[X86] Move the 2 byte VEX optimization for MOV instructions back to the X86AsmParser::processInstruction where it used to be. Block when {vex3} prefix is present.

Years ago I moved this to an InstAlias using VR128H/VR128L. But now that we support {vex3} pseudo prefix, we need to block the optimization when it is set to match gas behavior.

llvm-svn: 358046

3 files changed, 63 insertions, 54 deletions

diff --git a/llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp b/llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp
index fa079242e75..30411a232ef 100644
--- a/llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp
+++ b/llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp
@@ -2830,7 +2830,69 @@ bool X86AsmParser::ParseInstruction(ParseInstructionInfo &Info, StringRef Name,
 }
 
 bool X86AsmParser::processInstruction(MCInst &Inst, const OperandVector &Ops) {
-  return false;
+  const MCRegisterInfo *MRI = getContext().getRegisterInfo();
+
+  switch (Inst.getOpcode()) {
+  default: return false;
+  case X86::VMOVZPQILo2PQIrr:
+  case X86::VMOVAPDrr:
+  case X86::VMOVAPDYrr:
+  case X86::VMOVAPSrr:
+  case X86::VMOVAPSYrr:
+  case X86::VMOVDQArr:
+  case X86::VMOVDQAYrr:
+  case X86::VMOVDQUrr:
+  case X86::VMOVDQUYrr:
+  case X86::VMOVUPDrr:
+  case X86::VMOVUPDYrr:
+  case X86::VMOVUPSrr:
+  case X86::VMOVUPSYrr: {
+    // We can get a smaller encoding by using VEX.R instead of VEX.B if one of
+    // the registers is extended, but other isn't.
+    if (ForcedVEXEncoding == VEXEncoding_VEX3 ||
+        MRI->getEncodingValue(Inst.getOperand(0).getReg()) >= 8 ||
+        MRI->getEncodingValue(Inst.getOperand(1).getReg()) < 8)
+      return false;
+
+    unsigned NewOpc;
+    switch (Inst.getOpcode()) {
+    default: llvm_unreachable("Invalid opcode");
+    case X86::VMOVZPQILo2PQIrr: NewOpc = X86::VMOVPQI2QIrr;   break;
+    case X86::VMOVAPDrr:        NewOpc = X86::VMOVAPDrr_REV;  break;
+    case X86::VMOVAPDYrr:       NewOpc = X86::VMOVAPDYrr_REV; break;
+    case X86::VMOVAPSrr:        NewOpc = X86::VMOVAPSrr_REV;  break;
+    case X86::VMOVAPSYrr:       NewOpc = X86::VMOVAPSYrr_REV; break;
+    case X86::VMOVDQArr:        NewOpc = X86::VMOVDQArr_REV;  break;
+    case X86::VMOVDQAYrr:       NewOpc = X86::VMOVDQAYrr_REV; break;
+    case X86::VMOVDQUrr:        NewOpc = X86::VMOVDQUrr_REV;  break;
+    case X86::VMOVDQUYrr:       NewOpc = X86::VMOVDQUYrr_REV; break;
+    case X86::VMOVUPDrr:        NewOpc = X86::VMOVUPDrr_REV;  break;
+    case X86::VMOVUPDYrr:       NewOpc = X86::VMOVUPDYrr_REV; break;
+    case X86::VMOVUPSrr:        NewOpc = X86::VMOVUPSrr_REV;  break;
+    case X86::VMOVUPSYrr:       NewOpc = X86::VMOVUPSYrr_REV; break;
+    }
+    Inst.setOpcode(NewOpc);
+    return true;
+  }
+  case X86::VMOVSDrr:
+  case X86::VMOVSSrr: {
+    // We can get a smaller encoding by using VEX.R instead of VEX.B if one of
+    // the registers is extended, but other isn't.
+    if (ForcedVEXEncoding == VEXEncoding_VEX3 ||
+        MRI->getEncodingValue(Inst.getOperand(0).getReg()) >= 8 ||
+        MRI->getEncodingValue(Inst.getOperand(2).getReg()) < 8)
+      return false;
+
+    unsigned NewOpc;
+    switch (Inst.getOpcode()) {
+    default: llvm_unreachable("Invalid opcode");
+    case X86::VMOVSDrr: NewOpc = X86::VMOVSDrr_REV; break;
+    case X86::VMOVSSrr: NewOpc = X86::VMOVSSrr_REV; break;
+    }
+    Inst.setOpcode(NewOpc);
+    return true;
+  }
+  }
 }
 
