guards.ll
10.5 KB
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; RUN: opt < %s -jump-threading -dce -S | FileCheck %s
declare void @llvm.experimental.guard(i1, ...)
declare i32 @f1()
declare i32 @f2()
define i32 @branch_implies_guard(i32 %a) {
; CHECK-LABEL: @branch_implies_guard(
%cond = icmp slt i32 %a, 10
br i1 %cond, label %T1, label %F1
T1:
; CHECK: T1.split
; CHECK: %v1 = call i32 @f1()
; CHECK-NEXT: %retVal
; CHECK-NEXT: br label %Merge
%v1 = call i32 @f1()
br label %Merge
F1:
; CHECK: F1.split
; CHECK: %v2 = call i32 @f2()
; CHECK-NEXT: %retVal
; CHECK-NEXT: %condGuard
; CHECK-NEXT: call void (i1, ...) @llvm.experimental.guard(i1 %condGuard
; CHECK-NEXT: br label %Merge
%v2 = call i32 @f2()
br label %Merge
Merge:
; CHECK: Merge
; CHECK-NOT: call void(i1, ...) @llvm.experimental.guard(
%retPhi = phi i32 [ %v1, %T1 ], [ %v2, %F1 ]
%retVal = add i32 %retPhi, 10
%condGuard = icmp slt i32 %a, 20
call void(i1, ...) @llvm.experimental.guard(i1 %condGuard) [ "deopt"() ]
ret i32 %retVal
}
define i32 @not_branch_implies_guard(i32 %a) {
; CHECK-LABEL: @not_branch_implies_guard(
%cond = icmp slt i32 %a, 20
br i1 %cond, label %T1, label %F1
T1:
; CHECK: T1.split:
; CHECK-NEXT: %v1 = call i32 @f1()
; CHECK-NEXT: %retVal
; CHECK-NEXT: %condGuard
; CHECK-NEXT: call void (i1, ...) @llvm.experimental.guard(i1 %condGuard
; CHECK-NEXT: br label %Merge
%v1 = call i32 @f1()
br label %Merge
F1:
; CHECK: F1.split:
; CHECK-NEXT: %v2 = call i32 @f2()
; CHECK-NEXT: %retVal
; CHECK-NEXT: br label %Merge
%v2 = call i32 @f2()
br label %Merge
Merge:
; CHECK: Merge
; CHECK-NOT: call void(i1, ...) @llvm.experimental.guard(
%retPhi = phi i32 [ %v1, %T1 ], [ %v2, %F1 ]
%retVal = add i32 %retPhi, 10
%condGuard = icmp sgt i32 %a, 10
call void(i1, ...) @llvm.experimental.guard(i1 %condGuard) [ "deopt"() ]
ret i32 %retVal
}
define i32 @branch_overlaps_guard(i32 %a) {
; CHECK-LABEL: @branch_overlaps_guard(
%cond = icmp slt i32 %a, 20
br i1 %cond, label %T1, label %F1
T1:
; CHECK: T1:
; CHECK-NEXT: %v1 = call i32 @f1()
; CHECK-NEXT: br label %Merge
%v1 = call i32 @f1()
br label %Merge
F1:
; CHECK: F1:
; CHECK-NEXT: %v2 = call i32 @f2()
; CHECK-NEXT: br label %Merge
%v2 = call i32 @f2()
br label %Merge
Merge:
; CHECK: Merge
; CHECK: %condGuard = icmp slt i32 %a, 10
; CHECK-NEXT: call void (i1, ...) @llvm.experimental.guard(i1 %condGuard) [ "deopt"() ]
%retPhi = phi i32 [ %v1, %T1 ], [ %v2, %F1 ]
%retVal = add i32 %retPhi, 10
%condGuard = icmp slt i32 %a, 10
call void(i1, ...) @llvm.experimental.guard(i1 %condGuard) [ "deopt"() ]
ret i32 %retVal
}
define i32 @branch_doesnt_overlap_guard(i32 %a) {
; CHECK-LABEL: @branch_doesnt_overlap_guard(
%cond = icmp slt i32 %a, 10
br i1 %cond, label %T1, label %F1
T1:
; CHECK: T1:
; CHECK-NEXT: %v1 = call i32 @f1()
; CHECK-NEXT: br label %Merge
%v1 = call i32 @f1()
br label %Merge
F1:
; CHECK: F1:
; CHECK-NEXT: %v2 = call i32 @f2()
; CHECK-NEXT: br label %Merge
%v2 = call i32 @f2()
br label %Merge
Merge:
; CHECK: Merge
; CHECK: %condGuard = icmp sgt i32 %a, 20
; CHECK-NEXT: call void (i1, ...) @llvm.experimental.guard(i1 %condGuard) [ "deopt"() ]
