From 292e21d8bce463fb8bb833810f05d4382f61bdd0 Mon Sep 17 00:00:00 2001
From: Wouter van Oortmerssen <aardappel@gmail.com>
Date: Mon, 15 Jul 2019 22:13:39 +0000
Subject: [PATCH] [WebAssembly] Assembler: support special floats: infinity /
 nan

Summary:
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.

Reviewers: dschuff

Subscribers: sbc100, jgravelle-google, aheejin, sunfish, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D64770

llvm-svn: 366139
---
 .../AsmParser/WebAssemblyAsmParser.cpp        | 25 +++++++++++++++++++
 llvm/test/MC/WebAssembly/basic-assembly.s     |  4 +++
 2 files changed, 29 insertions(+)

diff --git a/llvm/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmParser.cpp b/llvm/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmParser.cpp
index e82923519f4c..e9a7f6977c2d 100644
--- a/llvm/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmParser.cpp
+++ b/llvm/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmParser.cpp
@@ -363,6 +363,28 @@ public:
     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 @@ public:
       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 @@ public:
         } 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());
diff --git a/llvm/test/MC/WebAssembly/basic-assembly.s b/llvm/test/MC/WebAssembly/basic-assembly.s
index 81d6001175b6..c3b7e9da25de 100644
--- a/llvm/test/MC/WebAssembly/basic-assembly.s
+++ b/llvm/test/MC/WebAssembly/basic-assembly.s
@@ -14,6 +14,8 @@ test0:
     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 @@ test0:
 # 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