getX86SubSuperRegister has a special mode with High=true for i64 which

exists solely to enable it to call itself for i8 with some registers.
The proposed patch simplifies the function somewhat to make the High
bit only meaningful for the i8 mode, which makes sense. No functional
difference (getX86SubSuperRegister is not getting called from anywhere
outside with i64 and High=true).



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@175762 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/X86/X86RegisterInfo.cpp

@@ -620,7 +620,15 @@ unsigned getX86SubSuperRegister(unsigned Reg, MVT::SimpleValueType VT,
   case MVT::i8:
     if (High) {
       switch (Reg) {
-      default: return getX86SubSuperRegister(Reg, MVT::i64, High);
+      default: return getX86SubSuperRegister(Reg, MVT::i64);
+      case X86::SIL: case X86::SI: case X86::ESI: case X86::RSI:
+        return X86::SI;
+      case X86::DIL: case X86::DI: case X86::EDI: case X86::RDI:
+        return X86::DI;
+      case X86::BPL: case X86::BP: case X86::EBP: case X86::RBP:
+        return X86::BP;
+      case X86::SPL: case X86::SP: case X86::ESP: case X86::RSP:
+        return X86::SP;
       case X86::AH: case X86::AL: case X86::AX: case X86::EAX: case X86::RAX:
         return X86::AH;
       case X86::DH: case X86::DL: case X86::DX: case X86::EDX: case X86::RDX:
@@ -740,22 +748,6 @@ unsigned getX86SubSuperRegister(unsigned Reg, MVT::SimpleValueType VT,
       return X86::R15D;
     }
   case MVT::i64:
-    // For 64-bit mode if we've requested a "high" register and the
-    // Q or r constraints we want one of these high registers or
-    // just the register name otherwise.
-    if (High) {
-      switch (Reg) {
-      case X86::SIL: case X86::SI: case X86::ESI: case X86::RSI:
-        return X86::SI;
-      case X86::DIL: case X86::DI: case X86::EDI: case X86::RDI:
-        return X86::DI;
-      case X86::BPL: case X86::BP: case X86::EBP: case X86::RBP:
-        return X86::BP;
-      case X86::SPL: case X86::SP: case X86::ESP: case X86::RSP:
-        return X86::SP;
-      // Fallthrough.
-      }
-    }
     switch (Reg) {
     default: llvm_unreachable("Unexpected register");
     case X86::AH: case X86::AL: case X86::AX: case X86::EAX: case X86::RAX: