From e93249befaa2383cc34c27771265123090cda085 Mon Sep 17 00:00:00 2001
From: Eli Bendersky <eliben@google.com>
Date: Thu, 21 Feb 2013 16:40:18 +0000
Subject: [PATCH] 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).

llvm-svn: 175762
---
 llvm/lib/Target/X86/X86RegisterInfo.cpp | 26 +++++++++----------------
 1 file changed, 9 insertions(+), 17 deletions(-)

diff --git a/llvm/lib/Target/X86/X86RegisterInfo.cpp b/llvm/lib/Target/X86/X86RegisterInfo.cpp
index 3b9144dc0b85..6b0a9154b16c 100644
--- a/llvm/lib/Target/X86/X86RegisterInfo.cpp
+++ b/llvm/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: