Improve an integer select optimization in two ways:
1. generalize
(select (x == 0), -1, 0) -> (sign_bit (x - 1))
to:
(select (x == 0), -1, y) -> (sign_bit (x - 1)) | y
2. Handle the identical pattern that happens with !=:
(select (x != 0), y, -1) -> (sign_bit (x - 1)) | y
cmov is often high latency and can't fold immediates or
memory operands. For example for (x == 0) ? -1 : 1, before
we got:
< testb %sil, %sil
< movl $-1, %ecx
< movl $1, %eax
< cmovel %ecx, %eax
now we get:
> cmpb $1, %sil
> sbbl %eax, %eax
> orl $1, %eax
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@120929 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/CodeGen/X86/select.ll b/test/CodeGen/X86/select.ll
index 9045ccd..9dadbb0 100644
--- a/test/CodeGen/X86/select.ll
+++ b/test/CodeGen/X86/select.ll
@@ -86,6 +86,7 @@
%tmp9 = icmp sgt i32 %tmp8, -1 ; <i1> [#uses=1]
%retval = select i1 %tmp9, x86_fp80 0xK4005B400000000000000, x86_fp80 0xK40078700000000000000
ret x86_fp80 %retval
+; CHECK: test7:
; CHECK: leaq
; CHECK: fldt (%r{{.}}x,%r{{.}}x)
}
@@ -96,4 +97,61 @@
%val = sub <6 x i32> %x, < i32 1, i32 1, i32 1, i32 1, i32 1, i32 1 >
store <6 x i32> %val, <6 x i32>* %dst.addr
ret void
+
+; CHECK: test8:
}
+
+
+;; Test integer select between values and constants.
+
+define i64 @test9(i64 %x, i64 %y) nounwind readnone ssp noredzone {
+ %cmp = icmp ne i64 %x, 0
+ %cond = select i1 %cmp, i64 %y, i64 -1
+ ret i64 %cond
+; CHECK: test9:
+; CHECK: cmpq $1, %rdi
+; CHECK: sbbq %rax, %rax
+; CHECK: orq %rsi, %rax
+; CHECK: ret
+}
+
+;; Same as test9
+define i64 @test9a(i64 %x, i64 %y) nounwind readnone ssp noredzone {
+ %cmp = icmp eq i64 %x, 0
+ %cond = select i1 %cmp, i64 -1, i64 %y
+ ret i64 %cond
+; CHECK: test9a:
+; CHECK: cmpq $1, %rdi
+; CHECK: sbbq %rax, %rax
+; CHECK: orq %rsi, %rax
+; CHECK: ret
+}
+
+define i64 @test9b(i64 %x, i64 %y) nounwind readnone ssp noredzone {
+ %cmp = icmp eq i64 %x, 0
+ %A = sext i1 %cmp to i64
+ %cond = or i64 %y, %A
+ ret i64 %cond
+; CHECK: test9b:
+; CHECK: cmpq $1, %rdi
+; CHECK: sbbq %rax, %rax
+; CHECK: orq %rsi, %rax
+; CHECK: ret
+}
+
+;; Select between -1 and 1.
+define i64 @test10(i64 %x, i64 %y) nounwind readnone ssp noredzone {
+ %cmp = icmp eq i64 %x, 0
+ %cond = select i1 %cmp, i64 -1, i64 1
+ ret i64 %cond
+; CHECK: test10:
+; CHECK: cmpq $1, %rdi
+; CHECK: sbbq %rax, %rax
+; CHECK: orq $1, %rax
+; CHECK: ret
+}
+
+
+
+
+