Add a new MOV8rr_NOREX, and make X86's copyRegToReg use it when

either the source or destination is a physical h register.

This fixes sqlite3 with the post-RA scheduler enabled.

llvm-svn: 69111

2 files changed, 20 insertions, 5 deletions

diff --git a/llvm/lib/Target/X86/X86InstrInfo.cpp b/llvm/lib/Target/X86/X86InstrInfo.cpp
index 77955a6a426..e64b2960179 100644
--- a/llvm/lib/Target/X86/X86InstrInfo.cpp
+++ b/llvm/lib/Target/X86/X86InstrInfo.cpp
@@ -1641,6 +1641,11 @@ X86InstrInfo::InsertBranch(MachineBasicBlock &MBB, MachineBasicBlock *TBB,
   return Count;
 }
 
+/// isHReg - Test if the given register is a physical h register.
+static bool isHReg(unsigned Reg) {
+  return Reg == X86::AH || Reg == X86::BH || Reg == X86::CH || Reg == X86::DH;
+}
+
 bool X86InstrInfo::copyRegToReg(MachineBasicBlock &MBB,
                                 MachineBasicBlock::iterator MI,
                                 unsigned DestReg, unsigned SrcReg,
@@ -1658,7 +1663,12 @@ bool X86InstrInfo::copyRegToReg(MachineBasicBlock &MBB,
     } else if (DestRC == &X86::GR16RegClass) {
       Opc = X86::MOV16rr;
     } else if (DestRC == &X86::GR8RegClass) {
-      Opc = X86::MOV8rr;
+      // Copying two or from a physical H register requires a NOREX move. Otherwise
+      // use a normal move.
+      if (isHReg(DestReg) || isHReg(SrcReg))
+        Opc = X86::MOV8rr_NOREX;
+      else
+        Opc = X86::MOV8rr;
     } else if (DestRC == &X86::GR64_RegClass) {
       Opc = X86::MOV64rr;
     } else if (DestRC == &X86::GR32_RegClass) {
diff --git a/llvm/lib/Target/X86/X86InstrInfo.td b/llvm/lib/Target/X86/X86InstrInfo.td
index 077b4563b06..4fd3320090b 100644
--- a/llvm/lib/Target/X86/X86InstrInfo.td
+++ b/llvm/lib/Target/X86/X86InstrInfo.td
@@ -783,10 +783,15 @@ def MOV32mr : I<0x89, MRMDestMem, (outs), (ins i32mem:$dst, GR32:$src),
                 "mov{l}\t{$src, $dst|$dst, $src}",
                 [(store GR32:$src, addr:$dst)]>;
 
-// A version of MOV8mr that uses i8mem_NOREX so that it can be used for
-// storing h registers, which can't be encoded when a REX prefix is present.
-def MOV8mr_NOREX : I<0x88, MRMDestMem, (outs), (ins i8mem_NOREX:$dst, GR8:$src),
-                   "mov{b}\t{$src, $dst|$dst, $src}  # NOREX", []>;
+// Versions of MOV8rr and MOV8mr that use i8mem_NOREX and GR8_NOREX so that they
+// can be used for copying and storing h registers, which can't be encoded when
+// a REX prefix is present.
+let neverHasSideEffects = 1 in
+def MOV8rr_NOREX : I<0x88, MRMDestReg, (outs GR8_NOREX:$dst), (ins GR8_NOREX:$src),
+                     "mov{b}\t{$src, $dst|$dst, $src}  # NOREX", []>;
+def MOV8mr_NOREX : I<0x88, MRMDestMem,
+                     (outs), (ins i8mem_NOREX:$dst, GR8_NOREX:$src),
+                     "mov{b}\t{$src, $dst|$dst, $src}  # NOREX", []>;
 
 //===----------------------------------------------------------------------===//
 //  Fixed-Register Multiplication and Division Instructions...