[X86] Don't randomly encode %rip where illegal

Differential Revision: https://reviews.llvm.org/D25112

llvm-svn: 283326

2 files changed, 27 insertions, 4 deletions

diff --git a/llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp b/llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp
index 87364b2a8ca..170f55cb1cd 100644
--- a/llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp
+++ b/llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp
@@ -840,6 +840,11 @@ static bool CheckBaseRegAndIndexReg(unsigned BaseReg, unsigned IndexReg,
   // If we have both a base register and an index register make sure they are
   // both 64-bit or 32-bit registers.
   // To support VSIB, IndexReg can be 128-bit or 256-bit registers.
+
+  if ((BaseReg == X86::RIP && IndexReg != 0) || (IndexReg == X86::RIP)) {
+    ErrMsg = "invalid base+index expression";
+    return true;
+  }
   if (BaseReg != 0 && IndexReg != 0) {
     if (X86MCRegisterClasses[X86::GR64RegClassID].contains(BaseReg) &&
         (X86MCRegisterClasses[X86::GR16RegClassID].contains(IndexReg) ||
@@ -1781,10 +1786,12 @@ std::unique_ptr<X86Operand> X86AsmParser::ParseIntelOperand() {
       !ParseRegister(RegNo, Start, End)) {
     // If this is a segment register followed by a ':', then this is the start
     // of a segment override, otherwise this is a normal register reference.
-    // In case it is a normal register and there is ptr in the operand this 
+    // In case it is a normal register and there is ptr in the operand this
     // is an error
-    if (getLexer().isNot(AsmToken::Colon)){
-      if (PtrInOperand){
+    if (RegNo == X86::RIP)
+      return ErrorOperand(Start, "rip can only be used as a base register");
+    if (getLexer().isNot(AsmToken::Colon)) {
+      if (PtrInOperand) {
         return ErrorOperand(Start, "expected memory operand after "
                                    "'ptr', found register operand instead");
       }
@@ -1865,6 +1872,11 @@ std::unique_ptr<X86Operand> X86AsmParser::ParseATTOperand() {
             SMRange(Start, End));
       return nullptr;
     }
+    if (RegNo == X86::RIP) {
+      Error(Start, "%rip can only be used as a base register",
+            SMRange(Start, End));
+      return nullptr;
+    }
 
     // If this is a segment register followed by a ':', then this is the start
     // of a memory reference, otherwise this is a normal register reference.
@@ -2044,7 +2056,16 @@ std::unique_ptr<X86Operand> X86AsmParser::ParseMemOperand(unsigned SegReg,
     // like "1(%eax,,1)", the assembler doesn't. Use "eiz" or "riz" for this.
     if (getLexer().is(AsmToken::Percent)) {
       SMLoc L;
-      if (ParseRegister(IndexReg, L, L)) return nullptr;
+      if (ParseRegister(IndexReg, L, L))
+        return nullptr;
+      if (BaseReg == X86::RIP) {
+        Error(IndexLoc, "%rip as base register can not have an index register");
+        return nullptr;
+      }
+      if (IndexReg == X86::RIP) {
+        Error(IndexLoc, "%rip is not allowed as an index register");
+        return nullptr;
+      }
 
       if (getLexer().isNot(AsmToken::RParen)) {
         // Parse the scale amount:
diff --git a/llvm/lib/Target/X86/X86RegisterInfo.td b/llvm/lib/Target/X86/X86RegisterInfo.td
index 373f9b4c65f..372a15aff15 100644
--- a/llvm/lib/Target/X86/X86RegisterInfo.td
+++ b/llvm/lib/Target/X86/X86RegisterInfo.td
@@ -345,6 +345,8 @@ def GR32 : RegisterClass<"X86", [i32], 32,
 // GR64 - 64-bit GPRs. This oddly includes RIP, which isn't accurate, since
 // RIP isn't really a register and it can't be used anywhere except in an
 // address, but it doesn't cause trouble.
+// FIXME: it *does* cause trouble - CheckBaseRegAndIndexReg() has extra
+// tests because of the inclusion of RIP in this register class.
 def GR64 : RegisterClass<"X86", [i64], 64,
                          (add RAX, RCX, RDX, RSI, RDI, R8, R9, R10, R11,
                               RBX, R14, R15, R12, R13, RBP, RSP, RIP)>;