conditional.ll
2.12 KB
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; RUN: opt -early-cse -S < %s | FileCheck %s
; RUN: opt -basicaa -early-cse-memssa -S < %s | FileCheck %s
; Can we CSE a known condition to a constant?
define i1 @test(i8* %p) {
; CHECK-LABEL: @test
entry:
%cnd1 = icmp eq i8* %p, null
br i1 %cnd1, label %taken, label %untaken
taken:
; CHECK-LABEL: taken:
; CHECK-NEXT: ret i1 true
%cnd2 = icmp eq i8* %p, null
ret i1 %cnd2
untaken:
; CHECK-LABEL: untaken:
; CHECK-NEXT: ret i1 false
%cnd3 = icmp eq i8* %p, null
ret i1 %cnd3
}
; We can CSE the condition, but we *don't* know it's value after the merge
define i1 @test_neg1(i8* %p) {
; CHECK-LABEL: @test_neg1
entry:
%cnd1 = icmp eq i8* %p, null
br i1 %cnd1, label %taken, label %untaken
taken:
br label %merge
untaken:
br label %merge
merge:
; CHECK-LABEL: merge:
; CHECK-NEXT: ret i1 %cnd1
%cnd3 = icmp eq i8* %p, null
ret i1 %cnd3
}
; Check specifically for a case where we have a unique predecessor, but
; not a single predecessor. We can not know the value of the condition here.
define i1 @test_neg2(i8* %p) {
; CHECK-LABEL: @test_neg2
entry:
%cnd1 = icmp eq i8* %p, null
br i1 %cnd1, label %merge, label %merge
merge:
; CHECK-LABEL: merge:
; CHECK-NEXT: ret i1 %cnd1
%cnd3 = icmp eq i8* %p, null
ret i1 %cnd3
}
; Replace a use rather than CSE
define i1 @test2(i8* %p) {
; CHECK-LABEL: @test2
entry:
%cnd = icmp eq i8* %p, null
br i1 %cnd, label %taken, label %untaken
taken:
; CHECK-LABEL: taken:
; CHECK-NEXT: ret i1 true
ret i1 %cnd
untaken:
; CHECK-LABEL: untaken:
; CHECK-NEXT: ret i1 false
ret i1 %cnd
}
; Not legal to replace use given it's not dominated by edge
define i1 @test2_neg1(i8* %p) {
; CHECK-LABEL: @test2_neg1
entry:
%cnd1 = icmp eq i8* %p, null
br i1 %cnd1, label %taken, label %untaken
taken:
br label %merge
untaken:
br label %merge
merge:
; CHECK-LABEL: merge:
; CHECK-NEXT: ret i1 %cnd1
ret i1 %cnd1
}
; Another single predecessor test, but for dominated use
define i1 @test2_neg2(i8* %p) {
; CHECK-LABEL: @test2_neg2
entry:
%cnd1 = icmp eq i8* %p, null
br i1 %cnd1, label %merge, label %merge
merge:
; CHECK-LABEL: merge:
; CHECK-NEXT: ret i1 %cnd1
ret i1 %cnd1
}