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authorEvan Cheng <evan.cheng@apple.com>2008-11-11 17:35:52 +0000
committerEvan Cheng <evan.cheng@apple.com>2008-11-11 17:35:52 +0000
commitbf97becf6793e5775553c60a984b902977d8b9de (patch)
tree5d4f71c02061ee838365fb151678984c663874fb /lib
parentfe9c35bec83f8aa1bfca04e6fe883cad759eabdd (diff)
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Add a README entry.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@59052 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib')
-rw-r--r--lib/Target/X86/README.txt17
1 files changed, 17 insertions, 0 deletions
diff --git a/lib/Target/X86/README.txt b/lib/Target/X86/README.txt
index 53c002b..9274762 100644
--- a/lib/Target/X86/README.txt
+++ b/lib/Target/X86/README.txt
@@ -1773,3 +1773,20 @@ gcc 4.3 generates:
movl 12(%ebp), %eax
popl %ebp
ret
+
+//===---------------------------------------------------------------------===//
+
+Teach tblgen not to check bitconvert source type in some cases. This allows us
+to consolidate the following patterns in X86InstrMMX.td:
+
+def : Pat<(v2i32 (bitconvert (i64 (vector_extract (v2i64 VR128:$src),
+ (iPTR 0))))),
+ (v2i32 (MMX_MOVDQ2Qrr VR128:$src))>;
+def : Pat<(v4i16 (bitconvert (i64 (vector_extract (v2i64 VR128:$src),
+ (iPTR 0))))),
+ (v4i16 (MMX_MOVDQ2Qrr VR128:$src))>;
+def : Pat<(v8i8 (bitconvert (i64 (vector_extract (v2i64 VR128:$src),
+ (iPTR 0))))),
+ (v8i8 (MMX_MOVDQ2Qrr VR128:$src))>;
+
+There are other cases in various td files.