigned MaxBytesToEmit = 0) override;
 
   void emitCodeAlignment(Align Alignment, const MCSubtargetInfo *STI,
@@ -1528,10 +1528,10 @@ void MCAsmStreamer::emitAlignmentDirective(uint64_t ByteAlignment,
   EmitEOL();
 }
 
-void MCAsmStreamer::emitValueToAlignment(Align Alignment, int64_t Value,
-                                         unsigned ValueSize,
+void MCAsmStreamer::emitValueToAlignment(Align Alignment, int64_t Fill,
+                                         uint8_t FillLen,
                                          unsigned MaxBytesToEmit) {
-  emitAlignmentDirective(Alignment.value(), Value, ValueSize, MaxBytesToEmit);
+  emitAlignmentDirective(Alignment.value(), Fill, FillLen, MaxBytesToEmit);
 }
 
 void MCAsmStreamer::emitCodeAlignment(Align Alignment,
diff --git a/llvm/lib/MC/MCAssembler.cpp b/llvm/lib/MC/MCAssembler.cpp
@@ -553,18 +553,11 @@ static void writeFragment(raw_ostream &OS, const MCAssembler &Asm,
   case MCFragment::FT_Align: {
     ++stats::EmittedAlignFragments;
     const MCAlignFragment &AF = cast<MCAlignFragment>(F);
-    assert(AF.getValueSize() && "Invalid virtual align in concrete fragment!");
+    assert(AF.getFillLen() && "Invalid virtual align in concrete fragment!");
 
-    uint64_t Count = FragmentSize / AF.getValueSize();
-
-    // FIXME: This error shouldn't actually occur (the front end should emit
-    // multiple .align directives to enforce the semantics it wants), but is
-    // severe enough that we want to report it. How to handle this?
-    if (Count * AF.getValueSize() != FragmentSize)
-      report_fatal_error("undefined .align directive, value size '" +
-                        Twine(AF.getValueSize()) +
-                        "' is not a divisor of padding size '" +
-                        Twine(FragmentSize) + "'");
+    uint64_t Count = FragmentSize / AF.getFillLen();
+    assert(FragmentSize % AF.getFillLen() == 0 &&
+           "computeFragmentSize computed size is incorrect");
 
     // See if we are aligning with nops, and if so do that first to try to fill
     // the Count bytes.  Then if that did not fill any bytes or there are any
@@ -579,17 +572,19 @@ static void writeFragment(raw_ostream &OS, const MCAssembler &Asm,
 
     // Otherwise, write out in multiples of the value size.
     for (uint64_t i = 0; i != Count; ++i) {
-      switch (AF.getValueSize()) {
+      switch (AF.getFillLen()) {
       default: llvm_unreachable("Invalid size!");
-      case 1: OS << char(AF.getValue()); break;
+      case 1:
+        OS << char(AF.getFill());
+        break;
       case 2:
-        support::endian::write<uint16_t>(OS, AF.getValue(), Endian);
+        support::endian::write<uint16_t>(OS, AF.getFill(), Endian);
         break;
       case 4:
-        support::endian::write<uint32_t>(OS, AF.getValue(), Endian);
+        support::endian::write<uint32_t>(OS, AF.getFill(), Endian);
         break;
       case 8:
-        support::endian::write<uint64_t>(OS, AF.getValue(), Endian);
+        support::endian::write<uint64_t>(OS, AF.getFill(), Endian);
         break;
       }
     }
@@ -733,8 +728,8 @@ void MCAssembler::writeSectionData(raw_ostream &OS,
       case MCFragment::FT_Align:
         // Check that we aren't trying to write a non-zero value into a virtual
         // section.
-        assert((cast<MCAlignFragment>(F).getValueSize() == 0 ||
-                cast<MCAlignFragment>(F).getValue() == 0) &&
+        assert((cast<MCAlignFragment>(F).getFillLen() == 0 ||
+                cast<MCAlignFragment>(F).getFill() == 0) &&
                "Invalid align in virtual section!");
         break;
       case MCFragment::FT_Fill:
diff --git a/llvm/lib/MC/MCELFStreamer.cpp b/llvm/lib/MC/MCELFStreamer.cpp
@@ -321,7 +321,7 @@ void MCELFStreamer::emitValueImpl(const MCExpr *Value, unsigned Size,
 }
 
