[llvm-commits] CVS: llvm/lib/Target/X86/README.txt

[Chris Lattner]

Changes in directory llvm/lib/Target/X86:

README.txt updated: 1.136 -> 1.137
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Log message:

add a note


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Diffs of the changes:  (+16 -0)

 README.txt |   16 ++++++++++++++++
 1 files changed, 16 insertions(+)


Index: llvm/lib/Target/X86/README.txt
diff -u llvm/lib/Target/X86/README.txt:1.136 llvm/lib/Target/X86/README.txt:1.137
--- llvm/lib/Target/X86/README.txt:1.136	Mon Sep 18 00:36:54 2006
+++ llvm/lib/Target/X86/README.txt	Wed Sep 20 01:32:10 2006
@@ -734,3 +734,19 @@
 	addl $12, %esp
 
 The add\sub pair is really unneeded here.
+
+//===---------------------------------------------------------------------===//
+
+We generate really bad code in some cases due to lowering SETCC/SELECT at 
+legalize time, which prevents the post-legalize dag combine pass from
+understanding the code.  As a silly example, this prevents us from folding 
+stuff like this:
+
+bool %test(ulong %x) {
+  %tmp = setlt ulong %x, 4294967296
+  ret bool %tmp
+}
+
+into x.h == 0
+
+