 bool X86AsmParser::validateInstruction(MCInst &Inst, const OperandVector &Ops) {
diff --git a/llvm/lib/Target/X86/X86InstrSSE.td b/llvm/lib/Target/X86/X86InstrSSE.td
index f2ce89bcebd..6ee2504beea 100644
--- a/llvm/lib/Target/X86/X86InstrSSE.td
+++ b/llvm/lib/Target/X86/X86InstrSSE.td
@@ -350,13 +350,6 @@ let Predicates = [UseSSE2] in {
             (COPY_TO_REGCLASS (MOVSDrm addr:$src), VR128)>;
 }
 
-// Aliases to help the assembler pick two byte VEX encodings by swapping the
-// operands relative to the normal instructions to use VEX.R instead of VEX.B.
-def : InstAlias<"vmovss\t{$src2, $src1, $dst|$dst, $src1, $src2}",
-                (VMOVSSrr_REV VR128L:$dst, VR128:$src1, VR128H:$src2), 0>;
-def : InstAlias<"vmovsd\t{$src2, $src1, $dst|$dst, $src1, $src2}",
-                (VMOVSDrr_REV VR128L:$dst, VR128:$src1, VR128H:$src2), 0>;
-
 //===----------------------------------------------------------------------===//
 // SSE 1 & 2 - Move Aligned/Unaligned FP Instructions
 //===----------------------------------------------------------------------===//
@@ -503,25 +496,6 @@ let SchedRW = [SchedWriteFMoveLS.YMM.RR] in {
 } // SchedRW
 } // Predicate
 
-// Aliases to help the assembler pick two byte VEX encodings by swapping the
-// operands relative to the normal instructions to use VEX.R instead of VEX.B.
-def : InstAlias<"vmovaps\t{$src, $dst|$dst, $src}",
-                (VMOVAPSrr_REV VR128L:$dst, VR128H:$src), 0>;
-def : InstAlias<"vmovapd\t{$src, $dst|$dst, $src}",
-                (VMOVAPDrr_REV VR128L:$dst, VR128H:$src), 0>;
-def : InstAlias<"vmovups\t{$src, $dst|$dst, $src}",
-                (VMOVUPSrr_REV VR128L:$dst, VR128H:$src), 0>;
-def : InstAlias<"vmovupd\t{$src, $dst|$dst, $src}",
-                (VMOVUPDrr_REV VR128L:$dst, VR128H:$src), 0>;
-def : InstAlias<"vmovaps\t{$src, $dst|$dst, $src}",
-                (VMOVAPSYrr_REV VR256L:$dst, VR256H:$src), 0>;
-def : InstAlias<"vmovapd\t{$src, $dst|$dst, $src}",
-                (VMOVAPDYrr_REV VR256L:$dst, VR256H:$src), 0>;
-def : InstAlias<"vmovups\t{$src, $dst|$dst, $src}",
-                (VMOVUPSYrr_REV VR256L:$dst, VR256H:$src), 0>;
-def : InstAlias<"vmovupd\t{$src, $dst|$dst, $src}",
-                (VMOVUPDYrr_REV VR256L:$dst, VR256H:$src), 0>;
-
 // Reversed version with ".s" suffix for GAS compatibility.
 def : InstAlias<"vmovaps.s\t{$src, $dst|$dst, $src}",
                 (VMOVAPSrr_REV VR128:$dst, VR128:$src), 0>;
@@ -3444,17 +3418,6 @@ def MOVDQUmr :   I<0x7F, MRMDestMem, (outs), (ins i128mem:$dst, VR128:$src),
 
