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; RUN: opt -S -jump-threading < %s | FileCheck %s
; Check that the heuristic for avoiding accidental introduction of irreducible
; loops doesn't also prevent us from threading simple constructs where this
; isn't a problem.
declare void @opaque_body()
define void @jump_threading_loopheader() {
; CHECK-LABEL: @jump_threading_loopheader
top:
br label %entry
entry:
%ind = phi i32 [0, %top], [%nextind, %latch]
%nextind = add i32 %ind, 1
%cmp = icmp ule i32 %ind, 10
; CHECK: br i1 %cmp, label %latch, label %exit
br i1 %cmp, label %body, label %latch
body:
call void @opaque_body()
; CHECK: br label %entry
br label %latch
latch:
%cond = phi i2 [1, %entry], [2, %body]
switch i2 %cond, label %unreach [
i2 2, label %entry
i2 1, label %exit
]
unreach:
unreachable
exit:
ret void
}
; We also need to check the opposite order of the branches, in the switch
; instruction because jump-threading relies on that to decide which edge to
; try to thread first.
define void @jump_threading_loopheader2() {
; CHECK-LABEL: @jump_threading_loopheader2
top:
br label %entry
entry:
%ind = phi i32 [0, %top], [%nextind, %latch]
%nextind = add i32 %ind, 1
%cmp = icmp ule i32 %ind, 10
; CHECK: br i1 %cmp, label %exit, label %latch
br i1 %cmp, label %body, label %latch
body:
call void @opaque_body()
; CHECK: br label %entry
br label %latch
latch:
%cond = phi i2 [1, %entry], [2, %body]
switch i2 %cond, label %unreach [
i2 1, label %entry
i2 2, label %exit
]
unreach:
unreachable
exit:
ret void
}
; Check if we can handle undef branch condition.
define void @jump_threading_loopheader3() {
; CHECK-LABEL: @jump_threading_loopheader3
top:
br label %entry
entry:
%ind = phi i32 [0, %top], [%nextind, %latch]
%nextind = add i32 %ind, 1
%cmp = icmp ule i32 %ind, 10
; CHECK: br i1 %cmp, label %latch, label %exit
br i1 %cmp, label %body, label %latch
body:
call void @opaque_body()
; CHECK: br label %entry
br label %latch
latch:
%phi = phi i32 [undef, %entry], [0, %body]
%cmp1 = icmp eq i32 %phi, 0
br i1 %cmp1, label %entry, label %exit
exit:
ret void
}
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