[x86][ms-inline-asm] use of "jmp short" in asm is not supported

Committing in the name of Ziv Izhar: After check-all and LGTM .

The following patch is for compatability with Microsoft.
Microsoft ignores the keyword "short" when used after a jmp, for example:
__asm {
      jmp short label
      label:
      }

A test for that patch will be added in another patch, since it's located in clang's codegen tests. Link will be added shortly.
link to test: https://reviews.llvm.org/D24958

Differential Revision: https://reviews.llvm.org/D24957

llvm-svn: 284211

1 files changed, 14 insertions, 0 deletions

diff --git a/llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp b/llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp
index 373cdf964d8..d51cd59da1f 100644
--- a/llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp
+++ b/llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp
@@ -2157,6 +2157,20 @@ bool X86AsmParser::ParseInstruction(ParseInstructionInfo &Info, StringRef Name,
   InstInfo = &Info;
   StringRef PatchedName = Name;
 
+  if (Name == "jmp" && isParsingIntelSyntax() && isParsingInlineAsm()) {
+    StringRef NextTok = Parser.getTok().getString();
+    if (NextTok == "short") {
+      SMLoc NameEndLoc =
+          NameLoc.getFromPointer(NameLoc.getPointer() + Name.size());
+      // Eat the short keyword
+      Parser.Lex();
+      // MS ignores the short keyword, it determines the jmp type based
+      // on the distance of the label
+      InstInfo->AsmRewrites->emplace_back(AOK_Skip, NameEndLoc,
+                                          NextTok.size() + 1);
+    }
+  }
+
   // FIXME: Hack to recognize setneb as setne.
   if (PatchedName.startswith("set") && PatchedName.endswith("b") &&
       PatchedName != "setb" && PatchedName != "setnb")