| Philip Reames | 7a738dd | 2015-05-07 00:19:14 +0000 | [diff] [blame] | 1 | ; RUN: opt -S -jump-threading %s | FileCheck %s |
| 2 | ; When simplify a branch based on LVI predicates, we should replace the |
| 3 | ; comparison itself with a constant (when possible) in case it's otherwise used. |
| 4 | |
| 5 | define i32 @test(i32* %p) { |
| 6 | ; CHECK-LABEL: @test |
| 7 | ; CHECK: icmp eq |
| 8 | ; CHECK-NEXT: br i1 %cmp, label %exit2, label %exit1 |
| 9 | ; CHECK-NOT: icmp ne |
| 10 | entry: |
| 11 | %cmp = icmp eq i32* %p, null |
| 12 | br i1 %cmp, label %is_null, label %not_null |
| 13 | is_null: |
| 14 | %cmp2 = icmp ne i32* %p, null |
| 15 | br i1 %cmp2, label %exit1, label %exit2 |
| 16 | not_null: |
| 17 | %cmp3 = icmp ne i32* %p, null |
| 18 | br i1 %cmp3, label %exit1, label %exit2 |
| 19 | exit1: |
| 20 | ret i32 0 |
| 21 | exit2: |
| 22 | ret i32 1 |
| 23 | } |
| 24 | |
| 25 | declare void @use(i1) |
| 26 | |
| 27 | ; It would not be legal to replace %cmp2 (well, in this case it actually is, |
| 28 | ; but that's a CSE problem, not a LVI/jump threading problem) |
| 29 | define i32 @test_negative(i32* %p) { |
| 30 | ; CHECK-LABEL: @test |
| 31 | ; CHECK: icmp ne |
| 32 | ; CHECK: icmp eq |
| 33 | ; CHECK-NEXT: br i1 %cmp, label %exit2, label %exit1 |
| 34 | ; CHECK-NOT: icmp ne |
| 35 | entry: |
| 36 | %cmp2 = icmp ne i32* %p, null |
| 37 | call void @use(i1 %cmp2) |
| 38 | %cmp = icmp eq i32* %p, null |
| 39 | br i1 %cmp, label %is_null, label %not_null |
| 40 | is_null: |
| 41 | br i1 %cmp2, label %exit1, label %exit2 |
| 42 | not_null: |
| 43 | br i1 %cmp2, label %exit1, label %exit2 |
| 44 | exit1: |
| 45 | ret i32 0 |
| 46 | exit2: |
| 47 | ret i32 1 |
| 48 | } |
| 49 | |
| 50 | ; In this case, we can remove cmp2 because it's otherwise unused |
| 51 | define i32 @test2(i32* %p) { |
| 52 | ; CHECK-LABEL: @test |
| 53 | ; CHECK-LABEL: entry: |
| 54 | ; CHECK-NEXT: icmp eq |
| 55 | ; CHECK-NEXT: br i1 %cmp, label %exit2, label %exit1 |
| 56 | ; CHECK-NOT: icmp ne |
| 57 | entry: |
| 58 | %cmp2 = icmp ne i32* %p, null |
| 59 | %cmp = icmp eq i32* %p, null |
| 60 | br i1 %cmp, label %is_null, label %not_null |
| 61 | is_null: |
| 62 | br i1 %cmp2, label %exit1, label %exit2 |
| 63 | not_null: |
| 64 | br i1 %cmp2, label %exit1, label %exit2 |
| 65 | exit1: |
| 66 | ret i32 0 |
| 67 | exit2: |
| 68 | ret i32 1 |
| 69 | } |