MC: Add support for treating $ as a reference to the PC
The binutils assembler supports a mode called DOLLAR_DOT which treats the dollar sign token as a reference to the current program counter if the dollar sign doesn't precede a constant or identifier. This commit adds a new MCAsmInfo flag stating whether or not a given target supports this interpretation of the dollar sign token; by default, this flag is not enabled. Further, enable this flag for PPC. The system assembler for AIX and binutils both support using the dollar sign in this manner. This fixes PR17353. llvm-svn: 191368
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@ -93,6 +93,10 @@ namespace llvm {
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/// this value. Factored out in .debug_frame and .debug_line.
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unsigned MinInstAlignment; // Defaults to 1.
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/// DollarIsPC - The '$' token, when not referencing an identifier or
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/// constant, refers to the current PC.
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bool DollarIsPC; // Defaults to false.
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/// SeparatorString - This string, if specified, is used to separate
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/// instructions from each other when on the same line.
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const char *SeparatorString; // Defaults to ';'
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@ -421,6 +425,9 @@ namespace llvm {
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unsigned getMinInstAlignment() const {
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return MinInstAlignment;
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}
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bool getDollarIsPC() const {
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return DollarIsPC;
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}
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const char *getSeparatorString() const {
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return SeparatorString;
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}
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@ -35,6 +35,7 @@ MCAsmInfo::MCAsmInfo() {
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LinkerRequiresNonEmptyDwarfLines = false;
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MaxInstLength = 4;
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MinInstAlignment = 1;
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DollarIsPC = false;
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SeparatorString = ";";
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CommentColumn = 40;
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CommentString = "#";
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@ -772,9 +772,19 @@ bool AsmParser::parsePrimaryExpr(const MCExpr *&Res, SMLoc &EndLoc) {
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case AsmToken::Identifier: {
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StringRef Identifier;
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if (parseIdentifier(Identifier)) {
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if (FirstTokenKind == AsmToken::Dollar)
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return Error(FirstTokenLoc, "invalid token in expression");
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return true;
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if (FirstTokenKind == AsmToken::Dollar) {
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if (Lexer.getMAI().getDollarIsPC()) {
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// This is a '$' reference, which references the current PC. Emit a
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// temporary label to the streamer and refer to it.
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MCSymbol *Sym = Ctx.CreateTempSymbol();
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Out.EmitLabel(Sym);
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Res = MCSymbolRefExpr::Create(Sym, MCSymbolRefExpr::VK_None, getContext());
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EndLoc = FirstTokenLoc;
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return false;
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} else
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return Error(FirstTokenLoc, "invalid token in expression");
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return true;
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}
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}
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EndLoc = SMLoc::getFromPointer(Identifier.end());
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@ -54,6 +54,8 @@ PPCLinuxMCAsmInfo::PPCLinuxMCAsmInfo(bool is64Bit) {
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// Debug Information
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SupportsDebugInformation = true;
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DollarIsPC = true;
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// Set up DWARF directives
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HasLEB128 = true; // Target asm supports leb128 directives (little-endian)
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MinInstAlignment = 4;
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@ -108,3 +108,8 @@
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# CHECK: beqa 0, 1024 # encoding: [0x41,0x82,0x04,0x02]
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beqa 1024
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# CHECK: # encoding: [0x42,0x9f,A,0bAAAAAA01]
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bcl 20, 31, $+4
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# CHECK: # encoding: [0x42,0x00,A,0bAAAAAA00]
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bdnz $-8
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