X86: optimization for max-like struct

This patch will optimize the following cases on X86
(a > b) ? (a-b) : 0
(a >= b) ? (a-b) : 0
(b < a) ? (a-b) : 0
(b <= a) ? (a-b) : 0

FROM
movl    %edi, %ecx
subl    %esi, %ecx
cmpl    %edi, %esi
movl    $0, %eax
cmovll  %ecx, %eax
TO
xorl    %eax, %eax
subl    %esi, %edi
cmovll  %eax, %edi
movl    %edi, %eax

rdar: 10734411


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@155919 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 42 insertions, 0 deletions

diff --git a/test/CodeGen/X86/jump_sign.ll b/test/CodeGen/X86/jump_sign.ll
index dbd133c..35f69c9 100644
--- a/test/CodeGen/X86/jump_sign.ll
+++ b/test/CodeGen/X86/jump_sign.ll
@@ -32,3 +32,45 @@ entry:
   %cond = select i1 %cmp, i32 %sub, i32 0
   ret i32 %cond
 }
+
+; rdar://10734411
+define i32 @h(i32 %a, i32 %b) nounwind {
+entry:
+; CHECK: h:
+; CHECK-NOT: cmp
+; CHECK: cmov
+  %cmp = icmp slt i32 %b, %a
+  %sub = sub nsw i32 %a, %b
+  %cond = select i1 %cmp, i32 %sub, i32 0
+  ret i32 %cond
+}
+define i32 @i(i32 %a, i32 %b) nounwind {
+entry:
+; CHECK: i:
+; CHECK-NOT: cmp
+; CHECK: cmov
+  %cmp = icmp sgt i32 %a, %b
+  %sub = sub nsw i32 %a, %b
+  %cond = select i1 %cmp, i32 %sub, i32 0
+  ret i32 %cond
+}
+define i32 @j(i32 %a, i32 %b) nounwind {
+entry:
+; CHECK: j:
+; CHECK-NOT: cmp
+; CHECK: cmov
+  %cmp = icmp ugt i32 %a, %b
+  %sub = sub i32 %a, %b
+  %cond = select i1 %cmp, i32 %sub, i32 0
+  ret i32 %cond
+}
+define i32 @k(i32 %a, i32 %b) nounwind {
+entry:
+; CHECK: k:
+; CHECK-NOT: cmp
+; CHECK: cmov
+  %cmp = icmp ult i32 %b, %a
+  %sub = sub i32 %a, %b
+  %cond = select i1 %cmp, i32 %sub, i32 0
+  ret i32 %cond
+}