%retPhi = phi i32 [ %v1, %T1 ], [ %v2, %F1 ]
%retVal = add i32 %retPhi, 10
%condGuard = icmp sgt i32 %a, 20
call void(i1, ...) @llvm.experimental.guard(i1 %condGuard) [ "deopt"() ]
ret i32 %retVal
}
define i32 @not_a_diamond1(i32 %a, i1 %cond1) {
; CHECK-LABEL: @not_a_diamond1(
br i1 %cond1, label %Pred, label %Exit
Pred:
; CHECK: Pred:
; CHECK-NEXT: switch i32 %a, label %Exit
switch i32 %a, label %Exit [
i32 10, label %Merge
i32 20, label %Merge
]
Merge:
; CHECK: Merge:
; CHECK-NEXT: call void (i1, ...) @llvm.experimental.guard(i1 %cond1) [ "deopt"() ]
; CHECK-NEXT: br label %Exit
call void(i1, ...) @llvm.experimental.guard(i1 %cond1) [ "deopt"() ]
br label %Exit
Exit:
; CHECK: Exit:
; CHECK-NEXT: ret i32 %a
ret i32 %a
}
define void @not_a_diamond2(i32 %a, i1 %cond1) {
; CHECK-LABEL: @not_a_diamond2(
br label %Parent
Merge:
call void(i1, ...) @llvm.experimental.guard(i1 %cond1)[ "deopt"() ]
ret void
Pred:
; CHECK-NEXT: Pred:
; CHECK-NEXT: switch i32 %a, label %Exit
switch i32 %a, label %Exit [
i32 10, label %Merge
i32 20, label %Merge
]
Parent:
br label %Pred
Exit:
; CHECK: Merge:
; CHECK-NEXT: call void (i1, ...) @llvm.experimental.guard(i1 %cond1) [ "deopt"() ]
; CHECK-NEXT: ret void
ret void
}
declare void @never_called(i1)
; LVI uses guard to identify value of %c2 in branch as true, we cannot replace that
; guard with guard(true & c1).
define void @dont_fold_guard(i8* %addr, i32 %i, i32 %length) {
; CHECK-LABEL: dont_fold_guard
; CHECK: %wide.chk = and i1 %c1, %c2
; CHECK-NEXT: experimental.guard(i1 %wide.chk)
; CHECK-NEXT: call void @never_called(i1 true)
; CHECK-NEXT: ret void
%c1 = icmp ult i32 %i, %length
%c2 = icmp eq i32 %i, 0
%wide.chk = and i1 %c1, %c2
call void(i1, ...) @llvm.experimental.guard(i1 %wide.chk) [ "deopt"() ]
br i1 %c2, label %BB1, label %BB2
BB1:
call void @never_called(i1 %c2)
ret void
BB2:
ret void
}
declare void @dummy(i1) nounwind argmemonly
; same as dont_fold_guard1 but there's a use immediately after guard and before
; branch. We can fold that use.
define void @dont_fold_guard2(i8* %addr, i32 %i, i32 %length) {
; CHECK-LABEL: dont_fold_guard2
; CHECK: %wide.chk = and i1 %c1, %c2
; CHECK-NEXT: experimental.guard(i1 %wide.chk)
; CHECK-NEXT: dummy(i1 true)
; CHECK-NEXT: call void @never_called(i1 true)
; CHECK-NEXT: ret void
%c1 = icmp ult i32 %i, %length
%c2 = icmp eq i32 %i, 0
%wide.chk = and i1 %c1, %c2
call void(i1, ...) @llvm.experimental.guard(i1 %wide.chk) [ "deopt"() ]
call void @dummy(i1 %c2)
br i1 %c2, label %BB1, label %BB2
BB1:
call void @never_called(i1 %c2)
ret void
BB2:
ret void
}
; same as dont_fold_guard1 but condition %cmp is not an instruction.
; We cannot fold the guard under any circumstance.
; FIXME: We can merge unreachableBB2 into not_zero.
define void @dont_fold_guard3(i8* %addr, i1 %cmp, i32 %i, i32 %length) {
; CHECK-LABEL: dont_fold_guard3
; CHECK: guard(i1 %cmp)
call void(i1, ...) @llvm.experimental.guard(i1 %cmp) [ "deopt"() ]
br i1 %cmp, label %BB1, label %BB2
BB1:
call void @never_called(i1 %cmp)
ret void
BB2:
ret void
}
declare void @f(i1)
; Same as dont_fold_guard1 but use switch instead of branch.
