Index: llvm/test/Transforms/InstCombine/add4.ll
===================================================================
--- llvm/test/Transforms/InstCombine/add4.ll
+++ llvm/test/Transforms/InstCombine/add4.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 i32 @use32(i32)
+
 define i64 @match_unsigned(i64 %x) {
 ; CHECK-LABEL: @match_unsigned(
 ; CHECK-NEXT:    [[UREM:%.*]] = urem i64 [[X:%.*]], 19136
@@ -127,3 +129,103 @@
   %t4 = add i32 %t, %t3
   ret i32 %t4
 }
+
+; TODO: (x + (-1)) + (x * 5) --> (x * 6) + (-1)
+define i8 @mul_add_common_factor_0(i8 %x) {
+; CHECK-LABEL: @mul_add_common_factor_0(
+; CHECK-NEXT:    [[A0:%.*]] = add i8 [[X:%.*]], -1
+; CHECK-NEXT:    [[M:%.*]] = mul i8 [[X]], 5
+; CHECK-NEXT:    [[A1:%.*]] = add i8 [[A0]], [[M]]
+; CHECK-NEXT:    ret i8 [[A1]]
+;
+  %a0 = add i8 %x, -1
+  %m = mul i8 %x, 5
+  %a1 = add i8 %a0, %m ; the mul operand is the right operand, should swap the operand
+  ret i8 %a1
+}
+
+; TODO: (x + 2) + (x * t) --> (t + 1) * x + 2
+define i128 @mul_add_common_factor_3(i128 %x, i128 %t) {
+; CHECK-LABEL: @mul_add_common_factor_3(
+; CHECK-NEXT:    [[A0:%.*]] = add i128 [[X:%.*]], 2
+; CHECK-NEXT:    [[M:%.*]] = mul i128 [[X]], [[T:%.*]]
+; CHECK-NEXT:    [[A1:%.*]] = add i128 [[A0]], [[M]]
+; CHECK-NEXT:    ret i128 [[A1]]
+;
+  %a0 = add i128 %x, 2
+  %m = mul i128 %x, %t
+  %a1 = add i128 %a0, %m
+  ret i128 %a1
+}
+
+; TODO: (x << 2) + (x - 1) --> (x * 5) + (-1)
+define i16 @shl_add_common_factor_1(i16 %x) {
+; CHECK-LABEL: @shl_add_common_factor_1(
+; CHECK-NEXT:    [[A0:%.*]] = add i16 [[X:%.*]], -1
+; CHECK-NEXT:    [[S:%.*]] = shl i16 [[X]], 2
+; CHECK-NEXT:    [[A1:%.*]] = add i16 [[S]], [[A0]]
+; CHECK-NEXT:    ret i16 [[A1]]
+;
+  %a0 = add i16 %x, -1
+  %s = shl i16 %x, 2
+  %a1 = add i16 %s, %a0 ; the shl operand is the left operand
+  ret i16 %a1
+}
+
+; TODO: (x + y) + (x << 2) --> (x * 5) + y
+define i32 @shl_add_common_factor_2(i32 %x, i32 %y) {
+; CHECK-LABEL: @shl_add_common_factor_2(
+; CHECK-NEXT:    [[A0:%.*]] = add i32 [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT:    [[S:%.*]] = shl i32 [[X]], 2
+; CHECK-NEXT:    [[A1:%.*]] = add i32 [[A0]], [[S]]
+; CHECK-NEXT:    ret i32 [[A1]]
+;
+  %a0 = add i32 %x, %y
+  %s = shl i32 %x, 2
+  %a1 = add i32 %a0, %s ; the shl operand is the right operand
+  ret i32 %a1
+}
+
+; TODO: (y + x) + (x << 2) --> (x * 5) + y
+define i32 @shl_add_common_factor_2_commute(i32 %x, i32 %y) {
+; CHECK-LABEL: @shl_add_common_factor_2_commute(
+; CHECK-NEXT:    [[A0:%.*]] = add i32 [[Y:%.*]], [[X:%.*]]
+; CHECK-NEXT:    [[S:%.*]] = shl i32 [[X]], 2
+; CHECK-NEXT:    [[A1:%.*]] = add i32 [[A0]], [[S]]
+; CHECK-NEXT:    ret i32 [[A1]]
+;
+  %a0 = add i32 %y, %x ; swap the operand
+  %s = shl i32 %x, 2
+  %a1 = add i32 %a0, %s
+  ret i32 %a1
+}
+
+; Negative test: The transformation should not create more instructions
+define i32 @shl_add_common_factor_4(i32 %x) {
+; CHECK-LABEL: @shl_add_common_factor_4(
+; CHECK-NEXT:    [[A0:%.*]] = add i32 [[X:%.*]], -1
+; CHECK-NEXT:    [[S:%.*]] = shl i32 [[X]], 2
+; CHECK-NEXT:    call void @use32(i32 [[S]])
+; CHECK-NEXT:    [[A1:%.*]] = add i32 [[S]], [[A0]]
+; CHECK-NEXT:    ret i32 [[A1]]
+;
+  %a0 = add i32 %x, -1
+  %s = shl i32 %x, 2
+  call void @use32(i32 %s) ; an extra use
+  %a1 = add i32 %s, %a0
+  ret i32 %a1
+}
+
+; TODO: (x << 2) + (x + 3) --> (x * 5) + 3
+define <2 x i64> @shl_add_common_factor_5(<2 x i64> %x) {
+; CHECK-LABEL: @shl_add_common_factor_5(
+; CHECK-NEXT:    [[A0:%.*]] = add <2 x i64> [[X:%.*]], <i64 3, i64 3>
+; CHECK-NEXT:    [[S:%.*]] = shl <2 x i64> [[X]], <i64 2, i64 2>
+; CHECK-NEXT:    [[A1:%.*]] = add <2 x i64> [[S]], [[A0]]
+; CHECK-NEXT:    ret <2 x i64> [[A1]]
+;
+  %a0 = add <2 x i64> %x, <i64 3, i64 3>
+  %s = shl <2 x i64> %x, <i64 2, i64 2> ; vector type
+  %a1 = add <2 x i64> %s, %a0
+  ret <2 x i64> %a1
+}