| ; RUN: opt -S -passes=jump-threading %s | FileCheck %s |
| ; When simplify a branch based on LVI predicates, we should replace the |
| ; comparison itself with a constant (when possible) in case it's otherwise used. |
| |
| define i32 @test(ptr %p) { |
| ; CHECK-LABEL: @test |
| ; CHECK: icmp eq |
| ; CHECK-NEXT: br i1 %cmp, label %exit2, label %exit1 |
| ; CHECK-NOT: icmp ne |
| entry: |
| %cmp = icmp eq ptr %p, null |
| br i1 %cmp, label %is_null, label %not_null |
| is_null: |
| %cmp2 = icmp ne ptr %p, null |
| br i1 %cmp2, label %exit1, label %exit2 |
| not_null: |
| %cmp3 = icmp ne ptr %p, null |
| br i1 %cmp3, label %exit1, label %exit2 |
| exit1: |
| ret i32 0 |
| exit2: |
| ret i32 1 |
| } |
| |
| declare void @use(i1) |
| |
| ; It would not be legal to replace %cmp2 (well, in this case it actually is, |
| ; but that's a CSE problem, not a LVI/jump threading problem) |
| define i32 @test_negative(ptr %p) { |
| ; CHECK-LABEL: @test |
| ; CHECK: icmp ne |
| ; CHECK: icmp eq |
| ; CHECK-NEXT: br i1 %cmp, label %exit2, label %exit1 |
| ; CHECK-NOT: icmp ne |
| entry: |
| %cmp2 = icmp ne ptr %p, null |
| call void @use(i1 %cmp2) |
| %cmp = icmp eq ptr %p, null |
| br i1 %cmp, label %is_null, label %not_null |
| is_null: |
| br i1 %cmp2, label %exit1, label %exit2 |
| not_null: |
| br i1 %cmp2, label %exit1, label %exit2 |
| exit1: |
| ret i32 0 |
| exit2: |
| ret i32 1 |
| } |
| |
| ; In this case, we can remove cmp2 because it's otherwise unused |
| define i32 @test2(ptr %p) { |
| ; CHECK-LABEL: @test |
| ; CHECK-LABEL: entry: |
| ; CHECK-NEXT: icmp eq |
| ; CHECK-NEXT: br i1 %cmp, label %exit2, label %exit1 |
| ; CHECK-NOT: icmp ne |
| entry: |
| %cmp2 = icmp ne ptr %p, null |
| %cmp = icmp eq ptr %p, null |
| br i1 %cmp, label %is_null, label %not_null |
| is_null: |
| br i1 %cmp2, label %exit1, label %exit2 |
| not_null: |
| br i1 %cmp2, label %exit1, label %exit2 |
| exit1: |
| ret i32 0 |
| exit2: |
| ret i32 1 |
| } |