[RISCV] Convert whole register copies as the source defined explicitly.

The implicit defines may come from a partial define in an instruction.
It does not mean the defining instruction and the COPY instruction have
the same vl and vtype. When the source comes from the implicit defines,
do not convert the whole register copies to vmv.v.v.

Differential Revision: https://reviews.llvm.org/D115866

Author: Hsiangkai

Diff for: llvm/lib/Target/RISCV/RISCVInstrInfo.cpp

@@ -201,8 +201,9 @@ static bool isConvertibleToVMV_V_V(const RISCVSubtarget &STI,
       if (MBBI->modifiesRegister(RISCV::VL))
         return false;
 
-      // Go through all defined operands, including implicit defines.
-      for (const MachineOperand &MO : MBBI->operands()) {
+      // Only converting whole register copies to vmv.v.v when the defining
+      // value appears in the explicit operands.
+      for (const MachineOperand &MO : MBBI->explicit_operands()) {
         if (!MO.isReg() || !MO.isDef())
           continue;
         if (!FoundDef && TRI->isSubRegisterEq(MO.getReg(), SrcReg)) {

Diff for: llvm/test/CodeGen/RISCV/rvv/vmv-copy.mir

@@ -313,14 +313,14 @@ body:             |
     ; CHECK-NEXT: $v8_v9_v10_v11_v12_v13_v14_v15 = PseudoVLSEG8E32_V_M1 killed $x12, $noreg, 5, implicit $vl, implicit $vtype
     ; CHECK-NEXT: $x0 = PseudoVSETIVLI 10, 80, implicit-def $vl, implicit-def $vtype
     ; CHECK-NEXT: $v15 = PseudoVLE32_V_M1 killed $x16, $noreg, 5, implicit $vl, implicit $vtype, implicit killed $v8_v9_v10_v11_v12_v13_v14_v15, implicit-def $v8_v9_v10_v11_v12_v13_v14_v15
-    ; CHECK-NEXT: $v24 = PseudoVMV_V_V_M1 killed $v8, $noreg, 5, implicit $vl, implicit $vtype
-    ; CHECK-NEXT: $v25 = PseudoVMV_V_V_M1 killed $v9, $noreg, 5, implicit $vl, implicit $vtype
-    ; CHECK-NEXT: $v26 = PseudoVMV_V_V_M1 killed $v10, $noreg, 5, implicit $vl, implicit $vtype
-    ; CHECK-NEXT: $v27 = PseudoVMV_V_V_M1 killed $v11, $noreg, 5, implicit $vl, implicit $vtype
-    ; CHECK-NEXT: $v28 = PseudoVMV_V_V_M1 killed $v12, $noreg, 5, implicit $vl, implicit $vtype
-    ; CHECK-NEXT: $v29 = PseudoVMV_V_V_M1 killed $v13, $noreg, 5, implicit $vl, implicit $vtype
-    ; CHECK-NEXT: $v30 = PseudoVMV_V_V_M1 killed $v14, $noreg, 5, implicit $vl, implicit $vtype
-    ; CHECK-NEXT: $v31 = PseudoVMV_V_V_M1 killed $v15, $noreg, 5, implicit $vl, implicit $vtype
+    ; CHECK-NEXT: $v24 = PseudoVMV1R_V killed $v8
+    ; CHECK-NEXT: $v25 = PseudoVMV1R_V killed $v9
+    ; CHECK-NEXT: $v26 = PseudoVMV1R_V killed $v10
+    ; CHECK-NEXT: $v27 = PseudoVMV1R_V killed $v11
+    ; CHECK-NEXT: $v28 = PseudoVMV1R_V killed $v12
+    ; CHECK-NEXT: $v29 = PseudoVMV1R_V killed $v13
+    ; CHECK-NEXT: $v30 = PseudoVMV1R_V killed $v14
+    ; CHECK-NEXT: $v31 = PseudoVMV1R_V killed $v15
     $x0 = PseudoVSETVLI $x14, 80, implicit-def $vl, implicit-def $vtype
     $v8_v9_v10_v11_v12_v13_v14_v15 = PseudoVLSEG8E32_V_M1 killed $x12, $noreg, 5, implicit $vl, implicit $vtype
     $x0 = PseudoVSETIVLI 10, 80, implicit-def $vl, implicit-def $vtype