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- ; RUN: opt -S -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(i32* %p) {
- ; CHECK-LABEL: @test
- ; CHECK: icmp eq
- ; CHECK-NEXT: br i1 %cmp, label %exit2, label %exit1
- ; CHECK-NOT: icmp ne
- entry:
- %cmp = icmp eq i32* %p, null
- br i1 %cmp, label %is_null, label %not_null
- is_null:
- %cmp2 = icmp ne i32* %p, null
- br i1 %cmp2, label %exit1, label %exit2
- not_null:
- %cmp3 = icmp ne i32* %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(i32* %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 i32* %p, null
- call void @use(i1 %cmp2)
- %cmp = icmp eq i32* %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(i32* %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 i32* %p, null
- %cmp = icmp eq i32* %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
- }
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