; triggers source code `ProcessThreadableEdges`.
define void @dont_fold_guard4(i1 %cmp1, i32 %i) nounwind {
; CHECK-LABEL: dont_fold_guard4
; CHECK-LABEL: L2:
; CHECK-NEXT: %cmp = icmp eq i32 %i, 0
; CHECK-NEXT: guard(i1 %cmp)
; CHECK-NEXT: dummy(i1 true)
; CHECK-NEXT: @f(i1 true)
; CHECK-NEXT: ret void
entry:
br i1 %cmp1, label %L0, label %L3
L0:
%cmp = icmp eq i32 %i, 0
call void(i1, ...) @llvm.experimental.guard(i1 %cmp) [ "deopt"() ]
call void @dummy(i1 %cmp)
switch i1 %cmp, label %L3 [
i1 false, label %L1
i1 true, label %L2
]
L1:
ret void
L2:
call void @f(i1 %cmp)
ret void
L3:
ret void
}
; Make sure that we don't PRE a non-speculable load across a guard.
define void @unsafe_pre_across_guard(i8* %p, i1 %load.is.valid) {
; CHECK-LABEL: @unsafe_pre_across_guard(
; CHECK-NOT: loaded.pr
; CHECK: entry:
; CHECK-NEXT: br label %loop
; CHECK: loop:
; CHECK-NEXT: call void (i1, ...) @llvm.experimental.guard(i1 %load.is.valid) [ "deopt"() ]
; CHECK-NEXT: %loaded = load i8, i8* %p
; CHECK-NEXT: %continue = icmp eq i8 %loaded, 0
; CHECK-NEXT: br i1 %continue, label %exit, label %loop
entry:
br label %loop
loop: ; preds = %loop, %entry
call void (i1, ...) @llvm.experimental.guard(i1 %load.is.valid) [ "deopt"() ]
%loaded = load i8, i8* %p
%continue = icmp eq i8 %loaded, 0
br i1 %continue, label %exit, label %loop
exit: ; preds = %loop
ret void
}
; Make sure that we can safely PRE a speculable load across a guard.
define void @safe_pre_across_guard(i8* noalias nocapture readonly dereferenceable(8) %p, i1 %load.is.valid) {
; CHECK-LABEL: @safe_pre_across_guard(
; CHECK: entry:
; CHECK-NEXT: %loaded.pr = load i8, i8* %p
; CHECK-NEXT: br label %loop
; CHECK: loop:
; CHECK-NEXT: %loaded = phi i8 [ %loaded, %loop ], [ %loaded.pr, %entry ]
; CHECK-NEXT: call void (i1, ...) @llvm.experimental.guard(i1 %load.is.valid) [ "deopt"() ]
; CHECK-NEXT: %continue = icmp eq i8 %loaded, 0
; CHECK-NEXT: br i1 %continue, label %exit, label %loop
entry:
br label %loop
loop: ; preds = %loop, %entry
call void (i1, ...) @llvm.experimental.guard(i1 %load.is.valid) [ "deopt"() ]
%loaded = load i8, i8* %p
%continue = icmp eq i8 %loaded, 0
br i1 %continue, label %exit, label %loop
exit: ; preds = %loop
ret void
}
; Make sure that we don't PRE a non-speculable load across a call which may
; alias with the load.
define void @unsafe_pre_across_call(i8* %p) {
; CHECK-LABEL: @unsafe_pre_across_call(
; CHECK-NOT: loaded.pr
; CHECK: entry:
; CHECK-NEXT: br label %loop
; CHECK: loop:
; CHECK-NEXT: call i32 @f1()
; CHECK-NEXT: %loaded = load i8, i8* %p
; CHECK-NEXT: %continue = icmp eq i8 %loaded, 0
; CHECK-NEXT: br i1 %continue, label %exit, label %loop
entry:
br label %loop
loop: ; preds = %loop, %entry
call i32 @f1()
%loaded = load i8, i8* %p
%continue = icmp eq i8 %loaded, 0
br i1 %continue, label %exit, label %loop
exit: ; preds = %loop
ret void
}
; Make sure that we can safely PRE a speculable load across a call.
define void @safe_pre_across_call(i8* noalias nocapture readonly dereferenceable(8) %p) {
; CHECK-LABEL: @safe_pre_across_call(
; CHECK: entry:
; CHECK-NEXT: %loaded.pr = load i8, i8* %p
; CHECK-NEXT: br label %loop
; CHECK: loop:
; CHECK-NEXT: %loaded = phi i8 [ %loaded, %loop ], [ %loaded.pr, %entry ]
; CHECK-NEXT: call i32 @f1()
; CHECK-NEXT: %continue = icmp eq i8 %loaded, 0
; CHECK-NEXT: br i1 %continue, label %exit, label %loop
entry:
br label %loop
loop: ; preds = %loop, %entry
call i32 @f1()
%loaded = load i8, i8* %p
%continue = icmp eq i8 %loaded, 0
br i1 %continue, label %exit, label %loop
exit: ; preds = %loop
ret void
}