 void MCELFStreamer::emitValueToAlignment(Align Alignment, int64_t Value,
-                                         unsigned ValueSize,
+                                         uint8_t ValueSize,
                                          unsigned MaxBytesToEmit) {
   if (isBundleLocked())
     report_fatal_error("Emitting values inside a locked bundle is forbidden");
diff --git a/llvm/lib/MC/MCFragment.cpp b/llvm/lib/MC/MCFragment.cpp
@@ -76,8 +76,8 @@ LLVM_DUMP_METHOD void MCFragment::dump() const {
   switch (getKind()) {
   case MCFragment::FT_Align: {
     const auto *AF = cast<MCAlignFragment>(this);
-    OS << " Align:" << AF->getAlignment().value() << " Value:" << AF->getValue()
-       << " ValueSize:" << AF->getValueSize()
+    OS << " Align:" << AF->getAlignment().value() << " Fill:" << AF->getFill()
+       << " FillLen:" << unsigned(AF->getFillLen())
        << " MaxBytesToEmit:" << AF->getMaxBytesToEmit();
     if (AF->hasEmitNops())
       OS << " Nops";
diff --git a/llvm/lib/MC/MCObjectStreamer.cpp b/llvm/lib/MC/MCObjectStreamer.cpp
@@ -580,13 +580,13 @@ void MCObjectStreamer::emitBytes(StringRef Data) {
   DF->appendContents(ArrayRef(Data.data(), Data.size()));
 }
 
-void MCObjectStreamer::emitValueToAlignment(Align Alignment, int64_t Value,
-                                            unsigned ValueSize,
+void MCObjectStreamer::emitValueToAlignment(Align Alignment, int64_t Fill,
+                                            uint8_t FillLen,
                                             unsigned MaxBytesToEmit) {
   if (MaxBytesToEmit == 0)
     MaxBytesToEmit = Alignment.value();
-  insert(getContext().allocFragment<MCAlignFragment>(
-      Alignment, Value, ValueSize, MaxBytesToEmit));
+  insert(getContext().allocFragment<MCAlignFragment>(Alignment, Fill, FillLen,
+                                                     MaxBytesToEmit));
 
   // Update the maximum alignment on the current section if necessary.
   MCSection *CurSec = getCurrentSectionOnly();
diff --git a/llvm/lib/MC/MCParser/AsmParser.cpp b/llvm/lib/MC/MCParser/AsmParser.cpp
@@ -567,7 +567,7 @@ class AsmParser : public MCAsmParser {
   bool parseDirectiveSet(StringRef IDVal, AssignmentKind Kind);
   bool parseDirectiveOrg(); // ".org"
   // ".align{,32}", ".p2align{,w,l}"
-  bool parseDirectiveAlign(bool IsPow2, unsigned ValueSize);
+  bool parseDirectiveAlign(bool IsPow2, uint8_t ValueSize);
 
   // ".file", ".line", ".loc", ".loc_label", ".stabs"
   bool parseDirectiveFile(SMLoc DirectiveLoc);
@@ -3340,7 +3340,7 @@ bool AsmParser::parseDirectiveOrg() {
 
