trivial-unswitch.ll
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; RUN: opt < %s -loop-unswitch -enable-new-pm=0 -loop-unswitch-threshold=0 -verify-loop-info -S < %s 2>&1 | FileCheck %s
; RUN: opt < %s -loop-unswitch -enable-new-pm=0 -loop-unswitch-threshold=0 -verify-loop-info -enable-mssa-loop-dependency=true -verify-memoryssa -S < %s 2>&1 | FileCheck %s
; This test contains two trivial unswitch condition in one loop.
; LoopUnswitch pass should be able to unswitch the second one
; after unswitching the first one.
; CHECK: br i1 %cond1, label %..split_crit_edge, label %.loop_exit.split_crit_edge
; CHECK: ..split_crit_edge: ; preds = %0
; CHECK: br label %.split
; CHECK: .split: ; preds = %..split_crit_edge
; CHECK: br i1 %cond2, label %.split..split.split_crit_edge, label %.split.loop_exit.split1_crit_edge
; CHECK: .split..split.split_crit_edge: ; preds = %.split
; CHECK: br label %.split.split
; CHECK: .split.split: ; preds = %.split..split.split_crit_edge
; CHECK: br label %loop_begin
; CHECK: loop_begin: ; preds = %do_something, %.split.split
; CHECK: br i1 true, label %continue, label %loop_exit
; CHECK: continue: ; preds = %loop_begin
; CHECK: %var_val = load i32, i32* %var
; CHECK: br i1 true, label %do_something, label %loop_exit
define i32 @test(i32* %var, i1 %cond1, i1 %cond2) {
br label %loop_begin
loop_begin:
br i1 %cond1, label %continue, label %loop_exit ; first trivial condition
continue:
%var_val = load i32, i32* %var
br i1 %cond2, label %do_something, label %loop_exit ; second trivial condition
do_something:
call void @some_func() noreturn nounwind
br label %loop_begin
loop_exit:
ret i32 0
}
; We will not be able trivially unswitch on the SwitchInst, as its input
; is a constant. However, since its a constant we should be able to figure
; out that the switch can be folded into a unconditional branch to %continue.
; Then we unswitch on the br inst in %continue.
;
; CHECK: define i32 @test2(
; This is an indication that the loop has been unswitched on %cond1.
; CHECK: br i1 %cond1, label %..split_crit_edge, label %.loop_exit.split_crit_edge
; CHECK: ..split_crit_edge: ; preds = %0
; CHECK: br label %.split
; CHECK: .split: ; preds = %..split_crit_edge
; CHECK: br label %loop_begin
; CHECK: loop_begin: ; preds = %do_something, %.split
; CHECK: switch i32
; CHECK: continue: ; preds = %loop_begin
; CHECK: %var_val = load i32, i32* %var
; CHECK: br i1 true, label %do_something, label %loop_exit
define i32 @test2(i32* %var, i1 %cond1) {
br label %loop_begin
loop_begin:
switch i32 1, label %continue [
i32 0, label %loop_exit
i32 1, label %continue
]
continue:
%var_val = load i32, i32* %var
br i1 %cond1, label %do_something, label %loop_exit
do_something:
call void @some_func() noreturn nounwind
br label %loop_begin
loop_exit:
ret i32 0
}
declare void @some_func() noreturn