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Minor x86 README updates.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@126054 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Eli Friedman 2011-02-19 21:54:28 +00:00
parent 37d42f8a50
commit 86b115c78b
1 changed files with 14 additions and 20 deletions
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34
lib/Target/X86/README.txt
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@ -710,23 +710,17 @@ This:
{ return !full_add(a, b).second; } { return !full_add(a, b).second; }
Should compile to: Should compile to:
addl %esi, %edi
setae %al
movzbl %al, %eax
ret
on x86-64, instead of the rather stupid-looking:
_Z11no_overflowjj: addl %esi, %edi
addl %edi, %esi setb %al
setae %al xorb $1, %al
ret movzbl %al, %eax
ret
FIXME: That code looks wrong; bool return is normally defined as zext.
on x86-64, not:
__Z11no_overflowjj:
addl %edi, %esi
cmpl %edi, %esi
setae %al
movzbl %al, %eax
ret
//===---------------------------------------------------------------------===// //===---------------------------------------------------------------------===//
@ -994,10 +988,10 @@ _foo:
instead of: instead of:
_foo: _foo:
movl $255, %eax movl $65280, %eax
orl 4(%esp), %eax andl 4(%esp), %eax
andl $65535, %eax orl $255, %eax
ret ret
//===---------------------------------------------------------------------===// //===---------------------------------------------------------------------===//