 /// parseDirectiveAlign
 ///  ::= {.align, ...} expression [ , expression [ , expression ]]
-bool AsmParser::parseDirectiveAlign(bool IsPow2, unsigned ValueSize) {
+bool AsmParser::parseDirectiveAlign(bool IsPow2, uint8_t ValueSize) {
   SMLoc AlignmentLoc = getLexer().getLoc();
   int64_t Alignment;
   SMLoc MaxBytesLoc;
diff --git a/llvm/lib/MC/MCStreamer.cpp b/llvm/lib/MC/MCStreamer.cpp
@@ -1328,9 +1328,7 @@ void MCStreamer::emitSLEB128Value(const MCExpr *Value) {}
 void MCStreamer::emitFill(const MCExpr &NumBytes, uint64_t Value, SMLoc Loc) {}
 void MCStreamer::emitFill(const MCExpr &NumValues, int64_t Size, int64_t Expr,
                           SMLoc Loc) {}
-void MCStreamer::emitValueToAlignment(Align Alignment, int64_t Value,
-                                      unsigned ValueSize,
-                                      unsigned MaxBytesToEmit) {}
+void MCStreamer::emitValueToAlignment(Align, int64_t, uint8_t, unsigned) {}
 void MCStreamer::emitCodeAlignment(Align Alignment, const MCSubtargetInfo *STI,
                                    unsigned MaxBytesToEmit) {}
 void MCStreamer::emitValueToOffset(const MCExpr *Offset, unsigned char Value,
diff --git a/llvm/lib/MC/WasmObjectWriter.cpp b/llvm/lib/MC/WasmObjectWriter.cpp
@@ -697,10 +697,10 @@ static void addData(SmallVectorImpl<char> &DataBytes,
       report_fatal_error("only data supported in data sections");
 
     if (auto *Align = dyn_cast<MCAlignFragment>(&Frag)) {
-      if (Align->getValueSize() != 1)
+      if (Align->getFillLen() != 1)
         report_fatal_error("only byte values supported for alignment");
       // If nops are requested, use zeros, as this is the data section.
-      uint8_t Value = Align->hasEmitNops() ? 0 : Align->getValue();
+      uint8_t Value = Align->hasEmitNops() ? 0 : Align->getFill();
       uint64_t Size =
           std::min<uint64_t>(alignTo(DataBytes.size(), Align->getAlignment()),
                              DataBytes.size() + Align->getMaxBytesToEmit());
diff --git a/llvm/lib/Target/SystemZ/MCTargetDesc/SystemZHLASMAsmStreamer.cpp b/llvm/lib/Target/SystemZ/MCTargetDesc/SystemZHLASMAsmStreamer.cpp
@@ -137,10 +137,10 @@ void SystemZHLASMAsmStreamer::EmitComment() {
 }
 
 void SystemZHLASMAsmStreamer::emitValueToAlignment(Align Alignment,
-                                                   int64_t Value,
-                                                   unsigned ValueSize,
+                                                   int64_t Fill,
+                                                   uint8_t FillLen,
                                                    unsigned MaxBytesToEmit) {
-  emitAlignmentDS(Alignment.value(), Value, ValueSize, MaxBytesToEmit);
+  emitAlignmentDS(Alignment.value(), Fill, FillLen, MaxBytesToEmit);
 }
 
 void SystemZHLASMAsmStreamer::emitCodeAlignment(Align Alignment,
diff --git a/llvm/lib/Target/SystemZ/MCTargetDesc/SystemZHLASMAsmStreamer.h b/llvm/lib/Target/SystemZ/MCTargetDesc/SystemZHLASMAsmStreamer.h
@@ -86,9 +86,8 @@ class SystemZHLASMAsmStreamer final : public MCStreamer {
 
   void emitAlignmentDS(uint64_t ByteAlignment, std::optional<int64_t> Value,
                        unsigned ValueSize, unsigned MaxBytesToEmit);
-  void emitValueToAlignment(Align Alignment, int64_t Value = 0,
-                            unsigned ValueSize = 1,
-                            unsigned MaxBytesToEmit = 0) override;
+  void emitValueToAlignment(Align Alignment, int64_t Fill, uint8_t FillLen,
+                            unsigned MaxBytesToEmit) override;
 
