[llvm] r355277 - Add test case for add to sub transformation. NFC

[Amaury Sechet via llvm-commits]

Author: deadalnix
Date: Sat Mar  2 12:12:25 2019
New Revision: 355277

URL: http://llvm.org/viewvc/llvm-project?rev=355277&view=rev
Log:
Add test case for add to sub transformation. NFC

Modified:
    llvm/trunk/test/Transforms/InstCombine/add.ll

Modified: llvm/trunk/test/Transforms/InstCombine/add.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/add.ll?rev=355277&r1=355276&r2=355277&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/add.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/add.ll Sat Mar  2 12:12:25 2019
@@ -947,3 +947,30 @@ define i32 @add_not_increment_commuted(i
   ret i32 %E
 }
 
+; E = (A + ~B) + 1 = A - B
+define i32 @add_to_sub(i32 %A, i32 %B) {
+; CHECK-LABEL: @add_to_sub(
+; CHECK-NEXT:    [[C:%.*]] = xor i32 [[B:%.*]], -1
+; CHECK-NEXT:    [[D:%.*]] = add i32 [[C]], [[A:%.*]]
+; CHECK-NEXT:    [[E:%.*]] = add i32 [[D]], 1
+; CHECK-NEXT:    ret i32 [[E]]
+;
+  %C = xor i32 %B, -1
+  %D = add i32 %A, %C
+  %E = add i32 %D, 1
+  ret i32 %E
+}
+
+; E = (~B + A) + 1 = A - B
+define i32 @add_to_sub2(i32 %A, i32 %B) {
+; CHECK-LABEL: @add_to_sub2(
+; CHECK-NEXT:    [[C:%.*]] = xor i32 [[B:%.*]], -1
+; CHECK-NEXT:    [[D:%.*]] = add i32 [[C]], [[A:%.*]]
+; CHECK-NEXT:    [[E:%.*]] = add i32 [[D]], 1
+; CHECK-NEXT:    ret i32 [[E]]
+;
+  %C = xor i32 %B, -1
+  %D = add i32 %C, %A
+  %E = add i32 %D, 1
+  ret i32 %E
+}