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| author | Benjamin Kramer <benny.kra@googlemail.com> | 2011-03-17 20:39:14 +0000 |
|---|---|---|
| committer | Benjamin Kramer <benny.kra@googlemail.com> | 2011-03-17 20:39:14 +0000 |
| commit | 1c10b8de46ce8e39178eeded4786b1e53722f099 (patch) | |
| tree | eac996256e2784243c516affcd8e5910c3226ec9 /test/CodeGen/X86/divide-by-constant.ll | |
| parent | d9103df51b858cf051a1650ac7eb33d416e9ac41 (diff) | |
| download | llvm-1c10b8de46ce8e39178eeded4786b1e53722f099.tar.gz llvm-1c10b8de46ce8e39178eeded4786b1e53722f099.tar.bz2 llvm-1c10b8de46ce8e39178eeded4786b1e53722f099.tar.xz | |
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
Diffstat (limited to 'test/CodeGen/X86/divide-by-constant.ll')
| -rw-r--r-- | test/CodeGen/X86/divide-by-constant.ll | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/test/CodeGen/X86/divide-by-constant.ll b/test/CodeGen/X86/divide-by-constant.ll index fe335b9369..08e3272a37 100644 --- a/test/CodeGen/X86/divide-by-constant.ll +++ b/test/CodeGen/X86/divide-by-constant.ll @@ -60,3 +60,14 @@ entry: ; 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 +} |