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Diffstat (limited to 'lib/Target/X86/README.txt')
| -rw-r--r-- | lib/Target/X86/README.txt | 37 |
1 files changed, 0 insertions, 37 deletions
diff --git a/lib/Target/X86/README.txt b/lib/Target/X86/README.txt index 6a8a4fd..b4285a0 100644 --- a/lib/Target/X86/README.txt +++ b/lib/Target/X86/README.txt @@ -1568,43 +1568,6 @@ The second one is done for: Atom, Pentium Pro, all AMDs, Pentium 4, Nocona, Core 2, and "Generic" //===---------------------------------------------------------------------===// - -Testcase: -int a(int x) { return (x & 127) > 31; } - -Current output: - movl 4(%esp), %eax - andl $127, %eax - cmpl $31, %eax - seta %al - movzbl %al, %eax - ret - -Ideal output: - xorl %eax, %eax - testl $96, 4(%esp) - setne %al - ret - -This should definitely be done in instcombine, canonicalizing the range -condition into a != condition. We get this IR: - -define i32 @a(i32 %x) nounwind readnone { -entry: - %0 = and i32 %x, 127 ; <i32> [#uses=1] - %1 = icmp ugt i32 %0, 31 ; <i1> [#uses=1] - %2 = zext i1 %1 to i32 ; <i32> [#uses=1] - ret i32 %2 -} - -Instcombine prefers to strength reduce relational comparisons to equality -comparisons when possible, this should be another case of that. This could -be handled pretty easily in InstCombiner::visitICmpInstWithInstAndIntCst, but it -looks like InstCombiner::visitICmpInstWithInstAndIntCst should really already -be redesigned to use ComputeMaskedBits and friends. - - -//===---------------------------------------------------------------------===// Testcase: int x(int a) { return (a&0xf0)>>4; } |
