llvm-6502/test/Transforms/InstSimplify/assume.ll at b51b170ce4edfe4240a2222e4a7694a5aa15b723 - llvm-6502 - Applefritter: Git

6502/llvm-6502

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Hal Finkel 8ef7b17dfc 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.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@213973 91177308-0d34-0410-b5e6-96231b3b80d8

2014-07-25 21:13:35 +00:00

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 ; 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