From 1fdfae05b0a4356d1ed0633bf3d6cdc6eba2e173 Mon Sep 17 00:00:00 2001 From: Benjamin Kramer Date: Sat, 24 Dec 2011 17:31:38 +0000 Subject: InstCombine: Canonicalize (2^n)-1 - x into (2^n)-1 ^ x iff x is known to be smaller than 2^n. This has the obvious advantage of being commutable and is always a win on x86 because const - x wastes a register there. On less weird architectures this may lead to a regression because other arithmetic doesn't fuse with it anymore. I'll address that problem in a followup. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@147254 91177308-0d34-0410-b5e6-96231b3b80d8 --- test/Transforms/InstCombine/sub-xor.ll | 12 ++++++++++++ 1 file changed, 12 insertions(+) create mode 100644 test/Transforms/InstCombine/sub-xor.ll (limited to 'test/Transforms/InstCombine/sub-xor.ll') diff --git a/test/Transforms/InstCombine/sub-xor.ll b/test/Transforms/InstCombine/sub-xor.ll new file mode 100644 index 0000000000..41e01fbdae --- /dev/null +++ b/test/Transforms/InstCombine/sub-xor.ll @@ -0,0 +1,12 @@ +; RUN: opt -instcombine -S < %s | FileCheck %s + +define i32 @test1(i32 %x) nounwind { + %and = and i32 %x, 31 + %sub = sub i32 63, %and + ret i32 %sub + +; CHECK: @test1 +; CHECK-NEXT: and i32 %x, 31 +; CHECK-NEXT: xor i32 %and, 63 +; CHECK-NEXT: ret +} -- cgit v1.2.3