From 15f895179953b258e4ca20860d0d58f25f3a3edb Mon Sep 17 00:00:00 2001
From: Chris Lattner <sabre@nondot.org>
Date: Sat, 9 Apr 2011 19:41:05 +0000
Subject: [PATCH] fix rdar://8735979 - "int 3" doesn't match to "int3". 
 Unfortunately, InstAlias doesn't allow matching immediate operands, so we
 have to write C++ code to do this.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129223 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Target/X86/AsmParser/X86AsmParser.cpp | 12 ++++++++++++
 lib/Target/X86/X86InstrSystem.td          |  7 +++++++
 test/MC/X86/x86-64.s                      |  4 ++++
 3 files changed, 23 insertions(+)

diff --git a/lib/Target/X86/AsmParser/X86AsmParser.cpp b/lib/Target/X86/AsmParser/X86AsmParser.cpp
index e0989b081e4..c352bfcd8cc 100644
--- a/lib/Target/X86/AsmParser/X86AsmParser.cpp
+++ b/lib/Target/X86/AsmParser/X86AsmParser.cpp
@@ -928,6 +928,18 @@ ParseInstruction(StringRef Name, SMLoc NameLoc,
       Operands.erase(Operands.begin() + 1);
     }
   }
+  
+  // Transforms "int $3" into "int3" as a size optimization.  We can't write an
+  // instalias with an immediate operand yet.
+  if (Name == "int" && Operands.size() == 2) {
+    X86Operand *Op1 = static_cast<X86Operand*>(Operands[1]);
+    if (Op1->isImm() && isa<MCConstantExpr>(Op1->getImm()) &&
+        cast<MCConstantExpr>(Op1->getImm())->getValue() == 3) {
+      delete Operands[1];
+      Operands.erase(Operands.begin() + 1);
+      static_cast<X86Operand*>(Operands[0])->setTokenValue("int3");
+    }
+  }
 
   return false;
 }
diff --git a/lib/Target/X86/X86InstrSystem.td b/lib/Target/X86/X86InstrSystem.td
index 2710425628a..f73cff39e86 100644
--- a/lib/Target/X86/X86InstrSystem.td
+++ b/lib/Target/X86/X86InstrSystem.td
@@ -34,9 +34,16 @@ let Uses = [EFLAGS] in
   def INTO : I<0xce, RawFrm, (outs), (ins), "into", []>;
 def INT3 : I<0xcc, RawFrm, (outs), (ins), "int3",
               [(int_x86_int (i8 3))]>;
+
+// The long form of "int $3" turns into int3 as a size optimization.
+// FIXME: This doesn't work because InstAlias can't match immediate constants.
+//def : InstAlias<"int\t$3", (INT3)>;
+
+
 def INT : Ii8<0xcd, RawFrm, (outs), (ins i8imm:$trap), "int\t$trap",
               [(int_x86_int imm:$trap)]>;
 
+
 def SYSCALL  : I<0x05, RawFrm, (outs), (ins), "syscall", []>, TB;
 def SYSRETL  : I<0x07, RawFrm, (outs), (ins), "sysretl", []>, TB;
 def SYSRETQ  :RI<0x07, RawFrm, (outs), (ins), "sysretq", []>, TB,
diff --git a/test/MC/X86/x86-64.s b/test/MC/X86/x86-64.s
index 1d41d5b2d5f..80b12dbfc2f 100644
--- a/test/MC/X86/x86-64.s
+++ b/test/MC/X86/x86-64.s
@@ -190,6 +190,10 @@ fadd %st(7)
 // CHECK: int3
 INT3
 
+// rdar://8735979 - int $3 -> int3
+// CHECK: int3
+int	$3
+
 
 // Allow scale factor without index register.
 // CHECK: movaps	%xmm3, (%esi)