diff options
| author | Evan Cheng <evan.cheng@apple.com> | 2012-01-04 01:41:39 +0000 |
|---|---|---|
| committer | Evan Cheng <evan.cheng@apple.com> | 2012-01-04 01:41:39 +0000 |
| commit | 56f582d664c54bf4567ec37d0bd16b6d4ea6a6eb (patch) | |
| tree | 885c9db256151200548df5cee4b3dfb938079b5a /test/CodeGen | |
| parent | 091523c6487fea71571a42f5d74eaf439f133f8c (diff) | |
For x86, canonicalize max
(x > y) ? x : y
=>
(x >= y) ? x : y
So for something like
(x - y) > 0 : (x - y) ? 0
It will be
(x - y) >= 0 : (x - y) ? 0
This makes is possible to test sign-bit and eliminate a comparison against
zero. e.g.
subl %esi, %edi
testl %edi, %edi
movl $0, %eax
cmovgl %edi, %eax
=>
xorl %eax, %eax
subl %esi, $edi
cmovsl %eax, %edi
rdar://10633221
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@147512 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'test/CodeGen')
| -rw-r--r-- | test/CodeGen/X86/jump_sign.ll | 16 |
1 files changed, 15 insertions, 1 deletions
diff --git a/test/CodeGen/X86/jump_sign.ll b/test/CodeGen/X86/jump_sign.ll index 5e8e162173..78dddf9568 100644 --- a/test/CodeGen/X86/jump_sign.ll +++ b/test/CodeGen/X86/jump_sign.ll @@ -1,7 +1,9 @@ -; RUN: llc < %s -march=x86 | grep jns +; RUN: llc < %s -march=x86 | FileCheck %s define i32 @f(i32 %X) { entry: +; CHECK: f: +; CHECK: jns %tmp1 = add i32 %X, 1 ; <i32> [#uses=1] %tmp = icmp slt i32 %tmp1, 0 ; <i1> [#uses=1] br i1 %tmp, label %cond_true, label %cond_next @@ -18,3 +20,15 @@ cond_next: ; preds = %cond_true, %entry declare i32 @bar(...) declare i32 @baz(...) + +; rdar://10633221 +define i32 @g(i32 %a, i32 %b) nounwind { +entry: +; CHECK: g: +; CHECK-NOT: test +; CHECK: cmovs + %sub = sub nsw i32 %a, %b + %cmp = icmp sgt i32 %sub, 0 + %cond = select i1 %cmp, i32 %sub, i32 0 + ret i32 %cond +} |