[X86][CodeGen] Prefer KMOVkk_EVEX than KMOVkk when EGPR is supported (llvm#74048)

In memory fold table, we have

```
 {X86::KMOVDkk, X86::KMOVDkm, 0},
 {X86::KMOVDkk_EVEX, X86::KMOVDkm_EVEX, 0}
```

where `KMOVDkm_EVEX` can use EGPR as base and index registers, while
`KMOVDkm` can't. Hence, though `KMOVkk` does not have any GPR operands,
we prefer to use `KMOVDkk_EVEX` to help register allocation.

It will be compressed to `KMOVDkk` in EVEX2VEX pass if memory folding
does not happen.

Author: KanRobert

llvm/lib/Target/X86/X86DomainReassignment.cpp

@@ -625,8 +625,10 @@ void X86DomainReassignment::initConverters() {
   createReplacerDstCOPY(X86::MOVZX64rm16,
                         HasEGPR ? X86::KMOVWkm_EVEX : X86::KMOVWkm);
 
-  createReplacerDstCOPY(X86::MOVZX32rr16, X86::KMOVWkk);
-  createReplacerDstCOPY(X86::MOVZX64rr16, X86::KMOVWkk);
+  createReplacerDstCOPY(X86::MOVZX32rr16,
+                        HasEGPR ? X86::KMOVWkk_EVEX : X86::KMOVWkk);
+  createReplacerDstCOPY(X86::MOVZX64rr16,
+                        HasEGPR ? X86::KMOVWkk_EVEX : X86::KMOVWkk);
 
   if (STI->hasDQI()) {
     createReplacerDstCOPY(X86::MOVZX16rm8,
@@ -636,9 +638,12 @@ void X86DomainReassignment::initConverters() {
     createReplacerDstCOPY(X86::MOVZX64rm8,
                           HasEGPR ? X86::KMOVBkm_EVEX : X86::KMOVBkm);
 
-    createReplacerDstCOPY(X86::MOVZX16rr8, X86::KMOVBkk);
-    createReplacerDstCOPY(X86::MOVZX32rr8, X86::KMOVBkk);
-    createReplacerDstCOPY(X86::MOVZX64rr8, X86::KMOVBkk);
+    createReplacerDstCOPY(X86::MOVZX16rr8,
+                          HasEGPR ? X86::KMOVBkk_EVEX : X86::KMOVBkk);
+    createReplacerDstCOPY(X86::MOVZX32rr8,
+                          HasEGPR ? X86::KMOVBkk_EVEX : X86::KMOVBkk);
+    createReplacerDstCOPY(X86::MOVZX64rr8,
+                          HasEGPR ? X86::KMOVBkk_EVEX : X86::KMOVBkk);
   }
 
   auto createReplacer = [&](unsigned From, unsigned To) {
@@ -647,7 +652,7 @@ void X86DomainReassignment::initConverters() {
 
   createReplacer(X86::MOV16rm, HasEGPR ? X86::KMOVWkm_EVEX : X86::KMOVWkm);
   createReplacer(X86::MOV16mr, HasEGPR ? X86::KMOVWmk_EVEX : X86::KMOVWmk);
-  createReplacer(X86::MOV16rr, X86::KMOVWkk);
+  createReplacer(X86::MOV16rr, HasEGPR ? X86::KMOVWkk_EVEX : X86::KMOVWkk);
   createReplacer(X86::SHR16ri, X86::KSHIFTRWri);
   createReplacer(X86::SHL16ri, X86::KSHIFTLWri);
   createReplacer(X86::NOT16r, X86::KNOTWrr);
@@ -662,8 +667,8 @@ void X86DomainReassignment::initConverters() {
     createReplacer(X86::MOV32mr, HasEGPR ? X86::KMOVDmk_EVEX : X86::KMOVDmk);
     createReplacer(X86::MOV64mr, HasEGPR ? X86::KMOVQmk_EVEX : X86::KMOVQmk);
 
