From 930469107d34d66b015f6e48b3f05554819216d8 Mon Sep 17 00:00:00 2001 From: Hal Finkel Date: Fri, 25 Jul 2014 21:13:35 +0000 Subject: Add @llvm.assume, lowering, and some basic properties This is the first commit in a series that add an @llvm.assume intrinsic which can be used to provide the optimizer with a condition it may assume to be true (when the control flow would hit the intrinsic call). Some basic properties are added here: - llvm.invariant(true) is dead. - llvm.invariant(false) is unreachable (this directly corresponds to the documented behavior of MSVC's __assume(0)), so is llvm.invariant(undef). The intrinsic is tagged as writing arbitrarily, in order to maintain control dependencies. BasicAA has been updated, however, to return NoModRef for any particular location-based query so that we don't unnecessarily block code motion. llvm-svn: 213973 --- llvm/test/Transforms/InstSimplify/assume.ll | 13 +++++++++++++ 1 file changed, 13 insertions(+) create mode 100644 llvm/test/Transforms/InstSimplify/assume.ll (limited to 'llvm/test/Transforms/InstSimplify/assume.ll') diff --git a/llvm/test/Transforms/InstSimplify/assume.ll b/llvm/test/Transforms/InstSimplify/assume.ll new file mode 100644 index 00000000000..4dd0a8f4a82 --- /dev/null +++ b/llvm/test/Transforms/InstSimplify/assume.ll @@ -0,0 +1,13 @@ +; RUN: opt -instsimplify -S < %s | FileCheck %s + +define void @test1() { + call void @llvm.assume(i1 1) + ret void + +; CHECK-LABEL: @test1 +; CHECK-NOT: llvm.assume +; CHECK: ret void +} + +declare void @llvm.assume(i1) nounwind + -- cgit v1.2.3