BuildUDIV: If the divisor is even we can simplify the fixup of the multiplied value by introducing an early shift.
This allows us to compile "unsigned foo(unsigned x) { return x/28; }" into
shrl $2, %edi
imulq $613566757, %rdi, %rax
shrq $32, %rax
ret
instead of
movl %edi, %eax
imulq $613566757, %rax, %rcx
shrq $32, %rcx
subl %ecx, %eax
shrl %eax
addl %ecx, %eax
shrl $4, %eax
on x86_64
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127829 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/CodeGen/X86/divide-by-constant.ll b/test/CodeGen/X86/divide-by-constant.ll
index fe335b9..08e3272 100644
--- a/test/CodeGen/X86/divide-by-constant.ll
+++ b/test/CodeGen/X86/divide-by-constant.ll
@@ -60,3 +60,14 @@
; CHECK: shrl $31, %ecx
; CHECK: sarl $18, %eax
}
+
+define i32 @test7(i32 %x) nounwind {
+ %div = udiv i32 %x, 28
+ ret i32 %div
+; CHECK: test7:
+; CHECK: shrl $2
+; CHECK: movl $613566757
+; CHECK: mull
+; CHECK-NOT: shrl
+; CHECK: ret
+}