From: Chris Lattner <sabre@nondot.org>
Date: Wed, 4 Feb 2009 19:09:07 +0000 (+0000)
Subject: Bill implemented this.
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=e6c1473e5628e719bddd10da16c54ae8b79e1ef2;p=oota-llvm.git

Bill implemented this.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@63752 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Target/X86/README-SSE.txt b/lib/Target/X86/README-SSE.txt
index 67cad42a354..71ad51c7984 100644
--- a/lib/Target/X86/README-SSE.txt
+++ b/lib/Target/X86/README-SSE.txt
@@ -840,42 +840,6 @@ _t:
 	shufps	$132, %xmm2, %xmm0
 	movaps	%xmm0, 0
 
-//===---------------------------------------------------------------------===//
-rdar://6037315
-
-llvm-gcc-4.2 does the following for uint32_t -> float conversions on i386:
-
-	uint32_t x;
-	float y = (float)x;
-
-becomes:
-
-movl	%eax,		-8(%ebp)	// write x to the stack
-movl	$0x3ff00000,	-4(%ebp)	// 2^52 + x as a double at -4(%ebp)
-movsd	-8(%ebp),		%xmm0
-subsd	[2^52 double], 	%xmm0	// subtract 2^52 -- this is exact
-cvtsd2ss %xmm0,		%xmm0	// convert to single -- rounding happens here
-
-On merom/yonah, this takes a substantial stall.  The following is a much 
-better option:
-
-movd	%eax,		%xmm0	// load x into low word of xmm0
-movsd	[2^52 double],	%xmm1 	// load 2^52 into xmm1
-orpd	%xmm1,		%xmm0	// 2^52 + x in double precision
-subsd	%xmm1,		%xmm0	// x in double precision
-cvtsd2ss %xmm0,		%xmm0	// x rounded to single precision
-
-IF we don't already need PIC, then the following is even faster still, at a 
-small cost to code size:
-
-movl		$0x3ff00000,	%ecx		// conjure high word of 2^52
-movd		%ecx,		%xmm1
-movss	%eax,		%xmm0	// load x into low word of xmm0
-psllq		$32,			%xmm1	// 2^52
-orpd		%xmm1,		%xmm0	// 2^52 + x in double precision
-subsd		%xmm1,		%xmm0	// x in double precision
-cvtsd2ss	%xmm0,		%xmm0	// x in single precision
-
 //===---------------------------------------------------------------------===//
 rdar://5907648