-    createReplacer(X86::MOV32rr, X86::KMOVDkk);
-    createReplacer(X86::MOV64rr, X86::KMOVQkk);
+    createReplacer(X86::MOV32rr, HasEGPR ? X86::KMOVDkk_EVEX : X86::KMOVDkk);
+    createReplacer(X86::MOV64rr, HasEGPR ? X86::KMOVQkk_EVEX : X86::KMOVQkk);
 
     createReplacer(X86::SHR32ri, X86::KSHIFTRDri);
     createReplacer(X86::SHR64ri, X86::KSHIFTRQri);
@@ -703,7 +708,7 @@ void X86DomainReassignment::initConverters() {
 
     createReplacer(X86::MOV8rm, HasEGPR ? X86::KMOVBkm_EVEX : X86::KMOVBkm);
     createReplacer(X86::MOV8mr, HasEGPR ? X86::KMOVBmk_EVEX : X86::KMOVBmk);
-    createReplacer(X86::MOV8rr, X86::KMOVBkk);
+    createReplacer(X86::MOV8rr, HasEGPR ? X86::KMOVBkk_EVEX : X86::KMOVBkk);
 
     createReplacer(X86::NOT8r, X86::KNOTBrr);
 

llvm/lib/Target/X86/X86InstrInfo.cpp

@@ -4070,6 +4070,7 @@ void X86InstrInfo::copyPhysReg(MachineBasicBlock &MBB,
   // First deal with the normal symmetric copies.
   bool HasAVX = Subtarget.hasAVX();
   bool HasVLX = Subtarget.hasVLX();
+  bool HasEGPR = Subtarget.hasEGPR();
   unsigned Opc = 0;
   if (X86::GR64RegClass.contains(DestReg, SrcReg))
     Opc = X86::MOV64rr;
@@ -4124,7 +4125,8 @@ void X86InstrInfo::copyPhysReg(MachineBasicBlock &MBB,
   // All KMASK RegClasses hold the same k registers, can be tested against
   // anyone.
   else if (X86::VK16RegClass.contains(DestReg, SrcReg))
-    Opc = Subtarget.hasBWI() ? X86::KMOVQkk : X86::KMOVWkk;
+    Opc = Subtarget.hasBWI() ? (HasEGPR ? X86::KMOVQkk_EVEX : X86::KMOVQkk)
+                             : (HasEGPR ? X86::KMOVQkk_EVEX : X86::KMOVWkk);
   if (!Opc)
     Opc = CopyToFromAsymmetricReg(DestReg, SrcReg, Subtarget);
 

llvm/test/CodeGen/X86/apx/kmov-kk.ll

@@ -0,0 +1,14 @@
+; RUN: llc < %s -mtriple=x86_64-unknown -mattr=+avx512f,+egpr -show-mc-encoding | FileCheck --check-prefix=EGPR %s
+
+define <16 x i32> @kmovkk(ptr %base, <16 x i32> %ind, i16 %mask) {
+; EGPR: kmovq   %k1, %k2                        # EVEX TO VEX Compression encoding: [0xc4,0xe1,0xf8,0x90,0xd1]
+  %broadcast.splatinsert = insertelement <16 x ptr> undef, ptr %base, i32 0
+  %broadcast.splat = shufflevector <16 x ptr> %broadcast.splatinsert, <16 x ptr> undef, <16 x i32> zeroinitializer
+  %gep.random = getelementptr i32, <16 x ptr> %broadcast.splat, <16 x i32> %ind
+  %imask = bitcast i16 %mask to <16 x i1>
+  %gt1 = call <16 x i32> @llvm.masked.gather.v16i32.v16p0(<16 x ptr> %gep.random, i32 4, <16 x i1> %imask, <16 x i32>undef)
+  %gt2 = call <16 x i32> @llvm.masked.gather.v16i32.v16p0(<16 x ptr> %gep.random, i32 4, <16 x i1> %imask, <16 x i32>%gt1)
+  %res = add <16 x i32> %gt1, %gt2
+  ret <16 x i32> %res
+}
+declare <16 x i32> @llvm.masked.gather.v16i32.v16p0(<16 x ptr>, i32, <16 x i1>, <16 x i32>)