[RISCV][GISel] Add s32 G_SELECT instruction select test for RV64. NFC

Author: topperc

llvm/test/CodeGen/RISCV/GlobalISel/instruction-select/select-rv64.mir

@@ -1,6 +1,36 @@
 # NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
 # RUN: llc -mtriple=riscv64 -run-pass=instruction-select %s -o - \
 # RUN: | FileCheck %s
+
+---
+name:            select_s32
+legalized:       true
+regBankSelected: true
+tracksRegLiveness: true
+body:            |
+  bb.0:
+    liveins: $x10, $x11, $x12
+
+    ; CHECK-LABEL: name: select_s32
+    ; CHECK: liveins: $x10, $x11, $x12
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: [[COPY:%[0-9]+]]:gpr = COPY $x10
+    ; CHECK-NEXT: [[COPY1:%[0-9]+]]:gpr = COPY $x11
+    ; CHECK-NEXT: [[COPY2:%[0-9]+]]:gpr = COPY $x12
+    ; CHECK-NEXT: [[Select_GPR_Using_CC_GPR:%[0-9]+]]:gpr = Select_GPR_Using_CC_GPR [[COPY]], $x0, 1, [[COPY1]], [[COPY2]]
+    ; CHECK-NEXT: $x10 = COPY [[Select_GPR_Using_CC_GPR]]
+    ; CHECK-NEXT: PseudoRET implicit $x10
+    %0:gprb(s64) = COPY $x10
+    %1:gprb(s64) = COPY $x11
+    %2:gprb(s64) = COPY $x12
+    %3:gprb(s32) = G_TRUNC %1
+    %4:gprb(s32) = G_TRUNC %2
+    %5:gprb(s32) = G_SELECT %0, %3, %4
+    %6:gprb(s64) = G_ANYEXT %5
+    $x10 = COPY %6(s64)
+    PseudoRET implicit $x10
+
+...
 ---
 name:            select_s64
 legalized:       true