Author: lattner
Date: Fri Jan 11 12:00:13 2008
New Revision: 45869
URL: http://llvm.org/viewvc/llvm-project?rev=45869&view=rev
Log:
add a note, remove a done deed.
Modified:
llvm/trunk/lib/Target/X86/README.txt
Modified: llvm/trunk/lib/Target/X86/README.txt
URL:
http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/README.txt?rev=45869&r1=45868&r2=45869&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/README.txt (original)
+++ llvm/trunk/lib/Target/X86/README.txt Fri Jan 11 12:00:13 2008
@@ -998,24 +998,6 @@
//===---------------------------------------------------------------------===//
-For code like:
-phi (undef, x)
-
-We get an implicit def on the undef side. If the phi is spilled, we then get:
-implicitdef xmm1
-store xmm1 -> stack
-
-It should be possible to teach the x86 backend to "fold" the store into the
-implicitdef, which just deletes the implicit def.
-
-These instructions should go away:
-#IMPLICIT_DEF %xmm1
-movaps %xmm1, 192(%esp)
-movaps %xmm1, 224(%esp)
-movaps %xmm1, 176(%esp)
-
-//===---------------------------------------------------------------------===//
-
This is a "commutable two-address" register coallescing deficiency:
define <4 x float> @test1(<4 x float> %V) {
@@ -1510,6 +1492,9 @@
if the flags of the xor are dead.
+Likewise, we isel "x<<1" into "add reg,reg". If reg is spilled, this should
+be folded into: shl [mem], 1
+
//===---------------------------------------------------------------------===//
This testcase misses a read/modify/write opportunity (from PR1425):
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