MCA: Remove relaxInstruction call

MCA inappropriately called the internal MCAssembler API
(https://reviews.llvm.org/D65948). In addition, most snippets are short.
We should display the short form of span-dependent instructions

Author: MaskRay

llvm/lib/MCA/CodeEmitter.cpp

@@ -22,12 +22,8 @@ CodeEmitter::EncodingInfo CodeEmitter::getOrCreateEncodingInfo(unsigned MCID) {
 
   SmallVector<llvm::MCFixup, 2> Fixups;
   const MCInst &Inst = Sequence[MCID];
-  MCInst Relaxed(Sequence[MCID]);
-  if (MAB.mayNeedRelaxation(Inst, STI))
-    MAB.relaxInstruction(Relaxed, STI);
-
   EI.first = Code.size();
-  MCE.encodeInstruction(Relaxed, Code, Fixups, STI);
+  MCE.encodeInstruction(Inst, Code, Fixups, STI);
   EI.second = Code.size() - EI.first;
   return EI;
 }

llvm/test/tools/llvm-mca/X86/show-encoding.s

@@ -74,4 +74,4 @@
 # WITHENCODINGS-NEXT:  1      1     0.50                         6     c4 c1 30 c6 c1 ff             vshufps	$255, %xmm9, %xmm9, %xmm0
 # WITHENCODINGS-NEXT:  1      1     1.00           *             6     c4 01 78 11 0c 8b             vmovups	%xmm9, (%r11,%r9,4)
 # WITHENCODINGS-NEXT:  1      1     0.50                         3     44 39 c6                      cmpl	%r8d, %esi
-# WITHENCODINGS-NEXT:  1      1     0.50                         6     0f 8c 00 00 00 00             jl	-90
+# WITHENCODINGS-NEXT:  1      1     0.50                         2     7c 00                         jl	-90