[GISel] Use G_ZEXT when widening G_EXTRACT_VECTOR_ELT/G_INSERT_VECTOR_ELT index. (#163416)

Author: topperc

llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp

@@ -3292,8 +3292,7 @@ LegalizerHelper::widenScalar(MachineInstr &MI, unsigned TypeIdx, LLT WideTy) {
     if (TypeIdx != 2)
       return UnableToLegalize;
     Observer.changingInstr(MI);
-    // TODO: Probably should be zext
-    widenScalarSrc(MI, WideTy, 2, TargetOpcode::G_SEXT);
+    widenScalarSrc(MI, WideTy, 2, TargetOpcode::G_ZEXT);
     Observer.changedInstr(MI);
     return Legalized;
   }
@@ -3325,8 +3324,7 @@ LegalizerHelper::widenScalar(MachineInstr &MI, unsigned TypeIdx, LLT WideTy) {
 
     if (TypeIdx == 2) {
       Observer.changingInstr(MI);
-      // TODO: Probably should be zext
-      widenScalarSrc(MI, WideTy, 3, TargetOpcode::G_SEXT);
+      widenScalarSrc(MI, WideTy, 3, TargetOpcode::G_ZEXT);
       Observer.changedInstr(MI);
       return Legalized;
     }

llvm/test/CodeGen/AArch64/GlobalISel/legalize-vector-compress.mir

@@ -15,8 +15,9 @@ body:             |
     ; CHECK-NEXT: [[C:%[0-9]+]]:_(s32) = G_CONSTANT i32 0
     ; CHECK-NEXT: [[C1:%[0-9]+]]:_(s64) = G_CONSTANT i64 0
     ; CHECK-NEXT: [[EVEC:%[0-9]+]]:_(s32) = G_EXTRACT_VECTOR_ELT [[COPY]](<4 x s32>), [[C1]](s64)
+    ; CHECK-NEXT: [[COPY2:%[0-9]+]]:_(s64) = COPY [[C1]](s64)
     ; CHECK-NEXT: [[C2:%[0-9]+]]:_(s64) = G_CONSTANT i64 4
-    ; CHECK-NEXT: [[MUL:%[0-9]+]]:_(s64) = G_MUL [[C1]], [[C2]]
+    ; CHECK-NEXT: [[MUL:%[0-9]+]]:_(s64) = G_MUL [[COPY2]], [[C2]]
     ; CHECK-NEXT: [[PTR_ADD:%[0-9]+]]:_(p0) = G_PTR_ADD [[FRAME_INDEX]], [[MUL]](s64)
     ; CHECK-NEXT: G_STORE [[EVEC]](s32), [[PTR_ADD]](p0) :: (store (s32))
     ; CHECK-NEXT: [[EVEC1:%[0-9]+]]:_(s16) = G_EXTRACT_VECTOR_ELT [[COPY1]](<4 x s16>), [[C1]](s64)
@@ -91,7 +92,8 @@ body:             |
     ; CHECK-NEXT: [[LOAD:%[0-9]+]]:_(s32) = G_LOAD [[PTR_ADD]](p0) :: (load (s32))
     ; CHECK-NEXT: [[C3:%[0-9]+]]:_(s64) = G_CONSTANT i64 0
     ; CHECK-NEXT: [[EVEC:%[0-9]+]]:_(s32) = G_EXTRACT_VECTOR_ELT [[COPY]](<4 x s32>), [[C3]](s64)
-    ; CHECK-NEXT: [[MUL1:%[0-9]+]]:_(s64) = G_MUL [[C3]], [[C2]]
+    ; CHECK-NEXT: [[COPY3:%[0-9]+]]:_(s64) = COPY [[C3]](s64)
+    ; CHECK-NEXT: [[MUL1:%[0-9]+]]:_(s64) = G_MUL [[COPY3]], [[C2]]
     ; CHECK-NEXT: [[PTR_ADD1:%[0-9]+]]:_(p0) = G_PTR_ADD [[FRAME_INDEX]], [[MUL1]](s64)
     ; CHECK-NEXT: G_STORE [[EVEC]](s32), [[PTR_ADD1]](p0) :: (store (s32))
     ; CHECK-NEXT: [[EVEC1:%[0-9]+]]:_(s16) = G_EXTRACT_VECTOR_ELT [[COPY1]](<4 x s16>), [[C3]](s64)