[InstCombine] add tests for mul+lshr; NFC

Baseline tests for D123453(issue #54824)

Author: bcl5980

llvm/test/Transforms/InstCombine/shift-logic.ll

@@ -1,6 +1,8 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
 ; RUN: opt < %s -passes=instcombine -S | FileCheck %s
 
+declare void @use(i64)
+
 define i8 @shl_and(i8 %x, i8 %y) {
 ; CHECK-LABEL: @shl_and(
 ; CHECK-NEXT:    [[TMP1:%.*]] = shl i8 [[X:%.*]], 5
@@ -254,3 +256,71 @@ define i32 @PR44028(i32 %x) {
   %t27 = ashr exact i32 %t0, 16
   ret i32 %t27
 }
+
+define i64 @lshr_mul(i64 %0) {
+; CHECK-LABEL: @lshr_mul(
+; CHECK-NEXT:    [[TMP2:%.*]] = mul nuw i64 [[TMP0:%.*]], 52
+; CHECK-NEXT:    [[TMP3:%.*]] = lshr exact i64 [[TMP2]], 2
+; CHECK-NEXT:    ret i64 [[TMP3]]
+;
+  %2 = mul nuw i64 %0, 52
+  %3 = lshr i64 %2, 2
+  ret i64 %3
+}
+
+define i64 @lshr_mul_nuw_nsw(i64 %0) {
+; CHECK-LABEL: @lshr_mul_nuw_nsw(
+; CHECK-NEXT:    [[TMP2:%.*]] = mul nuw nsw i64 [[TMP0:%.*]], 52
+; CHECK-NEXT:    [[TMP3:%.*]] = lshr exact i64 [[TMP2]], 2
+; CHECK-NEXT:    ret i64 [[TMP3]]
+;
+  %2 = mul nuw nsw i64 %0, 52
+  %3 = lshr i64 %2, 2
+  ret i64 %3
+}
+
+define <4 x i32> @lshr_mul_vector(<4 x i32> %0) {
+; CHECK-LABEL: @lshr_mul_vector(
+; CHECK-NEXT:    [[TMP2:%.*]] = mul nuw <4 x i32> [[TMP0:%.*]], <i32 52, i32 52, i32 52, i32 52>
+; CHECK-NEXT:    [[TMP3:%.*]] = lshr exact <4 x i32> [[TMP2]], <i32 2, i32 2, i32 2, i32 2>
+; CHECK-NEXT:    ret <4 x i32> [[TMP3]]
+;
+  %2 = mul nuw <4 x i32> %0, <i32 52, i32 52, i32 52, i32 52>
+  %3 = lshr <4 x i32> %2, <i32 2, i32 2, i32 2, i32 2>
+  ret <4 x i32> %3
+}
+
+define i64 @lshr_mul_negative_noexact(i64 %0) {
+; CHECK-LABEL: @lshr_mul_negative_noexact(
+; CHECK-NEXT:    [[TMP2:%.*]] = mul nuw i64 [[TMP0:%.*]], 53
+; CHECK-NEXT:    [[TMP3:%.*]] = lshr i64 [[TMP2]], 2
+; CHECK-NEXT:    ret i64 [[TMP3]]
+;
+  %2 = mul nuw i64 %0, 53
+  %3 = lshr i64 %2, 2
+  ret i64 %3
+}
+
+define i64 @lshr_mul_negative_oneuse(i64 %0) {
+; CHECK-LABEL: @lshr_mul_negative_oneuse(
+; CHECK-NEXT:    [[TMP2:%.*]] = mul nuw i64 [[TMP0:%.*]], 52
+; CHECK-NEXT:    call void @use(i64 [[TMP2]])
+; CHECK-NEXT:    [[TMP3:%.*]] = lshr exact i64 [[TMP2]], 2
+; CHECK-NEXT:    ret i64 [[TMP3]]
+;
+  %2 = mul nuw i64 %0, 52
+  call void @use(i64 %2)
+  %3 = lshr i64 %2, 2
+  ret i64 %3
+}
+
+define i64 @lshr_mul_negative_nonuw(i64 %0) {
+; CHECK-LABEL: @lshr_mul_negative_nonuw(
+; CHECK-NEXT:    [[TMP2:%.*]] = mul i64 [[TMP0:%.*]], 52
+; CHECK-NEXT:    [[TMP3:%.*]] = lshr exact i64 [[TMP2]], 2
+; CHECK-NEXT:    ret i64 [[TMP3]]
+;
+  %2 = mul i64 %0, 52
+  %3 = lshr i64 %2, 2
+  ret i64 %3
+}