 } // ExeDomain = SSEPackedInt
 
-// Aliases to help the assembler pick two byte VEX encodings by swapping the
-// operands relative to the normal instructions to use VEX.R instead of VEX.B.
-def : InstAlias<"vmovdqa\t{$src, $dst|$dst, $src}",
-                (VMOVDQArr_REV VR128L:$dst, VR128H:$src), 0>;
-def : InstAlias<"vmovdqa\t{$src, $dst|$dst, $src}",
-                (VMOVDQAYrr_REV VR256L:$dst, VR256H:$src), 0>;
-def : InstAlias<"vmovdqu\t{$src, $dst|$dst, $src}",
-                (VMOVDQUrr_REV VR128L:$dst, VR128H:$src), 0>;
-def : InstAlias<"vmovdqu\t{$src, $dst|$dst, $src}",
-                (VMOVDQUYrr_REV VR256L:$dst, VR256H:$src), 0>;
-
 // Reversed version with ".s" suffix for GAS compatibility.
 def : InstAlias<"vmovdqa.s\t{$src, $dst|$dst, $src}",
                 (VMOVDQArr_REV VR128:$dst, VR128:$src), 0>;
@@ -4423,11 +4386,6 @@ def MOVPQI2QIrr : S2I<0xD6, MRMDestReg, (outs VR128:$dst), (ins VR128:$src),
                       "movq\t{$src, $dst|$dst, $src}", []>;
 }
 
-// Aliases to help the assembler pick two byte VEX encodings by swapping the
-// operands relative to the normal instructions to use VEX.R instead of VEX.B.
-def : InstAlias<"vmovq\t{$src, $dst|$dst, $src}",
-                (VMOVPQI2QIrr VR128L:$dst, VR128H:$src), 0>;
-
 def : InstAlias<"vmovq.s\t{$src, $dst|$dst, $src}",
                 (VMOVPQI2QIrr VR128:$dst, VR128:$src), 0>;
 def : InstAlias<"movq.s\t{$src, $dst|$dst, $src}",
diff --git a/llvm/lib/Target/X86/X86RegisterInfo.td b/llvm/lib/Target/X86/X86RegisterInfo.td
index d81f08b0f06..e03f0492cd7 100644
--- a/llvm/lib/Target/X86/X86RegisterInfo.td
+++ b/llvm/lib/Target/X86/X86RegisterInfo.td
@@ -552,17 +552,6 @@ def VR128 : RegisterClass<"X86", [v4f32, v2f64, v16i8, v8i16, v4i32, v2i64, f128
 def VR256 : RegisterClass<"X86", [v8f32, v4f64, v32i8, v16i16, v8i32, v4i64],
                           256, (sequence "YMM%u", 0, 15)>;
 
-// Special classes that help the assembly parser choose some alternate
-// instructions to favor 2-byte VEX encodings.
-def VR128L : RegisterClass<"X86", [v4f32, v2f64, v16i8, v8i16, v4i32, v2i64, f128],
-                           128, (sequence "XMM%u", 0, 7)>;
-def VR128H : RegisterClass<"X86", [v4f32, v2f64, v16i8, v8i16, v4i32, v2i64, f128],
-                           128, (sequence "XMM%u", 8, 15)>;
-def VR256L : RegisterClass<"X86", [v8f32, v4f64, v32i8, v16i16, v8i32, v4i64],
-                           256, (sequence "YMM%u", 0, 7)>;
-def VR256H : RegisterClass<"X86", [v8f32, v4f64, v32i8, v16i16, v8i32, v4i64],
-                           256, (sequence "YMM%u", 8, 15)>;
-
 // Status flags registers.
 def CCR : RegisterClass<"X86", [i32], 32, (add EFLAGS)> {
   let CopyCost = -1;  // Don't allow copying of status registers.