From f73fb88688e5cbc851596d7ad50e1f257048953a Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Mon, 18 Sep 2006 05:36:54 +0000 Subject: [PATCH] add a note. Our 64-bit shifts are ~30% slower than gcc's git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@30457 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Target/X86/README.txt | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/lib/Target/X86/README.txt b/lib/Target/X86/README.txt index 62c8ab1dcc0..dd02948f870 100644 --- a/lib/Target/X86/README.txt +++ b/lib/Target/X86/README.txt @@ -59,7 +59,8 @@ One better solution for 1LL << x is: But that requires good 8-bit subreg support. - +64-bit shifts (in general) expand to really bad code. Instead of using +cmovs, we should expand to a conditional branch like GCC produces. //===---------------------------------------------------------------------===//