[PATCH] D64770: [WebAssembly] Assembler: support special floats: infinity / nan

[Wouter van Oortmerssen via Phabricator via llvm-commits]

aardappel created this revision.
aardappel added a reviewer: dschuff.
Herald added subscribers: llvm-commits, sunfish, aheejin, jgravelle-google, sbc100.
Herald added a project: LLVM.

These are emitted as identifiers by the InstPrinter, so we should
parse them as such. These could potentially clash with symbols of
the same name, but that is out of our (the WebAssembly backend) control.


Repository:
  rL LLVM

https://reviews.llvm.org/D64770

Files:
  lib/Target/WebAssembly/AsmParser/WebAssemblyAsmParser.cpp
  test/MC/WebAssembly/basic-assembly.s


Index: test/MC/WebAssembly/basic-assembly.s
===================================================================
--- test/MC/WebAssembly/basic-assembly.s
+++ test/MC/WebAssembly/basic-assembly.s
@@ -14,6 +14,8 @@
     i32.const   -1
     f64.const   0x1.999999999999ap1
     f32.const   -1.0
+    f32.const   -infinity
+    f32.const   nan
     v128.const  0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15
     v128.const  0, 1, 2, 3, 4, 5, 6, 7
     # Indirect addressing:
@@ -118,6 +120,8 @@
 # CHECK-NEXT:      i32.const   -1
 # CHECK-NEXT:      f64.const   0x1.999999999999ap1
 # CHECK-NEXT:      f32.const   -0x1p0
+# CHECK-NEXT:      f32.const   -infinity
+# CHECK-NEXT:      f32.const   nan
 # CHECK-NEXT:      v128.const  0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15
 # CHECK-NEXT:      v128.const  0, 1, 2, 3, 4, 5, 6, 7
 # CHECK-NEXT:      local.get   0
Index: lib/Target/WebAssembly/AsmParser/WebAssemblyAsmParser.cpp
===================================================================
--- lib/Target/WebAssembly/AsmParser/WebAssemblyAsmParser.cpp
+++ lib/Target/WebAssembly/AsmParser/WebAssemblyAsmParser.cpp
@@ -363,6 +363,28 @@
     return false;
   }
 
+  bool parseSpecialFloatMaybe(bool IsNegative, OperandVector &Operands) {
+    if (Lexer.isNot(AsmToken::Identifier))
+      return true;
+    auto &Flt = Lexer.getTok();
+    auto S = Flt.getString();
+    double Val;
+    if (S.compare_lower("infinity") == 0) {
+      Val = std::numeric_limits<double>::infinity();
+    } else if (S.compare_lower("nan") == 0) {
+      Val = std::numeric_limits<double>::quiet_NaN();
+    } else {
+      return true;
+    }
+    if (IsNegative)
+      Val = -Val;
+    Operands.push_back(make_unique<WebAssemblyOperand>(
+        WebAssemblyOperand::Float, Flt.getLoc(), Flt.getEndLoc(),
+        WebAssemblyOperand::FltOp{Val}));
+    Parser.Lex();
+    return false;
+  }
+
   bool checkForP2AlignIfLoadStore(OperandVector &Operands, StringRef InstName) {
     // FIXME: there is probably a cleaner way to do this.
     auto IsLoadStore = InstName.find(".load") != StringRef::npos ||
@@ -476,6 +498,8 @@
       auto &Tok = Lexer.getTok();
       switch (Tok.getKind()) {
       case AsmToken::Identifier: {
+        if (!parseSpecialFloatMaybe(false, Operands))
+          break;
         auto &Id = Lexer.getTok();
         if (ExpectBlockType) {
           // Assume this identifier is a block_type.
@@ -507,6 +531,7 @@
         } else if(Lexer.is(AsmToken::Real)) {
           if (parseSingleFloat(true, Operands))
             return true;
+        } else if (!parseSpecialFloatMaybe(true, Operands)) {
         } else {
           return error("Expected numeric constant instead got: ",
                        Lexer.getTok());


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