   void emitCodeAlignment(Align Alignment, const MCSubtargetInfo *STI,
                          unsigned MaxBytesToEmit = 0) override;
diff --git a/llvm/test/MC/ELF/mc-dump.s b/llvm/test/MC/ELF/mc-dump.s
@@ -8,7 +8,7 @@
 # CHECK-NEXT:MCSection Name:.text
 # CHECK-NEXT:0 Data Size:0 []
 # CHECK-NEXT:  Symbol @0 .text
-# CHECK-NEXT:0 Align Align:4 Value:0 ValueSize:1 MaxBytesToEmit:4 Nops
+# CHECK-NEXT:0 Align Align:4 Fill:0 FillLen:1 MaxBytesToEmit:4 Nops
 # CHECK-NEXT:0 Data Size:0 []
 # CHECK-NEXT:  Symbol @0 _start
 # CHECK-NEXT:0 Org Offset:3 Value:0
@@ -21,7 +21,7 @@
 # CHECK-NEXT:MCSection Name:.data
 # CHECK-NEXT:0 Data Size:0 []
 # CHECK-NEXT:  Symbol @0 .data
-# CHECK-NEXT:0 Align Align:4 Value:0 ValueSize:1 MaxBytesToEmit:4
+# CHECK-NEXT:0 Align Align:4 Fill:0 FillLen:1 MaxBytesToEmit:4
 # CHECK-NEXT:0 Data Size:4 [01,00,00,00]
 # CHECK-NEXT:4 Fill Value:0 ValueSize:1 NumValues:1
 # CHECK-NEXT:5 LEB Value:.Ltmp0-_start Signed:0
diff --git a/llvm/test/MC/RISCV/Relocations/mc-dump.s b/llvm/test/MC/RISCV/Relocations/mc-dump.s
@@ -5,13 +5,13 @@
 # CHECK-NEXT:MCSection Name:.text
 # CHECK-NEXT:0 Data Size:0 []
 # CHECK-NEXT:  Symbol @0 .text
-# CHECK-NEXT:0 Align Align:4 Value:0 ValueSize:1 MaxBytesToEmit:4 Nops
+# CHECK-NEXT:0 Align Align:4 Fill:0 FillLen:1 MaxBytesToEmit:4 Nops
 # CHECK-NEXT:0 Data LinkerRelaxable Size:8 [97,00,00,00,e7,80,00,00]
 # CHECK-NEXT:  Fixup @0 Value:specifier(19,ext) Kind:4022
 # CHECK-NEXT:  Symbol @0 $x
-# CHECK-NEXT:8 Align Align:8 Value:0 ValueSize:1 MaxBytesToEmit:8 Nops
+# CHECK-NEXT:8 Align Align:8 Fill:0 FillLen:1 MaxBytesToEmit:8 Nops
 # CHECK-NEXT:12 Data Size:4 [13,05,30,00]
-# CHECK-NEXT:16 Align Align:8 Value:0 ValueSize:1 MaxBytesToEmit:8 Nops
+# CHECK-NEXT:16 Align Align:8 Fill:0 FillLen:1 MaxBytesToEmit:8 Nops
 # CHECK-NEXT:]
 
 call ext
diff --git a/llvm/tools/llvm-exegesis/lib/SnippetFile.cpp b/llvm/tools/llvm-exegesis/lib/SnippetFile.cpp
@@ -202,8 +202,6 @@ class BenchmarkCodeStreamer : public MCStreamer, public AsmCommentConsumer {
   bool emitSymbolAttribute(MCSymbol *Symbol, MCSymbolAttr Attribute) override {
     return false;
   }
-  void emitValueToAlignment(Align Alignment, int64_t Value, unsigned ValueSize,
-                            unsigned MaxBytesToEmit) override {}
   void emitZerofill(MCSection *Section, MCSymbol *Symbol, uint64_t Size,
                     Align ByteAlignment, SMLoc Loc) override {}
 

Original file line number	Diff line number	Diff line change
`@@ -321,7 +321,7 @@ void MCELFStreamer::emitValueImpl(const MCExpr *Value, unsigned Size,`
`321`	`321`	`}`
`322`	`322`
`323`	`323`	`void MCELFStreamer::emitValueToAlignment(Align Alignment, int64_t Value,`
`324`		`- unsigned ValueSize,`
	`324`	`+ uint8_t ValueSize,`
`325`	`325`	`unsigned MaxBytesToEmit) {`
`326`	`326`	`if (isBundleLocked())`
`327`	`327`	`report_fatal_error("Emitting values inside a locked bundle is forbidden");`