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; Tests that check our handling of volatile instructions encountered
; when scanning for dependencies
; RUN: opt -basicaa -gvn -S < %s | FileCheck %s
; Check that we can bypass a volatile load when searching
; for dependencies of a non-volatile load
define i32 @test1(i32* nocapture %p, i32* nocapture %q) {
; CHECK-LABEL: test1
; CHECK: %0 = load volatile i32, i32* %q
; CHECK-NEXT: ret i32 0
entry:
%x = load i32, i32* %p
load volatile i32, i32* %q
%y = load i32, i32* %p
%add = sub i32 %y, %x
ret i32 %add
}
; We can not value forward if the query instruction is
; volatile, this would be (in effect) removing the volatile load
define i32 @test2(i32* nocapture %p, i32* nocapture %q) {
; CHECK-LABEL: test2
; CHECK: %x = load i32, i32* %p
; CHECK-NEXT: %y = load volatile i32, i32* %p
; CHECK-NEXT: %add = sub i32 %y, %x
entry:
%x = load i32, i32* %p
%y = load volatile i32, i32* %p
%add = sub i32 %y, %x
ret i32 %add
}
; If the query instruction is itself volatile, we *cannot*
; reorder it even if p and q are noalias
define i32 @test3(i32* noalias nocapture %p, i32* noalias nocapture %q) {
; CHECK-LABEL: test3
; CHECK: %x = load i32, i32* %p
; CHECK-NEXT: %0 = load volatile i32, i32* %q
; CHECK-NEXT: %y = load volatile i32, i32* %p
entry:
%x = load i32, i32* %p
load volatile i32, i32* %q
%y = load volatile i32, i32* %p
%add = sub i32 %y, %x
ret i32 %add
}
; If an encountered instruction is both volatile and ordered,
; we need to use the strictest ordering of either. In this
; case, the ordering prevents forwarding.
define i32 @test4(i32* noalias nocapture %p, i32* noalias nocapture %q) {
; CHECK-LABEL: test4
; CHECK: %x = load i32, i32* %p
; CHECK-NEXT: %0 = load atomic volatile i32, i32* %q seq_cst
; CHECK-NEXT: %y = load atomic i32, i32* %p seq_cst
entry:
%x = load i32, i32* %p
load atomic volatile i32, i32* %q seq_cst, align 4
%y = load atomic i32, i32* %p seq_cst, align 4
%add = sub i32 %y, %x
ret i32 %add
}
; Value forwarding from a volatile load is perfectly legal
define i32 @test5(i32* nocapture %p, i32* nocapture %q) {
; CHECK-LABEL: test5
; CHECK: %x = load volatile i32, i32* %p
; CHECK-NEXT: ret i32 0
entry:
%x = load volatile i32, i32* %p
%y = load i32, i32* %p
%add = sub i32 %y, %x
ret i32 %add
}
; Does cross block redundancy elimination work with volatiles?
define i32 @test6(i32* noalias nocapture %p, i32* noalias nocapture %q) {
; CHECK-LABEL: test6
; CHECK: %y1 = load i32, i32* %p
; CHECK-LABEL: header
; CHECK: %x = load volatile i32, i32* %q
; CHECK-NEXT: %add = sub i32 %y1, %x
entry:
%y1 = load i32, i32* %p
call void @use(i32 %y1)
br label %header
header:
%x = load volatile i32, i32* %q
%y = load i32, i32* %p
%add = sub i32 %y, %x
%cnd = icmp eq i32 %add, 0
br i1 %cnd, label %exit, label %header
exit:
ret i32 %add
}
; Does cross block PRE work with volatiles?
define i32 @test7(i1 %c, i32* noalias nocapture %p, i32* noalias nocapture %q) {
; CHECK-LABEL: test7
; CHECK-LABEL: entry.header_crit_edge:
; CHECK: %y.pre = load i32, i32* %p
; CHECK-LABEL: skip:
; CHECK: %y1 = load i32, i32* %p
; CHECK-LABEL: header:
; CHECK: %y = phi i32
; CHECK-NEXT: %x = load volatile i32, i32* %q
; CHECK-NEXT: %add = sub i32 %y, %x
entry:
br i1 %c, label %header, label %skip
skip:
%y1 = load i32, i32* %p
call void @use(i32 %y1)
br label %header
header:
%x = load volatile i32, i32* %q
%y = load i32, i32* %p
%add = sub i32 %y, %x
%cnd = icmp eq i32 %add, 0
br i1 %cnd, label %exit, label %header
exit:
ret i32 %add
}
; Another volatile PRE case - two paths through a loop
; load in preheader, one path read only, one not
define i32 @test8(i1 %b, i1 %c, i32* noalias %p, i32* noalias %q) {
; CHECK-LABEL: test8
; CHECK-LABEL: entry
; CHECK: %y1 = load i32, i32* %p
; CHECK-LABEL: header:
; CHECK: %y = phi i32
; CHECK-NEXT: %x = load volatile i32, i32* %q
; CHECK-NOT: load
; CHECK-LABEL: skip.header_crit_edge:
; CHECK: %y.pre = load i32, i32* %p
entry:
%y1 = load i32, i32* %p
call void @use(i32 %y1)
br label %header
header:
%x = load volatile i32, i32* %q
%y = load i32, i32* %p
call void @use(i32 %y)
br i1 %b, label %skip, label %header
skip:
; escaping the arguments is explicitly required since we marked
; them noalias
call void @clobber(i32* %p, i32* %q)
br i1 %c, label %header, label %exit
exit:
%add = sub i32 %y, %x
ret i32 %add
}
declare void @use(i32) readonly
declare void @clobber(i32* %p, i32* %q)
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