InstCombine: Implement X - A*-B -> X + A*B.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@119984 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 20 insertions, 0 deletions

diff --git a/test/Transforms/InstCombine/sub.ll b/test/Transforms/InstCombine/sub.ll
index 29bd7be2ff..d88860056a 100644
--- a/test/Transforms/InstCombine/sub.ll
+++ b/test/Transforms/InstCombine/sub.ll
@@ -281,3 +281,23 @@ define i32 @test26(i32 %x) {
 ; CHECK-NEXT: ret i32
 }
 
+define i32 @test27(i32 %x, i32 %y) {
+  %mul = mul i32 %y, -8
+  %sub = sub i32 %x, %mul
+  ret i32 %sub
+; CHECK: @test27
+; CHECK-NEXT: shl i32 %y, 3
+; CHECK-NEXT: add i32
+; CHECK-NEXT: ret i32
+}
+
+define i32 @test28(i32 %x, i32 %y, i32 %z) {
+  %neg = sub i32 0, %z
+  %mul = mul i32 %neg, %y
+  %sub = sub i32 %x, %mul
+  ret i32 %sub
+; CHECK: @test28
+; CHECK-NEXT: mul i32 %z, %y
+; CHECK-NEXT: add i32
+; CHECK-NEXT: ret i32
+}