[RISCV] Check vmerge's true is in same block in vmerge -> vmv.v.v peephole (#110861)

The peepholes in RISCVVectorPeephole need to be local and we were
failing to check if the true operand was in the same block as the
vmerge.

Fixes #110832

Author: lukel97

llvm/lib/Target/RISCV/RISCVVectorPeephole.cpp

@@ -419,8 +419,8 @@ bool RISCVVectorPeephole::convertSameMaskVMergeToVMv(MachineInstr &MI) {
   if (!NewOpc)
     return false;
   MachineInstr *True = MRI->getVRegDef(MI.getOperand(3).getReg());
-  if (!True || !RISCV::getMaskedPseudoInfo(True->getOpcode()) ||
-      !hasSameEEW(MI, *True))
+  if (!True || True->getParent() != MI.getParent() ||
+      !RISCV::getMaskedPseudoInfo(True->getOpcode()) || !hasSameEEW(MI, *True))
     return false;
 
   const MachineInstr *TrueV0Def = V0Defs.lookup(True);

llvm/test/CodeGen/RISCV/rvv/rvv-peephole-vmerge-to-vmv.mir

@@ -159,3 +159,29 @@ body: |
     $v0 = COPY %mask
     %x:vrnov0 = PseudoVMERGE_VVM_M1 $noreg, %false, %true, $v0, 4, 5 /* e32 */
 ...
+---
+# Shouldn't be converted because true is in a different block
+name: same_mask_diff_blocks
+body: |
+  ; CHECK-LABEL: name: same_mask_diff_blocks
+  ; CHECK: bb.0:
+  ; CHECK-NEXT:   successors: %bb.1(0x80000000)
+  ; CHECK-NEXT:   liveins: $v8, $v0
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT:   %false:vr = COPY $v8
+  ; CHECK-NEXT:   %mask:vr = COPY $v0
+  ; CHECK-NEXT:   $v0 = COPY %mask
+  ; CHECK-NEXT:   %true:vrnov0 = PseudoVADD_VV_M1_MASK $noreg, $noreg, $noreg, $v0, 4, 5 /* e32 */, 0 /* tu, mu */
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT: bb.1:
+  ; CHECK-NEXT:   $v0 = COPY %mask
+  ; CHECK-NEXT:   [[PseudoVMERGE_VVM_M1_:%[0-9]+]]:vrnov0 = PseudoVMERGE_VVM_M1 $noreg, %false, %true, $v0, 4, 5 /* e32 */
+  bb.0:
+    liveins: $v8, $v0
+    %false:vr = COPY $v8
+    %mask:vr = COPY $v0
+    $v0 = COPY %mask
+    %true:vrnov0 = PseudoVADD_VV_M1_MASK $noreg, $noreg, $noreg, $v0, 4, 5 /* e32 */, 0 /* tu, mu */
+  bb.1:
+    $v0 = COPY %mask
+    %5:vrnov0 = PseudoVMERGE_VVM_M1 $noreg, %false, %true, $v0, 4, 5 /* e32 */