From: Chris Lattner <sabre@nondot.org>
Date: Tue, 10 Jul 2007 20:03:50 +0000 (+0000)
Subject: add a note
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=36c5155d0f1d37b62e2782d89c084e1d5d9d0270;p=oota-llvm.git

add a note


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@38507 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Target/X86/README-SSE.txt b/lib/Target/X86/README-SSE.txt
index 08dcc278a1b..20e6a53267e 100644
--- a/lib/Target/X86/README-SSE.txt
+++ b/lib/Target/X86/README-SSE.txt
@@ -572,3 +572,29 @@ swizzle:
         ret
 
 //===---------------------------------------------------------------------===//
+
+This code:
+
+#include <emmintrin.h>
+__m128i test(long long i) { return _mm_cvtsi64x_si128(i); }
+
+Should turn into a single 'movq %rdi, %xmm0' instruction.  Instead, we 
+get this (on x86-64):
+
+_test:
+	movd %rdi, %xmm1
+	xorps %xmm0, %xmm0
+	movsd %xmm1, %xmm0
+	ret
+
+The LLVM IR is:
+
+target triple = "x86_64-apple-darwin8"
+define <2 x i64> @test(i64 %i) {
+entry:
+	%tmp10 = insertelement <2 x i64> undef, i64 %i, i32 0	
+	%tmp11 = insertelement <2 x i64> %tmp10, i64 0, i32 1
+	ret <2 x i64> %tmp11
+}
+
+//===---------------------------------------------------------------------===//