From 57ed0948b87206beadce58c406f95dda345fe62c Mon Sep 17 00:00:00 2001 From: Nick Lewycky Date: Sat, 31 Dec 2011 21:30:22 +0000 Subject: Make use of the exact bit when optimizing '(X >>exact 3) << 1' to eliminate the 'and' that would zero out the trailing bits, and to produce an exact shift ourselves. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@147391 91177308-0d34-0410-b5e6-96231b3b80d8 --- test/Transforms/InstCombine/shift.ll | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) (limited to 'test/Transforms/InstCombine/shift.ll') diff --git a/test/Transforms/InstCombine/shift.ll b/test/Transforms/InstCombine/shift.ll index 132d51a660..0dd969b8c0 100644 --- a/test/Transforms/InstCombine/shift.ll +++ b/test/Transforms/InstCombine/shift.ll @@ -542,3 +542,21 @@ define i32 @test45(i32 %a) nounwind { ; CHECK-NEXT: %y = lshr i32 %a, 5 ; CHECK-NEXT: ret i32 %y } + +define i32 @test46(i32 %a) { + %y = ashr exact i32 %a, 3 + %z = shl i32 %y, 1 + ret i32 %z +; CHECK: @test46 +; CHECK-NEXT: %z = ashr exact i32 %a, 2 +; CHECK-NEXT: ret i32 %z +} + +define i32 @test47(i32 %a) { + %y = lshr exact i32 %a, 3 + %z = shl i32 %y, 1 + ret i32 %z +; CHECK: @test47 +; CHECK-NEXT: %z = lshr exact i32 %a, 2 +; CHECK-NEXT: ret i32 %z +} -- cgit v1.2.3