[Attributor] Deduce "dereferenceable" attribute

Summary:
Deduce dereferenceable attribute in Attributor.

These will be added in a later patch.
* dereferenceable(_or_null)_globally (D61652)
* Deduction based on load instruction (similar to D64258)

Reviewers: jdoerfert, sstefan1

Reviewed By: jdoerfert

Subscribers: hiraditya, jfb, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D64876

llvm-svn: 366788

1 files changed, 52 insertions, 0 deletions

diff --git a/llvm/test/Transforms/FunctionAttrs/dereferenceable.ll b/llvm/test/Transforms/FunctionAttrs/dereferenceable.ll
new file mode 100644
index 00000000000..16459fc4c42
--- /dev/null
+++ b/llvm/test/Transforms/FunctionAttrs/dereferenceable.ll
@@ -0,0 +1,52 @@
+; RUN: opt -attributor --attributor-disable=false -S < %s | FileCheck %s --check-prefixes=ATTRIBUTOR
+
+
+; TEST 1
+; take mininimum of return values
+;
+define i32* @test1(i32* dereferenceable(4), double* dereferenceable(8), i1 zeroext) local_unnamed_addr {
+; ATTRIBUTOR: define nonnull dereferenceable(4) i32* @test1(i32* nonnull dereferenceable(4), double* nonnull dereferenceable(8), i1 zeroext)
+  %4 = bitcast double* %1 to i32*
+  %5 = select i1 %2, i32* %0, i32* %4
+  ret i32* %5
+}
+
+; TEST 2
+define i32* @test2(i32* dereferenceable_or_null(4), double* dereferenceable(8), i1 zeroext) local_unnamed_addr {
+; ATTRIBUTOR: define dereferenceable_or_null(4) i32* @test2(i32* dereferenceable_or_null(4), double* nonnull dereferenceable(8), i1 zeroext)
+  %4 = bitcast double* %1 to i32*
+  %5 = select i1 %2, i32* %0, i32* %4
+  ret i32* %5
+}
+
+; TEST 3
+; GEP inbounds
+define i32* @test3_1(i32* dereferenceable(8)) local_unnamed_addr {
+; ATTRIBUTOR: define nonnull dereferenceable(4) i32* @test3_1(i32* nonnull dereferenceable(8))
+  %ret = getelementptr inbounds i32, i32* %0, i64 1
+  ret i32* %ret
+}
+
+define i32* @test3_2(i32* dereferenceable_or_null(32)) local_unnamed_addr {
+; FIXME: Argument should be mark dereferenceable because of GEP `inbounds`.
+; ATTRIBUTOR: define nonnull dereferenceable(16) i32* @test3_2(i32* dereferenceable_or_null(32))
+  %ret = getelementptr inbounds i32, i32* %0, i64 4
+  ret i32* %ret
+}
+
+define i32* @test3_3(i32* dereferenceable(8), i32* dereferenceable(16), i1) local_unnamed_addr {
+; ATTRIBUTOR: define nonnull dereferenceable(4) i32* @test3_3(i32* nonnull dereferenceable(8), i32* nonnull dereferenceable(16), i1) local_unnamed_addr
+  %ret1 = getelementptr inbounds i32, i32* %0, i64 1
+  %ret2 = getelementptr inbounds i32, i32* %1, i64 2
+  %ret = select i1 %2, i32* %ret1, i32* %ret2
+  ret i32* %ret
+}
+
+; TEST 4
+; Better than known in IR.
+
+define dereferenceable(4) i32* @test4(i32* dereferenceable(8)) local_unnamed_addr {
+; ATTRIBUTOR: define nonnull dereferenceable(8) i32* @test4(i32* nonnull returned dereferenceable(8))
+  ret i32* %0
+}
+