invariant-load.ll
3.31 KB
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; Test if the !invariant.load metadata is maintained by GVN.
; RUN: opt -basic-aa -gvn -S < %s | FileCheck %s
define i32 @test1(i32* nocapture %p, i8* nocapture %q) {
; CHECK-LABEL: test1
; CHECK: %x = load i32, i32* %p, align 4, !invariant.load !0
; CHECK-NOT: %y = load
entry:
%x = load i32, i32* %p, align 4, !invariant.load !0
%conv = trunc i32 %x to i8
store i8 %conv, i8* %q, align 1
%y = load i32, i32* %p, align 4, !invariant.load !0
%add = add i32 %y, 1
ret i32 %add
}
define i32 @test2(i32* nocapture %p, i8* nocapture %q) {
; CHECK-LABEL: test2
; CHECK-NOT: !invariant.load
; CHECK-NOT: %y = load
entry:
%x = load i32, i32* %p, align 4
%conv = trunc i32 %x to i8
store i8 %conv, i8* %q, align 1
%y = load i32, i32* %p, align 4, !invariant.load !0
%add = add i32 %y, 1
ret i32 %add
}
; With the invariant.load metadata, what would otherwise
; be a case for PRE becomes a full redundancy.
define i32 @test3(i1 %cnd, i32* %p, i32* %q) {
; CHECK-LABEL: test3
; CHECK-NOT: load
entry:
%v1 = load i32, i32* %p
br i1 %cnd, label %bb1, label %bb2
bb1:
store i32 5, i32* %q
br label %bb2
bb2:
%v2 = load i32, i32* %p, !invariant.load !0
%res = sub i32 %v1, %v2
ret i32 %res
}
; This test is here to document a case which doesn't optimize
; as well as it could.
define i32 @test4(i1 %cnd, i32* %p, i32* %q) {
; CHECK-LABEL: test4
; %v2 is redundant, but GVN currently doesn't catch that
entry:
%v1 = load i32, i32* %p, !invariant.load !0
br i1 %cnd, label %bb1, label %bb2
bb1:
store i32 5, i32* %q
br label %bb2
bb2:
%v2 = load i32, i32* %p
%res = sub i32 %v1, %v2
ret i32 %res
}
; Checks that we return the mustalias store as a def
; so that it contributes to value forwarding. Note
; that we could and should remove the store too.
define i32 @test5(i1 %cnd, i32* %p) {
; CHECK-LABEL: test5
; CHECK-LABEL: entry:
; CHECK-NEXT: store i32 5, i32* %p
; CHECK-NEXT: ret i32 5
entry:
%v1 = load i32, i32* %p, !invariant.load !0
store i32 5, i32* %p ;; must alias store, want to exploit
%v2 = load i32, i32* %p, !invariant.load !0
ret i32 %v2
}
declare void @foo()
; Clobbering (mayalias) stores, even in function calls, can be ignored
define i32 @test6(i1 %cnd, i32* %p) {
; CHECK-LABEL: test6
; CHECK-LABEL: entry:
; CHECK-NEXT: @foo
; CHECK-NEXT: ret i32 0
entry:
%v1 = load i32, i32* %p, !invariant.load !0
call void @foo()
%v2 = load i32, i32* %p, !invariant.load !0
%res = sub i32 %v1, %v2
ret i32 %res
}
declare noalias i32* @bar(...)
; Same as previous, but a function with a noalias result (since they're handled
; differently in MDA)
define i32 @test7(i1 %cnd, i32* %p) {
; CHECK-LABEL: test7
; CHECK-LABEL: entry:
; CHECK-NEXT: @bar
; CHECK-NEXT: ret i32 0
entry:
%v1 = load i32, i32* %p, !invariant.load !0
call i32* (...) @bar(i32* %p)
%v2 = load i32, i32* %p, !invariant.load !0
%res = sub i32 %v1, %v2
ret i32 %res
}
define i32 @test8(i1 %cnd, i32* %p) {
; CHECK-LABEL: test8
; CHECK: @bar
; CHECK: load i32, i32* %p2, align 4, !invariant.load
; CHECK: br label %merge
entry:
%v1 = load i32, i32* %p, !invariant.load !0
br i1 %cnd, label %taken, label %merge
taken:
%p2 = call i32* (...) @bar(i32* %p)
br label %merge
merge:
%p3 = phi i32* [%p, %entry], [%p2, %taken]
%v2 = load i32, i32* %p3, !invariant.load !0
%res = sub i32 %v1, %v2
ret i32 %res
}
!0 = !{ }