New entry.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@29310 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/X86/README.txt b/lib/Target/X86/README.txt
index 8f5e15aa57df3ee256ee56b5285d7da0f0c7107b..c6b817b710b539df8675397b00cf09ade42e7007 100644 (file)
--- a/lib/Target/X86/README.txt
+++ b/lib/Target/X86/README.txt
@@ -729,3 +729,8 @@ float uint32_2_float( unsigned u ) {
 0000002a        flds    (%esp,1)
 0000002d        addl    $0x04,%esp
 00000030        ret
+
+//===---------------------------------------------------------------------===//
+
+When using fastcc abi, align stack slot of argument of type double on 8 byte
+boundary to improve performance.