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| author | Piotr Padlewski <piotr.padlewski@gmail.com> | 2018-07-12 23:55:20 +0000 |
|---|---|---|
| committer | Piotr Padlewski <piotr.padlewski@gmail.com> | 2018-07-12 23:55:20 +0000 |
| commit | c63b492bcdf2dd73b836e357cc7bc9fa02a69c00 (patch) | |
| tree | 39cbb920c4bf881f713344a3d183b9dd84281598 /llvm/test/Analysis/ValueTracking | |
| parent | c379d1a424badc74906db37c6c826e5b4a155b25 (diff) | |
| download | bcm5719-llvm-c63b492bcdf2dd73b836e357cc7bc9fa02a69c00.tar.gz bcm5719-llvm-c63b492bcdf2dd73b836e357cc7bc9fa02a69c00.zip | |
Simplify recursive launder.invariant.group and strip
Summary:
This patch is crucial for proving equality laundered/stripped
pointers. eg:
bool foo(A *a) {
return a == std::launder(a);
}
Clang with -fstrict-vtable-pointers will emit something like:
define dso_local zeroext i1 @_Z3fooP1A(%struct.A* %a) {
entry:
%c = bitcast %struct.A* %a to i8*
%call = tail call i8* @llvm.launder.invariant.group.p0i8(i8* %c)
%0 = bitcast %struct.A* %a to i8*
%1 = tail call i8* @llvm.strip.invariant.group.p0i8(i8* %0)
%2 = tail call i8* @llvm.strip.invariant.group.p0i8(i8* %call)
%cmp = icmp eq i8* %1, %2
ret i1 %cmp
}
and because %2 can be replaced with @llvm.strip.invariant.group(%0)
and that %2 and %1 will produce the same value (because strip is readnone)
we can replace compare with true.
Reviewers: rsmith, hfinkel, majnemer, amharc, kuhar
Subscribers: llvm-commits, hiraditya
Differential Revision: https://reviews.llvm.org/D47423
llvm-svn: 336963
Diffstat (limited to 'llvm/test/Analysis/ValueTracking')
| -rw-r--r-- | llvm/test/Analysis/ValueTracking/invariant.group.ll | 10 |
1 files changed, 4 insertions, 6 deletions
diff --git a/llvm/test/Analysis/ValueTracking/invariant.group.ll b/llvm/test/Analysis/ValueTracking/invariant.group.ll index 70c32e19172..ca81b9a6aad 100644 --- a/llvm/test/Analysis/ValueTracking/invariant.group.ll +++ b/llvm/test/Analysis/ValueTracking/invariant.group.ll @@ -2,9 +2,8 @@ ; CHECK-LABEL: define void @checkNonnullLaunder() define void @checkNonnullLaunder() { -; CHECK: %p = call i8* @llvm.launder.invariant.group.p0i8(i8* nonnull %0) -; CHECK: %p2 = call i8* @llvm.launder.invariant.group.p0i8(i8* nonnull %p) -; CHECK: call void @use(i8* nonnull %p2) +; CHECK: %[[p:.*]] = call i8* @llvm.launder.invariant.group.p0i8(i8* nonnull %0) +; CHECK: call void @use(i8* nonnull %[[p]]) entry: %0 = alloca i8, align 8 @@ -17,9 +16,8 @@ entry: ; CHECK-LABEL: define void @checkNonnullStrip() define void @checkNonnullStrip() { -; CHECK: %p = call i8* @llvm.strip.invariant.group.p0i8(i8* nonnull %0) -; CHECK: %p2 = call i8* @llvm.strip.invariant.group.p0i8(i8* nonnull %p) -; CHECK: call void @use(i8* nonnull %p2) +; CHECK: %[[p:.*]] = call i8* @llvm.strip.invariant.group.p0i8(i8* nonnull %0) +; CHECK: call void @use(i8* nonnull %[[p]]) entry: %0 = alloca i8, align 8 |
