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| -rw-r--r-- | lib/Target/X86/README.txt | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/lib/Target/X86/README.txt b/lib/Target/X86/README.txt index 1912888897..710bd03574 100644 --- a/lib/Target/X86/README.txt +++ b/lib/Target/X86/README.txt @@ -1883,3 +1883,17 @@ On Nehalem, it may even be cheaper to just use movups when unaligned than to fall back to lower-granularity chunks. //===---------------------------------------------------------------------===// + +Implement processor-specific optimizations for parity with GCC on these +processors. GCC does two optimizations: + +1. ix86_pad_returns inserts a noop before ret instructions if immediately + preceeded by a conditional branch or is the target of a jump. +2. ix86_avoid_jump_misspredicts inserts noops in cases where a 16-byte block of + code contains more than 3 branches. + +The first one is done for all AMDs, Core2, and "Generic" +The second one is done for: Atom, Pentium Pro, all AMDs, Pentium 4, Nocona, + Core 2, and "Generic" + +//===---------------------------------------------------------------------===// |