From cd9e155755dab1913238ffc0374111a39d500adf Mon Sep 17 00:00:00 2001 From: Dan Gohman Date: Tue, 19 Jan 2010 23:30:49 +0000 Subject: Fold (add x, shl(0 - y, n)) -> sub(x, shl(y, n)), to simplify some code that SCEVExpander can produce when running on behalf of LSR. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@93949 91177308-0d34-0410-b5e6-96231b3b80d8 --- test/CodeGen/X86/neg-shl-add.ll | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) create mode 100644 test/CodeGen/X86/neg-shl-add.ll (limited to 'test/CodeGen/X86/neg-shl-add.ll') diff --git a/test/CodeGen/X86/neg-shl-add.ll b/test/CodeGen/X86/neg-shl-add.ll new file mode 100644 index 0000000000..7aebc383dd --- /dev/null +++ b/test/CodeGen/X86/neg-shl-add.ll @@ -0,0 +1,17 @@ +; RUN: llc -march=x86-64 < %s | not grep negq + +; These sequences don't need neg instructions; they can be done with +; a single shift and sub each. + +define i64 @foo(i64 %x, i64 %y, i64 %n) nounwind { + %a = sub i64 0, %y + %b = shl i64 %a, %n + %c = add i64 %b, %x + ret i64 %c +} +define i64 @boo(i64 %x, i64 %y, i64 %n) nounwind { + %a = sub i64 0, %y + %b = shl i64 %a, %n + %c = add i64 %x, %b + ret i64 %c +} -- cgit v1.2.3