pr21210.ll
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; RUN: opt < %s -mtriple=x86_64-unknown-linux-gnu -instcombine -S | FileCheck %s
; Checks that the select-icmp optimization is safe in two cases
declare void @foo(i32)
declare i32 @bar(i32)
; don't replace 'cond' by 'len' in the home block ('bb') that
; contains the select
define void @test1(i32 %len) {
entry:
br label %bb
bb:
%cmp = icmp ult i32 %len, 8
%cond = select i1 %cmp, i32 %len, i32 8
call void @foo(i32 %cond)
%cmp11 = icmp eq i32 %cond, 8
br i1 %cmp11, label %for.end, label %bb
for.end:
ret void
; CHECK: select
; CHECK: icmp eq i32 %cond, 8
}
; don't replace 'cond' by 'len' in a block ('b1') that dominates all uses
; of the select outside the home block ('bb'), but can be reached from the home
; block on another path ('bb -> b0 -> b1')
define void @test2(i32 %len) {
entry:
%0 = call i32 @bar(i32 %len);
%cmp = icmp ult i32 %len, 4
br i1 %cmp, label %bb, label %b1
bb:
%cmp2 = icmp ult i32 %0, 2
%cond = select i1 %cmp2, i32 %len, i32 8
%cmp3 = icmp eq i32 %cond, 8
br i1 %cmp3, label %b0, label %b1
b0:
call void @foo(i32 %len)
br label %b1
b1:
; CHECK: phi i32 [ %cond, %bb ], [ undef, %b0 ], [ %0, %entry ]
%1 = phi i32 [ %cond, %bb ], [ undef, %b0 ], [ %0, %entry ]
br label %ret
ret:
call void @foo(i32 %1)
ret void
}