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Diffstat (limited to 'lib/Target/X86/README.txt')
| -rw-r--r-- | lib/Target/X86/README.txt | 27 |
1 files changed, 27 insertions, 0 deletions
diff --git a/lib/Target/X86/README.txt b/lib/Target/X86/README.txt index f3b091b..1f53227 100644 --- a/lib/Target/X86/README.txt +++ b/lib/Target/X86/README.txt @@ -1178,3 +1178,30 @@ We should sink the load into xmm3 into the LBB1_2 block. This should be pretty easy, and will nuke all the copies. //===---------------------------------------------------------------------===// + +This: + #include <algorithm> + inline std::pair<unsigned, bool> full_add(unsigned a, unsigned b) + { return std::make_pair(a + b, a + b < a); } + bool no_overflow(unsigned a, unsigned b) + { return !full_add(a, b).second; } + +Should compile to: + + + _Z11no_overflowjj: + addl %edi, %esi + setae %al + ret + +on x86-64, not: + +__Z11no_overflowjj: + addl %edi, %esi + cmpl %edi, %esi + setae %al + movzbl %al, %eax + ret + + +//===---------------------------------------------------------------------===// |