MC/AsmParser: Handle exponents in floating point literals.

llvm-svn: 114861

1 files changed, 30 insertions, 9 deletions

diff --git a/llvm/lib/MC/MCParser/AsmLexer.cpp b/llvm/lib/MC/MCParser/AsmLexer.cpp
index 1a71d24..7ca1ccc 100644
--- a/llvm/lib/MC/MCParser/AsmLexer.cpp
+++ b/llvm/lib/MC/MCParser/AsmLexer.cpp
@@ -64,6 +64,31 @@ int AsmLexer::getNextChar() {
   }
 }
 
+/// LexFloatLiteral: [0-9]*[.][0-9]*([eE][+-]?[0-9]*)?
+///
+/// The leading integral digit sequence and dot should have already been
+/// consumed, some or all of the fractional digit sequence *can* have been
+/// consumed.
+AsmToken AsmLexer::LexFloatLiteral() {
+  // Skip the fractional digit sequence.
+  while (isdigit(*CurPtr))
+    ++CurPtr;
+
+  // Check for exponent; we intentionally accept a slighlty wider set of
+  // literals here and rely on the upstream client to reject invalid ones (e.g.,
+  // "1e+").
+  if (*CurPtr == 'e' || *CurPtr == 'E') {
+    ++CurPtr;
+    if (*CurPtr == '-' || *CurPtr == '+')
+      ++CurPtr;
+    while (isdigit(*CurPtr))
+      ++CurPtr;
+  }
+
+  return AsmToken(AsmToken::Real,
+                  StringRef(TokStart, CurPtr - TokStart));
+}
+
 /// LexIdentifier: [a-zA-Z_.][a-zA-Z0-9_$.@]*
 static bool IsIdentifierChar(char c) {
   return isalnum(c) || c == '_' || c == '$' || c == '.' || c == '@';
@@ -71,12 +96,11 @@ static bool IsIdentifierChar(char c) {
 AsmToken AsmLexer::LexIdentifier() {
   // Check for floating point literals.
   if (CurPtr[-1] == '.' && isdigit(*CurPtr)) {
+    // Disambiguate a .1243foo identifier from a floating literal.
     while (isdigit(*CurPtr))
       ++CurPtr;
-    if (!IsIdentifierChar(*CurPtr)) {
-      return AsmToken(AsmToken::Real,
-                      StringRef(TokStart, CurPtr - TokStart));
-    }
+    if (*CurPtr == 'e' || *CurPtr == 'E' || !IsIdentifierChar(*CurPtr))
+      return LexFloatLiteral();
   }
 
   while (IsIdentifierChar(*CurPtr))
@@ -150,12 +174,9 @@ AsmToken AsmLexer::LexDigit() {
       ++CurPtr;
 
     // Check for floating point literals.
-    if (*CurPtr == '.') {
+    if (*CurPtr == '.' || *CurPtr == 'e') {
       ++CurPtr;
-      while (isdigit(*CurPtr))
-        ++CurPtr;
-
-      return AsmToken(AsmToken::Real, StringRef(TokStart, CurPtr - TokStart));
+      return LexFloatLiteral();
     }
 
     StringRef Result(TokStart, CurPtr - TokStart);