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llvm-mirror/test/CodeGen/AArch64/sdivpow2.ll
Chad Rosier 2cb7fd5dae [AArch64] Lower sdiv x, pow2 using add + select + shift.
The target-independent DAGcombiner will generate:
asr w1, X, #31 w1 = splat sign bit.
add X, X, w1, lsr #28 X = X + 0 or pow2-1
asr w0, X, asr #4 w0 = X/pow2

However, the add + shifts is expensive, so generate:
add w0, X, 15 w0 = X + pow2-1
cmp X, wzr X - 0
csel X, w0, X, lt X = (X < 0) ? X + pow2-1 : X;
asr w0, X, asr 4 w0 = X/pow2

llvm-svn: 213758
2014-07-23 14:57:52 +00:00

62 lines
1.2 KiB
LLVM

; RUN: llc -mtriple=arm64-linux-gnu -o - %s | FileCheck %s
define i32 @test1(i32 %x) {
; CHECK-LABEL: test1
; CHECK: add w8, w0, #7
; CHECK: cmp w0, #0
; CHECK: csel w8, w8, w0, lt
; CHECK: asr w0, w8, #3
%div = sdiv i32 %x, 8
ret i32 %div
}
define i32 @test2(i32 %x) {
; CHECK-LABEL: test2
; CHECK: add w8, w0, #7
; CHECK: cmp w0, #0
; CHECK: csel w8, w8, w0, lt
; CHECK: neg w0, w8, asr #3
%div = sdiv i32 %x, -8
ret i32 %div
}
define i32 @test3(i32 %x) {
; CHECK-LABEL: test3
; CHECK: add w8, w0, #31
; CHECK: cmp w0, #0
; CHECK: csel w8, w8, w0, lt
; CHECK: asr w0, w8, #5
%div = sdiv i32 %x, 32
ret i32 %div
}
define i64 @test4(i64 %x) {
; CHECK-LABEL: test4
; CHECK: add x8, x0, #7
; CHECK: cmp x0, #0
; CHECK: csel x8, x8, x0, lt
; CHECK: asr x0, x8, #3
%div = sdiv i64 %x, 8
ret i64 %div
}
define i64 @test5(i64 %x) {
; CHECK-LABEL: test5
; CHECK: add x8, x0, #7
; CHECK: cmp x0, #0
; CHECK: csel x8, x8, x0, lt
; CHECK: neg x0, x8, asr #3
%div = sdiv i64 %x, -8
ret i64 %div
}
define i64 @test6(i64 %x) {
; CHECK-LABEL: test6
; CHECK: add x8, x0, #63
; CHECK: cmp x0, #0
; CHECK: csel x8, x8, x0, lt
; CHECK: asr x0, x8, #6
%div = sdiv i64 %x, 64
ret i64 %div
}