Optimize icmp involving addition better

Allows LLVM to optimize sequences like the following:

%add = add nsw i32 %x, 1
%cmp = icmp sgt i32 %add, %y

into:

%cmp = icmp sge i32 %x, %y

as well as:

%add1 = add nsw i32 %x, 20
%add2 = add nsw i32 %y, 57
%cmp = icmp sge i32 %add1, %add2

into:

%add = add nsw i32 %y, 37
%cmp = icmp sle i32 %cmp, %x


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@179316 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 52 insertions, 0 deletions

diff --git a/test/Transforms/InstCombine/icmp.ll b/test/Transforms/InstCombine/icmp.ll
index 446c0e01dc..28fa33ba41 100644
--- a/test/Transforms/InstCombine/icmp.ll
+++ b/test/Transforms/InstCombine/icmp.ll
@@ -886,3 +886,55 @@ define i1 @icmp_mul0_ne0(i32 %x) {
   %cmp = icmp ne i32 %mul, 0
   ret i1 %cmp
 }
+
+; CHECK: @icmp_sub1_sge
+; CHECK-NEXT: icmp sgt i32 %x, %y
+define i1 @icmp_sub1_sge(i32 %x, i32 %y) {
+  %sub = add nsw i32 %x, -1
+  %cmp = icmp sge i32 %sub, %y
+  ret i1 %cmp
+}
+
+; CHECK: @icmp_add1_sgt
+; CHECK-NEXT: icmp sge i32 %x, %y
+define i1 @icmp_add1_sgt(i32 %x, i32 %y) {
+  %add = add nsw i32 %x, 1
+  %cmp = icmp sgt i32 %add, %y
+  ret i1 %cmp
+}
+
+; CHECK: @icmp_sub1_slt
+; CHECK-NEXT: icmp sle i32 %x, %y
+define i1 @icmp_sub1_slt(i32 %x, i32 %y) {
+  %sub = add nsw i32 %x, -1
+  %cmp = icmp slt i32 %sub, %y
+  ret i1 %cmp
+}
+
+; CHECK: @icmp_add1_sle
+; CHECK-NEXT: icmp slt i32 %x, %y
+define i1 @icmp_add1_sle(i32 %x, i32 %y) {
+  %add = add nsw i32 %x, 1
+  %cmp = icmp sle i32 %add, %y
+  ret i1 %cmp
+}
+
+; CHECK: @icmp_add20_sge_add57
+; CHECK-NEXT: [[ADD:%[a-z0-9]+]] = add nsw i32 %y, 37
+; CHECK-NEXT: icmp sle i32 [[ADD]], %x
+define i1 @icmp_add20_sge_add57(i32 %x, i32 %y) {
+  %1 = add nsw i32 %x, 20
+  %2 = add nsw i32 %y, 57
+  %cmp = icmp sge i32 %1, %2
+  ret i1 %cmp
+}
+
+; CHECK: @icmp_sub57_sge_sub20
+; CHECK-NEXT: [[SUB:%[a-z0-9]+]] = add nsw i32 %x, -37
+; CHECK-NEXT: icmp sge i32 [[SUB]], %y
+define i1 @icmp_sub57_sge_sub20(i32 %x, i32 %y) {
+  %1 = add nsw i32 %x, -57
+  %2 = add nsw i32 %y, -20
+  %cmp = icmp sge i32 %1, %2
+  ret i1 %cmp
+}