70 lines
1.7 KiB
LLVM
70 lines
1.7 KiB
LLVM
|
; 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
|
||
|
}
|