Convert SHUFPD with the same register for both sources to PSHUFD if it would prevent a register copy. Similar to SHUFPS, but requires the mask to be converted.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@148112 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 20 insertions, 1 deletions

diff --git a/lib/Target/X86/X86InstrInfo.cpp b/lib/Target/X86/X86InstrInfo.cpp
index cd74a25593..940ce7a102 100644
--- a/lib/Target/X86/X86InstrInfo.cpp
+++ b/lib/Target/X86/X86InstrInfo.cpp
@@ -1605,6 +1605,24 @@ X86InstrInfo::convertToThreeAddress(MachineFunction::iterator &MFI,
       .addReg(B, getKillRegState(isKill)).addImm(M);
     break;
   }
+  case X86::SHUFPDrri: {
+    assert(MI->getNumOperands() == 4 && "Unknown shufpd instruction!");
+    if (!TM.getSubtarget<X86Subtarget>().hasSSE2()) return 0;
+
+    unsigned B = MI->getOperand(1).getReg();
+    unsigned C = MI->getOperand(2).getReg();
+    if (B != C) return 0;
+    unsigned A = MI->getOperand(0).getReg();
+    unsigned M = MI->getOperand(3).getImm();
+
+    // Convert to PSHUFD mask.
+    M = ((M & 1) << 1) | ((M & 1) << 3) | ((M & 2) << 4) | ((M & 2) << 6)| 0x44;
+
+    NewMI = BuildMI(MF, MI->getDebugLoc(), get(X86::PSHUFDri))
+      .addReg(A, RegState::Define | getDeadRegState(isDead))
+      .addReg(B, getKillRegState(isKill)).addImm(M);
+    break;
+  }
   case X86::SHL64ri: {
     assert(MI->getNumOperands() >= 3 && "Unknown shift instruction!");
     // NOTE: LEA doesn't produce flags like shift does, but LLVM never uses
diff --git a/lib/Target/X86/X86InstrSSE.td b/lib/Target/X86/X86InstrSSE.td
index 27f51282a6..c9ecfee828 100644
--- a/lib/Target/X86/X86InstrSSE.td
+++ b/lib/Target/X86/X86InstrSSE.td
@@ -2330,7 +2330,8 @@ let Constraints = "$src1 = $dst" in {
                     TB;
   defm SHUFPD : sse12_shuffle<VR128, f128mem, v2f64,
                     "shufpd\t{$src3, $src2, $dst|$dst, $src2, $src3}",
-                    memopv2f64, SSEPackedDouble>, TB, OpSize;
+                    memopv2f64, SSEPackedDouble, 1 /* cvt to pshufd */>,
+                    TB, OpSize;
 }
 
 let Predicates = [HasAVX] in {