[InstCombine] add tests for opposing shifts separated by trunc; NFC

1 files changed, 91 insertions, 0 deletions

diff --git a/llvm/test/Transforms/InstCombine/shift-shift.ll b/llvm/test/Transforms/InstCombine/shift-shift.ll
index b53b5124ee4f..7c57cdf2f07f 100644
--- a/llvm/test/Transforms/InstCombine/shift-shift.ll
+++ b/llvm/test/Transforms/InstCombine/shift-shift.ll
@@ -1,6 +1,9 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
 ; RUN: opt < %s -instcombine -S | FileCheck %s
 
+declare void @use8(i8)
+declare void @use32(i32)
+
 ; These would crash if we didn't check for a negative shift.
 
 ; https://llvm.org/bugs/show_bug.cgi?id=12967
@@ -133,3 +136,91 @@ define <2 x i32> @lshr_lshr_vec(<2 x i32> %A) {
   %C = lshr <2 x i32> %B, <i32 4, i32 5>
   ret <2 x i32> %C
 }
+
+define i8 @shl_trunc_bigger_lshr(i32 %x) {
+; CHECK-LABEL: @shl_trunc_bigger_lshr(
+; CHECK-NEXT:    [[TMP1:%.*]] = lshr i32 [[X:%.*]], 2
+; CHECK-NEXT:    [[TMP2:%.*]] = trunc i32 [[TMP1]] to i8
+; CHECK-NEXT:    [[LT:%.*]] = and i8 [[TMP2]], -8
+; CHECK-NEXT:    ret i8 [[LT]]
+;
+  %rt = lshr i32 %x, 5
+  %tr = trunc i32 %rt to i8
+  %lt = shl i8 %tr, 3
+  ret i8 %lt
+}
+
+define i8 @shl_trunc_smaller_lshr(i32 %x) {
+; CHECK-LABEL: @shl_trunc_smaller_lshr(
+; CHECK-NEXT:    [[X_TR:%.*]] = trunc i32 [[X:%.*]] to i8
+; CHECK-NEXT:    [[TMP1:%.*]] = shl i8 [[X_TR]], 2
+; CHECK-NEXT:    [[LT:%.*]] = and i8 [[TMP1]], -32
+; CHECK-NEXT:    ret i8 [[LT]]
+;
+  %rt = lshr i32 %x, 3
+  %tr = trunc i32 %rt to i8
+  %lt = shl i8 %tr, 5
+  ret i8 %lt
+}
+
+define i8 @shl_trunc_bigger_lshr_use1(i32 %x) {
+; CHECK-LABEL: @shl_trunc_bigger_lshr_use1(
+; CHECK-NEXT:    [[RT:%.*]] = lshr i32 [[X:%.*]], 5
+; CHECK-NEXT:    call void @use32(i32 [[RT]])
+; CHECK-NEXT:    [[TR:%.*]] = trunc i32 [[RT]] to i8
+; CHECK-NEXT:    [[LT:%.*]] = shl i8 [[TR]], 3
+; CHECK-NEXT:    ret i8 [[LT]]
+;
+  %rt = lshr i32 %x, 5
+  call void @use32(i32 %rt)
+  %tr = trunc i32 %rt to i8
+  %lt = shl i8 %tr, 3
+  ret i8 %lt
+}
+
+define i8 @shl_trunc_smaller_lshr_use1(i32 %x) {
+; CHECK-LABEL: @shl_trunc_smaller_lshr_use1(
+; CHECK-NEXT:    [[RT:%.*]] = lshr i32 [[X:%.*]], 3
+; CHECK-NEXT:    call void @use32(i32 [[RT]])
+; CHECK-NEXT:    [[TR:%.*]] = trunc i32 [[RT]] to i8
+; CHECK-NEXT:    [[LT:%.*]] = shl i8 [[TR]], 5
+; CHECK-NEXT:    ret i8 [[LT]]
+;
+  %rt = lshr i32 %x, 3
+  call void @use32(i32 %rt)
+  %tr = trunc i32 %rt to i8
+  %lt = shl i8 %tr, 5
+  ret i8 %lt
+}
+
+define i8 @shl_trunc_bigger_lshr_use2(i32 %x) {
+; CHECK-LABEL: @shl_trunc_bigger_lshr_use2(
+; CHECK-NEXT:    [[RT:%.*]] = lshr i32 [[X:%.*]], 5
+; CHECK-NEXT:    [[TR:%.*]] = trunc i32 [[RT]] to i8
+; CHECK-NEXT:    call void @use8(i8 [[TR]])
+; CHECK-NEXT:    [[LT1:%.*]] = shl nuw nsw i32 [[RT]], 3
+; CHECK-NEXT:    [[LT:%.*]] = trunc i32 [[LT1]] to i8
+; CHECK-NEXT:    ret i8 [[LT]]
+;
+  %rt = lshr i32 %x, 5
+  %tr = trunc i32 %rt to i8
+  call void @use8(i8 %tr)
+  %lt = shl i8 %tr, 3
+  ret i8 %lt
+}
+
+define i8 @shl_trunc_smaller_lshr_use2(i32 %x) {
+; CHECK-LABEL: @shl_trunc_smaller_lshr_use2(
+; CHECK-NEXT:    [[RT:%.*]] = lshr i32 [[X:%.*]], 3
+; CHECK-NEXT:    [[TR:%.*]] = trunc i32 [[RT]] to i8
+; CHECK-NEXT:    call void @use8(i8 [[TR]])
+; CHECK-NEXT:    [[LT1:%.*]] = shl i32 [[RT]], 5
+; CHECK-NEXT:    [[LT:%.*]] = trunc i32 [[LT1]] to i8
+; CHECK-NEXT:    ret i8 [[LT]]
+;
+  %rt = lshr i32 %x, 3
+  %tr = trunc i32 %rt to i8
+  call void @use8(i8 %tr)
+  %lt = shl i8 %tr, 5
+  ret i8 %lt
+}