[llvm] [InstCombine] Fold adds + shifts with nsw and nuw flags (PR #88193)

[Matt Arsenault via llvm-commits]

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@@ -360,8 +360,64 @@ define <3 x i14> @mul_splat_fold_vec(<3 x i14> %x) {
   ret <3 x i14> %t
 }
 
+define i32 @mul_times_3_div_2 (i32 %x) {
+; CHECK-LABEL: @mul_times_3_div_2(
+; CHECK-NEXT:    [[TMP2:%.*]] = lshr i32 [[TMP1:%.*]], 1
+; CHECK-NEXT:    [[TMP3:%.*]] = add nuw nsw i32 [[TMP2]], [[TMP1]]
+; CHECK-NEXT:    ret i32 [[TMP3]]
+;
+  %2 = mul nsw nuw i32 %x, 3
+  %3 = lshr i32 %2, 1
+  ret i32 %3
+}
+
+  define i32 @shl_add_lshr (i32 %x, i32 %c, i32 %y) {
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arsenm wrote:

Indentation off 

https://github.com/llvm/llvm-project/pull/88193